[USRP-users] 10us+ sample delay between daughterboards

Marcus Müller marcus.mueller at ettus.com
Thu Jul 23 10:03:35 EDT 2020


ah perfect!

Re: post modifications
If you like GRC code generation, you will love Python snippets, which
allow for code insertion in the generated GRC file for exactly these
kinds of things.

On 23.07.20 15:50, Marcus D. Leech via USRP-users wrote:
> On 07/23/2020 06:13 AM, Marcus Müller via USRP-users wrote:
>> I also just realized that you can be reaaaally silly. If you have a
>> transistor and two resistors to spare, use the GPIO front panel
>> connector to generate a faux-PPS pulse, buffer it using the transistor,
>> and feed it back to the backpanel PPS input... might save you the extra
>> device, but of course the RPi solution is still elegant, as it allows
>> for not-quite-but-at-least-close-ish NTP synchronicity.
>>
>> Cheers,
>> Marcus
>>
> You don't need any external hardware at all.
> 
> B2xx, X3xx, N3xx all have a synthetic internal 1PPS if there is no other
> source.
> 
> The code generated by GRC for the "unknown PPS case" needs to be
> post-facto modified so that instead of setting a 0, it sets it to system
>   time (or whatever you desire).  This is simple to do.  It really would
> be nice if gr-uhd had an option to do this instead of setting to 0, but
>   it doesn't.
> 
> 
> 
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