LF: Re: PSK31 modulation (was: Jason Tests / PSK31)

[DL4YHF@aol.com]

Hello David, Jim and group,

As G0MRF wrote:
> With half the supply rail (lets say 6 Volts) on the pin, the RF output is zero. 
> As the voltage is increased towards 12V the output increases in proportion. 
> If the voltage is decreased from 6V towards zero then the RF output also increases 
> in proportion, but with the opposite phase. 

> So 6V = no output. 
>  > 6 V =  phase 0 degrees 
>  < 6V  =  -180 degrees 


Thanks for the explanation David. I have already sent Jim the information about a new 'two channel' output for PSKxx (implemented in Spectrum Lab) which uses the soundcard for this:
Left channel = Standard PSK signal with phase modulation and envelope shaping
Right channel = On/Off-keyed "audio carrier", ON for 180°, OFF for 0°
The AF carrier is required because the soundcard's output is not "DC" coupled.

I hope with two rectifier diodes and a simple lowpass filter, these signals are sufficient to drive Jim's transmitter for PSK31 with amplitude shaping. If not, the program could be easily adapted to produce different audio amplitudes similiar to the scheme you described. 
So, if someone wants to try this with the  SM6LKM/G0MRF DDS board just ask for an update. 

> A potentially good idea when we designed it, but lacking an application. 

   Maybe there's an application soon.

73 Wolf  DL4YHF.