Hi Craig,
> On Upper Sideband an audio note is heard when a signal is ABOVE the
> "effective BFO frequency" and in order to bring that note to zero beat,
> one must tune upward, lowering the pitch of the audio note until it is
> zero.
>
>
> That sure is the way it works but it seems counterintuitive. Upper sideband
> implies the signal on the upper side of the tuned frequency.
It is on the upper side. That is why as you tune higher up, it becomes
less on the upper side and the audio note gets lower.
When the signal is on the upper side (higher frequency side) of the
tuned (to zero beat) frequency, the audio note frequency will be
something greater than zero beat. As you tune upward, making the signal
not as far above the "tuned" (to zero beat) frequency, the audio note
frequency gets lower.
> If you tune up
> from zero beat, the signal should start at zero and go up in pitch, not the
> other way around.
>
It does, if your IF bandpass will let the signals BELOW the zero beat
frequency (the LSB signals) through.
>
> Bottom line is "upper" and "lower" do not refer to which side of zero beat
> you find yourself.
Yes they do. When listening to upper sideband signals, you are hearing
signals with RF frequencies above the RF frequency that would be zero
beat. As you tune upward, they become not as far above the zero beat
point and so their audio beat notes get lower in audio frequency.
> What does upper and lower refer to? Or - you are upper or
> lower in reference to what?
>
It refers to which side (in RF frequency) of the zero beat you are
listing to. Signals on either side of the RF zero beat frequency will
produce audio beat notes. (but IF filters in SSB receivers only let one
side through) Signals higher that the zero beat frequency will produce
higher audio beat notes as they get further away (higher frequencies).
Signals lower will also produce higher audio beat notes as they get
further away (the RF frequency is getting lower).
The confusion my be that instead of the signals moving higher or lower,
you are moving your zero beat reference higher or lower as the signals
coming into the receiver are staying at the same place. The relative
frequency difference, and thus the beat note, gets lower as you tune the
receiver upward when in USB
Ken N6KB
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