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Re: [Discuss-gnuradio] Run USRP at alternate clock frequency?
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] Run USRP at alternate clock frequency? |
Date: |
Fri, 10 Mar 2006 13:48:52 -0800 |
User-agent: |
Mutt/1.5.9i |
On Fri, Mar 10, 2006 at 11:21:08AM -0500, Clark Pope wrote:
>
> I would like to run my USRP off a 44 MHz clock instead of the 64 MHz clock
> that is currently used. A couple reasons:
> 1. the 64MHz rate exceeds the USB bandwidth even with byte-wide samples
> (64*8 = 512 mbps)
> 2. 44 MHz works much better for the wlan signals I'm after
>
> So the questions are:
> 1. can I generate a 44Mhz clock from the 64 MHz or do I have to change the
> crystal?
You need to change the crystal.
You'll also need to change the definition of
/*!
* \brief return frequency of master oscillator on USRP
*/
long fpga_master_clock_freq () const { return 64000000; }
in usrp_basic.h The rest of the code should follow, though I haven't
tested it. YMMV, patches welcome ;)
> 2. If I change over to 44 MHz will everything else still work? Especially
> the dbs and flex2400 boards?
Not sure about those. Paging Matt Ettus, paging Matt Ettus...
Eric
[Discuss-gnuradio] DC on antenna, Clark Pope, 2006/03/10