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Re: [Discuss-gnuradio] USRP2 - external clock pps python example

From: Matt Ettus
Subject: Re: [Discuss-gnuradio] USRP2 - external clock pps python example
Date: Wed, 13 Apr 2011 11:46:45 -0700
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On 04/13/2011 11:31 AM, Burak TUYSUZ wrote:
> It does not say if it is the falling edge or the rising edge of the
> pps. Is it possible to specify that or is it defined?

The PPS is *always* recognized on the rising edge of PPS.  To change
this you would need to change the FPGA.  The change would be trivial,
but I don't think that's what you'd want, since the rising edge is
essentially a universal standard.

The setting which Josh mentions allows you to choose whether PPS is
sampled on the rising or falling edge *of the clock*.  This is important
because there are varying phase differences between the PPS and 10 MHz.
 You should connect your source and see which way works better for your
particular source.


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