[TenTec] Omni VI FSK for psk?

[Ken Brown]

PSK and FSK are not the same thing. FSK uses two separate tones, only 
one at a time, to represent logical 1s and 0s. In FSK the tone selected 
is at full amplitude, and there is no information encoded in changes in 
amplitude. As with CW and FM, FSK can use class C amplifiers.

PSK uses two phases of a single tone. The two phases are in quadrature ( 
90 degrees relative to each other ) and are transmitted at various 
amplitudes. The two phases are called I and Q. A combination of the two 
phases and amplitudes is sent simultaneously. Various types of PSK use 
different numbers of possible amplitudes. The more amplitudes used the 
greater the number of possible points mapped in the PSK "constellation". 
If the constellation has four possible states, then two bits of data can 
be represented by a single point of the constellation. In digital 
microwave systems some forms of PSK may use an 8 X 8 or even larger 
constellation. Some systems are adaptive and can automatically switch 
between constellations with different numbers of possible states, fewer 
states for poorer propagation conditions (and lower baud rates), and 
more states (and faster baud rates) when the path is solid. Since the 
amplitudes of the two phases of the tone are essential to define the 
points in the constellation, linear amplifiers must be used.

The FSK input of a radio just switches the TX frequency between two 
discreet tones. Only one at a time, and each at full amplitude.

I don't know the details of PSK31, but I do know you cannot send it just 
by switching between two discreet tones of constant amplitude.

DE N6KB

Denton wrote:
> I am wondering about the fesability of tweeking my Omni VI's rtty, or fsk 
> port for use on psk31. Has anyone done this?
> I am using the usual soundcard route for that mode presently. 
>
>
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