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US 4,539,707 AGranted
Compressed single side band communications system and method
AssigneeAerotron, Inc.
InventorsPaul H. Jacobs, Douglas P. Collette
Life of this patent
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AssigneeAerotron, Inc.
InventorsPaul H. Jacobs, Douglas P. Collette
Estimating the term…
A compressed single side band communication system and method in which the audio signal is compressed prior to pre-emphasis and thereafter summed with a pilot tone for further compression prior to transmission. Initally, only the pilot tone is transmitted at full rated power to aid in acquisition of the signal by the receiver. Thereafter, the transmitter ALC is disabled and the pilot tone is attenuated. The receiver adjusts the frequency characteristics of the pilot tone filter and phase lock loop filter in the detector as a function of lock-on. The delay after loss of lock-on in reverting to wide band pilot tone and wideband loop filters is varied as a function of signal strength. The pilot tone may be modulated for tone coded squelch. The modulating source is located in the return end of the phase lock loop filter. A unique filter is provided to insure acquisition of the pilot tone. Automatic gain control of the audio signal is responsive to the tone signal without effecting the composite audio and tone signal.
A two-way, land mobile, single sideband, radio communciation system comprising:
A method of communicating between a base station and land mobile receiver comprising:
In a method of enhancing reception of a composite radio frequency signal including audio frequency components and a pilot tone component by a receiver having a radio frequency oscillator, a phase lock loop, and radio frequency and intermediate frequency amplifiers in which (a) the pilot tone component is detected by a pilot filter and rectifier means and the amplitude of the detected pilot tone component is used to control the gain of the radio frequency and intermediate frequency amplifiers within the receiver, (b) the audio frequency components are de-emphasized for application to a speaker, and (c) the phase lock loop receives both the detected pilot tone component and a locally generated pilot tone and adjusts the radio frequency oscillator for frequency errors in the received carrier frequency, the improvement wherein the frequency response characteristics of the pilot filter are selectively varied as a function of a phase lock loop lock-on.
A receiver comprising:
In a method of controlling the output power of a radio frequency transmitter in transmitting a composite audio modulation signal including audio signal components and a pilot tone component outside the audio signal passband but within the bandpass of the transmitter, the improvement including the steps of
A radio frequency transmitter comprising:
Dependencies are inferred from the claim text.