Архив за 14.06.2019

I’m never gonna get this back on.

I'm never gonna get this back on. submitted by /u/janispritzkau
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Exagear Windows Emulator with License

Exagear Windows Emulator with License submitted by /u/dankirm
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M2 & LRPT help request

M2 & LRPT help request submitted by /u/OneleggedPeter
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KerberosSDR • Re: Update rate not showing

I did run the tuner tests and they all came out fine.
I've been using the images provided - no manual installation. I can try giving the kerberos more power and see what that does

Statistics: Posted by stasia327 — Fri Jun 14, 2019 6:39 pm


KerberosSDR • Re: Update rate not showing

I should update as I started this thread, using the pre-made pi images and having good power sources (enough amps where it needs it, hint the kerberos needs more than the pi evidently) fixed my issues.

Though this doesn't answer why I could never get it to work with my own installs.

Statistics: Posted by TechCom — Fri Jun 14, 2019 6:35 pm


RTL-SDR Discussion • Re: Help with SSTV downlink from ISS on 145.8 MHz

If it is possible then I'd think a setting parameter would be published or shown by the help function.
The way I would try is to use a SDR program with bandwidth control.

Alan

Statistics: Posted by alanzfq — Fri Jun 14, 2019 6:16 pm


RTL-SDR Discussion • Help with SSTV downlink from ISS on 145.8 MHz

Hi folks

I am working on a simple RTL-SDR based way of receiving slow scan TV transmissions on 145.8 MHz from the International Space Station. The aim is that it's easy enough for secondary school teachers to follow and implement in class.

I'm having a few problems with hearing ground based voice transmissions that cover the ISS signal when it's passing over. Apparently there's a repeater on 145.7875 MHz, only 12 KHz away, and I hear them instead of the ISS.

Here's an example of the audio I'm getting;
https://soundcloud.com/user-135945298/i ... 90605-1356

I use rtl_fm on Linux (Raspbian on Raspberry Pi) to demodulate the FM with the following parameters;

CODE:

rtl_fm -M fm -f 145.8M -s 48k | play -r 48k -t raw -e s -b 16 -c 1 -V1 -
I then run QSSTV to decode the pictures.

My idea is that the FM bandwidth rtl_fm is listening to needs to be narrowed to exclude the repeater frequency from being processed. I'm currently not doing any Doppler correction because QSSTV can track the centre frequency of the tones and compensate automatically. I do have a python script that will do this though.

So if I can narrow the bandwidth rtl_fm is processing and do Doppler correction then I should be sorted right?

Trouble is, I am not sure how to do this with rtl_fm - is it possible? How do I do this?
Many thanks in advance

Dave

Statistics: Posted by Davespice — Fri Jun 14, 2019 12:59 pm


An SDR Wardriving kit

An SDR Wardriving kit submitted by /u/brains93
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Other SDR Devices • Re: MSi.SDR sound crackle pulses and spurs

no, in my instance it is not related to USB at all. These pulses are present with any gain and their pattern depends on LO frequency value. It doesn't depends on sample rate. I also tested with clean external lab power supply and ferrite beads to make sure that there is no issue with power supply. Tested it with RFI filters on USB cable. Nothing of my attempts doesn't affect that "pulse sound" issue at all. Also I tested it on different PC and notebook. There is no even a little correlation with power supply, USB noise or PC.

I also found that when you change LO, spurs are moving across bandwidth and at some frequencies they are merged together. Near these frequencies, these random pulses appears across entire waterfall and going to very loud. Also I tested EMI/RFI with RTLSDRv3 around this MSI.SDR pcb and there is no such pulses in reality. It happens inside chip due to some defect. So, this is definitely hardware defect.

Also, my MSI.SDR cannot work stable at 10 MHz sample rate. When I switch to 10 MHz, noise floor starts to jumping like crazy and all what I hear is just terrible noise, random oscillations, pulses and crackles :(

Also, I found that sometimes with 600 kHz filter and 2 MHz sample rate, sound periodically disappears and appears again. For example it plays sound for 2-3 seconds and then sound stops for a second and then playing again.

Also I found that crystal oscillator in MSI.SDR has very high phase noise. It leads to high "Batman ears" effect around clean sine source on the spectrum.

And also I found that my MSI.SDR has very high IMD distortions, it is much worse than RTLSDRv3. I connected both devices together, and MSI.SDR has distortions and curvature noise floor around power signals (45 dB above noise floor), where RTLSDR shows it with no distortions and with flat noise floor. I tried to connect MSI.SDR through bandpass filter which cuts just a very narrow piece of spectrum. But these IMD distortions are still present.

I'm very disappointed, MSI.SDR that I got works much-much worse than RTLSDRv3 (which costs just 21 USD).

Probably these MSI.SDR are attempt to sell factory rejected chips which is rejected from RSP manufacturing due to some defects. I'm just interesting, if other MSI.SDR also has such defects? Or it's just a random defect in my instance.

Statistics: Posted by radiolistener — Fri Jun 14, 2019 10:15 am


Question about CubicSDR Audio Out setting

When I select the "Audio Out" and select "default", everything works fine, but when I am clicking through different waterfall stations it removes the the Audio Out setting of default to blank and no audio. So every time I select a different waterfall I have to manually go back up and select default audio

Is there a way to keep it on default audio all the time?

submitted by /u/x_____________
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