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Old 14th Dec 2014, 3:54 am   #26
Synchrodyne
Nonode
 
Join Date: Jan 2009
Location: Papamoa Beach, Bay of Plenty, New Zealand
Posts: 2,943
Default Re: Quasi-Synchronous Demodulation

Upthread, post #20, I had wondered whether or not the Crosby exalted carrier receiver was ever realized in practice.

Well, apparently it was, judging by the attached item and advertisements from the early 1950s. Evidently Crosby Laboratories manufactured both SSB and exalted carrier receivers, amongst other equipment.

The Press Wireless endorsement (1953 July advertisement) is of note, given that this organization had its own manufacturing division (http://www.tmchistory.org/PressWirel...facilities.pdf) and eventually developed its own exalted carrier receiver. Perhaps there was some kind of connection between Crosby and Press Wireless, and its starting point was the Crosby receiver, which it then refined by the use of its version of the locked oscillator technique.

Another related idea of the late 1940s was that of Norgaard of GE, for the generation of ISB signals by wideband AF phase-shifting and quadrature modulation. The proposed receiver was of the locked oscillator type, with I and Q demodulation, audio phase-shifting and dematrixing, recognizable as the basic technique used in more recent HF receivers with PLL fully synchronous selectable sideband demodulation. A brief description of the Norgaard system was provided in Communications magazine for 1948 April, available here: http://www.americanradiohistory.com/...ns-1948-04.pdf, see page 12.

Cheers,
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