[hpsdr] NCO

[Ken]

With Mercury (and PowerSDR) there are a few magic frequencies where the NCO
hits the frequency exactly. But, on most frequencies, you will see what
looks like a random error of +/- up to 30 milli-Hertz.  But it is not a bug.
Knowing the exact way that Mercury works, you can calculate a correction to
tell you what frequency the radio is actually tuned to.  I used these
corrections in an FMT a few years ago and did quite well.  I had the Mercury
LO locked to a GPSDO.

 

Regards

Ken

KE2N

 

 

> On 12/9/2012 5:09 AM, Graham / KE9H wrote:

> 

>> /PowerSDR itself, as used with Flex radios, and as it was used with 

>> Mercury/Ozy, does not contribute to frequency error. It gets a packet 

>> of data, and returns a packet of processed data. As long as the 

>> packets are sent and received in time with the clock domain in the 

>> radio, and you are getting your receive audio through the
speaker/headphone jack on the radio, you should not see any errors from
PowerSDR.

>> /

> 

> I suppose that in PowerSDR there is, as in any other SDR program, an 

> NCO used to bring to zero IF the frequency of interest. So, at least 

> theoretically, an error in the computations of that NCO could cause a 

> tuning error.

> 

> Just a speculation. I don't have PowerSDR and I am not speaking from 

> experience on it.

> 

> --

> /*73 Alberto I2PHD*/

> 

Yes, all things are possible when software "bugs" are present.

 

:-)

 

--- Graham

 

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