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Re: [Discuss-gnuradio] USRP data rates
From: |
Richard Clarke |
Subject: |
Re: [Discuss-gnuradio] USRP data rates |
Date: |
Thu, 09 Aug 2007 16:41:35 +1200 |
User-agent: |
Thunderbird 2.0.0.6 (Windows/20070728) |
Actually I believe 16MHz is only achieved by reducing the sample bit
depth from 16 to 8, which I've read somewhere can be done.
8 Mega complex samples per second -> 8MHz when the real and imaginary
parts of the complex sample are each 16 bits wide. (=32Mbytes/sec)
16 Mega complex samples per second -> 16MHz when I/Q are reduced to 8
bits each (=32Mbytes/sec)
Somebody correct me if I'm wrong but I'm pretty sure that's right.
Cheers
Richard
Lisa Creer wrote:
The USRP sales brochure lists as a feature "Capable of processing
signals up to 16 MHz wide". I can only figure out how it can process
signals up to 8 MHz wide. What am I missing?
Since samples sent across the USB are 16-bit signed integers (16-bit I
and 16-bit Q for complex samples) that makes each complex sample size
4 bytes. Since the USB max is 32MB/s, we have a limit of 8MS/s which
translates to an effective bandwidth of 8MHz wide.
I noticed that there is another method besides usrp.source_c() to
retrieve data from the USRP, it is usrp.source_s(). Is this returning
an even smaller sample that would somehow get us to the 16 MHz wide
bandwidth? What exactly is this method returning?
Thanks in advance.
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