A good portion of this has already been done. Check the HPSDR group.
Also look at the ADAT. The final hurdle is to do this at the legal limit.
We did have transmitters back when AM was dominant. I fondly remember
the Viking 500 but I do not think such an approach is practical for
commercial production as not everyone can use a full limit TX and would
not pay for it.
On 5/3/12 6:03 PM, Dan Mills wrote:
> On Thu, 2012-05-03 at 17:29 -0400, W2XJ wrote:
>> I agree. A complete transmitter would solve many technical issues and
>> depending on the implementation, could drastically improve performance.
>> Solid State broadcast transmitters that transmit digital carriers along
>> with analog and therefore must run in linear mode can achieve IMD under
>> -80 DBC using techniques most easily implemented in a composite unit.
>> For an I/Q interface, I think SDR has evolved to the point that Ethernet
>> is all that is required. Any control or tuning can use the same Ethernet
>> connection.
> I was thinking in terms of taking the data (possibly as ethernet frames)
> straight into a modest FPGA and then doing the upsample followed by
> cordic carrier generation thing in the gate array.
> Something like a very modest cyclone III should suffice I would have
> thought.
>
> Output could be either full on EER/PWM or partial EER with cartesian
> feedback via a high speed ADC with the loop closed right in the gate
> array.
>
> Regards, Dan.
>
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