Forum

Welcome Guest 

Show/Hide Header

Welcome Guest, posting in this forum requires registration.





Pages: [1]
Author Topic: Processing doppler data from a .wav file
boffin
Beginner
Posts: 15
Permalink
Post Processing doppler data from a .wav file
on: December 6, 2012, 03:45
Quote

Greg

While I'm waiting for my power splitter to arrive from Minicircuits, I thought I'd have a look at the software to understand how it works.

In the read_doppler.m file, I notice that the data is read from the .wav file in blocks of 11025 samples (0.25 seconds worth of data at 44100 samples/sec). Is there a good reason for using 11025 rather than a power of 2, e.g. 8192 or 16384?

I ask because the ifft function can only use the FFT when using data blocks of length 2^N, otherwise it has to use a slower technique to compute the Fourier Transform. I intend to rewrite the software using Fortran 95 as this will be much faster, hence my question.

charvatg
Administrator
Posts: 115
Permalink
Post Re: Processing doppler data from a .wav file
on: December 6, 2012, 18:29
Quote

The longer duration of data block the higher the SNR for this mode of operation. So 0.2 s should provide about 3dB more SNR than 0.1s with higher doppler resolution too.

But there are trade offs, 0.01s has very few samples and therefore lower SNR and poor doppler resolution.

My suggestion is to pick a power of 2 close to about 0.1s of data. That should be the sweet spot!

Good luck, post your results soon as you can.

Greg

Pages: [1]
Mingle Forum by cartpauj
Version: 1.0.34 ; Page loaded in: 0.031 seconds.