[Heath] DSB...

[ChrisIwata]

Chuck

I did some research, and looks like you're right.

With suppressed (reduced) carrier DSB the carrier level stays the same 
with modulation.  Unbalancing the
balanced modulator in a side band scheme doesn't imply the carrier goes 
up with the modulation.

With controlled carrier AM the carrier rises with the modulation. But 
unless well designed, not linearly.

Still, I think I was right about saying both can be demodulated with an 
envelope (AM) detector.  However, I've read that if the AM receiver uses 
AGC,  carrier controlled AM usually sounds bad

Tnx

Chris


On 5/20/2018 6:14 AM, Chuck Moore wrote:
> If memory serves me correct suppressed carrier had a
> fixed level reduced carrier. With controlled carrier
> the carrier amplitude varied with the sideband
> amplitude. Am I confusing the two?
>
>
> Chuck Moore
> wcmoore at verizon.net
>
>
> -----Original Message-----
> From: ChrisIwata via Heath <heath at puck.nether.net>
> To: heath <heath at puck.nether.net>
> Sent: Sun, May 20, 2018 9:04 am
> Subject: Re: [Heath] DSB...
>
>
> I don't mean zero carrier DSB, I mean suppressed carrier. In modern
> day this amounts to unbalancing the balanced DSB modulator, so that some
> carrier is there even in the absence of modulation.
>
> I'm not talking about the implementation, I'm talking about the signal.
>
> Yup, I agree controlled carrier AM is much easier to implement. Both on
> the transmitting end and the receiving end, compared to DSB.
>
> Seems to me the signal generated by controlled carrier AM is the same as
> suppressed carrier DSB? Neither one has zero carrier with no
> modulation, and the carrier increases with modulation. I don't know,
> maybe the controlled carrier signal is not a linear representation of
> the modulation as is the case with suppressed DSB? That is, if you
> speak twice as loud, the controlled carrier might not go up twice as much?
>
> The one big feature of this signal is it can be detected with a simple
> envelope (AM) detector, just like plate modulated AM
>
> When you think about it, aside from CW, modern ham radio communication
> has become very complex. I guess this is why home-brewing is becoming a
> lost art.
>
> Chris, KL7DM
>
>
> On 5/19/2018 4:34 PM, Kenneth G. Gordon wrote:
> > OK. I did some research: generating a DSB signal requires a balanced 
> modulator
> > somewhere in the system.
> >
> > In one case I remember, the two 1625s in an "ARC-5" transmitter were 
> used as a
> > direct-to-antenna DSB transmitter.
> >
> > The screens were fed push-pull audio, while the plates were 
> parallel-connected. As I
> > remember it, an oscilloscope was required to get it adjusted properly.
> >
> > DSB is far more complex than the simple controlled-carrier systems 
> in our simple
> > transmitters.
> >
> > If anyone here is interested, here is a link to the "Double-Sideband 
> Junior" from GE Ham
> > News of March-April 1958.
> >
> > 
> http://n4trb.com/AmateurRadio/GE_HamNews/issues/GE%20Ham%20News%20Vol%2013
> > %20No%202.pdf
> >
> > Ken W7EKB
> >
> > ---
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