Re: [Discuss-gnuradio] Doppler shift on waterfall plot with audio signal

[Garver, Paul W]

I'm not familiar with your application. But you would get better frequency 
resolution for the same length FFT if you decimate after the BPF. It would 
probably be easier to see what is going on. Is there a reason you are 
significantly oversampled?

Paul Garver


> On Oct 21, 2016, at 3:31 PM, Chris Kuethe <address@hidden> wrote:
> 
> I've been meaning to do some more experimentation here using CW, FMCW,
> and chirps.
> 
> You should be seeing a bright line down the middle of the waterfall.
> If not, your hardware isn't working - I'm thinking it's your speakers
> since you do seem to be gettting *something* from the microphone on
> your FFT. You won't hear the tones since they're ultrasonic, but is
> your sound muted?
> 
>> On Fri, Oct 21, 2016 at 10:01 AM, Steve Gough <address@hidden> wrote:
>> Hi All,
>> 
>> I am interested in analyzing the doppler shift of a transmitted signal.
>> 
>> As a first step, I want to see if I can capture hand movements in a
>> Waterfall sink for an audio signal (tone). For that I use a flow graph like
>> the attached screenshot based on
>> https://github.com/ckuethe/gnuradio-examples/tree/master/doppler_sonar and
>> https://www.youtube.com/watch?v=9trGfdcMPtk&noredirect=1.
>> 
>> I don't observe any doppler shift when I move my hand/walk in the vicinity.
>> I can see the FFT plots change in shape on motion, but nothing is observed
>> on the Waterfall sink.
>> 
>> Could you please tell me if I am missing something here?
>> 
>> The observed waterfall spectrogram is also attached.
>> 
>> Thanks,
>> Steve
>> 
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> 
> 
> 
> -- 
> GDB has a 'break' feature; why doesn't it have 'fix' too?
> <Screenshot_2016-10-21_12-46-58.png>
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