[hpsdr] CW Offset still causing me transmit frequency problems

[Graham / KE9H]

  Merv:

For various reasons, this kind of transmitter can not transmit with an 
offset of zero.

There is a very small mathematical "black hole" at exactly zero, and if 
you go there, you will
sucked to the center of the earth, or sent out to infinity, or something 
appropriately
unpleasant and unpredictable like that.   Since this would no doubt 
violate some regulatory
rule or other, the writers of PowerSDR were just trying to protect you 
with the minimum
offset of 200 Hz.    :-)

So either set the transmit frequency low by 600 Hz, then transmit CW 
with an offset
of + 600 Hz.

OR:

Use a mode like AM, where the signal is intended to
transmit a carrier at a specific center or carrier frequency, then just 
don't
modulate it.  In this case, PowerSDR is offsetting internally by an IF 
frequency,
canceling the image, and then correcting the math before displaying.

Essentially what I suggested you do with CW above, but it is all 
automatic and hidden
from you, so you won't have to do any math.

--- Graham / KE9H

==

On 10/20/2010 9:28 PM, Merv Thomas wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> A few days ago I posted a problem I was having in that my transmit 
> freq was different to the freq I keyed in on PowerSDR VFO A - answers 
> suggested that I had a CW offset and this was true and I thought by 
> entering a zero in this field and hitting Tab it would set it to zero 
> - it certainly shows as zero on the screen but in fact a 200Hz offset 
> is still present.
>
> As I choose between CWL/CWU/USB/LSB my VFO A frequency keeps on 
> changing and gets way off the freq I want to transmit on and in most 
> cases the measured transmit freq is not what is shown in the VFO A 
> window.
>
> What am I doing wrong?  It seems the 200Hz offset is a hard-coded 
> figure in PowerSDR because if I try to reduce the figure by clicking 
> on the down arrow in the Pitch Freq(Hz) area on the main screen it 
> will not go below 200Hz. Is there a way to totally disable CW or to 
> get the offset to stay as zero??
>
> Thanks for any help provided.
>
> Regards,
>
> Merv  VK6BMT
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