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Re: [Discuss-gnuradio] KD7LMO GPS sample and sample rate nomenclature

From: mgray
Subject: Re: [Discuss-gnuradio] KD7LMO GPS sample and sample rate nomenclature
Date: Fri, 26 Jan 2007 09:05:47 -0700 (MST)

Either I recorded them as 64-bit floats (double) or I did the conversion
from time in seconds to samples incorrectly.  The capture script I wrote
is located at:


The code calls the file_sink method.  I'm not sure what units/types it 

    dst = gr.file_sink (gr.sizeof_gr_complex, filename)

    head = gr.head(gr.sizeof_gr_complex, sample_count)

    fg.connect(src, head, dst)

So the recording may be 1 seconds, instead of 500mS.

On Thu, 25 Jan 2007, Chris Stankevitz wrote:

> Hi,
> KD7LMO provides a binary GPS recording, presumably made with the USRP 
> (thank you!).  It is advertised as "4msps / complex GPS Snapshot (500 
> mS)".  I use these ratios to determine what the file size should be:
> 500e-3 seconds
> 4e6 complex_samples / second
> 2 floats / complex_sample
> 32 bits / float
> 1/8 bytes / bit
> Multiply them all together and I get 16e6 bytes.  However, KD7LMO's file 
> is 32e6 bytes large.  Can someone explain the discrepancy or 
> misunderstanding?
> Thank you!
> Chris
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