bpnjensen wrote:
On Jan 14, 4:18 am, dave wrote:
[...]
The K3 has synchronous AM, effortlessly realized in DSP. You need a
base receiver for $1,600, a wide filter for $100 and the General
Coverage filter set. Run you abt $2k.

Is it, by chance, sideband selectable? Or would it be necessary to
use a passband to (more or less) achieve one side or the other?

Thanks,
BJ



I don't know if the K3 uses phasing selectable-sideband synchronous
detection, or if it requires passband tuning to get a similar effect.

But one should greatly prefer the phasing method, since on AM or DSB
signals it gives a 6 dB advantage over using IF filters, because
using the phasing method with a sync detector cancels the
_interference_ in the opposite sideband, but it does _not_ cancel
the opposite sideband energy of the desired signal.

The reason is that the Q detector contains essentially no audio from
the desired signal (the detector's locally generated carrier is
locked at 90 degrees difference from the real or imputed transmitted
carrier, putting the desired audio into a deep null), and therefore
no cancellation of any part of the desired signal takes place.

It's too bad the Eton and Sony sync detectors don't provide the
option of listening only to the Q channel output. That would provide
the ability to literally listen to what was underneath any DSB/AM
signal. Some amateur experimenters have done this with homebrew
gear, allowing operation in the close vicinity of 500-kW broadcast
invaders of the 40 meter band.

See the article "SSB Q-Channel Communications" for more details:

http://www.antennex.com/preview/Folder01/Nov4/ssb-q.htm


With all good wishes,


Kevin, WB4AAIO.
--
http://kevinalfredstrom.com/