SSB System with pilot coded squelch
First Claim
1. A single sideband communications system for conveying a message through a transmitter to at least one predetermined receiver and employing a coded squelch signal unique to that receiver, comprising:
- means for generating and transmitting a radio frequency signal comprising a single sideband signal and pilot both angle modulated with the coded squelch signal at a predetermined deviation;
means for receiving the radio frequency signal and tracking to predetermined limits the frequency excursions of said pilot so as to essentially eliminate frequency distortion of the message;
means for demodulating the single sideband signal; and
means for demodulating the coded squelch signal from said received radio frequency signal in cooperation with said frequency excursion tracking means thereby avoiding interference to said single sideband signal demodulating means and said frequency tracking means.
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Accused Products
Abstract
A single sideband communications system conveying a message through a transmitter to one or more predetermined receivers which are enabled by a coded squelch signal unique to the predetermined receivers is disclosed. The transmitter comprises means to angle modulate both the pilot signal and the information bearing single sideband signal with the coded signal at a predetermined deviation and to transmit the resulting signal.
Each receiver frequency control means tracks the frequency excursions of a selected portion of the transmitted signal up to predetermined limits so that the message can be demodulated without frequency distortion being introduced. Each receiver demodulates the coded squelch without interfering with the message demodulation or tracking functions and activates the receiver squelch of those preselected receivers.
66 Citations
36 Claims
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1. A single sideband communications system for conveying a message through a transmitter to at least one predetermined receiver and employing a coded squelch signal unique to that receiver, comprising:
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means for generating and transmitting a radio frequency signal comprising a single sideband signal and pilot both angle modulated with the coded squelch signal at a predetermined deviation; means for receiving the radio frequency signal and tracking to predetermined limits the frequency excursions of said pilot so as to essentially eliminate frequency distortion of the message; means for demodulating the single sideband signal; and means for demodulating the coded squelch signal from said received radio frequency signal in cooperation with said frequency excursion tracking means thereby avoiding interference to said single sideband signal demodulating means and said frequency tracking means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A receiver for processing a single sideband signal and pilot additionally angle modulated with a coded squelch signal and providing an output, comprising:
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means for detecting the level of the pilot and correspondingly adjusting the receiver to effect a substantially constant level at the output of the receiver; means for tracking the frequency excursions of the pilot to predetermined limits thereby allowing an essentially frequency distortion free demodulation of the single sideband signal; means, coupled to said means for tracking the frequency excursions, for demodulating the coded squelch signal whereby interference to said single sideband signal, said tracking means, and said level detecting means is essentially avoided; and means for decoding and comparing the demodulated coded squelch signal to an internally stored reference thereby activating the receiver output upon a detected match. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A transmitter for transmitting a message and a coded squelch for enabling at least one predetermined receiver in a single sideband communications system, comprising:
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means for creating a single sideband signal modulated by the message; means for generating a pilot and combining it with said single sideband signal; means for further combining said combined signal with a coded squelch signal to derive a single sideband radio frequency signal angle modulated at a predetermined deviation with said coded squelch signal; and means for transmitting said radio frequency signal. - View Dependent Claims (25, 26, 27, 28, 29, 30)
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31. A method of enabling by coded squelch at least one predetermined receiver to receive a single sideband modulated message from a transmitter and deliver the message to an output, comprising the steps of:
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deriving a radio frequency signal comprising a pilot and the message carrying single sideband signal angle modulated with the coded squelch signal at a predetermined deviation; transmitting the resulting radio frequency signal; receiving and tracking the frequency excursions of said pilot of said radio frequency signal to predetermined limits; demodulating the single sideband modulated message essentially frequency distortion-free as a result of said frequency excursion tracking; and demodulating said coded squelch signal from said radio frequency signal essentially without interference to said single sideband message demodulating step as a result of said frequency tracking step. - View Dependent Claims (32, 33, 34, 35, 36)
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Specification