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

[Ellis, Duane]

steve> I don't observe any doppler shift when I move my hand/walk in the 
vicinity.
steve>> I can see the FFT plots change in shape on motion, but nothing is 
steve>> observed on the Waterfall sink.

If you want to see this, a QAM or BPSK constellation plot would be a better 
choice.

Have you gone through the math? What frequency change/shift are you expecting 
(mathematically) to see?

Here's an example from Georgia State University that explains the math.

This screen does the math for you (just plug in numbers)
        http://hyperphysics.phy-astr.gsu.edu/hbase/sound/dopp.html#c4

At 25C (77F) - a 440hz sound (the classic "A" sound) - 
With a 1 meter per second motion (speed of your hand waving) you see a +1.27hz 
increase approaching

A 10% change in frequency requires almost 30 meter/sec (aka: 67 miles per hour)

What is the scale/range of your waterfall graph? 
Given that scale - Would a 40hz change be visible?

--------

As an aside...

Clifford Stolls TED talk Video talks about this indirectly 
He's using a microphone + oscilloscope - to display the audio wave form.

https://www.ted.com/talks/clifford_stoll_on_everything?language=en

-Duane.