[BC] Null Distortion (WAS: Westinghouse at NAB)

[Cowboy]

On Friday 09 June 2006 02:11 am, Phil Alexander wrote:
> On 8 Jun 2006 at 0:00, miltron wrote:
> 
> > In some instances, can't there be overmodulation in or near the 
> > nulls due to having more power in the sidebands than carrier power?
> 
> Hmmmm .... interesting question I've never considered. I'll have
> to puzzle over that one a day or two, but it is probably
> irrelevant.

 Not entirely....

> The problem with overmodulation is carrier cutoff in 
> the Tx causing splatter.

 Correct !

> In the case you suggest, the audio would 
> sound very distorted, but it shouldn't generate splatter the way
> PA cutoff does.

 Also correct, just like any DSBSC phase rig !

 Because the carrier may be phase canceled, just like ( or similar to )
 a DSBSC phase rig does not mean "over mod" but it DOES mean that
 the carrier is reduced below the point where an envelope detector can work,
 and a product detector with BFO would be required to properly demodulate
 the DSBSC signal.

 There used to be two ways to generate DSB, and three ways to generate
 SSB. Phase cancelation of the carrier was one of them.

-- 
Cowboy