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The "Wadley-drift-canceling-loop", also known as a "Wadley loop", is a system of two oscillators, a frequency synthesizer, and two frequency mixers in the radio-frequency signal path. The system was designed by Dr. Trevor Wadley in the 1940s in South Africa. The circuit was first used for a stable wavemeter. (A wavemeter is used for measuring the wavelength and therefore also the frequency of a signal).
There is no regulation loop in a "Wadley-loop", which is why the term is in quotation marks. However, the circuit configuration is not known by more accurate names.[2]
The "Wadley loop" was used in radio receivers from the 1950s to approximately 1980. The "Wadley loop" was mostly used in more expensive stationary radio receivers, but the "Wadley loop" was also used in a portable radio receiver (Barlow-Wadley XCR-30 Mark II).[3][4]
- ^ radiomuseum.org: Yaesu FRG-7000 Citat: "...Wadley-Loop principle (including dual superhet)..."
- ^ "The Wadley Loop - A Drift-cancelling Receiver Tuning Principle". February 2017. Archived from the original on 2020-01-30.
They, not its creator, call it a loop, but it is no such thing. In order for it to be a loop it must have feedback, which it does not. There is so much misinformation about the circuit I often wonder if people really understand what it is... The Wadley Loop... it's a tuning concept that cancels the drift of one oscillator in the receiver by using it twice in the conversion scheme...
- ^ radiomuseum.org: Barlow-Wadley XCR-30 Mark II
- ^ Barlow-Wadley XCR-30 Mark II