"Kristoff Bonne" wrote in message
...

It can image that a AM-decoder can decode this correctly for CHU, but I
don't know if this would apply for a broadcasting-signal.

Why not? CHU contains human voice announcements in USBc so why would a SSBc
broadcast signal be any different as far as an envelope detector is
concerned?

I wonder what would happen if you would have a situation like this:
- Say that you have a radio-station in 5 Khz USB SSBc at (say) 7200 Khz
(hence, taking up 7310 to 7315 Khz; just a random frequency)

(you mean the 5 kHz USBc carrier is at 7310, not 7200)

- and you have a second signal just below (either a SSBc from 7305 to
7310, or a DSB-AM from 7300 to 7310).

(i.e. a USBc or a DSBC at 7305)


How would a AM-decoder react if it was tuned to 7310Khz. Wouldn't he think
this is a DSB-AM station from 7305 to 7315 Khz and completely decode this
incorrectly?

If the IF shifts the 7310 to the centre of its 5 kHz passband, then both an
envelope detector or a sync AM detector centred in the passband are going to
see the upper 2.5k of the upper sideband of the lower adjacent freq. As you
tune the receiver higher in frequency, less of the undesired sideband and
more of the desired will be seen, thus improving the S/I. A correctly
designed selectable sideband synch AM receiver would correctly align the
passband on the selected sideband and with the synchronous BFO.

A DSP/ASIC based signal might be programmed to see that the signal at
7305-7310 Khz is completely different then 7310-7315 KHz and switch to
SSBc because of that, but how would an "analog" AM-decoder react to this?

Because sync AM has a lock-in time or latency, it might be desirable to use
envelope detection for rapid and coarse tuning with an optional automatic
switch to sync AM mode. Of course, a DXer would want to exercise manual
control. I have no idea whether such auto switching is realisable in any
practical way.

I'm replying in digestible chunks - more later!

73, Tom