Search found 23 matches

by jpsa
Tue Feb 14, 2017 1:40 pm
Forum: Code Corner
Topic: Raspberry Pi problem?
Replies: 18
Views: 24741

Re: Raspberry Pi problem?

That looks like HDMI interference to me. Each state lasts for a variable period of typically an hour or two. Does this happen to correlate with your screen saver? ;-) Thanks for the thought, but I'm pretty certain that's not it: the noise switches on and off in the middle of the night, it looks ide...
by jpsa
Sat Feb 11, 2017 10:37 am
Forum: Code Corner
Topic: Raspberry Pi problem?
Replies: 18
Views: 24741

Re: Raspberry Pi problem?

In fact the problem is visible directly in the IQ data passed to the stream callback... iq.png Also suspicious is that the average spacing between noise bursts is 126 samples, which is exactly one quarter of the numSamples=504 samples passed to the stream callback. This data was taken with no antenn...
by jpsa
Fri Feb 10, 2017 6:15 pm
Forum: Code Corner
Topic: Raspberry Pi problem?
Replies: 18
Views: 24741

Raspberry Pi problem?

I've got some code, written against the SDRplay API, which searches for intermittent signals caused by reflections from the ionisation trails left by meteors. It does this by running an FFT over IQ samples and then searching the result for a spike caused by such a reflection. This seems to work nice...
by jpsa
Wed Jan 11, 2017 8:16 pm
Forum: Code Corner
Topic: rfchanged etc. semantics
Replies: 2
Views: 6026

Re: rfchanged etc. semantics

Thank you!
by jpsa
Tue Jan 10, 2017 2:27 pm
Forum: Code Corner
Topic: rfchanged etc. semantics
Replies: 2
Views: 6026

rfchanged etc. semantics

Hi... I'm trying to work out what the semantics are of the grChanged , rfChanged and fsChanged parameters to the mir_sdr_StreamCallback_t stream callback. I have a couple of questions which don't seem to be answered by the documentation... If, say, rfChanged is non-zero, does that indicate that the ...
by jpsa
Tue Jan 03, 2017 11:18 pm
Forum: SDRplay related
Topic: SDRplay RSP1 gain control
Replies: 8
Views: 9523

Re: SDRplay RSP1 gain control

Oh... I've just read more carefully and realised the gRidx parameter is in-out. So when I make the second call gRidx = 50 SetGrAltMode(&gRidx,TRUE,...) what actually happens is that gRidx is returned as 74, and the resulting RSP setup is BB GR=74, Mixer GR=0, LNA GR=0 -> System GR=74 I.e. the same S...
by jpsa
Tue Jan 03, 2017 10:50 pm
Forum: SDRplay related
Topic: SDRplay RSP1 gain control
Replies: 8
Views: 9523

Re: SDRplay RSP1 gain control

In that case I still don't understand what you're saying! Perhaps I'm being thick, but my reading of the API documentation and gain reduction tables says that if, for a band 1/2/3 frequency, I call SetGrAltMode(50,FALSE,...) , I get BB GR=50, Mixer GR=0, LNA GR=24 -> System GR=74 If I then turn the ...
by jpsa
Tue Jan 03, 2017 7:44 pm
Forum: SDRplay related
Topic: SDRplay RSP1 gain control
Replies: 8
Views: 9523

Re: SDRplay RSP1 gain control

That's what we do - I can't speak for other SDR application authors.
Where 'we' means SDRuno, I assume?

Thanks again!
by jpsa
Tue Jan 03, 2017 1:41 pm
Forum: SDRplay related
Topic: SDRplay RSP1 gain control
Replies: 8
Views: 9523

Re: SDRplay RSP1 gain control

Thank you! A couple of follow on questions, though... I can't see the behaviour you describe in the SetGrAltMode gain reduction tables. Take a requested gain reduction of 50 dB in the 'up to band 4/5' table as an example: the table says I get a gain reduction of 74 dB with the LNA off, and 50 dB wit...
by jpsa
Sun Jan 01, 2017 10:32 pm
Forum: SDRplay related
Topic: SDRplay RSP1 gain control
Replies: 8
Views: 9523

SDRplay RSP1 gain control

I'm been trying to understand how gain control works when using SDR Console V3 with an SDRplay RSP1. I *think* the following is what's going on, but I'd welcome confirmation! The RSP gain can be controlled in either 'normal' (mir_sdr_SetGr), or 'alternate' (mir_sdr_SetGrAltMode) mode[1]. The latter ...