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Messages - IQ_imbalance

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SDR - Software Defined Radio / Re: RTLSDR based scanner for P25
« on: January 19, 2019, 1516 UTC »
I'm not a hardware (or software!) guy so probably not the most informed opinion....but i wonder if dedicated hardware still has the edge for scanning purposes.  I think the fast scanners do about 100 channels/s (of course, you have to identify the channels first!), but with the wide bandwidth of the SDRs it would make sense that they could identify and track transmissions a lot faster _as long as the transmissions are in that reception bandwidth_!  I think it would be an interesting exercise to build something on top of a framework like rtl_power that grabs a power spectrum over a chunk of bandwidth and then shifts to the next chunk, etc. while looking for repeated transmissions on a frequency over a user-defined time frame.  Unfortunately by the time i have those skills everything will be digital and encrypted, probably  :-\ >:(

Anyone care to comment on the bottleneck is for SDR based scanners....data transfer over the network, demodulation, ??? 

There's also the issue of with things going digital, it's not so much the # of different frequencies you can scan but whether or not you can parse the data coming in.

SDR - Software Defined Radio / Re: RTLSDR based scanner for P25
« on: January 15, 2019, 2136 UTC »
ARGH.  It's decoding the traffic (or at least recognizing broadcasts from the various talkgroups) but I can't get it to push the decoded audio to my headphones.  The headphones and software audio device works (at least for speaker-check!), but I don't know if it's a decode problem or a communications problem between rx.py and the audio system :(

SDR - Software Defined Radio / RTLSDR based scanner for P25
« on: January 15, 2019, 0239 UTC »
Ran across this tutorial, and it worked very well for getting a somewhat operational (still working on audio issues!) scanner going based on a rtl-sdr stick and a Raspberry Pi...


HF Mystery Signals / Re: UNID 9000 kHz 1914 UTC 11 Jan 2019
« on: January 12, 2019, 2021 UTC »
Thanks!!  No point chasing TDoA if it's just analyzing noise. 

One update....there's some drift in the carrier this afternoon.  Looks like it's a few Hz below 9000kHz now, but drifting back up.....

HF Mystery Signals / Re: UNID 9000 kHz 1914 UTC 11 Jan 2019
« on: January 12, 2019, 1823 UTC »
Has it moved again?  Would be nice to catch some indication on the spectrum that there was a switch.....

Any TDoA experts care to weigh in?  Are we just chasing timing errors or is this carrier really being broadcast at multiple sites?

HF Mystery Signals / UNID 9000 kHz 1914 UTC 11 Jan 2019
« on: January 11, 2019, 2017 UTC »
Maybe our 8000kHz carrier moved to a new frequency?  -87dBm here, started around 1914 UTC 11 Jan.  The spectrogram looks very similar. TDoA is all over the place, but seems to converge in the midatlantic area somewhere. 

HF Mystery Signals / Re: UNID 8000kHz persistent signal
« on: January 11, 2019, 1723 UTC »
Back on for ~4 min 1719-1723 UTC 11 Jan and intermittently for a few minutes after:  TDoA suggests not on the east coast this time:

HF Mystery Signals / UNID 8000 kHz 1434 UTC 10 Jan 2019 signal
« on: January 11, 2019, 0202 UTC »
Strong carrier (-85 dBm at my location currently); about 3Hz wide; might be LSB?.  Has been on since at least 1434 UTC 10 Jan.  TDoA during the day (~2000 UTC) suggests possibly two transmitters...one east coast, one midwest. 

1958: steely dan
2000: station ID as Yeah Man Radio & more steely dan

S2-3 w/ fades.  SIO 333-ish

Booming here....S5+, SIO 555

1852:  another speech

Equipment / Re: Eddystone 830-4
« on: December 08, 2018, 0410 UTC »

SIO 444.  Some minor fading.

0242: reporting on the Sea of Azov incident

via WYFR.  Grrr. 

Clandestine Stations / Radio Marti 7355 AM 0227 UTC 27 Nov 2018
« on: November 27, 2018, 0228 UTC »
SIO 555.  Not a trace of jamming, signal peaks up to S8 (!)

Just above the noise floor here.  Off at 2237

Drum intro, then jazz.....S4
2140: station ID

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