[hpsdr] MOX and Duplex

[Bob Cowdery]

I've always been slightly unsure about the NCO settings so the mistake
could be there.
The NCO's are 1-8 and the docs say 1 is TX and 2-8 are RX_1 - RX_7 but
I've found that not to be correct in practice.

This is what I do:
TX - always sets only NCO_1 with TX freq.
RX - if only one receiver and simplex I set both NCO_1 and NCO_2 with
the RX-1 frequency. I found it necessary to set NCO_1.
    otherwise more than one or duplex I only set NCO_1+RXid which means
NCO_2 - NCO_8

It doesn't look right although I tune correctly on the receivers.

73 Bob G3UKB

On 22/11/2014 19:48, Joe Martin K5SO wrote:
> Hmm, perhaps RX1 is being set to “0 Hz” or at least some frequency other than the Tx frequency via the C&C bytes when in Tx mode in your code?
>
> 73, Joe K5SO
>
> On Nov 22, 2014, at 12:21 PM, Bob Cowdery wrote:
>
>> Hi Joe,
>>
>> Thanks for the detailed explanation. I'm working out how best to do my
>> transmit path so I first need to understand what the firmware is doing.
>> I do plan to start looking at the firmware code but that will be a bit
>> later on.
>>
>> In my software at the moment all I do is link the RX1 and TX frequency
>> if not duplex but otherwise the MOX and Duplex signals I generate set
>> the appropriate bits in the CC,  and then for MOX, if there is more than
>> one receiver I stop all except RX1. When I say stop I just stop the DSP
>> processing and then start DSP processing for the TX. Similarly for MOX
>> off I start DSP for any other receivers and stop for the TX. Apart from
>> (un)linking the frequency and setting the CC bit I do nothing with
>> Duplex in the PC code yet.
>>
>> For testing I've just removed the antenna from Mercury and put a dummy
>> load on Penny (I don't have PA or filters attached yet). Now I know I'm
>> not doing this right yet as I'm deliberately leaving RX1 running
>> regardless of the duplex setting in the firmware.
>>
>> What I notice is that I can hear the signal in RX1 only if duplex is set
>> in the firmware and I wondered what I was doing wrong as if the firmware
>> does nothing to inhibit the signal I would expect to hear it regardless
>> of duplex. It may be I have some frequency offset somewhere or I'm
>> setting the wrong NCO bytes in one of the cases.
>>
>> 73 Bob G3UKB


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