[hpsdr] QSD gain and noise.

[Ahti Aintila]

Phil,

Comments between the lines:

On 24/09/2007, Phil Harman <phil at pharman.org> wrote:
>
> Thanks Ahti,
>
> Are there any figures for the 180 degree QSD over the range 160m to 6m
> i.e. are we sure that changing to 180 degree switching really fixes the
> NF problem? If not then the H mode seems a better option.

Reliable figures are still missing. I got fed up with the oscillator
noise and some common mode interference from my lab power supplies.
I'm now working with the AD's evaluation board of AD9912 to be used as
a signal generator and/or clock source. Due to some other high
priority projects, the progress is slow!

The H mode possibly is the best option for wide dynamic range applications.
>
> If anyone wants to work on this further I can put a CORDIC NCO, fully
> controlled from PowerSDR, into the existing Ozy code so that you can
> have the necessary drive waveforms without the need to build a 90
> degree DDS and support chips. There is lots of room spare in the Ozy
> FPGA for exactly these kind of experiments!

Good idea! Maybe useful for me, as soon as I can arrange more time for
this project.

73, Ahti OH2RZ

 1190637366.0