[Boatanchors] Independent sideband suppressed-carrier

[Chris Trask]

>
>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.
>

     Not necessrily.  If the pilot tone is injected into both sidebands the Costas Loop will lock onto that as it will be coherent while seeing the independent sidebands as incoherent noise.  After the post-detection quadrature phase shifter the two outputs are summed and differenced in separate channels, yielding the two sidebands independently.

     It only requires that the pilot tone be included in the transmitter and an additional summation (or differencing) stage be added to the receiver.

     I devised one of these decades ago to send both SSTV and audio simultaneously.  The proper term for such a system is "vestigial (sp?) sideband".


Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/