[time-nuts] FE-5680A FAQ update: question about frequency synthesizer architecture

Javier Herrero jherrero at hvsistemas.es
Sat Jan 28 14:44:22 EST 2012

I've checked now that they do not seem to be any activity on the DDS SPI 
lines during normal operation. I've tried with several small offsets 
through the serial port, and the square wave at FSELECT seems to be same 
square, no appreciable duty cycle variation.



El 28/01/2012 20:32, ed breya escribió:
> The lower bits can be pulse width modulated to get finer resolution, 
> but it gets harder to maintain monotonicity. Eventually you run out of 
> processing resolution, or the control signal falls into the noise 
> floor, whether the system is digital, analog, or both.
> Ed
> Javier Herrero wrote:
> Sat Jan 28 18:38:53 UTC 2012
> It can be... but the resolution of the center frequency of two DDS
> frequencies would be limited to half DDS LSB... so not enough. I will
> try to monitor FSELECT and also to extract some SPI data if I found some
> free time today or tomorrow :)
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Javier Herrero
Chief Technology Officer                  EMAIL: jherrero at hvsistemas.com
HV Sistemas S.L.                          PHONE:         +34 949 336 806
Los Charcones, 17                         FAX:           +34 949 336 792
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