[Boatanchors] double-sideband suppressed-carrier

[Gary Schafer]

As I recall the Costas receiver derived the carrier for reinsertion from the
two coherent side bands by limiting and rectifying them.
With this system the carrier was always exactly in proper phase with the
side bands so that they could add their outputs. No pilot carrier was
required to synchronize.

This would not work on SSB however. To receive SSB a separate BFO had to be
switched in.

73
Gary K4FMX

> -----Original Message-----
> From: Boatanchors [mailto:boatanchors-bounces at mailman.qth.net] On Behalf
> Of rbethman
> Sent: Sunday, October 19, 2014 5:38 PM
> To: boatanchors at mailman.qth.net
> Subject: [Boatanchors] double-sideband suppressed-carrier
> 
> Gentlemen,
> 
> This concept *WAS* adopted.
> 
> However, with a *twist*!
> 
> It has been deployed by the USAF as *Independent Sideband Suppressed
> Carrier*.
> 
> Each sideband carries a different signal, and can be used for data on
> one sideband, while voice is used on the other.
> 
> The USAF has been doing it for some decades, and continues even today.
> 
> Regards,
> Bob - N0DGN
> 
> 
> 
> On 10/19/2014 5:25 PM, Jim Haynes wrote:
> >
> > John Costas of G.E. was a proponent of double-sideband suppressed-
> carrier
> > AM.  His paper on the topic, along with pictures of the equipment, was
> > in Proceedings of the IRE.  "Synchronous Communications" in ProcIRE
> > December 1956, reprinted in Proceedings of the IEEE in August 2002.
> > Also a paper in IRE Transactions on Communications Systems with the
> > same title in March, 1957.  And a lighter weight article "Synchronous
> > Detection of AM Signals" in Tele-Tech, July 1952.
> >
> > I assume G.E. was trying to sell the Air Force on DSBSC while Collins
> > was selling SSB.  Costas' argument is basically that while DSB takes
> > twice the bandwidth of SSB the two sidebands add coherently so you can
> > use half the transmitter power.  And as a bonus you can receover the
> > exact carrier frequency, whereas with SSB you are dependent on the
> > accuracy of oscillators to get the carrier frequency close enough for
> > good intelligibility.  It seems that SSB won the battle; perhaps it
> > really was superior operationally, or perhaps the friendship of
> > Art Collins and Curtis LeMay had something to do with it.
> >
> > In my limited knowledge prototype equipment like that was surplused
> > as soon as the experiment was over.
> >
> > Jim W6JVE
> 
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