[hpsdr] QSD gain and noise.

[Phil Harman]

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.

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!

73's Phil...VK6APH




Quoting Ahti Aintila <oh2rz.sdr at gmail.com>:

> Phil,
>
> Here are a couple of links for different mixers:
>
> http://groups.yahoo.com/group/softrock40/
> Look in the Files section for "QSD Switching Duration..." from K5BCQ
> (Kees). He is interested in 180 degree switching (like me) using fast
> switches like SN74LVC1G3157. I think that the shorter switching times


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