RE: [Discuss-gnuradio] Changing external reference frequency with USRP2...

[Ian Holland]

Thanks Matt

I tried to change to get the external reference frequency to be 36 MHz, by 
setting B to 50 (i.e. 0x32) and R to 36 (i.e. 0x24). To do this, I modified 
lines 43 and 85 respectively to the following:

ad9510_write_reg(0x06, 0x32);
ad9510_write_reg(0x0C, 0x24);

However, when I rebuilt the firmware (txrx.bin) and wrote it to the SD card,
I was no longer able to see an OFDM signal I had been transmitting from another 
SDR at 2.4 GHz. This occurred both when I had configured the receiving SDR to 
lock onto the 36 MHz reference
(device->config_mimo(usrp2::MC_WE_LOCK_TO_SMA))
And when I configured the receiving SDR to use its internal reference
(device->config_mimo(usrp2::MC_WE_DONT_LOCK))

Have I done something wrong in my modifications? If so, can you please suggest 
what I am doing wrong? According to the AD9510 datasheet I believe my changes 
should have been correct.

Best Regards

Ian.

-----Original Message-----
From: Matt Ettus [mailto:address@hidden
Sent: Saturday, 14 August 2010 2:15 AM
To: Ian Holland
Cc: address@hidden
Subject: Re: [Discuss-gnuradio] Changing external reference frequency with 
USRP2...


gnuradio/usrp2/firmware/lib/clocks.c, starting at line 40.  You probably
want to read the AD9510 datasheet to help with selecting values.

Matt


On 08/13/2010 12:34 AM, Ian Holland wrote:
> Hi
>
> I have read on the FAQ that is possible to change the external reference
> frequency for the USRP2 from 10 MHz to another value simply by changing
> one line in the firmware.
>
> However, I have as yet been unable to locate the actual source file in
> which I need to make this change, and what the name of this variable is.
> Could someone please let me know?
>
> Many Thanks
>
> Ian.
>
>
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