[hpsdr] Diversity experience.

[Joe Martin]

> If the bit is not set then the two receivers are updated simultaneously and therefore 

I typed too quickly, sorry.  I meant: 

"If the bit is not set then the two receivers are NOT updated simultaneously and therefore…”
 
On Nov 14, 2015, at 1:59 PM, Joe Martin wrote:

> Hi Kjell,
> 
> This suggests to me that perhaps the Command and Control bit C4[7] when C0=0000_000x, the so-called “Common Mercury Frequency” control bit,  is not being set when not in CTUN in PowerSDR and frequency is changed.  This control bit tells the firmware to assign identical frequencies/phase words to the two receivers simultaneously so they will be coherent (in phase) with each other regardless of the actual frequency setting.  If the bit is not set then the two receivers are updated simultaneously and therefore will not have indentical phase words.
> 
> We will have to check that this is what is happening but it would explain the symptoms you have observed, except for the “90 degree” phase shift you mention.  I’d bet that the 90-shift you observe is not strictly 90-degrees all the time but is a result of allowing the two receivers to update frequency at different instances of time, which in turn results in slightly different phase words to be used for the two receivers, thus resulting in a different phase setting in the Diversity window to re-establish a null.  
> 
> Thanks for the report!  If this is what is happening it would explain a lot about confusion on the issue for me that has persisted for a while now.  
> 
> 73, Joe K5SO
> 
> 
> On Nov 14, 2015, at 1:17 PM, Kjell Karlsen wrote:
> 
>> Hi Joe.
>> 
>> I have experimented some more with the Diversity. If I suppress the noise using CTUN I can then tune to and listen/send on any frequency in the shown band segment.
>> 
>> But if I disable CTUN, the noise canceling is lost and the canceling has to be done again.
>> 
>> If I do the canceling (in CTUN), then move the frequency 50Hz, then switch off and on CTUN and do a new canceling the Phase angle is 90 deg. different.
>> 
>> When I cancel the noise on one specific frequency in the middle of the shown segment, the noise is canceled in the whole band segment. This is true for the 6 noise peaks that come from the same source.
>> 
>> 73, Kjell
>> 
>> 
>> 
>