Title: Single sideband transceiver

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Abstract: A transmitter unit comprises two resonant circuits which are caused to oscillate during transmission to produce two pilot signals of predetermined frequencies. The pilot signals are mixed with an audio signal and used to modulate a transmission carrier signal in a balanced modulator which forms two sideband signals. The transmission carrier signal and one of the sideband signals are suppressed to form a single sideband signal which is used to modulate a channel signal for transmission. A receiver unit comprises a voltage controlled local oscillator which produces a local oscillator signal which is hetrodyned with the modulated channel signal to recover the single sideband signal. A reception carrier signal is hetrodyned with the single sideband signal in a balanced demodulator to recover the pilot signals and audio signal, the latter of which is fed to a speaker. The pilot signals are applied to a first frequency detector which detects the difference frequency thereof and triggers a voltage sweep generator to apply a voltage sweep to the local oscillator thereby causing a local oscillator frequency sweep. The pilot signals are further fed to the resonant circuits which are used during reception as second and third frequency detectors which detect when the heterodyned pilot signals reach their predetermined frequencies and interrupt the control voltage sweep at that instant, maintaining the local oscillator signal at the proper frequency. Means are provided to reset the receiver unit to manual local oscillator control if a control voltage sweep is completed without detection of the pilot signals by the second and third frequency detectors.


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