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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:
http://www.kd7lmo.net/ground_gnuradio_software.html
The code calls the file_sink method. I'm not sure what units/types it
generates.
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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