[hpsdr] clocking janus

[Greg - ZL3IX]

Hi Bruce,

I have also had problems with the 10 MHz input, but my problem was on 
Penny.  I have modified the Penny code and added a couple of ns of 
debounce.  If you are interested, let me know directly, and I will dig 
out the code for you over the weekend.

73, Greg, ZL3IX

Bruce Walker wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>   
>
> ------------------------------------------------------------------------
>
> Last night, I finally got around to hooking up a GPSDO (Thunderbolt) 
> to Atlas.  My immediate goal is to get precision sampling (frequency) 
> from Janus.  I'm not a HW engineer, and my interface from the 
> Thunderbolt is pretty naive: terminated with 50ohms, then coupled 
> through a capacitor to a voltage divider between 3.3V and GND into 
> C16.  I don't have a scope, so if anyone has a suggestion of proper 
> components for an interface which gets the levels right from a 
> ~10dBm/50ohm Tbolt input, please share.
>
> Using PowerSDR PennyMerge, if I have Penny in the system and select 
> Atlas for 10MHz, it seems to work correctly. Sampling frequency is 
> spot on as far as I could easily measure, though there are occasional 
> short drop-outs on the audio which lead me to believe the clock is 
> marginal.  With Penny not installed, it does not work: Janus seems to 
> revert to it's own oscillator rather than lock to the 10MHz, off by 
> ~100ppm.  Not clear to me why this would be, unless just having Penny 
> further down the bus is providing better termination for the signal.  
> I have not played with slot location any further.
>
> If anyone has gone through this exercise or has suggestions to "do it 
> right", please advise.  I suppose I could put something like a Clock 
> Block in front of it to drive it with a stiffer square wave, but 
> looking for a minimal robust solution.
>
> --bruce w1bw
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> HPSDR Discussion List
> To post msg: hpsdr at hpsdr.org
> Subscription help: http://lists.hpsdr.org/listinfo.cgi/hpsdr-hpsdr.org
> HPSDR web page: http://hpsdr.org
> Archives: http://lists.hpsdr.org/pipermail/hpsdr-hpsdr.org/


 1224781052.0