SDR (Software Defined Radio)

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24 Aug 2023
@yalekthelembine5435:matrix.orgyalekthelembine5435I use HDSDR00:36:13
@yalekthelembine5435:matrix.orgyalekthelembine5435and although the stinking v4 has been released, Im gonna probably wairt00:36:37
@issoumachankla:matrix.orgIsaBangIt Linux compliant?00:38:53
25 Aug 2023
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26 Aug 2023
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28 Aug 2023
@the_gamer_guy:gamerscrackshack.ca@the_gamer_guy:gamerscrackshack.ca joined the room.02:16:27
@the_gamer_guy:gamerscrackshack.ca@the_gamer_guy:gamerscrackshack.ca do you guys have any tips for figuring out what this medium and shortwave band interference im getting is? it starts at 500 khz, really peaks in strength at 0.8-1.2 MHz and finally tapers off around 4 MHz. it sounds like a really aggressive sawtooth wave that kind of pulses in amplitude. ive tried all the obvious stuff. different laptop, shut down my entire house, etc. its just everywhere it seems like. 06:10:24
@the_gamer_guy:gamerscrackshack.ca@the_gamer_guy:gamerscrackshack.ca someone on reddit suggested powerline interference. i do notice that the noise decreases when it rains and after it rains for a short time. would that confirm that theory? 06:12:34
@sa2kng:matrix.orgsa2kngI recommend hooking up a oscilloscope for those frequemcies, preferably with FFT functionality. 06:42:40
@sa2kng:matrix.orgsa2kngwhat sdr are we talking about ? antennas, preamps, cables ?06:44:55
@sa2kng:matrix.orgsa2kngif you have a laptop, going out with it and the sdr + small antenna you can perhaps see if it changes.06:51:04
@sa2kng:matrix.orgsa2kngif it's possible, filtering out the interference, not possible with wideband crap thou06:52:44
@issoumachankla:matrix.orgIsaBangSmart oscilloscope are accurate 08:08:29
@okoy:matrix.orgAler Estigoy joined the room.11:26:33
@okoy:matrix.orgAler Estigoy
In reply to @yalekthelembine5435:matrix.org
yes mate it is
@okoy:matrix.orgAler Estigoy
In reply to @yalekthelembine5435:matrix.org
what dongle?
i am using chromebook lenovo
@okoy:matrix.orgAler Estigoy
In reply to @okoy:matrix.org
i am using chromebook lenovo
rtl sdr dongle
@issoumachankla:matrix.orgIsaBangE4000 or 820 tuner ?12:07:43
@the_gamer_guy:gamerscrackshack.ca@the_gamer_guy:gamerscrackshack.ca sa2kng: Ive got the NESDR Smart XTR with the Ham it up plus upconverter. This bundle, specifically: https://www.nooelec.com/store/nesdr-smart-xtr-sdr.html

I have a long shielded USB cable that I use to get the dongle away from the EMI of the laptop with great success in that regard. I've tried using both the monopole that comes with the bundle and a 2m dipole i bought afterwards. The monopole seems to give me the best signal on MW and SW, but it only barely works when the laptop isn't grounded. The dipole doesn't give as strong of a signal but it works the same with the laptop grounded or not. Both get absolutely hammered by the interference and the SNR seems to be the same on both : /

I took my setup to a cottage we rented last year and the buzzing interference wasn't there. Noise floor was really low, and at night I actually briefly managed to pick up KVOH broadcasting from LA on the shortwave band (I'm in eastern canada for reference). I also heard lots of stuff on the 80 & 40m ham bands. At home they're always just noise.
@sa2kng:matrix.orgsa2kngOk, I do have the ham it up as well, not used it for ages thou. regarding antennas and the setup specifics, it is really important that this is done right and not just the easy way. you cannot use the usb cable as a ground return, the antenna ground needs to be on the sma side of the sdr, at the feedpoint of the antenna or close, depending on type. take the example with a monopole, this should be grounded as close as possible to where it is mounted. the coax can benefit from a choke here as well so to isolate the crap coming from that side. in the shack you can also put a choke on the coax close to the sdr, this way you create a decent separation of all the interference conducted towards the antenna. if you are using dipoles, these need to have some sort of balun and impedance matching, impedance not as important for rx but the balanced part is. 21:37:51
@sa2kng:matrix.orgsa2kngmy setup for shortwave is TRX - choke - coax that runs part way down in the ground (few cm deep) - choke balun + lightning protection + ground rod - antenna(s)21:40:20
@sa2kng:matrix.orgsa2kngIf I omit any part of that, I get more noise in the RX. 21:41:20
@sa2kng:matrix.orgsa2kngI did also try out the mini-whip, but it was just way too sensitive to mount anywhere close to the house (5-10m not sufficient). operating it with a handheld sw radio I got decent results some 100m away from any buildings, NDB beacons on ~300kHz easily audible21:43:10
@the_gamer_guy:gamerscrackshack.ca@the_gamer_guy:gamerscrackshack.ca interesting... So would I ground the case of the dongle, or should I connect the ground to the brass on the SMA connector? The monopole doesn't have anywhere for me to ground it except there. The dipole I bought is part of a kit with mounting equipment and it did say it came with a balun installed in the base mount. It actually works extremely well for higher frequencies. FM band, marine, air traffic, 2m & 70cm ham etc. In terms of actually grounding, do I need to drive my own ground into the dirt, or does my house ground work? 23:17:13
29 Aug 2023
@kmcdon:matrix.kmcdon.comkmcdon changed their display name from notbrad to bard.04:19:36
@sa2kng:matrix.orgsa2kngthat small dipole and the one that comes with the kit is mostly vhf and uhf, as it is about 1/4 wavelength elements. I'm not suggesting you use these for anything in the low MHz range, rather get some longwire or loop for this and try using my tips. grounding in the house carries a lot of crap from all the equipment hooked up to it. it suffices as station ground, but I would not use it as antenna ground. conducted noise is very hard to get rid of, it is carried by the power cable, usb cable and coax shield and is picked up by the antenna and fed into the receiver. you want to isolate this in every step. chokes on power, usb and coax cable.06:27:49
@sa2kng:matrix.orgsa2kngas you were speaking of short and medium wave I'm using that as the topic, vhf and uhf is a bit different as you probably have seen. there's a lot less noise there, but the propagation works very differently as well so we are basically talking line of sight. these also benefit from properly using chokes, and baluns where needed (dipoles).06:32:47
@kmcdon:matrix.kmcdon.comkmcdon changed their display name from bard to kmcdon.14:08:16
@the_gamer_guy:gamerscrackshack.ca@the_gamer_guy:gamerscrackshack.ca I see. Thanks for the tips. 17:55:42

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