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welcome to 2021's ham radio, shortwave, broadcast radio, pirate radio, SDR, lorawan, CB, FRS, GMRS, and crystal radio thread this is a space to discuss radio nerd hijinks, ask how to solder an SMA connector you don't, share links of cool advances in hacker radio tech, ask questions, study for your ham license, and show pics of your dumbass radios and exploits here. I will keep the OP short-ish, but for those of you that are newer to yos, I have been playing with radio for 35 years, got my US ham license 29 years ago, and have been the top license class ("Extra") for about thirteen years now. I love radio more than any other pastime or hobby on earth, and it is my confirmed life goal to get as many people as interested in the hobby and, if they take to it, get them as set up as possible for success, fun, and liberation over the airwaves. 2021 is an interesting point to revisit this at. We have Section 230 threats everywhere, which raises the possibility of every social network dying. Really good wifi gear is available for cheap and can be hacked to work on the 2.4 and 5.8 GHz ham bands that are right next door to the consumer bands. Wanna run 1500 watts of 5.8 GHz? Budget aside, you can get the entry level US ham license and do so. But on a more serious note, a lot of people want to prepare for instability and possibly build up parallel communication networks in case the Internet turns into a lovely on-demand cable TV provider. Questions, answers, pic posts, and general rambling is welcome. I and the fellow yoshams in the cabal will do our best to guide you on your path to the magical end goal of pulling microvolt level radio waves out of the sky and turning them into rambling rants on how the new world order is deploying 5g to give everybody coronavirus. LETS GO
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Jan 2, 2021 00:27
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thanks jonny. i'll just repost my question from the idiot thread any recommendations for a book about radio, with an emphasis on SDR? i've got a mathy background so lots of math is ok by me. i got a little DVB-T type dongle/SDR for christmas and i'm going to gently caress around with it and see what kind of signals i can catch on my 3rd floor apartment. i've got the dongle plus a dipole antenna with long/short extendable antennas. i think it's more of a "toy" but i've got some software on my mac and i'm going to see how far i can get with this thing.
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Jan 2, 2021 00:43
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yes yes! ok so thing 1: the rtl sdr dongles are actually not at all toys. i have one here on my desk. It is as sensitive as any radio on my bench. The place where it falls short is _filtering_. You wanna keep really strong signals that you aren't tuned to out of these, because they'll do dumb poo poo and all of a sudden you have thirty local AM broadcast stations making GBS threads up the whole shortwave spectrum. So, the RTL stick is a great start! My suggestion would be to visit http://radioreference.com (assuming you're in the US - side note, if anybody has licensing or 'what can i pick up' Q's it's very helpful to include your general nation or metro region) and see what local services have listings. Some areas you can still listen to the cops on. Some others (like denver) it's all crypto, and no, you're not cracking it. Most areas still have in-the-clear transmissions of FD, EMS and city services. http://repeaterbook.com is a good place to find out what ham radio repeaters are in your region. Setting up an RTL stick to pick up shortwave requires a bit of finesse, not because it's difficult, but because there's no gain control when it's in 'shortwave mode'. So you need to find a way to block out the AM radio stations in your area, which are 10,000 times louder than distant shortwave stations, in order to pick up the weak ones. We can get into that a bit down the road, but the VHF/UHF stuff requires a 1-3 foot antenna; a shortwave setup likes 50 feet or more of wire out your window. So, yeah, for a start, take your antenna and set it up so that it's about 18 inches long. Then put it in the window and start tuning around the VHF (technically 30-300 MHz, but we're talking about 108-174 MHz) band for any stations that radioreference or repeaterbook has listed. These days the 440-470 MHz UHF band is also pretty busy, but VHF will kick a bit farther and bend over the horizon a tiny bit. The NOAA weather stations - again, assuming you're in the US here - around 162 MHz are excellent "does this poo poo actually work?" tests. For PC I prefer SDRSharp, on a mac I use gqrx for my SDRs. Both are competent and reasonably polished programs. Make sure you google 'rtl sdr driver install' and get the right drivers in. These things were initially designed to be digital TV receivers for the Asian market, so even getting them working on conventional radio is a "hack", but it's very well established these days and most of them are designed with ham/scanner poo poo first in 2021.
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Jan 2, 2021 00:54
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lol. jonny is the op again. 
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Jan 2, 2021 00:54
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I've cut a shortwave multiband antenna with the longest segment over 100' (I forget the exact value I used, quarter wave maybe?) but I'm not sure how to support it. I doubt my longest 16ga copper wire is going to be able to hold up the rest of it. I've the wires running through PVC tubes where each antenna ends to keep them spread. Can I just use a piece of steel cable as the support line or is that going to screw with my reception?
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Jan 2, 2021 01:02
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i've run 150 foot runs of 14 gauge home depot THHN wire in the air before and it's plenty strong. My current preferred antenna wire is 26 gauge copper-clad steel wire from "The Wireman" https://thewireman.com/product/antenna-wire-26-awg-copper-clad-steel-stranded-jacketed/ . at RF it works just fine and it's really strong, and it's thin enough that it disappears against foliage or a gray sky. Steel wire rope itself is a fully adequate shortwave receive conductor. It's got like 10 ohms resistance along its length, versus the actual antenna impedance of a few hundred ohms. Layman's terms: you'll lose 1% of the received signal compared to running pure copper. Anyways, even lovely speaker wire will stay strung up for years. Have faith in the copper.
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Jan 2, 2021 01:07
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Here's my favorite hamtweet of 2020: https://twitter.com/KC4YLV/status/1218015470625808384 there are five diodes in the bottom right package. which is what i wanted. they were shipped in the box at top right.
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Jan 2, 2021 01:41
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thanks! i tried out the gqrx and it worked on my mac. ive been loving around with gnuradio too. i was confused about the drivers though. i just got both of them packaged as applications, so they both have librtlsdr inside the package (well i know gnuradio said they did it that way). is that the driver or is there a deeper macOS library i need to gently caress with? but yeah ill take a look for some of the weaker signals. i can get the local npr station pretty well and i can pick out the digital signals (haven’t gotten to decoding them yet), but i don’t yet know where to look for more interesting things. shortwave stuff may be a long way off for me. ive got a balcony but it’s not that big so im limited in how long of an antenna i can put up. the railing is metal too so i don’t know how much that could cause interference.
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Jan 2, 2021 02:36
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great thread. can't wait to see you moonbounce to malasia. I hope you get lots of post cards and all your signals are five five five
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Jan 2, 2021 15:13
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Once when I was flying the tower was coming in all scratchy and I responded "sorry tower, I read you three by five" and my instructor was like "what? what does that mean" but the tower understood exactly what I meant and changed something and came back clearer and asked "how about now, better?" and I felt pretty cool
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Jan 2, 2021 16:48
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I want to see how long and girthy your mast antenna is
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Jan 2, 2021 17:22
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i dont have any big antennas up right now, my landlord yelled so right now i only have 3 up: a 43 foot long wire, a small loop for shortwave and then a VHF antenna that i'm hiding in a tree out back
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Jan 2, 2021 20:12
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boo that landlord
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Jan 2, 2021 21:05
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Silver Alicorn posted:boo that landlord
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Jan 2, 2021 22:44
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lol my apartment directly overlooks the leasing office so i can't do poo poo without them immediately noticing. there's a guy in the neighborhood that has what i assume is a big HAM tower. 
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Jan 2, 2021 23:25
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posting in the SNOTEL HAMWAN thread
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Jan 3, 2021 04:45
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Eeyo posted:lol my apartment directly overlooks the leasing office so i can't do poo poo without them immediately noticing. i think this is appropriate thread to educate people that ham is not an acronym. a radio ham is just a guy who does radio stuff and that's why it's called ham radio. jonny probably knows the etymology better. don't be one of those insufferable people in the airplane threads who always talk about RADAR systems
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Jan 3, 2021 04:48
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It's because radio folks like to ham it up on the airwaves
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Jan 3, 2021 04:50
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look its capitalized in the title so i'm just following the style guidelines
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Jan 3, 2021 05:30
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honey baked ham is delicious and appropriate at all times of year
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Jan 3, 2021 06:17
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i am, of course, writing in regards to The Honey Baked Ham™ by The Honey Baked Ham Company®
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Jan 3, 2021 06:18
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Jonny 290 posted:Some areas you can still listen to the cops on. Some others (like denver) it's all crypto, and no, you're not cracking it. lmao you'd be surprised how many places still use DES, because AES (at least when I checked a few years ago) was extra money. Double-bonus for the fact that various implementation flaws knock it down to a level where you can CUDA the whole key space in a few days.
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Jan 3, 2021 06:38
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I helped my friend catch the Radio Bug this summer but it was in the context of them buying a whole stack of SDRs to archive the entire P25 data stream for their city and record the MURS bands that the various militia groups love to use. They just bought their own place and I'm currently trying to convince them that the next correct life choice they need to be making is getting their license, erecting a tower in their backyard, and setting up a repeater for all the local lefty groups to hang out on.
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Jan 3, 2021 06:48
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Jimmy Carter posted:I helped my friend catch the Radio Bug this summer but it was in the context of them buying a whole stack of SDRs to archive the entire P25 data stream for their city and record the MURS bands that the various militia groups love to use. Is there a proper leftist radio hangout? Im in Seattle so the local repeater sounds chill but I'd rather be among comrades. Also tell me more about militias and MURS my other weird hobby is bill cooper tourism.
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Jan 3, 2021 07:37
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I'm in the middle of a move and don't have the time right now but once I'm settled I'm gonna be buying some gear and getting this all set up. super stoked to do this I mentioned in a other thread I was into ham back in the day because my dad is an old school radio guy. he worked his way up in the highway patrol (acab) as the comms director and used to climb towers and put up/repair antennas and lights and stuff, did all the car radios and tech and poo poo. they used to let him keep all the poo poo that was broken or getting replaced and he would try to teach me how to fix poo poo but I was too distracted being 12 ham
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Jan 3, 2021 13:00
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there's not a real strong lefty presence in any particular worldwide sense YET beyond DMR. there are some good hangouts on the DMR network where the chuds generally aren't present. seattle's probably a good venue to take over a dead repeater or something. if its anything like denver there are 7 clubs, each of which have 13 repeaters on hilltops, and only 3 of the whole collection ever get used in any given day once the clubs age out to literal i-cant-get-to-the-transmitter-site-in-a-hoveround levels, either things go off the air or a younger crew can step in.
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Jan 3, 2021 21:13
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Jonny 290 posted:there's not a real strong lefty presence in any particular worldwide sense YET beyond DMR. there are some good hangouts on the DMR network where the chuds generally aren't present. just pretend it's an ubisoft game and you gotta liberate the tower to unlock more of the map
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Jan 3, 2021 21:24
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what's the cheapest way to do ft8 in a backpack? one of the qrp-guys kits, a battery, and a wire over a tree branch?
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Jan 3, 2021 21:32
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don't use those DSB radios for digital stuffme posted:DSB is a cool trick but it can piss people off on the air. there was a few month period last year where people were recommending cheap DSB transceivers to run FT8 on, which is extremely rude (14.074 zero beat frequency + 1500 hz audio tone - you're now making GBS threads out inverted FT8 down on 14.072.5 and annoying Olivia folks) https://www.hfsignals.com/index.php/ubitx/ is about the cheapest i'd go. it's a real ssb radio
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Jan 3, 2021 21:38
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word, thanks!
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Jan 4, 2021 00:49
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I have one of those RTL SDRs with the silly cheap antenna it came with stuck to my window. It works decently well but as a second-floor apartment I wonder if I could do better. I have it hooked up to a raspi3b right now with whatever server SDR# connects to. Haven't been listening to it lately because manually tracking channels is a huge pain in the rear end , but it's fun to occasionally pick up Vegas hotels or the county school bus system.
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Jan 6, 2021 12:29
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cool thanks
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Jan 6, 2021 12:33
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Zamujasa posted:I have one of those RTL SDRs with the silly cheap antenna it came with stuck to my window. It works decently well but as a second-floor apartment I wonder if I could do better. sdr sticks require a little bit of Focus because they can do so much. one weak point of them is they were basically designed as least-cost receivers for asian digital TV. Digital codecs don't care about distortion or overload because they have so much error correction, so the automatic and manual gain controls are very lacking. Ideally if you want to use one of the rtl sdr "v3" sticks (which have built in shortwave functionality) on lower frequencies, you'd put a box that is a combo antenna matcher and attenuator in front of it, because it has no gain controls down on AM/shortwave. everything is full throttle. and as a result, since AM broadcast signals are like 10000x stronger than weak shortwave ones, the former just overloads and you hear local nazi sports talk radio every 10khz. They do very well when you have a preselector or attenuator ahead of them, between the SDR and the antenna.
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Jan 7, 2021 21:57
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Jonny 290 posted:sdr sticks require a little bit of Focus because they can do so much. I hate how long it took me to figure this out. "Why the gently caress am I hearing this signal way the hell over here". You'll have to show us your rig for this now  .
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Jan 8, 2021 01:08
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so some kind of band-pass filter? is that the same effect for an FM signal like this?  (also not sure what that little spike is on the left, there's also a bit on the left edge of the digital band as well)
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Jan 8, 2021 03:58
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same idea, different values. you need much bigger capacitors and inductors down at HF for the same effect. ill post some pics of my little sdr setup this weekend
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Jan 8, 2021 04:01
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So speaking of super-cheap gear along the lines of RTL-SDR dongles, I just picked up a nanovna: Here we see a capacitor putting on its inductor hat above 22MHz. I don't really have any one use planned for this but antenna tuning/SWR and a reasonable LCR meter are worth the price of admission, and I'm sure I'll be characterizing filters and amps with it before long.
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Jan 8, 2021 06:25
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iv'e been waiting for this thread tbh. i have rtl sdr and a book about certifying in canada + moving out to the forest where i can put up a bunch of antenna and stuff as i see fit but dunno where to get started
aol keyword party fucked around with this message at 07:17 on Jan 8, 2021 |
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Jan 8, 2021 07:15
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Stack Machine posted:So speaking of super-cheap gear along the lines of RTL-SDR dongles, I just picked up a nanovna: Check out the NanoVNA Saver app (https://github.com/NanoVNA-Saver/nanovna-saver) it is a QoL for actually using the data.
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Jan 8, 2021 16:16
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drunk mutt posted:Check out the NanoVNA Saver app (https://github.com/NanoVNA-Saver/nanovna-saver) it is a QoL for actually using the data. Good call!  Yeah that's the stuff. Now I can actually get these measurements into CSV files and... I'm not really sure what comes after that but it'll probably be fun.
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Jan 9, 2021 04:34
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