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Jim Silly-Balls posted:This isn’t specifically radio related but radio adjacent. I picked up this oscilloscope. It’s a 2 channel 100mhz Instek from the early 00’s Found something, I'll start here https://core-electronics.com.au/tutorials/automating-test-equipment-with-python.html Beve Stuscemi fucked around with this message at 19:54 on Dec 21, 2021 |
# ? Dec 21, 2021 19:51 |
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# ? May 30, 2024 12:54 |
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More firsts: borrowed some gear and made my first HF contacts today. That is really addictive Vs tuning around on VHF and getting nothing at all. God, this is a whole new world! I worked North Carolina, Italy, and Russia on 50W with an 857 and a Buddipole knock-off. I need my own gear, pronto. Also worked another satellite today, managed to get into AO-91 really well and SO-50 again so this crappy antenna definitely isn’t a fluke. Surprised how simple it was to get into. Hand-aiming definitely not easy though. What’s the best iOS app for live tracking with azimuth/elev etc? Maybe tape my phone to the boom or make a little cradle for it.
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# ? Dec 22, 2021 17:55 |
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thehustler posted:More firsts: borrowed some gear and made my first HF contacts today. That is really addictive Vs tuning around on VHF and getting nothing at all. God, this is a whole new world! I worked North Carolina, Italy, and Russia on 50W with an 857 and a Buddipole knock-off. Yeah I was really not feeling this hobby after almost four years without an HF rig. If I hadn't gotten the 991A I probably would've sold my FT-60 and hosed off to another interest. HF is just another plane of existence compared to the smoothbrain Elmers that infest UHF/VHF.
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# ? Dec 23, 2021 23:29 |
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I really want one of those, the 991 is massive by comparison. Sure an internal ATU is nice, but not 5KG nice. Yaesu hosed by up discontinuing it.
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# ? Dec 23, 2021 23:43 |
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It was better than I expected. Not TOO heavy and also has 50W. If you’re doing portable and don’t mind the extra weight it’s a good choice.
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# ? Dec 24, 2021 01:01 |
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just got this on the last iss pass:
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# ? Dec 28, 2021 15:13 |
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could someone please take a look at this screenshot of my radio's waterfall, and help me understand this sudden change in "noise" signals? the screenshot shows the lower part of the MW band -- the strong signal on the left is 580 kHz for reference. you can see the "real" radio signals are continuous, but the "noise" signals have a sudden discontinuity! What could cause this discontinuity? I don't think i touched anything on my radio!
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# ? Dec 29, 2021 18:39 |
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Switching power supply, USB3 device, etc. come to mind first as "things around my radio that I'd be looking at". Have you put ferrite cores on all the cables in/out around whatever that is that's producing the waterfall to see if you can lower your noise floor?
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# ? Dec 29, 2021 18:48 |
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Motronic posted:Switching power supply, USB3 device, etc. come to mind first as "things around my radio that I'd be looking at". Have you put ferrite cores on all the cables in/out around whatever that is that's producing the waterfall to see if you can lower your noise floor? i haven't tried the ferrite cable chokes yet... the RFI situation in my shack is hardly ideal! It's on the 2nd floor, and I'm not permitted to punch holes in the walls or run cables out the window. So, the radio and antenna are completely ungrounded. The antenna is a telescopic whip, extended to its full length of about 116 cm. It's indoors, and very close to all kinds of noisy stuff: computers, speakers, computer monitors, laptops, cell phones, etc. I know there are many things I need to do before I can eliminate the noise. The ferrite chokes are a good suggestion, because I don't have to put holes in the walls or relocate my shack. But for the moment, I'm more interested in studying the noise than eliminating it! I know that there are different kinds of noise, and I'm hoping someone can identify this stuff based on the screenshot. Switching power supplies around the house would be my guess too. But, if that's right, what could cause them to change the frequencies of their emissions like that? Something happening with the electrical utility's equipment -- maybe a transformer?
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# ? Dec 29, 2021 19:34 |
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Do they go if you disconnect the whip?
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# ? Dec 29, 2021 19:44 |
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Helianthus Annuus posted:i haven't tried the ferrite cable chokes yet... the RFI situation in my shack is hardly ideal! It's on the 2nd floor, and I'm not permitted to punch holes in the walls or run cables out the window. So, the radio and antenna are completely ungrounded. Those vertical lines could theoretically be generated by something plugged in your house, even if it's far from the radio itself. My uneducated understanding is that sometimes the rfi can travel across building wiring. Possibly it could be generated by something in your neighbor's (if you have one) apartment or even from a neighboring building through the outside power lines since the wiring is close/actually connected somewhere. The best thing would be to turn off all power to the building and then turn breakers on one-by-one and check the waterfall each time. But it sounds like you probably don't have good access to that, so you could unplug everything in your apartment and then plug them back in one-by-one to see what generates which lines and also which lines are gone when everything's unplugged. If you have lines but nothing plugged in, then you can rule out stuff in your apartment causing it and your options to fix them start narrowing. One thing that's killing my noise floor right now are christmas lights -- ones on my house as well as neighbors'. It helps to have an external battery when testing this stuff so you can completely eliminate interference to the transceiver coming through the power lines. Buy yourself a big bag of ferrites/chokes because once you start hunting RFI and noticing improvements, you'll never stop seeking the interference.
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# ? Dec 29, 2021 19:50 |
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switching power supplies have notoriously unstable oscillators and you'll see shifts like that whenever something gets plugged into or disconnected from them, they heat up, they cool down, a stray neutron hits them, butterfly flaps its wings in Tibet...the list goes on. They suck real bad.
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# ? Dec 29, 2021 19:53 |
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thehustler posted:Do they go if you disconnect the whip? yes, thanks for asking! heres a screenshot of that happening. you can see the noise floor come up when i first lay hands on the antenna. then it goes mostly dark when i actually unscrew it out of the magnetic mount. you can see it come back when i screw it back in.
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# ? Dec 29, 2021 19:57 |
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Helianthus Annuus posted:I know that there are different kinds of noise, and I'm hoping someone can identify this stuff based on the screenshot. Switching power supplies around the house would be my guess too. But, if that's right, what could cause them to change the frequencies of their emissions like that? Something happening with the electrical utility's equipment -- maybe a transformer? Voltage changes from the utility, voltage sags in your house (i.e., fridge, oven, other high current devices turning on), the equipment on the load side of the switching supply changing loads, pretty much anything like that. I would expect it to be close to your receiver if it's coming through that way. If you really want to narrow things down run everything radio-related on battery and start turning thing on and off in your house. Or just start will being on battery and killing the main breaker. Then see what you have. Then start putting on ferrite chokes/rearranging cables to get your rig as quiet as possible. Then start turning things back on and see what's spewing what.
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# ? Dec 29, 2021 19:58 |
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Jonny 290 posted:switching power supplies have notoriously unstable oscillators and you'll see shifts like that whenever something gets plugged into or disconnected from them, they heat up, they cool down, a stray neutron hits them, butterfly flaps its wings in Tibet...the list goes on. They suck real bad. do you suppose all these noise bands are coming from the same switching power supply? am i just seeing harmonics from some lower fundamental frequency? or is there some other reason why i see noise at multiple, separate frequencies? Tommah posted:Those vertical lines could theoretically be generated by something plugged in your house, even if it's far from the radio itself. My uneducated understanding is that sometimes the rfi can travel across building wiring. Possibly it could be generated by something in your neighbor's (if you have one) apartment or even from a neighboring building through the outside power lines since the wiring is close/actually connected somewhere. it's fun for me to walk around with a portable AM radio, tuned to an "unused" frequency, and then walk around pointing the antenna at suspected sources of EMI. The moment I step outside the building, the most intense noise source goes away. But, that thing doesn't have a waterfall, so I can't be sure I'm hearing the same thing I'm seeing on my SDR's waterfall. Seems likely, though! Motronic posted:Voltage changes from the utility, voltage sags in your house (i.e., fridge, oven, other high current devices turning on), the equipment on the load side of the switching supply changing loads, pretty much anything like that. I would expect it to be close to your receiver if it's coming through that way. I suppose I should augment my portable AM radio by getting the SDR working on a laptop, and then take readings from various locations. And if I did that, I could also do as you suggest and shut off my power at the breaker, and see what happens.
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# ? Dec 29, 2021 20:16 |
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Helianthus Annuus posted:do you suppose all these noise bands are coming from the same switching power supply? am i just seeing harmonics from some lower fundamental frequency? or is there some other reason why i see noise at multiple, separate frequencies? YUP! They don't bother generating a clean sine wave for the 60khz or whatever it is chopper circuit, since they have a rectifier and filter after that. Just open palm slam a square wave on the AC input and deal with it in post
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# ? Dec 29, 2021 20:29 |
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Helianthus Annuus posted:yes, thanks for asking! heres a screenshot of that happening. Okay - just making sure they aren’t generated by the radio itself/having the gain up high, etc. Always good to check!
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# ? Dec 29, 2021 21:02 |
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Crusader posted:just got this on the last iss pass: I managed to get this with my baofeng held up to my mobile phone doing the decoding. I'm absolutely shocked it worked so well.
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# ? Dec 30, 2021 00:59 |
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yoloer420 posted:
drat, you really just put a speaker up to a mic, and it worked? i'm also shocked!
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# ? Dec 30, 2021 03:17 |
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would anyone like to look at another screenshot from my waterfall? this one is from the 80m band, someone was sending a signal that I don't recognize. Is this SSTV? I got the I/Q recording, so I can try to demodulate it, if it indeed is a SSTV signal. I also see that the person is printing their call sign directly to my waterfall, which is neat. I was looking up how to do this, and I read that some SSTV software will do this automatically.
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# ? Dec 30, 2021 03:20 |
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Helianthus Annuus posted:drat, you really just put a speaker up to a mic, and it worked? i'm also shocked! Yeah, that was the whole thing. I went outside at the time the ISS was going overhead, turned up the volume, held my phone next to the speaker and.. yeah. What surprised me even more, was I tried it without going outside (it was 44c/111f) and got this: After that I was reading about adding a wire counterpoise to HTs and tried it. It made a small improvement so I coiled the wire around my handheld for easy storage. Immediately I started picking up signals that I couldn't before, the result is *far* better than the rat tail approach, but I can't figure out why. I've checked the AARL Antenna book, and did some googling, but I can't find anything that would explain it. Does anyone have any idea why this works well? Repeaters that are 80KM away are now crystal clear without going outside, where before I couldn't receive them at all. I'd expect it would just induct a heap of noise into the antenna ground but.. yeah.
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# ? Dec 30, 2021 04:02 |
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previously the only 'ground' the radio had was the few square inches of whatever metal it had, and then then whatever that could capacitively couple to your hand. now you got a nice quarter wave of wire for all that return current to dump into and the transmitter and receivers are both happier tiger tail type counterpoises are very good, big fan here. dorky but i mean you're already operating a ham radio so
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# ? Dec 30, 2021 05:03 |
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Yes but the question is why specifically coiling it around the HT makes it better, I guess? Some sort of coupling?
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# ? Dec 30, 2021 11:26 |
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Even more so given that it's a coil wound around a speaker. That should be resulting in all sorts of garbage ending up on ground.
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# ? Dec 30, 2021 11:32 |
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Could be stronger coupling, could be that you made a little inductor that added some reactance and got it resonating better. It's really hard to say especially in the context of an HT, which is gonna have <gesticulates vaguely, shrugs> impedance range on the antenna port
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# ? Dec 30, 2021 17:22 |
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it always comes back to "RF is weird"
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# ? Dec 30, 2021 18:52 |
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Is there a website that shows when the iss will be over your location? I’m down to stand in my yard with my phone smashed to my baofeng
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# ? Dec 31, 2021 00:38 |
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I use Heavens Above but there’s plenty of others, n2yo.com is used a lot too. Just gotta pop your location in.
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# ? Dec 31, 2021 00:49 |
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heavens-above is pretty good but make sure to uncheck the 'visible passes only' cause that hella filters
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# ? Dec 31, 2021 01:15 |
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Jim Silly-Balls posted:Is there a website that shows when the iss will be over your location? I’m down to stand in my yard with my phone smashed to my baofeng I use Look4Sat or ISS Detector on Android. They're probably on iOS too. Hurry though, SSTV broadcasts stop soon!
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# ? Dec 31, 2021 01:41 |
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yoloer420 posted:I use Look4Sat or ISS Detector on Android. They're probably on iOS too. This post made me jump on getting an SSTV pic, and I am pretty sure I was recording when they stopped, around 1615UTC. Welp, better than nothing!
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# ? Dec 31, 2021 19:29 |
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I bought a little Yaesu FT7 a few months back. Made a random wire tuner. Chucked just under 5m of wire in a tree next to my window. Bam. Instantly i hear myself (in cw) on the Spanish webSDR (my location is the northwest of the netherlands). The depressing bit is that i don't hear poo poo from my own receiver. The noise floor (white noise with buzzing sounds every 10khz or so) is just so high, that even though i can get a signal out i can't hear stuff. For a white noise type of QRM, would an X Phase qrm eliminator be any good?
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# ? Dec 31, 2021 19:48 |
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the phasing noise reduction boxes are generally most useful when you have one 'good' antenna (that picks up signals + noise) and one 'crappy' antenna (that just picks up the noise, which you can then phase cancel against the main). I've got one, it's a neat gadget, but I generally don't use it that much.
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# ? Dec 31, 2021 19:50 |
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I have no idea if my bit of wire outside picks up enough 'wanted' signals, because of the big amount of noise. An indoor antenna will pick up plenty of noise, that's for sure. The meter on the FT7 says it's S9 on 80m LSB. I think the FT101 also indicates something in that order of magnitude. I can always go set up the stuff in the park, but it's much nicer to be able to do it from home. E: Ordered one. Will be a week at least before it gets here because of the christmas vacation that last forever here. LimaBiker fucked around with this message at 13:08 on Jan 2, 2022 |
# ? Dec 31, 2021 19:59 |
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I'm buying a 2m/70cm antenna to go on my roof. What connector type should I go with? The options are Type N and PL-259. I'm in Australia so I've got a lot of heat, dust, and sometimes rain.
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# ? Jan 7, 2022 03:19 |
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N if you wanna be a boy scout about it, yeah. They seal better. Performance difference isn't really noticeable, they're just much nicer connectors.
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# ? Jan 7, 2022 03:23 |
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Thanks, the cost difference is minimal if anything at all. I'll go Type N. Sadly I've just found out all the radio stores in my country seem to be on holiday. I'll order when they reopen.
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# ? Jan 7, 2022 04:32 |
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UPDATE: i was reading about digital SSTV today, and i saw a picture of a waterfall that looked just like the one I recorded! https://www.sigidwiki.com/wiki/WinDRM Apparently, if i want to decode this, I'm supposed to downloaded a sketchy unsigned .exe for EasyPal from this extremely 90s website http://www.g0hwc.com/easypal_setup_help.html I attempted to replay, demodulatem and decode this in EasyPal. I didn't get an image, but it did tell me the filename is supposed to be "de_W5NOW-18-new-jersey-picture-id622781084.jpg." Cool! But it told me the file was unrecoverable. It saved a 0 byte file to my drive, uselessly. I wanted to see exactly what data I got, but i found EasyPal to be not-so-easy in this instance. After doing a little more research, I found this thing https://github.com/DazDSP/EasyDRF which appears to be a more modern and less feature-rich implementation. EasyDRF also thinks the filename was supposed to be "de_W5NOW-18-new-jersey-picture-id622781084.jpg," but this time, it wrote 154 bytes to my drive. Well, here they are: code:
Well, thanks for reading my digital SSTV story.
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# ? Jan 11, 2022 02:49 |
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Helianthus Annuus posted:UPDATE: i was reading about digital SSTV today, and i saw a picture of a waterfall that looked just like the one I recorded! https://www.sigidwiki.com/wiki/WinDRM kind of a weird long shot, but the waterfall image looks like it is mirrored, like they transmitted it on LSB.. and the decoder is expecting the upper side band? I'm not sure how you would go about inverting the recording though.
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# ? Jan 11, 2022 05:29 |
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# ? May 30, 2024 12:54 |
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ickna posted:kind of a weird long shot, but the waterfall image looks like it is mirrored, like they transmitted it on LSB.. and the decoder is expecting the upper side band? I'm not sure how you would go about inverting the recording though. i omited a detail: The orientation of the callsign looked correct in EasyPal's waterfall, after it correctly displayed the filename. Still, i tried replaying the raw I/Q again, and demodulated the signal using the upper-sideband mode (instead of lower-sideband mode, the conventional choice on the 80m band). Didn't work at all! I had it right before, I guess. this tiny amount of data might be using what the EasyPal author calls "hybrid mode," which just uploads the image to some FTP server, and then uses the WinDRM protocol to encode a link. source: http://www.g0hwc.com/easypal_setup_help.html quote:The 2nd type of file to be sent with EasyPal is called Hybrid. This way of sending a file is much quicker but you are not receiving the image via the radio, you are only receiving a short header that tells EasyPal where to go and download the file and display it on your screen, This all goes on within the program. The sending station uploads "FTP" a file to a server then transmits its location and your program grabs it via the internet and displays it. This is nice when the bands are real busy as you have more chance of getting the short header than getting a 3 minute transmission. When receiving a Hybrid image there is no progress bar. Sadly, the author died in 2015, and so EasyPal's default FTP server is down. Now, people who keep using this app would need to run their own FTP servers. So even if it was "hybrid mode" i would need to know the login to some specific FTP server, and we don't know which one, because the URL isnt included in the transmission (its assumed to be set in the app). Here's a couple more links: https://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiplexing https://hamsci.org/sites/default/files/publications/2018_HamSCI/20180224_180_HamSCI2018_Engelke_AB4EJ_FT8Image.PDF
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# ? Jan 11, 2022 06:44 |