>
> The STAR generates it's I-Q in software and uses that for sideband
> rejection ... so does the RX320 which cannot do sideband in
> hardware
[snip]
I think I have to clarify my previous message which admittedly was a
bit too short and maybe not clear enough.
When I said that you cannot separate the wanted from the unwanted
sideband in software unless the hardware provides the I/Q components,
what I meant of course was referred to the unwanted sideband of the
conversion to 15 kHz. So, if you convert from 455 kHz to 15 kHz, using
a high side injection, then you have a LO of 470 kHz. The image
frequency is at 485 kHz. This image frequency must be either
eliminated with a hardware filter, or you must use a quadrature mixer
to get rid of it. You cannot do it with software only.
Once you have your 15 kHz IF signal, cleaned from its image, then of
course you can use the software I/Q generation to further
differentiate between upper and lower sidebands. Supposing you
have a CW signal at 16 kHz, and another at 14 kHz, on the opposite
sides of the central 15 kHz IF, you can choose to listen at the upper
sideband, and you will hear a tone at 1 kHz which is the original 16
kHz CW signal, or at the lower sideband, and you will hear the other
CW signal, still with a 1 kHz tone. To do this, you don't need to
input the 15 kHz in I/Q form.
But you need a hardware I/Q mixer (or a crystal filter) to get rid of
the image of the 15 kHz themselves, as this cannot be done with
software only.
Hope this clears a little the confusion.
73 Alberto I2PHD
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