Re: [Discuss-gnuradio] changing the vctcxo

[Hans Glitsch]

Hi,
Thanks for the replies.

Yes, I have had it working with the rational resampler, but I'm trying to 
eliminate that block.  I'm eventually going to use a very low power, fanless 
pc to run the software, so we're trying to shave off as many cycles as 
possible.

I attached an external signal generator at 38.4MHz and decimated by 250 to 
get down to a sample rate of 153.6KHz per channel (we use four rx channels). 
This works well, gives the needed bandwidth, and lowers the usb data rate 
down to a minimum.  If I can replace the vctcxo for a few dollars and 
eliminate this block, then I think it's worth it.

I just found this one on Digikey: 
http://www.abracon.com/Oscillators/ASVTX11.pdf

I'm not an experienced hardware guy, but it looks like it would work in the 
usrp.  Please tell me if I'm wrong.

Thanks,
Hans



----- Original Message ----- 
From: "Eric Blossom" <address@hidden>
To: "Hans Glitsch" <address@hidden>
Cc: "gnuradio mailing list" <address@hidden>
Sent: Thursday, March 08, 2007 3:25 PM
Subject: Re: [Discuss-gnuradio] changing the vctcxo


> On Thu, Mar 08, 2007 at 02:44:12PM -0800, Hans Glitsch wrote:
> > Hello,
> >
> > I want to change the clock on the usrp.  Anyone know of a mail order
> > place that would have the right kind of vctcxo at 38.4MHz ?  I tried
> > Digikey and Mouser. no luck.
> >
> > Thanks,
> > Hans
>
> Not sure about where to get them.
> Are you sure you need to reclock the USRP?
>
> How about using the rational resampler with N = 3, M = 5?
> At the data rates I suspect you're running at, this shouldn't be a
> problem.
>
> See gnuradio-examples/python/audio/test_resampler.py for an example.
> The example is at audio, but it works fine at IF too.
>
> Eric
>
>
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