[Boatanchors] Independent sideband suppressed-carrier

[Gary Schafer]

An independent side band transmitter is nothing more than an upper and a
lower side band transmitter sharing the same carrier.

The Costas system requires that both side bands be the same and coherent
with each other. 
The advantage being that both side bands add together after detection like
an ordinary AM signal does but no carrier needs to be transmitted.

In order to detect a DSB signal without this type of phase lock system a
single side band receiver is needed and all of the energy in the other side
band goes to waste as the other side band will not be in phase and will
cause distortion if it is not filtered out.

The other way to make the other side band useful is to transmit a low level
pilot carrier to phase lock the receiver to and then both side bands can be
used and they will add together in the receiver like an AM signal.

The disadvantage in either the Costas or the pilot carrier method is the
rather complex receiver. 
With the Costas loop, Interference on one side of the signal can upset the
phase lock.
It can not be used as an independent side band signal.

73
Gary  K4FMX


> -----Original Message-----
> From: Boatanchors [mailto:boatanchors-bounces at mailman.qth.net] On Behalf
> Of rbethman
> Sent: Monday, October 20, 2014 7:32 AM
> To: boatanchors at mailman.qth.net
> Subject: [Boatanchors] Independent sideband suppressed-carrier
> 
> Yes, I DO know that this was NOT the Costas proposal.
> 
> It is actually better in many ways.
> 
> 
> 
> 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
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