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Re: LF: Jason Tests / PSK31

from [G0MRF] [Permanent Link][Original]
To: [email protected]
Subject: Re: LF: Jason Tests / PSK31
From: [email protected]
Date: Sun, 27 Jan 2002 19:00:45 EST
Reply-to: [email protected]
Sender: <[email protected]>
In a message dated 1/27/02 4:34:34 PM GMT Standard Time, [email protected] writes:


Hello Jim and David,

I have modified the PSK31 core in Spectrum Lab a bit so it can now produce an on/off keyed "audio carrier" with a few kHz which only needs to be rectified to have the raw phase keying information.

What I did not understand completely is how Jim produces the amplitude shaping. I think the PA supply voltage is variable, but where does the "envelope" signal come from ? One could (with a bit more programming work and more CPU power) deliver the "pulse shaping envelope" on the second channel of a stereo card.

73 Wolf  DL4YHF.




Hello Wolf.

Not sure about Jim's system. Best let him answer.
However, The SM6LKM/G0MRF DDS has an input pin that allows a DC voltage to control the output level and phase. ( A balanced modulator using 2 diodes)
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

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

Thanks

David  G0MRF
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