RadioBanter - DSB SC Mode

RadioBanter (https://www.radiobanter.com/)

- CB (https://www.radiobanter.com/cb/)

- - DSB SC Mode (https://www.radiobanter.com/cb/96297-dsb-sc-mode.html)

"Telstar Electronics" wrote:
Yes... at least the discussion is something interesting... instead of
dougie this and dougie that... whoever dougie is... LOL

Here's who dogie is. (like you didn't know, griffey)

http://n8wwm.4t.com/photo.html

"Steveo" wrote in message
...
"Telstar Electronics" wrote:
Yes... at least the discussion is something interesting... instead of
dougie this and dougie that... whoever dougie is... LOL

Here's who dogie is. (like you didn't know, griffey)

http://n8wwm.4t.com/photo.html

He's been here long enough to know. The question is whether he is playing
stupid or just plain stupid.

"Telstar Electronics" wrote in message
oups.com...
Yes... at least the discussion is something interesting... instead of
dougie this and dougie that... whoever dougie is... LOL

I still trying to research this topic.... since there seems to be
considerably different views of DSB-SC out here. I'm starting to think
my original statement that a very high swing AM transmission can be
considered a DSB-SC... and requires no special BFO tuning.

www.telstar-electronics.com

I agree that we finally have a topic worth discussing. The sad part is you
call yourself a professor, and design and build amps, leading one to believe
you know about radio, yet are having a tough time grasping the DSB-SC theory

"DrDeath" wrote:
"Steveo" wrote in message
...
"Telstar Electronics" wrote:
Yes... at least the discussion is something interesting... instead of
dougie this and dougie that... whoever dougie is... LOL

Here's who dogie is. (like you didn't know, griffey)

http://n8wwm.4t.com/photo.html

He's been here long enough to know. The question is whether he is playing
stupid or just plain stupid.

He's been kissing up to him for years..ask anyone that would know. They've
both have an angle to sell something, and there's nothing wrong with that
as long as you're careful who you are in business with.

On a sunny day (Mon, 12 Jun 2006 20:22:15 GMT) it happened james
wrote in :

On Sun, 11 Jun 2006 14:38:54 GMT, 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.
+++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?
**************************

DSB-SC reception is not restricted to just SSB-SC receivers. A DSB-SC
signal can be received by reinjecting the carrier, even on a DSB
receiver.
It can be received even on an AM receiver if you feed in a local oscillator
at fc, I have done this, so what is your point?

On a sunny day (Mon, 12 Jun 2006 23:19:21 GMT) it happened Bob Dobbs EC42
wrote in pan.2006.06.12.23.19.18.864000@Quetzalcoatl:

On Mon, 12 Jun 2006 15:28:30 +0000, Jan Panteltje wrote:

snipped the cerebral cesspool

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.

OK
Here's what your learned suggestion yielded; http://tinyurl.com/g7wy6

I have to admit the results exceeded my ability to correlate them to the
topic of discussion, so I guess you win by virtue of posting sufficient
arcane bull**** to shock and awe me into submission. ;-)
idiot.

On a sunny day (Tue, 13 Jun 2006 00:32:38 GMT) it happened james
wrote in :

A product Detector is prefered due to its mixer characteristics. Being
balanced, the two inputs are supressed sufficiently to make filtering
their components in the output much easier. Product detectors and
Envelope dection is not the only means of detecting DSB-SC and DSB-LC
signals. They are the most simplest and easiest to implement.

I have used sampling to demodulate QAM, In any color TV you will find it,
carrier is regenerated in phase from the color burst, look up NTSC.
And there we have 2 modulating systems, here is how that works in the
time domain:
http://groups.google.com/group/sci.e...ce23fcbb253646

The main thing is perhaps that you can see that in SSB, if we have 1MHz
carrier, and 1kHz sine modulation, we get a 1.001 MHz carrier (or 0.999 if
the other sideband is used.
So to get the original back, it would be sufficient to substract the 1MHz
again in the first case (1.001 - 1) = 1kHz, or in the other case 1 - .999.

In the DSB-SC case we would have 1.001 AND .999 AT THE SAME TIME.

Using one sideband is enough. DSB uses double the bandwidth and as such
is less efficient then SSB,

Distortion of the RF waveform may not nescessarily indicate that the
detected audio is unintelligable. As long as the recovered audio is
reproduced accuarately during demodulation then there is no
distortion.

But it won't [work].
What the 4 diode ring modulator does, is make a RF amplitude phase phi
when the audio signal goes positive proportional to the audio amplitude,
and the same with phase phi+180 degrees when the audio signal goes negative.
If you do AM envelope detector (as the you normally do with a diode and RC
lowpass) you get a wave form that is no longer a sine, but looks like double
phase rectified sine when filtered.

Spectral content of the demodualted signal can be set by
post detection filtering. This can reduce to some extent the harmonics
of the modulating signal.

By the way the lab you point to is more about the generation of a DSB
signal. From figure 4 you are making statements about demodulation.

Of course, lok at that waveform, build a 'non distorting AM detector
for it without carrier re-insertion (BFO, some oscillator), you CANNOT.
Modulation /demodulation is related.

Please build one, try it,

Since the information in both sidebands are indentical the only need
for the second sideband is to increase demodulated audio.

Yes, we agree here.

Please try it:

But for the non-believers, try it out, all you need is an audio amp,
oscillator, 4 diodes, and of course a 27 HHz xtal oscillator.
http://www.nzart.org.nz/nzart/examin...les/Mixers.htm
There is a description and diagram a bit down on the page.

Listen to it on an AM receiver, and you will KNOW.

On a sunny day (12 Jun 2006 13:42:26 -0700) it happened "Telstar Electronics"
wrote in
.com:

So let me get this straight... In DSB-SC... both sidebands are
transmitted... but there is no carrier sent at all? Correct?... and the
carrier is re-inserted at the receiver.

100% correct.

Now with the swing set-up... both sidebands are transmitted... along
with the carrier... but the carrier's amplitude changes from extremely
low to a normal AM carrier when the modulation is added.

right again.

www.telstar-electronics.com

On a sunny day (Mon, 12 Jun 2006 23:22:52 GMT) it happened Bob Dobbs EC42
wrote in pan.2006.06.12.23.22.49.949000@Quetzalcoatl:

On Mon, 12 Jun 2006 11:20:24 -0700, Telstar Electronics wrote:

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

Yeah, me too.
I'm hoping that Panteltje dude can get over his constipation and offer
something more enlightening than the flatulence blowing from his
keyboard.
idiot

On a sunny day (Mon, 12 Jun 2006 23:34:57 GMT) it happened Bob Dobbs EC42
wrote in pan.2006.06.12.23.34.54.717000@Quetzalcoatl:

On Mon, 12 Jun 2006 18:34:51 +0000, Jan Panteltje wrote:

There is in fact no need for the 'other' sideband in DSB-SC, no problem
if the receiver filters it out, that is why you can receive DSB-SC both
with USB and LSB!

Without both sidebands, it would no longer be DSB, and the reason stations
use DSB instead of SSB is for the use of ordinary receivers that lack a
BFO.

How about providing a source of those 'undetectable" DSBSC signals that
one might encounter within or nearby to the CB band, instead of some
technobabble with irrelevant circuitry illustrations?

OK for the last time before you enter my killfile:
DSB is not AM. AM is AM, and AM has both sidebands, but when we say 'DSB we mean DSB-SC.
idiot