Hi Ed:
Thanks. No, I don’t have the Tucker articles. The closest I have to those is the August 1948 Wireless World article by “Cathode Ray”, which seems to have been based upon Tucker’s work. The synchrodyne receiver shown therein used a locked oscillator (not a phase locked oscillator) and a diode ring demodulator. I think that was around the same time that the single valve locked oscillator FM demodulator first appeared, which thus might be considered the FM counterpart to the AM synchrodyne demodulator. As a corollary, the nonode FM demodulator from about the same time would be the FM counterpart to the AM homodyne demodulator, and also the antecedent of the solid state quadrature FM demodulator that came into favour, in IC form, in the late 1960s.
The TV vision demodulation case is an interesting one. References cited in the Rzeszewski paper suggest that the problems with envelope demodulation of vestigial sideband signals was know from the earliest days. But realization of improved methods was very difficult in the valve era. I have a 1957 (?) RCA paper entitled “Synchronous and Exalted-Carrier Detection in Television Receivers” that suggests that there is a continuum of improvements available between simple envelope demodulation through exalted carrier techniques to fully synchronous.
One thus supposes that when the IC era arrived and allowed economic realization of improved demodulation techniques, the early efforts, such as the Motorola MC1330, were aimed at the same increment that would be available from exalted carrier technique, and were not reaching for perfection. A rough qualitative assessment of what this could bring is provided by those HF receivers that have quasi-synchronous AM demodulators, for example the JRC NRD525. Here the receiver may be detuned to the point where the carrier is slipping down the edge of the IF bandpass without the intrusion of the gross distortion that typically would be evident with a conventional diode demodulator.
Talking of HF receivers, whilst there was a whole plethora of ad hoc ICs for developed television vision quasi-synchronous demodulation, few seem to have been developed for HF AM work. Maybe it was assumed that most designers would build their demodulators from single-function ICs, such as the MC1496. Two ad hoc ICs that I have identified are the Plessey SL624C, for which I have limited information, and the TDA1071 (used by Eddystone in the 1570/1590 series), about which there is otherwise absolutely nothing on the web. (It seems to have sunk without trace.) Working from the Eddystone schematics, the TDA1071 appears to have combined a two-part IF amplifier, with accessible interstage, followed by a multiplying demodulator that may be configured for quasi-synchronous AM or quadrature FM, and was used by Eddystone in both roles in the 1570, and also for AM AFC. I have a vague notion that the TDA1071 was used by a portable receiver maker (Roberts?) but then I might be confusing it with the Philips/Mullard TDA1072 AM radio subsystem.
Coincidentally, some of the issues that PLL synchronous demodulation resolves as compared with the quasi-synchronous approach, essentially related to purity of the reference carrier, come out in the Wireless World September 1970 Portus and Haywood article on their phase-locked stereo decoder that was recently posted in the thread: “Wireless World MC1310 pll decoder article” at:
https://www.vintage-radio.net/forum/...t=81838&page=2.
Cheers,