Hello All:

Yeah Double Side band, suppressed carrier.

A lot of the CB radios use to transmit DSB, not SSB. Many commercial
radios did also in commercial use. But as time has allowed for circuits
to be made around a integrated circuit, SSB Single Side band has taken
over, as its more efficient. Ya get more effective output with SSB than DSB.

Jay in the Mojave

On a sunny day (11 Jun 2006 06:53:18 -0700) it happened "Telstar Electronics"
wrote in
.com:

Jay,

Yes... SSB has it's advantages... but several disadvantages. The main
reason I stay away from SSB is the critical tuning. Somebody always
comes on sounding like Donald Duck... LOL. I spend more time tuning
people in then talking to them. And then there's the three way
conversation... where you have to tune back and forth between the other
two guys. Forget it. And last, there's alway the fact that until the
CBs reach a stable operating temperature... your tuning like crazy.
Nope, SSB is not for me... I have my DSB-SC... and it doesn't have
those problems.

Something wrong here, DSB-SC received on a normal set can only be
made 'inteligible' if it is received as SSB.
SSB is simply one sideband of the 2 DSB sends, so your BFO is [just as]
critical.
If you BFO is of center (so you re-insert the wrong carrier) and your RX
filter already removed the other sideband, then you have all the 'duck'
sound of SSB.
Moderns CB sets have no 'DSB' option, only USB / LSB, so always use one
sideband.
In case a set DOES pass both sideband, you get double the problem....

Maybe you mean something else by DSB-SC altogether? Leave SOME carrier?

Not sure what you're talking about. When I say DSB... I'm referring to
what others call the AM mode.

www.telstar-electronics.com

On a sunny day (11 Jun 2006 13:35:21 -0700) it happened "Telstar Electronics"
wrote in
.com:

Not sure what you're talking about. When I say DSB... I'm referring to
what others call the AM mode.

www.telstar-electronics.com


DSB-SC (as you originally referred to) stands for:
Double Sideband Suppressed Carrier.
So, if the carrier is surpressed, then you have only 2 sidebands if a signal
is present (single tone modulation), nothing if no modulation is present.
http://www.ece.drexel.edu/courses/ECE-S306/lab3.pdf
Look at figure 4, for a single tone modulating audio signal.
You will notice it is quite different from AM!

Normal AM is also DSB, but the carrier is not surpressed.
Better to say AM if you mean AM, DSB is often used for DSB-SC.

I looked at your document. It's exactly what I'm talking about AM...
without a solid carrier at no modulation. That's exactly what mode I'm
running. With my amplifier being able to key on a multiplexed signal
from my radio... The DSB-SC mode really is impressive on the air at
high power levels. I would never go back to pure AM mode. And you
already know my feelings about SSB... it's got too many negatives for
my liking.

www.telstar-electronics.com

On a sunny day (11 Jun 2006 16:51:31 -0700) it happened "Telstar Electronics"
wrote in
.com:

I looked at your document. It's exactly what I'm talking about AM...
without a solid carrier at no modulation. That's exactly what mode I'm
running. With my amplifier being able to key on a multiplexed signal
from my radio... The DSB-SC mode really is impressive on the air at
high power levels. I would never go back to pure AM mode. And you
already know my feelings about SSB... it's got too many negatives for
my liking.

www.telstar-electronics.com

Hmmm does not clear up confusion, do you receive it with an AM receiver
and no BFO? Then it is no DSB-SC.

There exist AM modulation modes where the carrier is somewhat reduced during
low modulation levels..... This wil lwork, but is still AM.
Maybe that is what you mean?

You will note the 'double phase rectifier' like waveform for DBS-SC.
In case of that modified AM you have sine wave.

So: if you can receive it on an AM receiver without BFO it is AM or
a variant there of.
If you need a BFO in any way it is DSB-SC, SSB, LSB, USB whatever.

As far as range is concerned, SSB DSB will beat any system (with SSB being
better then DSB).

The variable carrier level AM, if used to give some 'extra' power to the AM
stage at high amplitudes, will give some extra rane.
however for weak passages in the audio there will be more noise then a similar
AM system with noraml carrier, as simply there will be less carrier output.

Some AM broadcast statons, if not all? Use that system.

But who knows HiFi these days.. mp3... low bitrates...

I guess you're right. In the strictest sense DSB-SC, there is no
transmission of the carrier at all. That is not the mode I'm talking
about. I guess I was using DSB-SC interchangably with the mode where
the carrier is only temporarily supressed. I would certainly not be
interested in the mode where the carrier is no longer transmitted...
for the same reason I don't like like the SSB mode... mainly the
constant fussing over the tuning. Thanks for the correction...

www.telstar-electronics.com

On a sunny day (Mon, 12 Jun 2006 13:13:42 GMT) it happened Bob Dobbs EC42
wrote in pan.2006.06.12.13.13.40.351000@Quetzalcoatl:

On Sun, 11 Jun 2006 14:38:54 +0000, Jan Panteltje wrote:

Something wrong here, DSB-SC received on a normal set can only be
made 'inteligible' if it is received as SSB.
SSB is simply one sideband of the 2 DSB sends, so your BFO is [just as]
critical.

DSB-SC can be received by an ordinary AM detector, no BFO required. The
two sidebands work with one another to provide the entirety of the signal
so there is no garble effect as encountered when one of the sidebands is
suppressed.

Bull****.

On a sunny day (Mon, 12 Jun 2006 15:09:45 GMT) it happened Bob Dobbs EC42
wrote in pan.2006.06.12.15.09.44.566000@Quetzalcoatl:

On Mon, 12 Jun 2006 14:11:03 +0000, Jan Panteltje wrote:

Bull****.

Is that your concise description of coherent detection?

Bet you do not know what 'coherent detection' is.

because if you did, you would not have written that.

Ok, now rent a brain for a day, and thinks.

*IF you have an AM receiver, and set the transmitetr carrier to zero,
as in the case of DSB-SC with no modulation (= silence remember),
then what WOULD you hear?
I will tell you: All the noise in the band.
Not good for silence, specially if good conditions exist!

So you could have figured that out if you had been created with a brain.

Also, you did not bother to look up the waveform, you just write some bull,
never even designed a DSB-SC transmitter, much less ever used one.

No this is perhaps not a politically correct answer, but hopefully you
wil lread those papers, gooogle DVB-SC, and learn something, and then
stop spreading dis-information.

Hmmm... that's what I thought originally. Now I'm getting confused. I'm
real interested how this discussion shakes out...

www.telstar-electronics.com


DSB-SC can be received by an ordinary AM detector, no BFO required. The
two sidebands work with one another to provide the entirety of the signal
so there is no garble effect as encountered when one of the sidebands is
suppressed. In SSB the BFO supplies the missing side's opposite phase and
because it's local and not sent with the signal is why it's precise
tuning (or phase relationship) is critical.