[Elecraft] [K3] K3 RF speech processor > aliasing ?

[pd0psb]

Hi All,

Yesterday I sinned and whistled shortly into my microphone to see my watt
meter reading.
I apologize for this bad bad operator habbit...

To my surprise I heard a second whistle monitoring the signal.When I
whistled "up" the other whistle was going down in frequency, when I whistled
"down" the byproduct was going up.

It seems like there is a quite strong aliasing (mirroring against nyquist
freq) product in my TX audio. First I suspected the clock of the A-D
converter of the ingoing audio. Fortunately there is no aliasing at all with
the RF processor turned off.

Is this exemplary for my K3 or do others also notice this aliasing in the RF
processor?
It's easy to test copying my bad behaviour in ("TX test mode"!!) monitoring
yourself.

I wonder if there is any 1/2 nyquist filtering in the RF processor
algorithm, and what the actual sampling rate of the RF processed TX signal
is. Listening to the aliasing products samplerate seems pretty low.
Also wonder what this does to the TX audio spectrum, though I assume the
aliasing products do not exceed the TX passband in final transmitted signal.

73'
Paul
PD0PSB




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