SSB System with pilot coded squelch

A receiver for processing a single sideband signal and pilot additionally angle modulated with a coded squelch signal and providing an output, comprising:

• 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.

A transmitter for transmitting a message and a coded squelch for enabling at least one predetermined receiver in a single sideband communications system, comprising:

• 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.

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:

• 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.