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My partner's physics class and others from our city did their launches for the Global Space Balloon Challenge yesterday, and it was amazing fun helping her class out. The students did everything - designing the payload structure, setting up the GPS, radios and other electronics, up to and including launching the balloon. We all had a blast working together to chase them down and find them, with the spread being about 70km for landing area. Most of them landed in farmer's fields, but one of them required some bush-bashing and miraculously landed in the one clearing in a forest. Most of the students were relying on APRS.fi, and while her school's balloon was showing up loud and clear, the other schools weren't able to see theirs from what we're thinking was lower power (I got brand-spanking-new batteries from the hardware store ten minutes before launch when their voltage readings were looking all funky). One of the schools had done multiple balloon launches in the past, and were all decked out with proper radio equipment and licensing for the whole endeavour. They were a big help with teaching students from other school using their past experience, as well as with tracking stuff after is disappeared from APRS. On top of their improved ability to locate things, the communications issues we were having with mobile phones in an incredibly rural area was really obvious to the students who are used to always having a data plan nearby; a bunch of them want to get their amateur radio licenses as a result, which is really awesome. At the end of the day, I think four out of five payloads were recovered without any complications, and only one is unaccounted for. The one that landed in a forest appeared out of nowhere when I think someone in the area turned on their receiver and it appeared on APRS again. That class is going to be sending that dude a thank you card, since they were about to give up before it appeared and we trucked it out there.
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Apr 26, 2015 04:23
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Jonny 290 posted:the most entertaining thing that i learned this year is that you can buy a synology NAS with a celeron chip (translation: can run docker), install the OpenWebRX docker image, jam a god drat RTL stick in the front USB port and you have a web sdr running on your NAS. no configuration file fiddling, no horseshit. I think I had to add one line to the docker run command to have it mount the USB device. I was unironically amazed at how simple it was. Is something like that what would let me run one of those WebSDR sites that people can connect to in order to check out the radio in my area? Running it on my NAS instead of my Pi feels a bit sketchy, but maybe I can figure out how to run it in a jail instead or something. Worst case it's just for me and close friends who can VPN in to my network. I still don't have money for a transmitter right now but I needed a break from work and I wanted to see if I could get more OTA channels than the patch antenna that's up on my wall. Antenna construction seems more this thread's style than anything in IYG, so here's today's work with nothing more than random scrap and components around the house.   The Gray-Hoverman design seems to be the cat's pajamas, but I don't have enough thick gauge solid wire for its big driven element, so went with the DB4 design that's really common online due to the dipoles being easily made from scrap wood and metal, and it can be built in half an hour. Hanging by the window I'm able to get the station from 40km away that my store bought one could never pick up so I'm already ahead of the game. It's not picking up the lower-powered stations from the other side of my building that are much closer and (I believe) higher-powered, so a better antenna can only do so much against concrete and brick construction I guess. No point in putting on a reflector since the stations are 180 degrees apart from each other. The balun in the first picture was so flimsy and the wires inside so gossamer that I decided to try making my own 4:1 transformer, following the directions from here. Good thing I had the foresight to get bags and bags of ferrite toroids of varying size back in my RC days. I have no idea how to confirm with a multimeter if I did it right, but so far it's much more robust than the pre-built one that broke wires just by tightening the leads. I made another one so I could make and connect a 300Ω dipole to the 75Ω input on my AVR and the FM radio band definitely sounds better than with the length of bicycle cable I had shoved in there previously.
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Dec 18, 2020 10:32
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Got it. It's the only tool I have on hand right now so it's not a big deal if I can't do any formal testing. Everything's working better than before so I'm assuming I did something right and won't fret over it. The thing about it thrashing an older Pi is what's making me think of putting it on my NAS, since I've already got some other stuff running on my 3B+. Not like I can't give it a try with a different SD card if I can get my hands on the needed hardware in the future though.
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Dec 18, 2020 17:20
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I'm a student right now so I have to be more picky with my purchases, unfortunately. It's also why a lot of my hobby time these days is spent on fabricating useful things from literal trash. I hear about people just finding Pis or having them given to them for free at events and such, but I've had no such luck. I'm really glad I got this thing before I started school, since it's saved me a ton of money on standalone appliances that are double the price with less features, and once I can get actively back into radio stuff again there seems to be a ton of uses for another Pi. Might as well also ask about this while I'm here. My dad passed away a couple years ago and while sorting through his stuff at my parents place I found what I'm pretty sure is the first radio he bought after immigrating here in the 60s or 70s. I haven't tried plugging it in because I've heard you have to be careful with that on older radios. This is a solid state receiver though so I don't know how much it matters. I opened it up to remove the decades of pipe smoke that accumulated in there and while the caps look good and not puffy, I dunno if I should go ahead and replace them because of their age anyways. He was an elderly parent so playing with radios and running antennas and stuff as he got really old is one of the few things we were able to do together. Right now it's just looking pretty in my entertainment center so I think it'd be cool if I could make an antenna for it and start using it again without breaking it.  
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Dec 18, 2020 18:01
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Plugged it in and local AM stations come in perfectly with 50' of 22AWG speaker wire I had kicking around. CBC Radio One has less static on this thing than it does on the FM band using my AVR with the dipole I hooked up. I definitely need to take it apart again and hit it with some contact cleaner though, the volume dial crackles like crazy and the switches don't switch reliably unless I do it slowly and partway. It also doesn't seem to switch to band 4 reliably half the time unless I do it really slowly. It seems to be picking some stuff up on the higher bands, but my antenna placement can probably be improved from "tossing it along the length of my balcony horizontally and hope for the best". How should I properly run a single wire antenna with this setup? The radio is below my TV and while I just have it going along the baseboards and out the door, I can probably run it out with the air conditioner which is to the right of my couch next to the door. The length of the balcony is about 10m and I'm 25m up. If vertical is better I can try sneakily hanging the wire down for testing, but obviously that won't be a permanent installation.  Edit: hosed down the dials with contact cleaner and all the switches and dials work properly now. Can't want to see what I can get with it, playing with analog dials feels so much more satisfying than adjusting stuff on those online radios for some reason. Coxswain Balls fucked around with this message at 00:08 on Dec 19, 2020 |
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Dec 18, 2020 21:59
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I just tossed the wire over my balcony and got a lot better luck on the higher bands, it was a lot like fishing and seeing what I'd catch. Got a couple of what sounded like preachers, but also a few that were pulsing in a melodic fashion, with one of them having a dude saying something I couldn't understand every few minutes. It'd be cool if it was something like a numbers station, but it's probably something boring like a signal from the airport or something from the National Research Council.
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Dec 19, 2020 01:04
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I got the wrong country and instead of the National Research Council time signal, it's the NIST time signal from all the way in Colorado which makes it super frickin' cool to me because I'm all the way up in Canada. I also got this which I'm trying to figure out what it is. I think it's in the CB band and different jingles would come up every couple of minutes. https://www.youtube.com/watch?v=4L9DUnwAsH0 Signal fishing is fun but I think I'll have to make it a night activity so I don't bother all the people below me with the lines I'm casting out.
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Dec 19, 2020 01:20
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Pham Nuwen posted:The video could have been the ARRL's code practice transmission on 28.0675. The schedule is at http://www.arrl.org/w1aw-operating-schedule The time matches up and it certainly sounds like that's what it is. I think I'll try tuning in to it next time I have a chance to give decoding it a try, sounds like it should be fun. Sir Bobert Fishbone posted:It's funny, I live about 40 miles south of WWV and I got super excited the other day cause I picked up Canada's time signal. Hahahah, that's awesome. It's the same with that HDTV antenna I just built; I'm way more enamored with the fact that I'm managing to pull a distant signal out of the air than the content of the signal itself, which is pretty dismal with broadcast TV that's not the local news if I'm gonna be honest.
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Dec 19, 2020 02:04
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Soldered and heatshrinked a 30m 22AWG wire I can hang from my balcony to almost the ground. Originally put a fishing weight on it but that seemed like a bad idea if the wind took it and hit someone who was out for a smoke. I was able to pick up football chat from KBGG in Des Moines Iowa on 1.7MHz broadcasting at 1kW, and I think a high school or college football game on 3.5 MHz? I heard Alabama but they might just be talking about NCAA stuff. So far from what I gather AM radio in the US is all about football. I think I got the NRC time signal in Ottawa at 3.3 MHz but it kept cutting out before the top of the minute so I could set my clocks. Tried to hit up the NIST one but no more luck at this time. A few other channels with regular tones that I forgot to write down, but so far so good. I'm guessing the wire bends for clean routing in my apartment aren't great and ideally the only kink in the antenna should be when it goes over the railing and then straight down?
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Dec 19, 2020 09:44
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Didn't realize I had to do a channel scan with the new antenna to fine tune it, now it's getting everything in the city perfectly so my building wasn't actually blocking anything. Compared it to the store-bought and it's no contest, my trash-tenna beats the pants out of it. There's only one more station it's not getting and that's because it's at the bottom of the VHF Hi band, which these DB4 antennas aren't suited for. If I can get my hands on enough thick-gauge solid-core wire I think I'm gonna take a crack at building a Gray-Hoverman antenna with NARODs, which are supposed to work really well with everything in both the VHF and UHF bands. Antenna design seems really cool and building them with improvised materials is super fun. It also seems to have the bonus of not having to deal with shitheads on the air. If I can get all the local stations working perfect, I think I'm gonna try building a high-gain antenna to get some American stations. It'll have to do for now until I can finally get a modern HT to play with.
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Dec 22, 2020 02:59
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Going crazy trying to find my dad's Radio Shack DX-400 since I found the manual for it while going through his radio stuff. It should be able to receive SSB signals and it's more portable than the S-125 I posted earlier. I've got the bug now after playing with some SDRs on Christmas since we're in lockdown, so I want something I can take out to the middle of nowhere. I did find a Holiday 2318, but it's beat to hell and doesn't have any external antenna connections that I can find, plus no SSB capability that I can see.
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Dec 28, 2020 01:23
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What's involved with becoming a time nerd, it sounds cool.
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Dec 31, 2020 22:24
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To me it's the same thing as a lot of radio stuff, it's super cool to be able to pull stuff like that out of thin air. I'm just about ready to cave and get my own SDR to experiment with. What's a good, cheap kit to start with that I can get in Canada? I see a bunch of NooElec sets on Amazon but I'm not that well educated on what all the available options are. Not interested in transmitting right now, just receiving and doing more trash antenna construction.
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Jan 1, 2021 08:19
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Someone local is going to give me a couple of these that he doesn't need any more so I can try setting up a WebSDR page. It's an older RT820 model but they should be good to learn with, and I can't complain about the price.
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Jan 2, 2021 08:09
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Would there be any issues with replacing the Belling-Lee connector in my SDR stick with an RCA jack so I can use regular AV coax cords as antenna cables? Using an adapter or replacing it with an F-type connector would be the normal way to do it, but I already have a couple of RCA jacks in my parts bin with no shortage of cabling, and a thinner cord would be much easier to run through the wall where my air conditioner is without letting in a draft. I'm thinking of just making the outside end a terminal block where I can connect whatever antenna I feel like using on a particular day.
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Jan 9, 2021 14:43
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Probably a noob question, but how do you guys try to figure out and learn what certain radio signals are in your area when farting around with an SDR? I'm having fun just scanning up and down and finding interesting patterns and stuff. While in the 70cm band I'm seeing this huge burst on 434MHz happening at 30 second intervals, and the smaller one slightly below at 34 second intervals.  432-438 MHz is allocated primarily for radiolocation here with amateur use being secondary. I'm in a big building right under the flightpath of an airport so I'm thinking that's what it is, but I could be way off base. Is it just a matter of trolling through the Signal Identification Guide wiki?
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Jan 14, 2021 05:24
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It completely slipped my mind that I have a weather station on my balcony, that's exactly what that huge burst at 30 seconds is. I wasn't expecting it to be that strong, but on the other hand it's not like I have much in the way of transmitting equipment in my home to compare it against that isn't regular 2.4GHz stuff. That 34 second burst is still going, along with a bunch of other regular signals. I'll check out rtl_433 to see if I can read those other signals, probably more weather stations and the like. e: That's exactly what I'm pulling up, and dang there's some people around here with some fancy-rear end setups. Now I want to use the data from the person who has this sweet rig that puts mine to shame. Stack Machine posted:I have definitely been helped by https://www.sigidwiki.com/wiki/Signal_Identification_Guide in the past and it's also a great place to browse around for signals to look for. I got a lot of use out of that page when playing with HF WebSDRs and trying to figure out what this one signal was that was happening every night in the 40m band for an hour. Turned out to be a Digital Radio Mondiale station in Romania. Coxswain Balls fucked around with this message at 06:28 on Jan 14, 2021 |
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Jan 14, 2021 05:55
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Does anyone have advice or websites on setups for mounting antennas to balconies? Because of my location overlooking the airport FlightAware is sending me a dedicated ADS-B feeder so I want something sturdier for permanent antennas as well as swapping in antennas as I make them and check out different bands. I ran it by the building manager and as long as it's for hobby use there shouldn't be a problem as long as it's safe and the permanent antennas aren't an eyesore. Plans for fabricating one are preferred over pre-built solutions, since I'm trying to keep costs down and DIY would probably make something with better fit (on top of just being more fun). I have a Metal Supermarket down the street so whatever I can't find with scrap I can get from them. This is the balcony I'll be mounting it on, with pigeons for scale. 
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Jan 16, 2021 01:44
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Sounds like you need an SDR to play with. I've been having a ton of fun with mine that I was lucky enough to get for free. My current interest is seeing how far I can track aircraft ADS-B signals for using antennas made from parts in my scrap and recycling bin. My current record is 416km with a soft drink antenna.
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Feb 8, 2021 19:11
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net work error posted:I've found when using SDRSharp the application will crash sometimes when moving around frequencies. Is this because I'm overloaded the receiver or because the application is kind of it janky? I think it's just janky, especially when you're connecting to your SDR over a network via Spyserver. One thing I noticed that makes it crash a lot is when I select a frequency from my favorites it switches in the spectrum and waterfall view, but the dial still has the old frequency in there which causes something to go out of sync and bad things happen if I start changing frequencies in either. Double-clicking the favorite a second time gets the dial to line up with what's in the rest of the program which has cut down the amount of crashes that happen considerably.
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Feb 13, 2021 03:14
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I think it's like that for any hobby with lots of old white people. CGN is the most established buy and sell place in Canada for firearm stuff with web design firmly in the early 00s, but you only go into the discussion areas if you're actively trying to self-harm. Just make your bookmark go directly to the buy and sell and you never have to deal with it, and when those people croak sooner rather than later you get yourself some nice gear for a song at their estate sales.
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Apr 9, 2021 21:56
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https://www.kijiji.ca/v-general-electronics/winnipeg/kenwood-2-ways-for-sale-3-60-dollars-each-with-mics/1560370528 How's this for a basic transceiver to start with in the 70cm band? I've got some friends who are interested in going in on this and I'm hoping it'll be enough to finally push me to get licensed. It looks small enough that it's something I can stuff in a bike pannier as a portable rig which would be neat.
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Apr 13, 2021 01:48
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Motronic posted:I'm not sure why you would bother with a mobile radio to put on a bike. Just get a cheap chinese HT. I just figure it'd be a neat project to have a station that I can take out of my truck and stuff onto my bike when the fire bans this year mean the only way I can get out into the middle of nowhere is on my bike. If it was just for bike use then yeah an HT would be more convenient, but I'd also be using it at home or in my vehicle as well. It also wouldn't be the first stupid thing I strapped onto my bike for shits and giggles. Stuff like this looks cool, but it definitely makes more sense with like an HF setup. http://www.k5pa.com/Ham%20Radio/Bicycle%20Mobile.htm
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Apr 13, 2021 02:59
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My bike is already a hoss but yeah, probably no point in getting that over a dual band HT to start with if it's the same price. It's been a while since I looked at cheap handsets and I found a place with TYT TH-UV88 handsets for the same price. After looking around a bit they seem to be better than the Baofengs with regards to spurious emissions. Anyone here have any experience with them? https://baofengradio.ca/collections/analog-radios/products/tyt-th-uv88-dual-band-analog-two-way-radio https://www.youtube.com/watch?v=8pYrrdGF1UU https://www.youtube.com/watch?v=uW27RdBIsoE
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Apr 13, 2021 05:05
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Jonny 290 posted:there's enormous ham interest in StArLiNk because so many of them are weirdo preppers in lovely backwoods compounds. 99% of them have musk brain. It's a sad fall from when this used to be "the EE's hobby" I've been watching a bunch of videos on how to use and program the HT I just picked up and it was a roll of the dice whether I'd get a well informed radio enthusiast or weirdo preppers and HSLD larpers talking about poo poo like "tactical comms" with their Baofengs. I ended up going with that TYT TH-UV88 and it's been easy enough to use so far. The stereotype of it being old people talking about their ailments is hilariously true, but there was something endearing about the guy last night talking about getting the Lasiks and being so happy about being able to do stuff like again like... use more radios where before he was having trouble reading the instruments.
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Apr 26, 2021 20:07
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ickna posted:I’m partial to the Nagoya NA-771.. if you don’t mind a 16 inch whip for 2.5db of gain. ~$20 I've heard good things about the Nagoya, but the problem is that there are so many counterfeits out there that it can be a hassle to get your hands on a real one. The Super-elastic Signal Stick seems like a similarly good upgrade for an HT, and you're buying them directly from the guy who makes them so you know it's not a bootleg. The profit goes towards funding HamStudy, I believe. As soon as a couple of my friends also get their certificates and first radios I'm going to do a bulk order, since they no longer offer the $1 shipping to Canada unfortunately.
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Apr 29, 2021 15:54
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Looks like a connection point for a 300 ohm antenna. Here's how to make one if you have some scrap wire lying around. https://www.electronics-notes.com/articles/antennas-propagation/dipole-antenna/fm-dipole-antenna.php
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Sep 23, 2021 04:55
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Gettin' some strong UK vibes from these photos
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Sep 23, 2021 05:30
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Jonny 290 posted:we got a 30 foot dumpster in our driveway for a month back at the old house, i found a bolt and attached coax hot to it, hammered some scrap copper into the ground next to it for coax shield, and made several hilarious contacts one day on 20m and 40m ssb. tuners rule. My building's exterior is going to be undergoing an overhaul over the next six months which made me think of this post. I'm going to have ten stories x fifty meters of scaffolding adjacent to my balcony, is there any way I can leverage this into a stupid antenna?
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Apr 12, 2022 19:46
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Awesome, I'm gonna try starting with that Hallicrafters radio and if that goes well then I'll look into picking something up that's newer and can do SSB. I was never able to find my dad's DX400 so hopefully I can find something for cheap. My SDR line can be hooked up easily enough but I don't think there's much point? I can always give it a shot and compare it to the ADS-B cantenna that's been working really well for me. Here's where it's at today, still a couple more floors to go. 
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Apr 13, 2022 01:23
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Clamped a wire to the scaffold and it's definitely picking up way more signals. Right now I've just been checking the 2m and 70cm bands so I can compare it to my handheld and it's getting stuff loud and clear that my handheld can only barely make out if it hears anything at all.
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Apr 20, 2022 00:21
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I'm trying to view the hydrogen line by following this paper as a base, and so far I've got the thing bashed together at least. It was snowing today so I couldn't set it up outside, but it's working well enough to triangulate some spurious emissions on 1419 MHz somewhere on campus. If I want to fine tune things more it sounds like I need a VNA, but I'm not sure which one I should get. NooElec has the NanoVNA H4 and the NanoVNA v2 SAA2 for the same price ($163 CAD), and while it seems like I should just go with the latter because it has a higher frequency range, I'm sure there must be more to it than that which I'm missing. The guys in the microwave lab seem pretty interested in what I'm doing, but I couldn't work up the nerve to ask them if I can hook a piece of cookware up to a $100k Agilent VNA. 
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Feb 14, 2024 04:49
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Thanks for the tips. The one I picked up came in and I've been having fun testing all my antennas. I think I got the hang of it but I'm wondering if I'm missing any critical steps for using it properly. The first time I hooked it up to the radiotelescope I got this reading. That seems way too good to be true for my very first try at building the dipole with a 1/4 wave balun with no measuring tools other than a ruler. The reason I ask if I'm doing it right is because the coax inside the antenna mast broke and I had to rebuild it (didn't have proper strain relief, my bad), and now when I'm testing things my return loss isn't anywhere near as good nor is it centred in the right area (around a hundred-ish MHz off). As I'm testing it now, the VNA is connected much closer to the antenna (just a little below the balun), whereas before there was around two feet of coax before soldering on a connection. I was originally connecting all of the calibration standards directly to the VNA port before hooking up the feed line to the antenna. Am I correct in assuming that was going about it the wrong way, which explains the almost perfect values in the above image at my target frequency? I'm using all the same parts and the only thing different is shorter coax and cutting a new balun.
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Feb 23, 2024 08:39
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Fantastic, I think now I can safely assume that the values I'm getting now are realistic numbers that I was probably dealing with from the start and now I have to put some work in to center it onto my band of interest. To be honest, I was kind of disappointed when I first hooked it up and it looked that good, I really wanted to have to use the VNA to get it tuned and learn while doing so, and now it looks like I'll have that chance. I feel like I need to be less sloppy with the balun, but the chunk of dremeled PCB I'm mounting stuff too is also pretty janky.
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Feb 23, 2024 09:50
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Here's where I'm at so far, checking to see if I'm still doing things right.  I ran across this page while looking for tips on tuning a hydrogen line dipole, and he was having similar issues with the target frequency being lower than expected for the element dimensions. Apparently he wasn't taking velocity factor into account so he cut it a bit shorter until things lined up nicely. That worked up to an extent for me, but it still wasn't looking great at 1.42 GHz. I figured maybe I also needed to take velocity factor into account for the ¼λ balun. My best guess for the RG-174/U I got out of a scrap pile was a velocity factor of 0.66, so I shortened it by that amount and got the much better values in the picture. When looking online I'm seeing people say that velocity factor shouldn't matter for a Pawsey stub but it appears to be having some effect on mine. I don't know what I'm doing! Antenna design is fun, but hard!
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Feb 26, 2024 03:57
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 Went back to a 5.3cm balun after putting it in the reflector. It's so sensitive to movement and positioning, but I think this is the best I'm going to get. That sharp drop still seems suspect to me, but it's a very short coax now so I don't know what else it could be.
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Feb 27, 2024 06:53
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https://burningjustice.net/diy/wokscope/timelapse_01.mp4 Found out that it's relatively radio quiet in a friend's backyard so I set up there to collect data for 12 hours. Very happy with the results, even with the weird noise floor fluctuations going on. That spike at 1420.8 MHz seems to be an artifact from either the LNA or the SDR, but when it spikes up everything else drops. Might also be temperature related? Plenty of room for more experimentation, overall I'm pleased with imaging two areas that are redshifting and blueshifting so I can make some velocity calculations. The university is offering to reimburse me for parts because they want to make it part of their honours lab curriculum starting next year, which feels great. My lab report is going to double as a lab manual for the honours lab physics students next year, so while my statistical analysis capabilities are a bit rough I hope I can pull it together to make something decent. The actual procedure, theory, and construction stuff I have a good handle on and had a lot of fun with it so hopefully I can get my poo poo together to properly calculate my uncertainties and distributions. I already have a friend who wants me to do a guest talk at her high-school's science club so I'll also be preparing that, and when I'm collecting data in a park or other similarly radio-quiet area I get lots of interest and questions. It's like when I used to do outreach for astronomy, but because it's radio you can do it during the day which helps a lot with outreach type stuff.
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Mar 15, 2024 08:31
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