[hpsdr] Janus Rev B Update

[Lyle Johnson]

> Nice job! However, as I have discussed before with Phil_H, this design 
> may not be full duplex capable, ie useable to work a satellite 
> transponder. I understand that PWM has certain limitations, please 
> correct me if I am wrong.

I believe this is a full duplex solution.

> The AK5394A is used for RX and the processed audio is output on the 
> speaker or headphone of the TLV320AIC23B.
> 
> The TX audio is fed to the MIC input of the TLV with the only TX output 
> option being PWM. The Line-out cannot be used if the speaker is in use.
> 
> Would a DAC for TX output not be a better option? I somehow dont trust 
> that the PWM option will be satisfactory for TX.

A DAC could certainly be used.  I think that Phil and Bill want to play 
with PWM for this, and if it works well for Tx IF it is a cheap and 
linear solution.

Note also that the PWM *could* be used for user audio "line" output and 
the line out or phones out could then be used for Tx IF.  This would be 
limited to 48 or 96 kHz sampling rates, of course.

73,

Lyle KK7P


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