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-   -   SSB in DX-398 (https://www.radiobanter.com/shortwave/59874-ssb-dx-398-a.html)

Scott A. January 25th 05 10:34 PM

starman wrote in :

Due to the nature (physics) of how SSB works it's difficult to make
the audio sound like the original. One problem is the original pitch
range is missing from an SSB signal and there's no way to know exactly
what it was. For example, I have heard Art Bell, the AM radio talk
show host, operating on the ham' bands in SSB. It sounds like Art but
it's not the same as hearing him on an AM broadcast station. It does
help if there is musical content to an SSB signal which can act as a
reference for adjusting the pitch correctly. Since SSB is mostly used
for voice only, it doesn't really matter if the pitch is not exactly
like the original.


Thanks for the info. I was, after some practice, able to get the station
to sound pretty good. It's kinda weird how you can change the pitch of the
voice or music by changing the tuning. All this time I was convinced that
the ssb on my radio didn't work right, especially since it's one of the
selling points for this model. Guess I'm still a little wet behind the
ears.

Caveat Lector January 25th 05 10:49 PM

The thing that is missing in SSB is the carrier -- it was suppressed. And
unlike AM only one side band is transmitted -- either the upper sideband
(USB) or the lower sideband (LSB).

Only one sideband is needed to transmit intelligence.


Thus Single SideBand Suppressed carrier is the whole name for SSB
transmissions.

At the receiver side you reinsert a carrier (BFO) which then allows
demodulation.

As you tune the receiver, the BFO is inserted at different points until it
sound natural.

A little practice and you can tune right in on it. Hams do it all the time.

SSB modulation is nicely illustrated at URL:
http://www.williamson-labs.com/480_ssb.htm

It explains the big advantages of using SSB along with pictorials

--
Caveat Lector



"Scott A." wrote in message
...
starman wrote in :

Due to the nature (physics) of how SSB works it's difficult to make
the audio sound like the original. One problem is the original pitch
range is missing from an SSB signal and there's no way to know exactly
what it was. For example, I have heard Art Bell, the AM radio talk
show host, operating on the ham' bands in SSB. It sounds like Art but
it's not the same as hearing him on an AM broadcast station. It does
help if there is musical content to an SSB signal which can act as a
reference for adjusting the pitch correctly. Since SSB is mostly used
for voice only, it doesn't really matter if the pitch is not exactly
like the original.


Thanks for the info. I was, after some practice, able to get the station
to sound pretty good. It's kinda weird how you can change the pitch of
the
voice or music by changing the tuning. All this time I was convinced that
the ssb on my radio didn't work right, especially since it's one of the
selling points for this model. Guess I'm still a little wet behind the
ears.




CW January 26th 05 01:56 AM

Nothing weird about it. Just like any other radio signal, you have to tune
the radio correctly.

"Scott A." wrote in message
...
It's kinda weird how you can change the pitch of the
voice or music by changing the tuning.




Michael Black January 26th 05 04:16 AM


"CW" ) writes:
Nothing weird about it. Just like any other radio signal, you have to tune
the radio correctly.

But when people don't understand SSB, of course it's "weird".

Tune a regular AM signal, and the carrier ensures that it is always tuned
properly. The only thing the tuning does is move the signal into
the passband of the IF filter. Mistune it, and you get reduced amplitude,
and altered frequency response.

With an SSB signal, mistuning likewise moves the signal out of the passband.
But it also has to be tuned properly in relationship to the "reinserted
carrier", ie the BFO, and if that isn't right, then you will be translating
the modulation to the wrong place in the audio spectrum. Voice can be
ambiguous, since you often won't know how someone sounds (because you
don't know their voice), so mistuning can merely make someone sound squeaky,
or even sound right even if not exactly as the person sounds in real life.
Music is absolute tones, and if you don't tuen that right, not only will
you not hear the proper notes, but the relationship of the notes to each
other is off. You know what a given note sounds like, and not much mistuning
messes things up.

Michael

"Scott A." wrote in message
...
It's kinda weird how you can change the pitch of the
voice or music by changing the tuning.






starman January 26th 05 08:17 AM

"Scott A." wrote:

Thanks for the info. I was, after some practice, able to get the station
to sound pretty good. It's kinda weird how you can change the pitch of the
voice or music by changing the tuning. All this time I was convinced that
the ssb on my radio didn't work right, especially since it's one of the
selling points for this model. Guess I'm still a little wet behind the
ears.


I imagine other newbies might also come to the conclusion that their
radio was defective when trying to listen to SSB transmissions, so your
post could be quite helpful.


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Jmpngtiger January 27th 05 01:17 AM

He is not complaining about picking the signal up but making it
understandable. You can't do this with DX-398. No SSB mode or BFO means
no SSB detection.


My 398 does it just fine. (????)

jt

Caveat Lector January 27th 05 01:55 AM

From the DX-398 Manual at URL:


TUNING SSB STATIONS
Your receiver receives both USB and LSB transmissions. Follow these steps to
receive SSB stations.

The page (18) goes on to give a step by step tuning procedure

"making it understandable" is covered as follows (from the DX-398 Manual

Note: SSB stations sound distorted when you tune to them in the normal SW
band. To help you find SSB stations, watch for deflections on the signal
strength indicator. Since SSB is transmitted with a suppressed carrier, the
signal strength indicator will move more quickly when there is a
transmission and more slowly during pauses in the transmission.

When you have located an SSB station, press AM MODE to receive the
transmission. Repeatedly press AM MODE to switch between USB or LSB
transmissions (try LSB for frequencies below 10 MHz or USB for frequencies
above 10 MHz).

4. Set STEP to SLOW then readjust MANUAL TUNING slowly for maximum
intelligibility.

73
--
Caveat Lector



"Jmpngtiger" wrote in message
...
He is not complaining about picking the signal up but making it
understandable. You can't do this with DX-398. No SSB mode or BFO means
no SSB detection.


My 398 does it just fine. (????)

jt





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