Pragmatic 39: Look Ma, No Wires

4 October, 2014

CURRENT

Radio and Amateur/Ham Radio played a huge role in John’s career in Engineering. We delve into EM Waves, Antennas, Transmission Lines as well as many of the facets of Amateur Radio including DX-peditions, Fox-hunting, Hamfests, Moonbounce and more.
Transcript available
Welcome to pragmatic weekly discussion show concertina practical application technology exploring real-world trade-offs with great ideas are transformed into products and services that can change nothing is a simple thing this episode sponsored by Linden.com Lynda.com is the easy and affordable way to learn we can instantly stream thousands of forces created by experts in the fields of business software web development graphic design and lots and lots more visit LY NDA.com/pragmatic to get a free seven-day trial if you ever want to learn something new what are you waiting for pragmatic is also sponsored by audible visit audible podcast.com/pragmatic for a free audiobook download will talk more about the sponsors during the show on your host John CGL joined today by my co-host cousin Aidan Vic Granger fantastic while I'm excited before you started to our Dom I'm on my new audio setup and I say new because its brand spanking new Axa dressmaking is that is an Australian-ism or is denied them in my Minnesota arm AAA over it before it it's commonly used already a good rally not quite as much as it used to be but you're deftly not the first person ever has a release artist away I worry sometimes I speak sometimes and some Australian-ism so they go to check just checking checking limits test and I so yeah I now have fun thanks to Dan Benjamin of 5 x 5 and his absolute brilliance are podcasting equipment guide our blows in the days of hive logic and caused more recently updated 5 x 5 are intermittent offers well are I did research and I have been using an audio technique are 2180 R 2100 USB microphone but I've upgraded that now to a higher LPR 40 which is a dynamic microphone is me sober and they are and I'm also running it through and onyx are blackjack which is our one made by a Mackie and that's a USB interface and dates are 24 bits are 80 C unit which is better than the 16-bit came in the ATR 2100 are the frequency response and the high was much better and as well as the dynamic range and our Johnson & Johnson test recording and it is just lovely so hopefully hopefully this term the pond cusses are that little bit slightly nicer on your ears and in addition to that I've also mistakenly starting to edit in the logic pro acts which seems to be armed the most favoured the podcast editing tool out there the moment so you although all the upgrades of the moment my job still using the original shock mount which is designed for it and the pop filter and boom arm so and a boom I'm struggling because this mica something like twice as heavy as the other one anyway so they go that start inside podcasting another that okay so this not a bunch of quick reminders once again yes we are lost during the show and there is an icy chat room on free no.net but if you go to the URL to exhaustion.com/live you can access the stream that we can use the embedded IRC chat box to join at that URL are we a Q&A segment after every show during the course of showing the lifestream you have any questions you compose them with our! QA and they will try to estimate the end no I am not dying at least don't think so I am unfortunately coming down with something so I apologise if I coughed and splutter during the show arm ordinarily I have amusing thing I'll try and edit that out later my editing thing is not working in the latest beta of Yosemite yikes anyway that's fine yarn I'm running, I'm running your beta operating system are think GM is one out actually idiot lass note here anyway. The available public the public beta for one out which I'm sure is very similar but in any case whatever I also show what is running so to capture title suggestion so again are! Are an asphalt tile suggestions if you would like to participate in that once again the show is doing regular recording same time every week so if you want in life you can as the same time every week okay right as in the preamble so today we can talk about radio specifically amateur radio and one the reasons I want to about this is because of something that is very near and dear to my heart historically are it's been a big part of my life it's what got me into electrical engineering in the first place and set me on the path I'm onto now I daresay that if I didn't get into radio that I wouldn't be problem would be podcasting on our super would be hearing my voice so if you like a domino effect in and in and that sort of thing while we note this is one of the big dominoes in my in my life professionally and personally so it's a big deal to me and I want to talk about because a lot of people out there that is a diameter radio ham radio you know that is an Ashley don't really know all the different aspects of it what's interesting about our so I thought you were talking about now I have talked about radio previously on episode five which is the next ubiquitous thing I refer you to that episode if you are interested in learning more about Marconi and the basics of broadcast but will quickly touch on some of that now just as a quick refresher as to what what radio is on and so on but before I do that little bit about my history with radio so I access Sun City rating is 14 years old are you the very cheap radio was a young North dear very cheap are it was a you unit and arm PC 55 and I picked up really cheap and darting over these lantana maiden built mining town I had an old piece of calyx it was the wrong kind so a 75 character should have been 50 kayaks and unfortunately that caused lots of problems with my poor little radio not understanding than what I do now army I kill that radio Sony open six months time idea and I want anyway so moved on from that and some you got better radios and learn more Bilbo Baron Tanner's so-and-so fourth portal of my all my pocket money and signing Tillotson's arm and so-and-so fourth May lots of interesting people and are then I decided on Maya first year of university that it was that I wanted to become an amateur radio operator so IT choices at a point I could have have waited till the end of my degree and gotten the advance theory gratis so if you show up with your advanced degree with sorry advanced degree got the shot with an engineering degree electrical engineering degree and you wave that at the right people they would give you and the pass on the advance theory exam that you have to sit up which was kinda nice yet but me being impatient and while you Hayward I thought I was impatient back then dislike I am now a leaguer arm anyway being impatient I decided not knock on weights I studied and sat my advance theory exam anyway even my first year you can be a could be bothered weighing them away are also added to the regulations arm which I note I actually passed my advance theory are on the first arm on the first sitting by actually failed my rags on the first sitting arm chair what's I failed something anyway so you either set my regulations a second time will our anyway I also went for our back on the day of back in those times it was 94 are back at that time or scope is a requirement set out to Morse code there was a novice and there was advanced and novice was five was a minister and receive and advance was a 10 woodsman and receive so I I have in order to get life what I call full call amateur radio operator license for call unrestricted than you had set advance theory rags and CA advance to Morse which was 10 woodsman so I also learned that the Dars and again failed on my first attempt at more at the 10 woodsman are most people smart neighbour gave the start of five and a wet WAP attendant mean you stupid me anyway US saddles I had theirs handed stupid me that email is fine is fine I sat on a second ago and arm the answer be blitzed on my second attempt to walk in there and read the sentence often no gossip means it nice so there you go no mistakes floors anyway on second attempt first attempt so as I often mention and some people have said hey it's bingo time John said the word Nortel on the podcast of ego we go again so yes I work for Nortel Networks arm and Cy was in the RF hardware design group between 19 90,001 arm I worked on the HF modernisation projects for Boeing fall between 2001 2003 cities that are more recently in telemetry systems which are based on now is radio based telemetry are the long reach Shas telemetry system design the Douglas northern arbitrary implants are Townsville telemetry system design and I was an option study for the Trong pipeline which is the pipeline that runs from our benefit from power/120: longer water pipeline for the cooling water and are that interests into the slush option study on that so that that's nice my background experience so real quick recap of what radio is so radio refers to our armour at radio RF is a radiofrequency energy and that refers to electro-magnetic wave and is depending upon and all radio waves are essentially sine waves and those sine wave travels on was a sideways are depending upon their period and therefore the frequency are depends on you the bands we called band frequency band arm that you transmit information over so are range of about 3 Hz up to 300 GHz now the formula for a wave's vehicles at Lander which is the loss equals frequency times wavelength therefore from frequency can figure out are the wavelength and the wavelength of that 3 Hz is sale 100,000 km which is very big and 300 GHz is 1 mm so the huge variety of wavelengths and that that that's important comes to internal design will get to later but anyway so are EMI's travel through space not panel and compression waves so anyway the velocity of our electronic wages speed of light are which is three times in the 8 m/s which is zippy are literally waves exist perpendicular to each other so you'll have far in the seaplane and the H plane they refer to as the NIH plane so well in the plane you'll have the electric say in the H plane you'll have the magnetic field and each each field sort of follows the other facet of hard to describe that but one that is it's hard to describe but anyway I'm going to link to over eventually up for a presentation on the site I did for rum are for a company I work for the election weighs only exist where they both exist so if you kill the electric field of the magnetic field your killer Ian wave arm which is of course other titles the first episode of pragmatic was Faraday's cage so this so Michael Farrakhan this idea of a cage that you could use to kill the electric field and hence are the argument for the trimming alleyways would just stop passing through that into the case anything inside the cage would not radiate out anything outside the cage could not radiate insular Germanic waves which was useful for testing and so-and-so fourth radio talk about different frequencies for different purposes and a lot of it comes to do with permeability and permeability not in the magnetic stance are but permeability in the sense of how much it'll penetrate physical objects penetrate Yates is partly penetrate it's partly bend because you wave theory wave theory suggests that as a waves pass through pass and edge that they can actually diffraction bend around the edge not just as they travel through mediums of difference arm month ago I think his identity but is not density being my school is anything that isn't going to bend a radio signal arm through its roots through a arm through charged particles for example and an example of those the ionosphere shall get to a minute so the idea is that way they do travel straight lines you can get them to bend thing and event too much and high-frequency guide are less likely they are to bend so low-frequency signals are better for that which is one of the reasons that I am radio started at low frequencies between the 535 kHz to about 61.7 megahertz that's where I am radio sets but the problem that of course is that I am radio because you got such a small snippet of spectrum you have a massive bandwidth that you can encode information on my audio so as a result of you will have lots of radio stations reasons to have a very narrow frequency they operate on it means that the quality of the audience can be much less probable cause down that that region of the spectrum is that you lot of atmospheric noise so the lightning strike get lots of low-frequency impulses you get my background likely radiation the matter where you are what frequency and get it Dustin to travel further than FM though doesn't yes exactly that's why yes and that's why they chose it because we have is that it tends to bend with the earth a lot more so whereas FM is high-frequency and therefore doesn't while it does little bit that doesn't really so the propagation of Ian waves is dependent upon their frequency through the atmosphere so that most coveted parts of the arm mobile phone spectrum traditionally have been low-frequency soap in Australia for example Telstra have access to the low-frequency so 700 MHz 250 MHz spectrum sailing under 1 GHz is going to get much better building penetration because of its low-frequency think about building penetration is that if you look at the wavelength and you look at the size of an aperture like a window think of how much of that energy in terms of its wavelength could actually penetrate the window if that election amount wave was appointed approximately at the window so the idea is that the lower the frequency arm you will get a much larger probability that energy will get in through that aperture then you're going to get if it's a much high-frequency signal which is generally far more precisely directed if that makes any sense such of them the sum total amount of energy is only much less and once was that the wavelength is so small arm Yates is to come down to just luck arm like reflections on and pure chance to get a signal but no assuming you're not living inside Faraday's cage was so any so though some are saying that ultimately frequencies they went for that stuff because it's got far better if he was the old analog network they then shifted across to Oracle next G which is running a city might and I say CDMA its arm its ILT even right is a sentiment I guess what I'm getting at is that as you-frequency that's when things start to go wrong in in that respect but then of course things get better for things like satellite we want them to pass through the atmosphere unmolested so without any ionospheric interference subtle trade-offs once you really high-frequency of course I like Germanic waves cease to be arm cease to be interpreted that way because then we start reaching our visible spectrum that's are not not all matter that's another story asked the radio waves also have another problem Marge called the inverse square law because essentially rather Germanic waves are emanate as a bubble are and in theory there is a point is the point in space that they call the anisotropic radiator anisotropic radiator is a theoretical antenna noticeably appointed space that radiates equally in all directions to imagine that radiating equal in all directions that's expanding like a perfect sphere so the idea is that any distances that say distance from the centre point if you are distance axed from the centre point and then you go a distance of two acts in the centre point than the overall amount of energy and any one point will be one cook 1/4 m is one over two squared video three times the distance axed then it'll be one of three square or 1/9 as the inverse square law simply because the same amount of energy is being spread over a much larger area so you can't you can't escape that which is why course you are pumped beyond the fact that the stopping radio doesn't actually exist you that the simplest form of an intangible is actually a dipole dipole has 2.14 DB of gain over anisotropic radiator so you assume that mastery radiator is a theoretical starting point and that's all well and good you understand that that's why you want directional antennas because you want your focus that energy in in one specific direction which is the whole point of an antenna well since its the whole point of a directional antenna it all away signal going in directions that you know Erica to receive it out anyway exactly right yes precisely so unethical to building an omnidirectional antenna which is like a vertical antenna you the idea that causes adult tradesmen receive equally in all directions but you know the true the truth is that some young that's boring but will talk about rights are getting are getting the signal to from the radio to the antenna are used in reasoning I call a transmission line and transmission lines sole purpose is to not lose power so to take the signal generator the radio and then transfer that to the antenna without losing any that signal obviously there is no such thing as a perfect transmission line but the two that this is essentially three most common transmission lines in use first one is the golf fashion ladder line now I'm assuming that you know until now I say landline I think the old TV set yet old TV sets are happiest things like 22 black wires and I joined every so often with a benefit thick black plastic and if you looked at it you held up look like a ladder arm in later years they would encapsulate the entire thing and we just sometimes of May a clear plastic but more often than I was black anyway arm ladder line is what's referred to as alia is a balanced transmission line and was favoured for quite some time but the truth is it's very prone to interference the next most common type is coaxial cable is an unbalanced transmission line the idea is that you have a common conduct of the centre and insulated only wrapped around with a shield and that shield and is then wrapped in and insulated itself to coaxial cable is by far and away the most common transmission lines connecting antennas to radios when you are pirate frequency that's asked for part and you far better off going something that is far more cool cynical waveguide and waveguides what they do is only really are effective in terms of their physical size once you get up to go multiple gigahertz of wavelength and waveguides essentially are bounce the radio signal from one end to the other fascinating idea but it actually does work so to utilise like Germanic waves fit for carrying information the concept yet instead a concert of residence so if I have a radio the radio as a source of a radio energy that radiator RF energy is oscillating a certain frequency mallet say CB relates CB radio nag H FCB radio which operates a 27 MHz oscillator whatever frequent up was among those hands are in a theophany under certain defining as it is the best analogy is the tuning fork now you done an experiment school we got two identical tuning forks and you hold one up in the air tap the other one get it to vibrate and you hold them right next to each other I have not heard about the while the idea is that what happens is the sound compression waves from the one that is vibrating what they do is they travel through the air to the one you're holding next to it and it starts to vibrate they call it a sympathetic vibration or resin is supposed to match rate yes is right and it's because the natural frequency of vibration of that tuning fork is exactly the same thing with an antenna except because of the Germanic waves so what you do is you tune less opportune" tune on doing a quote you antenna are to a specific frequency to get the maximum amount of gain out of antenna because if it's not in tune while happen is you can get power reflected back to the radio so the idea is think of the power transfer as if I've got 10 what's in my radio and I have a transmission line going out to an antenna if antenna is off by some percent then I won't deliver 10 what's directly to the antenna on the loose in my transmission line of course but I'm really a power reflected back from my antenna back into the radio and that's a bad thing because if you're especially were silicon because silicon doesn't like the heat solar power that is not being dissipated because of the mismatched that's bad out the radio you will and it is with my first CB radio if you recall now about 1520 minutes ago we started I said I'd I had the wrong kayaks I had I built one in 10 I had no idea what I was doing arm and I destroyed my right my first radio I buy blew the final transistors because arm the final stage transistor amplifiers because was happening was I had such a bad mismatch all a lot of power was being directed backbe delivering either 115 what radio forget what was and was five what are your arm out of which I be lucky if one what was actually getting out so of the antenna because it wasn't tune wasn't matched and was the wrong plenty transmission lines that a joke and that's okay I was 14 and I was still learning the hard way anyway so are we measure signal loss we measured in dB are which is a ratio are typically of power so a 1 mW for example arm be referenced as it with a reference for what would what's typically referred to as DBM and are the DB Amazon is essentially a power measurements are also okay well I've got a 25 what radio my antenna gives me 33 arm satire the 20 was let the let some guy with 1 mW because the numbers are in front of me I can do this in my head it for a morning after 1,000,001 mW radio is as a zero DBM sources of other zero DBM source and I've got a three dB gain antenna than that only get a total of three dB worth of the of power at which I can then convert back into milliwatts of wanting and the reason we work in dB is that it summarises is very helpful for other things similar to again become again in dB power are typically in the in DBM are okay okay that gives you a common scale yes exactly Everything is normalising your common scale so arm antenna polarisation arm vertical horizontal so if you have a vertical antenna than essentially what you what you're doing is you're taking a dipole which is which is essentially a straight line idea a dipole is that you have are half when half wavelength site say that your toys are megahertz away things around at 10 m long so half of that is our 5 m C cut in half again so you've got to caller wavelengths and they're fed in the centre with the with the your coaxial cable arm through a device called Ballan which is about unbalanced arm a transformer if you're right well isolated on right anyway our end point is that sound that particular design of the most basic antenna port you want to do if you go vertical joint analytes and and what you can do is you can use the ground as a mirror so you chop off the bottom half of the antenna and you have 1/4 wavelength above the ground and is vertical so you'll see vertical antennas all over the place are your see them on cars video everywhere well maybe you once and is often cars these days but in those vertical antennas now I said that the most basic forms quarter wavelength of this other ones over this 38558 wave you can load these things up and not negotiable in detail about those events and as I do the basics in Ghent amateur radio so anyway that's hot vertical polarisation horizontal polarisation you know why that should be obvious is that you got the antenna says dipole and is mounted horizontally above the ground everything is relative to the ground of course in at the moment so why is this important it's important to understand because if you go vertical antenna and you're going to another vertical antenna than you're going to have a polarisation match if you have a horizontal going to a vertical antenna or vice versa you again over polarisation mismatched and a polarisation mismatch can cost you 20 dB worth of energy as quite a lot so to overcome the problem of waves bending and mutating and doing loud good and bad stuff if you're doing line of sight transmission you want to go polarisation to polarisation so that say I'm a one-sided town be on the other side of town direct line of sight you will go vertical vertical or horizontal horizontal if you can to get the maximum are signal if you're going if you're going ionospheric propagation where things get bent out of shape and twisted around while that is, not a big deal although I probably could see could gain you a few dB here and there the truth is though if you got a television broadcast station you don't have any that's all you do is you know were not the TV antennas can be vertically or horizontally polarised supporting Adobe because as all gravity is on the TV sets could be whatever angle you choose usually at some diagonal angle relative to the earth so what you do, came up with this idea of circular polarisation actually are which is also used in space transmission space has no concept of ground and there is no up-and-down left-to-right stuff is in space and anyway yet so are circular polarisation is essentially a rotating Ian wavefront and that is so hard to describe in words on the leave it there just trust me it is seen of two kinds left-hand sample arm circular right hand circular and are a variant of circular polarisation is elliptical polarisation same idea it's just that the year are essentially the X and Y axes are of the wavefront are somewhat squished anyway same kind of idea are left hand circular right hand circular polarisation are air inside of you mismatched so if you've got arm LCP gum transmission going to RCP antenna you will lose our 20 dB and vice versa so of course you you can't win right the matter what you do but the differences if you go from an LCP or an ICP to a vertical hole horizontally polarised and how young illusory dB yeah and is a bad three devious half-hour so makes it ideal for space and for broadcast applications which outline circular prices yes but the DB scale is logarithmic rate correct so when youth when you say you're going down from 20 to 3 that's a lot more significant than just the integer values would imply exactly CSU 20 dB massive massive maximum loss some highest Ganey Argie's arm that you'll get you only give you 1516 dB again so losing 20 dB is horribly bad which is why people are serious in AM radio arm and amateur radio will do as I have of horizontal and vertically polarised arm antenna such that they can switch polarisation is to get the maximum amount of power because you don't know which ones can be and some antennas at some amateur radio's leave and have you know are have circular polarised antennas as it waives the antenna array is absolutely my that's is one reason those lantana races are now nothing but get it that's absolutely true so right arm and honour go to much more into that boats are adjustable heads up when we met again from antenna with doing some measuring arm are we measuring the maximum amount again and plotted on the H and E plane and so that's a maximum of power as measured at a distance from centrepoint centrepoint is usually the feed point or in the case of an isotropic radio which doesn't exist at that point source so a lot of antennas are measured against isotopic radio which Christ sucks because that's a BS measurement so if I have an antenna and I say yeah it's got 2.14 dB again I've isotropic you like yeah great as dipole year okay good I mean what is actually mean is meaning so when people equate Antonius arm binders and has grazed the 10 DB of gain are really 10 dpi or 10 DVD cements a big difference 1X 2.14 dB difference J so you you'll often find that these sales pitches are almost always in DVI because it sounds better and are whereas the reality is that if you put a dipole up and you put up this this competing Yardley let's say you have a running I see an improvement of of a DB of gain because you that you can get to DB for free because dipole compared isotropic to some give in mind if you finance out rights talked about that screen independence and can talk about standing wave ratio of talk about Yardley's case Yardley what is the Argie ago so Mrs R Mr Yardley Mr user so technically the full name is because it was declarative effort was that is the Argie user but some Mr user unfortunately his name got dropped off whatever reason he was calling the Argie anyway young these are essentially the highest gain linear antenna that you can get without building a parabolic dish and the way they work is your have a feed element arsenals call the driven element or a driver and that will be your dipole and I'll resonate at whatever frequency you want to get maximum again at then you'll have one element behind it which is slightly longer and that's called the reflector some young diesel had two reflectors but it's one of those laws of diminishing returns I found by adding more reflectors behind that you didn't get appreciable improvement in your run in front to back ratio then in front of that you're the driven now and you'll have a bunch of direct elements and the directors are slightly smaller than your our driver element the spacing is of course critical also has a bunch of formulas to figure that out are what the spacing is between the elements and of course once you get past about 10 director elements you it gets to the point of diminishing returns we can keep adding more just confuses the radiation pattern get reduced again by every director you add deferred addressing noise yet exactly you're distorting the pattern so much that you're not getting appreciable improvements in gain soulless radio and she's been bent forward and reflected from the back so the ratio of power from what comes off the back live versus the front lives call the front back ratio as all other authors of other measures like side rejection arm and also do other things the whole point is that your try maximising our forward game that you get out of the antenna by bending the electro magnetic ways forward very cool idea works very well but you'll see argues all over the place the very very common so whatever you see when you see an antenna that looks like AR one essentially there was a look like it's hard to describe a thriving analogy of what these things actually look like you've got a long boom which is usually made out of steel ring of judges conductive and nonconductive beams it's a different set of equations for each anyway and then you have a bunch of of of much smaller arm conductive bits of metal and are they will be spaced out across an asset really is hard to describe looks like as it looks a bit like a hairbrush that Scott spikes on either side Dion Solomon cool old school TV antagonist yet exactly as of you annual TV antenna you will see a Yardley and all aerial in the UK perhaps aerial exactly through TV aerials arm however there is a big cabin on that are yet the Argie is neither not and arm I think I might just quickly arm break to talk about first sponsor before we go into one of a member@1sponsorislynda.com.com is an easy and affordable way to learn you can instantly stream thousands of courses created by experts in their fields of business software web development graphic design audio and lots and lots more weight to mentalist here and I have an enormous library of tiles to choose from new courses added every day to make sure the library is both relevant and up-to-date they work directly with experts from many different industries and soffit evolving companies to provide timely training often the exact same day the newest release becomes available so you know that you've got the latest information the moment you are most likely to need it now these are nothing at all I can't do home-made tutorial videos you might find a new tube that might 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content on offer years and I'm really happy to be able to provide pragmatic lessons of the special offer to access all the courses were free for seven days visit Lynda.com/pragmatic to try Lynda.com free for seven days that LY NDA.com/pragmatic thank you to Lynda.com for sponsoring pragmatic okay so I said TV antennas the yard is that they might what I mean is that the probably Argie is that they're very fixed frequency so once you vary too much from the centre frequency they tend to lose a lot again that is obvious and what you want TV is spread over a massive area you it's down started hundreds of megahertz hundred megahertz goes up very close and to the gigahertz range it's a huge band huge range of wavelengths in your literally starting down my 50 cm and ending up around about the arm God and Oriental mathematics had legislated huge for a huge variation you cannot design a Yardley that has useful gain over such a wide frequency range in 1957 couple of bright people crunched some really mindbending mathematics and came up with the idea of all of a log periodic knives is love log periodic scholar to the mouth and it's just how it's beautiful I mean is mathematics goes if you do that sort of thing I guess but look under St really Corp so guy call on our HD Hamel I do not know the first name sorry NDE is Bell came up with the idea of a log periodic rate such that it will give you wideband wideband with but high directionality so and while I hate to log periodic's if you look closely is that what they do is I'll start off with and it looks like a reflector element and then they taper off very quickly down to a director element but they taper off kinda like a triangle is not exactly triangle obviously it's logarithmic but you know it looks a bit like that was a Yardley you'll have a wider rear element a slightly narrow driven element then we directors will be pretty much the same size or as a log periodic it's it's more of a progression down to a fine point at the front if you look really closely you'll see on on and on log periodic that it's not like a Yardley whereby the dreaded all the elements are actually a physics physically continuous so what you get is a longer boom is you'll have a log periodic is you'll have one half of the element on the lower side are and the other side will be essentially isolated from each other to the non-electrical connected and then along the course of the boom you'll see a zigzag pattern whereby each half of the preceding element is fed across to the other side of the boom of the element front in a zigzag pattern to the front loop at the front zigzag to the back and the feedback or if it front or back that is my point is arm is that if the alternating cross feed, does is it creates a as the resonant frequency changes what it does is it increases the relative impedance of the section of the antenna towards the front or the back based on the frequency so that the active driven point changes in distance along the boom of the antenna based on frequency is so cool it's not funny while you I would like the stuff anyway so what what you often find is that the log periodic itself needs a bit of help on the extremes so what are they do a TV antenna you will often find has an extra feature it's not just a log periodic it's got a few Yardley features as well so have a log periodic in the centre of the antenna and have a larger reflector element at the back which is a Yardley feature and the have a few smaller much more direct realms of the front so that's referred to as a log Argie because well it's log periodic as he argued therefore log Argie and is almost all television antennas are the hi again once silica wide frequency range plus they got a mixture of the best of both the hybrid antenna some of them got what they call a corner reflector and corner reflectors of these is also a fan things that the job either side of the log periodic element in their design to Dragon more antenna more antenna trade in my talent night Dragon more radio energy from above and below anyway right after enough of the coolness so I'm just the I talk quickly about some parabolic dishes are parabolas of course no radio energy or light whatever it might be the head the parabola they'll reflect into a common focus focal point are one of the things that people often forget about is that some matters multiple ways Jack's amount these things you have axial front feed a offset off axis offset feeds arm there is another method which is our Cassegrain and its are sort of like as a reflector and you've actually you go you hit the parabola you come back out you had another reflector many go back to a file not secondary focal point arm and right sort of hard to explain our and then there's the ERI Gregorian one which the idea is that you use a convex or use a concave secondary reflector and that will then refocus the the energy back to the surface point on the actual dish that you have feed their respective hounds done parabolic dishes are brilliant at high frequencies at lower frequencies they suck is a huge okay were II swear were getting closer to an amateur radio any time AA so atmospheric propagation absolutely have to talk about this in order for a lot of stuff and is ready to make any sense while skyline consent the cool stuff to make sense I say because doctors like Michael whatever may be other people don't I do so the idea is that there's a few layers in the ass atmosphere this troposphere and above that you restart going into the ionospheric layers ionosphere essentially allows the ass atmosphere that are consist of charged particles and as the sun hits them they charge the particles and they then act like a mirror for electromotive waves between certain frequency range and the layers of the ionosphere are lettered so you've got delay RTF one F2 the most common ones in no radio propagation or why course I ionospheric propagation so the delay is; is up F layers hundred 20 Athos i.e. layers hundred 20 F1 is 200 and F2 lace 340 km quite way out and the point is that as the sun goes up it charges all the way down to the bottom as the sun goes down charge biggest dissipate and that exposes the outer layers now why that matters is the angle that the radio waves hit so the ones that are close to the ground therefore you'll end up with the much less propagation as a result because the mirror is close to the ground but as that mirror goes outs after the sun goes down you will start to get ionospheric propagation from much further away which is wife on on on radio signals broadcast out from one point I came radio and during the day on here local stations with nighttime you'll hear stations from much much further away and that's because sun goes down the Lorenz ferry layers discharge and you start to get reflections from further away anyway call is critical that I always wondered why there was all that young sphere which is conical and that means of course that you can intentionally ask if signals and that's why some people refer to a skip you can skip signals between the earth and the ionosphere all around the world and is unfortunately a lot has the sunspots ever I like it sunspots a bad thing with your radio sunspots like your friend because if you get sunspots than will happen is that those that those big waves of radiation or charge of the ionosphere and create patterns in the atmosphere that give your propagation path between certain locations bouncing off the earth as that is the easier part especially near the coastline because when you coastline of the ocean is a very good conductor so if you bounce it from your see if your exam bounces off the ionosphere and then comes back down again on an ocean is very likely to skip back up again and and basically bounce around the world so in order to take advantage of that sort of skip you really need a directional antenna and your yard is an off by far the most common and are at one point I was running Acer six element stardust which is a C between 7 MHz RCB radio antenna and was running on's on the last single sideband modulation arm would while technically the lower side and anyway gonna modulation methods as whole another podcast anyway and the eye with mom my crowning achievements were two things one was I reached Oregon and arm of course this is before the Internet are anyway and so I was talking to one some people in Oregon I would regularly talk to Hawaii and is our after a while there was one time I had a particularly lucky bit of skip where I have my own echo in other words are my signal travelled the entire way around the world and once you take your finger way out he used here your own echo which a circle that would because very cool arm because it caused the time delay takes for a arm even the speed of light travel around the world and must talked on long-distance phone between consonants will know this arm you on Skype of course offers from as well so you cool stuff arm and a causal done with no wise seat look Ma no wise okay her home not at all about final zones are modulation methods and puzzlement that arm movements chance therein okay so for little things things like repeaters now people you may have heard of repeaters Nigeria's that if I'm a high-frequency and I want to talk to someone and as a mountain or some physical barrier between the two of us how I talk to my counsel directly because of a high-frequency I can't the signal wideband, punch through the hell is gonna be in a black stone so I can't talk to you because your going on on the other side of the hill and neither is no Internet and has no mobile phones around offices radiometer from summer so we don't you put a repeat on the top of the repeater on the top of that you do and then I can see repeater and you can see the repeater and I talk to the repeater and it repeats what I say real simple you wanted to do that because you can't do that this too kind repeater simplex and duplex assemblies repeater is, like a store and forward so are an simplex voice repeaters are virtually unheard of it's pretty much a digital thing are those out there have been our simplex voice repeaters the idea is that I'll talk to on one specific frequency of saves in 04 38.1125 MHz and speak a number whatever so on I talk talk talk and you'll store up to 20 seconds or 30 seconds and then I I release III unpeeled list key on the radio button. On an annual relay that signal and repeated on the same frequency feminist to hear but that's very problematic in all sorts of ways so it weighed in it definitely introduces a nice little Agadir conversation absolutely but you know in some cases it's a requirement me got very limited frequencies but honestly it's more of a digital thing the idea is packet packet packet raced packet-based data is ideally suited for simplex transmission and we think about it arm you know there's a lot of buses out there that the do this the do a simple to do packet based simplex transmissions but if you want speed and you want usability you go duplex knowledge have an uplink and downlink on one frequency which are separated by certain amount of space on the other frequencies I don't interfere with each other the transmit online and you receive on the other so the idea is that some grown-up length channels to the repeater and then it'll live rebroadcast that on a different frequency so that everyone else can listen and I refer to the sum of the split operation to the idea is that that your repeater is there to help you but there's one problem caused repeaters and that is that you won repeater and what takes is the person the louder signal to overrun the repeater and takeover so they say on the via jerk and I'll just keep up and play music for just be a jerk and yet is the problem radio rate is that there are a lot of Jefferson City radio turns up that this is the thing is this is I fully prepared the lease to this episode because I can talk to the staff of the top my head for hours and I probably would if any side of the rain myself in here someone really cool things about arm about learning the stuff when I was younger as I was taken listen to my professional career so far repeaters and so on used in telemetry simplex duplex data all that stuff all over radio it's a vastly done that is as part of my professional job but I learned about first when I was a Yahweh when I was amateur radio operator so for me it's sort of you it's been one of those really great dad dovetails are between my personal and my professional careers personal career young men okay so amateur radio now it started out in the late 19th century that really took off nearly 20 and as a result of my casework and ham radio actually was meant as an insult our respect to mock radio operators that were didn't do a professional just because you have professional radio operators and they operated telegraphs the communication you ship to shore in our Intel telegraph operators even then the fruit work were referred under the same kind of terminology you are so are something ham-fisted or ham actor that's out that's what I thought yet exactly so ham radios, get your radio operator you suck ass like what lovely good God anyway it not very nice so I prefer and and frankly outside of the United States everyone else because of amateur radio that I caught him radio numerous southern states and arm when I was over there I was constantly correcting myself I am arm amateur radio operator that looked funny a goal ham radio you can only deliver great even I was insulting yard and anaphora long time and I know why people in North America persist in calling it ham radio because frankly you know these days is the other way round there are practically no professional radio operators left in 08 and now we've got left in terms of radio are the amateur radio operators yet why think that over here at the time distance from Wayne that the terminology first came to be ham radio I don't think anybody even here associated with ham-fisted or or an insult anymore I think they just go and radio optional absolutely mean this is the problem with with expressions as they start out with a basis on a foundation and then as time goes on it becomes a colloquialism and then that the entomology of the oppression is lost so young I don't think anyone says it is an insult not missing on your ham radio operator and I don't say like at that essay in terms of that is what is so right I agree and and and that's true but the problem is knowing the entomology of it can't flinch every time I hear it turning so anyway alright fun fun fun so us hammy is this almost we need to stick together so there's a bunch of organisations out there that you may or may not have heard of the most common one in North America is the AWI realm is the American radio relay leak which is opening up of a weird name but hey came from a different era to the aid of RL are in Australia we have a whilst Institute of Australia the WIA and every different country a lot of different countries have their own institution all league, Heatherwood league I keep thinking league of extraordinary gentlemen which I thought was a really cool movie even I was completely ridiculous it was still call and I remember they had this one scene had that that every shooter cost millions of dollars they screw up something snotty focused anyhow so are all of the different frequencies arm that amateur alprazolam to use are set by the International telecommunications Union or ITU short but the representation of amateur and operators as a collective whole, the union if you will is by the WIA in a double RL another petition and say I know we need access to these frequencies because of course spectrum is money you is at an end ever since the explosion of mobile devices yellow FM radio television all that you get whatever you know that mobile phones all my God there is so much pressure and of course now Wi-Fi as well and and Bluetooth and all these different snippets in the radio spectrum and the pressure has never been greater to rip the frequencies away from amateur radio operators and to be honest happening and it will continue to happen more and why is simply because the number of people are actually practising amateur radio operators is is is collapsing as a hobby it's a gas appearing in 2004 there was an estimated 4 million operators amateur appraiser active around the world into thousand 11 that estimate was downed half to 2 million in 2011 so in less than a decade it's half what it was now I would expect that to be less than a million for that much longer now and then it can be measured in the hundreds of thousands there and the reason I put down to this is simply the fact of it's gone from being anyone can talk without wires if our radio operator they could talk overseas and white stuff all guess what two things happened one Internet happened in into mobile phones became ubiquitous why on earth would I sit exams wonderful I pay thousand dollars for a radio build an antenna which looks well debatably horrible or beautiful depending upon your point of view for me is beautiful but whatever my wife and our hand while earth would you all that trouble just to talk to mate down the street or cross outside of town or maybe Mount propagation inside the world when you get a speakerphone dial number go on Skype or whatever one way what why would you go down wanted a while the trouble why no saturated operator they say hey look Mano wires what I said before a cool will yes call but guess what you know it's also expensive is a high bar to get the high barrier of entry and and the joy of entry is no longer all that interesting I can get on yard chat rule that out anybody can download skate yet I could call people randomly bumming on chat relating general IRC you can talk to whoever heck you want whatever heck you want on the Internet what's the attraction of of amateur radio in no if if you're really into it that's great that you honestly these two things I think have killed or if they haven't killed it down speaking of debt already is not but it's dying and death is inevitable and always be enthusiasts don't get me wrong there will always be enthusiasts there but now that I've gone and prognostic ADR the end of radio of amateur radio little bit more about AA your callsign is AAC in amateur radio it's absolutely critical that you have a callsign to identify who you are and why is because it is licensed so any old Joe Bob and Fred can't jump on and just start talking on amateur radio tenancy radio and a manager you need to have a need to be licensed and they need to be able to and your pay fees and is now country anyone freshly stood to America so I'll pay you a life of five years and that would give me a callsign of my choosing provider was available now at my callsign lapse I still call myself an amateur radio operator and I am qualified to be another walked into the arm and are in the SMA tomorrow/medications media authority I can register my southern amateur radio operator with my my certificates and I could do pay a license fee not to get alarm callsign tomorrow for want and only Miles is this lake at a Twitter handle that you register like a domain name perfect analogy exactly what someone else's got your analogue's anyway arm size DOG on our order to influence Andre operator I'm not an active amateur radio operator of soul all my radio gear basically I just I chose online pod casting and doing a website I'm not keen on the radio anyway so callsign is typically ardent are by country so the first two or three digits are country are alphanumeric I should say so for example Australia is VK and is our in our North America it's our VE and and and arms a few others as non-smokers got one or two more amateur and present Australia Sydney you can just get away with the with the two letters so are what I why doing strays a split state ligament number so Queenslanders for so I'm are VK for and can last two or 312 also want to or three digits are then basically all the different possibilities from the classical science and your space to announce your callsign periodically when you're on the radio so you might be up and say aliases are VK for JSP and done transmission paid on and then every 10 minutes say arm European course I say is VK for JSP getting back to you it irritates me when people say continuously every single time you know and when in a conversation yea if you are really strict about I guess you can but she gets irritated especially varied back-and-forth you got aside 10 seconds long so are you here this sort of thing sometimes and Ray as a VK for JSP is VK for JS why Heydon you VK for jazz was VK for JSP until good Heydon back to you VK for JSP VK four days what are my God that would get tiring the 80% of what you just bloodily said your callsign as I get it I know who you are our crikey waiver anyway the minor sites move on bans most power restrictions amateur radio have got a whole bunch of a set of frequencies and power power levels of been permitted by the ITU been fought for four years and the often refer to them by their bands by the wavelength so for example are thus at 80 m band and at the wavelength and yet 80 m band is about 3 1/2 MHz and then you got 40 m which is about 7 MHz and then the 20 m bandages 14 MHz and so on and the reason we refer to it in terms of the wavelength is simply because our backs directly related to the size the entice so that my theory members another reason as to why but I was figured that that was why am I so arm I still like working my favourite band I can best man the world is our 20 m bands because you're just above most atmospherics but you've got really great propagation from an ionospheric point of view it bends nicely are you only live transit centre as a power that varies from country to country's Australia we might have 100 are what output limit but in America you have 1 kW cycle whole wow so they go lots of juice that is idea notes are hundred watts here so I'm on most frequencies so you got your restricted how much power that you can have at the back of your radio because you put into into an antenna and an antenna amplifies that and you get 20 B again more realistically what they tend to be a game you then obviously you have much more peak power are and that's fine but certain regulations on certain frequency stipulate that it's the actual delivered power at the maximum gain of the antenna so that's that, blows that idea out of the water but most the time is not measured when it comes to professional white cemeteries systems they take that very seriously so you can't get away of tricks like that with your 1 W radio and you want to go 27 km you want to put in a really high gain antenna will guess we can't close the regulation stated can't be more than this number of DB Saigon be careful banging on right health is not a free for is not free for a can't be because of interference right because if you much power you are stumbling over another frequencies of other people's antennas are receivers can be overwhelmed by the power that you're transmitting asset frequencies so that all sorts of other different filters like you have not felt as vampires for source of stuff that goes into our radio systems in order to prevent cross interference alrighty so before we go any further our startle make you codes next is a lot of our second spots of this episode that audible so audible as a leading provider of premium spoken audio information and entertainment that allows listeners to choose from the audio versions of their favourite books and why do I do this while many outdated activities you need arise in the job so when is a book you really want to read the essay on you're too busy well if you too busy I think this can't find the time that that's what audiobooks can come in and help because it's much easier to multitask when you're listening to music pod casts or an audiobook when you're driving doing housework and yardwork with all you can still quote unquote read your favourite book and not miss out it's really cool see my books either individually or in some of the audible listener programming gives you book credits each month for a low monthly fee you download your audiobook to your PC Mackie windows financial IOS device and listen to it wherever you might be nice to me I'm a huge Douglas Adams fan and I make no secret of that arm I had to have a look when when I first looked audible see what they had in the way of his books as is audiobooks what is about 20 of them in the orals library and they include all the drugs got a galaxy books my favourite to Dirk gently books as well as to a Doctor Who associate involved with include the unfinished shader episode as a base the first chapter gently book for those that that no Douglas Adams and some arm the best part though is that some of the books are read by Douglas Adams himself now I'm enlisting the choices Detective agency was to apply through now is fantastic but if you're not into listening to the original author read their own books sometimes a book can be better with with a great narrator now this plenty of other options now like Harry Enfield and he reads long time to time the salt is well and you have those and remembers from he was determined to behave badly maybe people do remember that I do all has books and business classics arm erotica sexuality fiction a history romance mystery thriller sci-fi fantasy self-development kids young adult and lots lots more with over hundred 50,000 titles and pretty much every genre you can imagine your financial looking for the right now you're free audiobook and a 30 day trial by signing up@audiblepodcast.com/pragmatic please make sure you use a specific URL audible pod casts.com/pragmatic debt free audiobook in person I think audible for sponsoring pragmatic Q codes generally until about and do not go now folder say 10 coats would you not until I do not go now I say this 10 for roast duck Goodbody yet now is all about 10 for archiving under okay so in America the 10 codes were used by the police department and they actually came after the Q codes and Q codes waxy develop of the British government late 1910s and is there basically a way of abbreviating questions and answers are in phonetics essentially so the phonetic alphabet of course being arm are alpha bravo in a foxtrot golf hotel India you use a word is distinctive to represent the latter get it right so the Q codes all start with oddly the Q so got the most four underscores the four most common ones QS wine which is committed to be asked the question or they can be an answer all they become uses nouns in a conversation which is a bit freaky but the go secures why is EOD why change to a different frequency, or I have changed to a different frenzy or I'm going to change to a different frequency or we should change the different frequency so you can use in all those contexts are USA young Alex QS why you home 14 150 and that'll be ongoing change frequency now number to this frequency you or in the CB sense of the UHF our sense you might say I am curious why Channel 38 whatever I HRM our radio interference QIP is low-power Duracell is our acknowledge receipt so those are the four most common ones I've come across okay so what are some of the different aspects of amateur radio and I talked about propagation but is actually a lot more to it lots of little facets and I want as quickly cover the big ones mainly the ones I was involved with the first start with is ARDS nicer ARDS amateur radio direction finding and most people I say what the hell are you talking but then I say foxhunting and then most people know what I mean the economy my say foxhunting I do not K arm it's not like actually getting gun and shooting a fox which is a assumed it was no use and you assume correctly yet now it's not enough obviously is not that so no foxes were a hot night foxes were harmed in the making of this episode arm so someone builds a very low-power transmitter battery in it and hides it somewhere in the bush usually and then what you do is you all start from a common starting point stopwatch and is now your job to find the fox first and find fox wins by causing the fox look at foxhunting so do this while there was that what you have with you is some you have to understand is are the basics of triangulation and you need a highly directional antenna and you also need a power attenuator so the idea is that you have a radio that listens on the frequency of the foxes transmitting on using the fossil transmits the series a Morse code delivered our data data that are whatever and LBR right continuous repeat on the frequency listen for that and you have a handheld antenna and he sort of sweep around to find the highest frequent high start most directional are that the most best direction of signal and then you gotta run across to another area to take another reading and to try and triangulate where exactly is coming from a distance and then as you getting closer are essentially are you have to increase the amount of attenuation otherwise it'll overload your receiver so those components go together as maps and whether this all before GPS so to help you locate the fox and these competitions are only a worldwide about with our with a RDF it's still a big thing sire I wonder foxhunting now Clearview I was very lucky that's are one of the guys was good was begin to compete internationally I never did arm but there is a amateur radio weekend in North America they call the Hammerfest and are anyway so we we we just call the Clearview weekend we had to to Rycroft in Rockhampton there was one Clearview which is so much the way to Mackay are North Rockhampton is another one out west at half Fairburn dam and these, once a year and this is for me Hammerfest to amateur radio was. As a sort of get-together in you do amateur radio if things arm you can peg year buy-sell staff are fun actually the ask the oxen is the best but the sitter foxhunting are some guy was very nice not to lend me his gear so couple rounds and are of the foxhunting and I participated in around and successfully sprained my ankle asks for strong run through bushland chasing foxes now as it is more hazardous than you might think year the fox God dammit are crap is to direction and cosmic trip I viewed on a break this hundred dollar antenna rate so you're gonna take the beating nothing antenna and you fall over and get stabbed by the antenna allow my God that yes I'm picturing by generative gaze that don't normally see much outdoor ties of strapped down with expensive year old a person for you now that that your sums it up wholeness ungainly antenna in front with a funny pistol grip on it yet it is bizarre but anyway it's also conical angling aura will isolate school anywhere therefore school possibly not right so moving on to about propagation so there are these things called our DEX competitions RDX being short for run while distance transmission I was just referred to as DEX So any chasing Skippy chasing from Vyas very propagation adjacent DEX is the one that won the lingo slayings the values anyway so they will have the our DEX competitions where you essentially this time I will start as a 12 midnight on one date finish by 9 AM the next day or whatever 24-hour 48 hours contest any active contact as many other people doing the contest at that time Novi minimum distance so you can't contact local call that a contact they have to be greater than a few hundred miles away otherwise an account that otherwise has to be actual propagation you can't just have a competition and talk or talk to locals I'm sure those conditions existed but no that would not be a DEX competition when it are anyway so far I've displayed one of those arm it was the are the Jack fast contest and some yards I made hundred and two contacts and I came 78th in Australia so you pretty pest for showing really but I know it's okay's young mother went in and the only made two contacts on Morse are the rest of them and animate another two could get bonus points for Morse and dumb if you are doing fridges was made a couple contacts on hundred 60 m bend as well I was also hard because an enormous antenna as also did exchange or nighttime anyway our right living on so far that's DEX competitions what's what's are also an adjunct to that is the DEX cc: and that's river sometimes referred to as the century club are all the works 100 countries award any idea behind that is that over a period of time if you are have confirmed contacts with other people in 100 different countries around the world than you are eligible for the DEX cc: which is something that not too many people have and frankly you may be is not a big thing anymore but telephone dial hundred countries allow a lot less time stay committed to the friend of mine around the corner from me literally round the corner from me arm had their DEX cc: arm certificate says he had done really well arm Clive friend of mine and is anyway our great like to buy the way help me a lot early days are actually was one of was the local WIA representative who were are who witnessed/administered my my entry exams so one must rent very very cool guy anyway arm such DEX cc: for those people a discount enough DEX and I feel even more hard-core than that they have the things called the expeditions so that's where you go to at an island or territory and you set up your radio gear and intra-contact as many people as possible and so for example VK zero arm Macquarie Island is one example so it's tiny little patch of island and I mean tiny literally camp on supper and Tanner's bunch of solar panels batteries and so on and so forth and it is no contact people now I have never been ID expedition I have never attempted DEX cc: I did one DEX competition some say I like commitments far as I'm concerned I was sane all the other people wholly crazy but anyway you know what hey go for a guy's right moving on packet radio packet radio is exactly what it sounds like packets of data transmitted over the radio what else can I say so I had a bold 9600 board TMC atom low control and connected up to an old XT and 8086 8088 sorry was only 88 anyway I picked up sheep it wasn't new our neighbours the second am I bought was virtue of like 25 bucks perfect running packet and set off in the back corner and CA would go a humdinger earlier inherent in the insert data noise impersonation that ends it would take off the background and you can send and receive data in emails and is a dingy Peter and all the stuff simply stingy Peter and myself and again that was all happening that start happening just before the Internet took off them and Internet took off arm it till packet because of course packet radio and radiofrequency forgotten FM charlatan 25 kHz wide I'm not gonna get much more than 9600 board in your 19 200 maybe maybe I doubt you start bleeding across and the adjacent house because you need more bandwidth to have more data are shown is there in which I skipped being shown a theorem point is packet radio was simply too slow and it is died and I still around that honestly it's so much an interesting hybrid are recently with the Internet though is the I RLP and SDR Internet radio linking project where you take repeaters and using arm are tone calling you can literally dial up and say I want to connect this repeater with another repeater on the other side of the world and the Internet becomes a bearer and connects the two so rather like duplex operation locally when the two repeaters are linked you'll start getting transmissions and receptions from the other side well potentially if their links together that's really cool is very cool season going together. With the right equipment in a connection you can do is go dial-up on a talk to trip are in Calgary which young I did do just that Hackett wants are and I dial then on to me to bands and I was talking over to me advance or radio to repeater which then then went to the Internet sprung out in Calgary came back out ornamental V6 which you know is cool but let's be honest is that while we dislike despite so the ADR feedback to wireless radios nine still it's a thing are and it's cool and the okay to assault so basically just the Radeon the last mile is exactly yes that is exactly what and is honestly just they did it because they could get here anyway alright well that the radiographs not exactly a month ago soak yourself cards yourself yourself which I said earlier cure cell is now acknowledge receipt to what hectic yourself can't cure cell card is coming a postcard but it's a physical acknowledgement that I talked to you so I'd say I talk on radio and I'm saying they are heavy doses VK for JSP speaking to Vic and N1 whatever whatever Hayden wanted them for a good but eventful now you can see Vlingo and your amateur radio now we know we don't use it and God is here no anyway the point is an icy got yelled at once from the length of the 10 coats I came from CB radio so okay so will happen is the end of that contact you may choose a semi-cure cell card so we will exchange physical mailing addresses over the air other option of course is that you can register any cure cell database so if you are like having us off over the manicurist database is essentially a service where I sign up you sign up and you say right I want this to get to such and such a set off to an address at an inner country and it will be forwarded on to that particular individual for a fee or you can civilly opt to they get your physical address and an master to daily life are the point is the cure cell card disorder proven on ice to collect yourself cards and I got a couple from states and Yale. It's conical and most inventive part of Australia and Ivan friend of my unctuous cards back when I was in CB radio endowments of your radio I hear my course on that I made up for myself because in CB radio you can make a bit of course only want our was a 20 3S150 in and down which is no latitude and longitude of Rockhampton essentially are those creative gas and yes IAI friend of my unctuous cards wouldn't and send them out to people that I make contact with and is colonising our so I acknowledge receipt how to cure cell card anyway or are we not worry are things in amateur radio is QIP which is low-power and the challenging QIP is use a minimum amount of power possible copies usually defined as 1 W of output power radio or less and with low power to make contacts over the same distance someone said any idiot can put a kilowatt shoebox in the back your rig and blasted out to the states because it was not me talking but the point is anyone can do that I say anyone and with money but the perception is that it takes what skill talent I don't know whether to operate in QIP and make same contact so may initially have the lowest loss coaxial cable the highest efficiency antenna height gain possible knowing exactly when the skipper is going to come in come out the best polarisation to use all the best frequencies to work on all that stuff all goes into being out of make contacts on low-power where others would fail so QIP operations while those things and are you you put that together for exam with the SEC system you have got QIP the SEC are certificates say 100 countries on low-power anyway I was never in QIP although I did build a transceiver once disorder and get them a gay arm to more things talk about and then what about my projects and are done so Oscar now not in Miami Oscar grouch arm I mean are oddly orbital orbiting and I don't mean some kind of award that people winter Oscars are acting right you how much I pay attention okay Oscar orbiting satellite carrying amateur radio that substantial so since the late 50s early 60s women wanting satellites and some of them have carried amateur radio gear some of them have been entirely funded by amateur radio community for amateur radio operators to use and is in a similar packet rate packet repeaters and so and so forth are have a seven satellites so you know there have been times where I've I didn't personally that our family Rockhampton have satellite tracker with an elevation of our azimuth the rotator and using some computer software he was able to calculate and track onto some the low earth orbit satellites and essentially you have a global bulletin board and this is before the Internet right arm and accent I think back if this was before the Internet I first saw it wasn't but it was available technology before the Internet and before computer software you needed the tracking yourself so that the tracking plots and times of day in earth location to figure out what locations every every two minute or two you would you would tweak the antenna position as an elevation baseness numbers are in a table and that would attract satellite for you to get maximum signal that was what was doing a pass right that is a Passover over Ludlow envelope is not like nine earth orbit typically satisfies the higher space station and you'll get you like a depending on the elevation above the horizon you'll have anywhere from a minute to your 15 minutes of of times upload watching it upload and then a course in an after hour before your window close that right once when I closes on a course you are lucky you if you feel applied in finish in that time you screwed and then across people on the other side of the world can download what have you uploaded those, I can orbiting are in orbiting BDS and sent in a sense very very cool stuff anyway did get in that myself really wish I could have though arm but just the bar was too high in terms of expense no one ourselves and the space station is not a dream of mine never happened alas anyway moon bounce as Larson will talk about his allotment bounce and I love my mouth because it is such a cool idea now imagines for a second that the moon was a really good reflector it isn't but imagine that it was and it was a big mirror well if you point a big enough antenna off of the moon than you could actually bounce your radio signal off the moon and back to the earth again and you be able to get reliable round-the-clock communication to another part of the planet so call this arm EME earth moon earth but moon bounce to sound somewhat more cool sources government bounce some bouncers because of the moon baby all year and in order to do that in order to do that you need an enormous amount of power you need enormous array of antennas and summaries moon bounce antenna razor gossamer 24 yard he's all phased together through a cut of directly facing phasing array and then transmitting a light 1 kW of power through that and to receive on the other end is a similar substance to receive it so yikes I don't know what the path lost is but it's enormous and the tracking has to be precise because you transmitting of such a large distance you you need to make sure the antenna is perfectly aligned with the moon yikes and that's why yard when they did the PO single St John from the moon that's why you had this massive radiotelescope in parks in New South Wales that brought the signals back ever seen a movie called the dishes in Australian movie but arm still very quiet I enjoyed it and submit it to Ken Pastor generally is very good are about story of Armenia that the radiotelescope in parks in New South Wales I would have been to where and how it used to how pick up signals from the telogen signal signals from the moon and relay them around the world are when first steps in the moon are the so are they signed a big parabolic dish because you know Hayes hard to pick up the signals the long way away yet again another facet of amateur radio never really got into moon bounce so my projects hardier now built some antennas and finally but say what friend of mine are Sean as an avid FM brew FM broadcast radio listener and is not affected until about not ironing on a spec propagation cynical ducting so what you get is an effect at certain frequencies between about 50 MHz and is about 700 MHz we are going to get so what I call tropospheric ducting are caused by tablature inversion layer and the idea is that our because of an inversion in temperatures than tablature inversion and turbulence is created are causes the radio signals to bend our high-frequency enormous and rather than punching out to the ionosphere and then punching our space they bend back enough and they ricochet down this little duck tents that they call ducting the tropospheric ducted that the barrier between the two temperature layers in the atmosphere and those ducks often open up all over the place usually no I open up between places that you there is no one living so you know about but when I have a between places that there are lots of FM radio signals for example you'll sometimes hear so for example in Brisbane you know we would have others I'd be 15 and triple M radio stations and you could pick up on Rockhampton if the tropospheric ducting was in is a better you could buy generic yellow FM radio log periodic from Dixon Electronics or RadioShack wherever right but unfortunately they were designed for 88 to 108 MHz which is the FM broadcasting and unfortunately there again therefore is not as high social lasts marketing utilising to antennas if I could design him and antenna that would give him the highest amount again in the sweet spot which was between it was 1 MHz range are not Yaqui but a log periodic high gain log periodic from much narrower fruits event set up that some data is been my favourite antennas I designed and built after the FM broadcast and specifically to pick up the two favourite radio stations of his from Brisbane from Rockhampton are which is about 600 km away which is about 400 miles away so that that remains my favourite antennas despite the fact that after a while a big fat burst on it and snapped some the elements but no mine at next the net the written version 2 of John's log periodic for FM broadcast would have had much thicker insulators on understanding stronger once you because it's not just about physics about physical strength as well again let the hardware as I that one day showed up at his place and saw one of my elements was saving down the side been snapped is a sad day anyhow right, right next are idle summary of wire antennas it ain't funny but one that I did build out of recovered wire from a hardier pick up some surplus transformer wire which is essentially just coated coated, what is coding a clear lacquer used for winding up transformers anyway suspect that she and as you do and are anyway I turned it into a wire Yaqui so most values are made out of physical light tubes of aluminium is much stronger by May 1 out of wire because I couldn't afford that just because what I can afford build arm now was a kid I was a Yank 16 1516 years I have money to build all or expertise later I got better at FM broadcast Yardley I built when I was swot 19 I think arm you know the why yard he was not still mid teenager and is yet it worked okay fixed direction of course because of strong up in trees and so on that it worked sort of a anyway arm I'd like to say my sorry optimum along one I did an inverted hour-long wire once and in order to match that I pulled an old's arm capacitor and air capacitor out of an old TV said valve to be set to visit and the worst part of it was that being young and stupid at times and realise that RF energy is kind dangerous if not careful and this visit your thing here on the front of the TV it had a Bakelite's are not which would have shafted connected into the actual shaft of the capacitor so as you as you change the channel from the television would change the capacitance that would change the frequency that would change the TV channel was away is to be done the old good old days there is a problem right is that I'd taken a Bakelite connector off site was now exposed the whole thing was one conductive piece of metal with two sets of insulated plates like sets of fingers ago in and out of each other, so I had to keep this thing up is because you can't measure reflected powers outputting power into the antenna so I was and I was measuring and tuning it to try and get the standing wave ratio of the antenna down to tune down to an acceptable level I was in a block file transistors on the radio so what I do reached out with my right hand to tune it and that's at the moment where the RF energy jumped across the wedding in my right hand and law chunk out of my hand was a huge but owl owl year that lot so that's when I discovered the arm the tried-and-true way my panda method after that was to get a wooden clothes peg and put that on the things that I didn't claim while the wedding anyway the minor settlement things the hard way okay finally arm I like to call my crowning achievement but let's be honest only half worked so it's my crowning half achievement in amateur radio was I built my own transceiver the design was a very popular designed by radio amateur called NN 1G bicycle anyway and recall that the anyone G transceiver design for 20 Miliband the receiver mostly work to didn't tune across the entire range arm was it your conversion to Betadine I believe from memory and the transmitter though are here and need a couple toroid is Anna from the Torrens was that arm I had to get specific toroid to the specific with specific characteristics and the design called for ordering from digicam at the time I couldn't get the cheeky stuff because it was in states and I was not and they didn't order overseas so I was stuck and I tried some different torrents that I could sourced locally in Australia turns out they were not exactly the right to characteristics of the trans transmitter poet portion never worked by Esther circuit boards I buy a solid or myself all components assemble myself the receiver mostly work to transmitter never worked but still that was my crowning achievement in terms of the physical hardware i.e. our however my future in software was somewhat a little bit so foretold at one point because I had ADR and ICOM IC 706 radio and are very simple arm TTL converter are to plug into my the DB 940 report on my computer time which is a 8386 whatever health anyway and so on plug in a sling and and it be great if I could talk to the radio and you some software set frequencies at hundred memories daughter did as a rival software was based on Dos written Noah Borland arm RC and arm there was a new sarong bar menu so two-dimensional rowing bar menu so you all done through the keyboard also mouse support and are used direct interrupted in use any of the libraries because I dislike doing things the hard way and wait and now yeah it so it won second prize in the home homebrew competition and that was a 90 I forget 9798 so forget someone anyway so critical you was recall actually and most of the homebrew entrance arm in the shredder competition locally were of course now hardware like amplifiers low noise amplifiers yellow and transceivers that worked around like mine and is arm yard but mine was different minor software non-attendance software before style setting in one second prize might of novelty than anything else rather being any good I never sold as products although a problem should have armour within a year or so of mine arm when a prize someone release Windows version which was let's face it a heck of a lot more user-friendly so arm you mine, never really saw the light of day of screenshots of anymore I have the original source code somewhere I think that anyway should put up as there is yet this was useful once Hall of Famer something and I anyway and honestly that's it I can talk more I could talk a lot more and honestly I'm not going to because well let's face it I don't know how many people camper here go the go someone had asked me to do an episode about's arm my background with amateur radio and radio generosity again a note and done are hopefully some that's been interesting but honestly bottom line is that as a as a hobby it is dying and whilst semi on the path that it did into electrical engineering and further on in two controls imaginings on doing now arm the Internet is so much easier in so many ways model phones much easier in so many ways and frankly writing software for that stuff is is is just the school and pushes a lot of those of the buttons amateur radio to push the mess I still feel like I'm not missing out are in that respect so yes those of asset and I see we have a couple of questions arm for the Q&A session that will be happening after show stick around after the music after his music are if you listen to podcast off-line and you will hear that so stick around for the Q&A so one yet anyway colossal morality can reach me on Twitter and John's edginess JH NCH IDG why and check out my writing attack distortion.com if you like 70 feedback please use the feedback form on the website that we also function as the episode in the pod casts pragmatic you can also also follow transaction on Twitter seashell announcements like ongoing life example and any other related materials that might crop up I like to thank my co-host Vic Hudson for joining me once again and of it was the best way to building in touch with you are they can follow me or are plainly on Twitter at the code someone I was go like thing audible for sponsoring a show please make sure you visit this URL all upon cars.com/pragmatic your free audiobook also like to thank Lynda.com a new sponsor for sponsoring pragmatic there's anything you'd like to learn about and you're looking for an easy and affordable way to learn and Lynda.com can help you instantly stream thousands of courses predator experts in the fields of business software web development graphic design and lots more visit LY NDA.com/pragmatic to get free seven-day trial and want to learn something new what are you waiting for an asset face listening everyone and thanks again Vic so arm let's go through the Q&A connection and there is a rusty asking about the Russell Russ newcomers are in the chat room asks can you talk and italicise and signal reception as if you have a bigger antenna is reception necessarily better answer is yes bigger is better because you're capturing more RF energy and that there is if the theorem the reciprocal theorem of antenna such that if I design it had had maximal gaining transmission it will have maximal reception are as well so let's say you are one incidental balance beam with out the beam with this that the angle from the centre point of your antenna to the two points are the two 3D power points on your on your plot so you're plotting the maximum amount of gain are around your antenna and the maximum gain is in the forward direction usually is the front of the lobe but as you move to the left and the right of that live eventually the power will drop off to 2 3D be less than the maximum they call that half PowerPoint to 3 DB points that anglers shall beam width so when you quote and angles arm in with your little beaver states on oath 45 so this 25 off so of basically says what the 12 1/2 each side of centre where you can get a proximally maximum gain so are the idea is that yes the big downturn you go the better your signal reception is going to be hands things like heresy though however one incidental about our Dean think that a mental does now is the other idea which is creating a virtually big antenna through facing now phase arrays do this idea get-togethers want to inbounds but the idea is that you will get I say you get 20 antennas and each of them will feed in through I call phasing harness and under phasing harness is that each of the connections from each of the antennas is exactly perfectly the same length all the antennas are exactly perfectly the same match exactly perfectly the same and they all come into a common fee point such that all the signals coalesce and they essentially arm there all interface so signals are in phase of course they the additives they amplify Seagate or signal reception sober phasing houses have to be very precisely made everything has to be all very well calculate that work and I sat phasing harnesses and all that little or really cool stuff and the macro scale of this is if you look at radio telescopes is our one the funding the first one is the very long base array in New Mexico are and is whole bunch business from all around the world now becoming quite very popular radio telescope ready radio astronomy is that each of those antennas are simply a small parabolic but you've got lots of them and spread out in the X and Y direction and the idea is that you can then add all of their signals together to 2 essentially create a similar capture area to an enormous arm enormous virtual radio antenna so the same idea and that you can move the different antennas along a bunch of railroad tracks arm to position them to change the size of the attacks a larger area different gain characteristics depending upon which one listens most phase arrays are fixed however not nonadjustable but in radio astronomy you go that's the trouble you make an adjustable dog if you ask but most of them should be mobile are follow-up question Russ asks a phasing houses are not a home option right will sure why not absolute you can amend the laws of visible physics, you want no phase couple and socio-non-stop and in fact I have seen some people that live in our bad TV signal reception areas are do that so I seen are multiple realities and you'll see them stacked horizontally and vertically and are so you'll see like two or three or four antennas either in any configuration so I seen a houses that have got 4 yard visa for well that there logged out his arm for TV antennas that have gone gone through a phasing harness into the into the house to pick up yakuza and fringe area you and if you want bigger TV that's your option so you know it's much less common these days course with now with cable television and in Australia like Foxtel and whenever I see a satellite TV as long as you've got a view of the sky you got satellite TV right so shrug my question is more a statement that the amateur radio's treelike public access television US yes yet is a bit envious so a lot of people take 10 and those about it that name zombie apocalypse you want the radio guy around our ideal antenna for my HDTV out of old clothes hangers absolutely wine knots and works better than the antenna liable from the store what you that's the thing is that television antennas are funny beasts because a rabbit is television antenna is so heavily loaded are you and once again how loading onto about is that your load up with an inductor in a capacitor or and or inductors and pastas depend on the match does is it reduces the physical length of the antenna needs to be because while your chronicle your loading rates the idea is that arm electrically it appears longer that's really physically is and is that's great for shrinking antennas making tiny it's terrible for efficiency so if you're having sufficient antenna remedies are not your friend Ravi is only useful in high signal reception areas so if you're out of sticks need an external antenna free from your house free from the walls free from the roof arm for high gain in order to get performance versus reality so what's in these newer outriggers collective arm if you got the story of C and now they sell digital TV antennas and it basically just looks like a little UFO desk mascot as was referred to the loans are just a coil of wire it is but it's, it's it's loaded and it's got a low noise amplifier and sometimes has an active matching circuits of the idea is that some of them will detect the frequency specifically the John and altering themselves that frequency so that you get the best possible efficiency at the frequency you're trying to tune into other ones from commonly are simply a low noise amplifier to the idea is that they will take the raw signal and they'll amplify it before it goes into the coaxial cable into your own to TV set for your rate of outsider that would be a skill amplify noise and operate us right but the low noise amplifiers hence the name the name suggests an hour emanated designed allies are very common in microwave transmission and the reason is that you want to boost the singular signal kick before it goes in the coaxial is panic height so far better amplify before it goes into the transmission line was pick up noise and lose power than after because all radio receiver is a TV receiver is is an amplifier in empathy it amplifies the received signal to a level which you can strip off the data and then display it you are all presented in audible form to speak so ultimately ultimately it's all about the sensitivity and if you have a good low noise amplifier at the end as close possibly antenna then you can improve your chance of picking up is the weakest possible signal which is wine radio telescopes they will have arm the lowest line I sympathise you can get wishes are usually caused by liquid nitrogen because what you do is you want to reduce are the amount of molecular movement in the actual receiver in the low noise amplifier because if you reduce the amount of power you end up are with the cleanest possible sorry if you reduce that the temperature be reduced molecular movement that reduces than the Gaussian noise that you get in the amplifier obviously that's also ridiculously over-the-top in a funny arm for home unless you want to have a really really really low noise amplifier with a bunch liquid nitrogen you gotta keep topping up which I'm never did and binding on and would ever do while maybe there be some numbers that would do it by me I say not as me and my survivalists and if you're a survivalist with a low noise amplifier with liquid nitrogen how the hell you make your liquid nitrogen wants to go scrap the menu does not hire me how you do that you have your home nitrogen factory because you not get figures out the locality for the bike I sold my radio gear we are listening God I'm not licensed anymore, has think that matter at that point one has been a radio has been�
Duration 1 hour, 50 minutes and 50 seconds Direct Download

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People

Vic Hudson

Vic Hudson

Vic is the host of the App Story Podcast and is the developer behind Money Pilot for iOS.

John Chidgey

John Chidgey

John is an Electrical, Instrumentation and Control Systems Engineer, programmer, podcaster and runs TechDistortion and the Engineered Network. John has produced and appeared on many podcasts as well as Pragmatic.