REMOTE CONTROL COMMUNICATIONS SYSTEM

• US 3,746,991 A
• Filed: 07/15/1970
• Issued: 07/17/1973
• Est. Priority Date: 07/15/1970
• Status: Expired due to Term

• Current Assignee: George E. Gautney
• Original Assignee: George E. Gautney
• Inventors: Gautney, George E.
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US05/055,101
• Time in Patent Office: 1,098 Days
• Field of Search: 325/30,49,50,55,64,63,58,37,420,421,422,423 340/170,171,167 343/225,227,228 179/15BY
• US Class Current: 455/218
• CPC Class Codes: G08B 27/00 Alarm systems in which the alarm condition is signalled from a central station to a plurality of substations

Abstract

A transmitter, which remotely controls the demuting of a normally muted radio receiver, derives a command signal from a carrier wave, the command signal having a frequency or a duration which is precisely related to the frequency of the carrier wave. The receiver derives a reference signal from the received carrier wave, having a frequency which is a predetermined fraction of the frequency of the carrier wave, detects the command signal, and compares a time parameter of the command signal (either its frequency or duration) with the frequency of the reference signal. If a predetermined relationship exists, a control signal is provided for controlling a muting/demuting circuit in the receiver. Selective addressing of a particular receiver may be effected by providing the transmitter with means for deriving a plurality of command signals, each having a different time parameter corresponding to a particular receiver, and selective keying means for selecting one of the command signals for transmission. The carrier wave may be a pilot carrier which, in turn, modulates a main carrier wave of the transmitter.

Claims

1. A communications system, comprising:

a transmitter and a remote receiver;

said transmitter including a source of a carrier wave, means to derive a command signal from said carrier wave having a time parameter having a fixed relationship with the frequency of said carrier wave, means to modulate said carrier wave with said command signal, and means to transmit the modulated carrier wave; and

said receiver including means to receive said modulated carrier wave, means to derive a reference signal from said received carrier wave having a time parameter which is a function of the frequency of said received carrier wave, means to detect said command signal modulated on said received carrier wave, comparison means for comparing said time parameters of said detected command signal and said reference signal and for providing a control signal in response to a predetermined relationship between said time parameters, and apparatus controlled by said control signal.

2. A communications system as recited in claim 1, said system being a muting/demuting system and said receiver including means for muting an output from said receiver and responsive to said control signal for demuting said output from said receiver.

3. A communications system as recited in claim 2, wherein said transmitter includes means for transmitting an intelligence signal and said receiver includes means for detecting said intelligence signal and providing said intelligence signal as said output.

4. A communications system as recited in claim 1, wherein said means to derive a command signal comprises frequency divider means for providing a command signal having a frequency which is a predetermiNed fraction of the frequency of said carrier wave, said frequency of said command signal being said time parameter of said command signal.

5. A communications system as recited in claim 4, wherein said means to derive said command signal further comprises keying means for selectively providing said command signal.

6. A communications system as recited in claim 4, wherein said comparison means comprises means for deriving a timing signal from said detected command signal the duration of which is a function of the frequency of said command signal.

7. A communications system as recited in claim 1, wherein said means to derive a command signal comprises means for providing a command signal which is a predetermined fraction of the frequency of said carrier wave, and wherein said comparison means includes a frequency multiplier for multiplying said command signal by the inverse of said predetermined fraction and phase comparison means for comparing the phase of said carrier wave and the output signal from said frequency multiplier.

8. A communications system as recited in claim 1, wherein said means to derive a command signal is adapted to derive a plurality of command signals from said carrier wave, each having a different time parameter, and comprises selective keying means to transmit a selected command signal, and wherein said system comprises a plurality of remote receivers, the comparison means in each of said receivers being adapted to provide a control signal in response to the reception of a particular one of said command signals, whereby only receivers responsive to the selected command signal will provide a control signal.

9. A communications system as recited in claim 1, wherein said carrier wave is a pilot carrier wave, wherein said transmitter comprises a source of a main carrier wave, said main carrier wave being modulated by said pilot carrier wave after said pilot carrier wave is modulated by said command signal, and wherein said receiver comprises means to receive said modulated main carrier wave and to detect said modulated pilot carrier wave.

10. A communications system as recited in claim 1, wherein said receiver comprises hold means for maintaining said control signal for a time interval following cessation of said command signal.

11. A carrier wave receiver, comprising:

means for receiving a carrier wave modulated by a command signal having a time parameter having a fixed relationship with the frequency of said carrier wave;

means to derive a reference signal from said received carrier wave having a time parameter which is a function of the frequency of said received carrier wave;

means to detect said command signal modulated on said received carrier wave;

comparison means for comparing said time parameters of said detected command signal and said reference signal and for providing a control signal in response to a predetermined relationship between said time parameters; and

apparatus having at least two states and including means for effecting one of said states when said control signal is provided and for effecting the other of said states in the absence of said control signal.

12. A carrier wave receiver as recited in claim 11, wherein said apparatus comprises means for muting an output from said receiver and responsive to said control signal for demuting said output.

13. A carrier wave receiver as recited in claim 12, further comprising means for detecting an intelligence signal modulated on said carrier wave, said detected intelligence signal comprising said output.

14. A transmitter for remotely controlling a remote receiver comprising:

a source of a carrier wave;

means to derive a command signal from said carrier wave having a time parameter having a fixed relationship with the frequency of said carrier wave;

means to modulate said carrier wave with said command signal;

means to transmit the modulated carrier wave; and

means to transmit an intelligence signaL;

wherein said means to derive a command signal comprises frequency divider means for providing a command signal having a frequency which is a predetermined fraction of the frequency of said carrier wave; and

further comprising a receiver of said carrier wave, means for deriving said command signal from said carrier wave, means for multiplying the frequency of said command signal by the inverse of said predetermined fraction, means for comparing the phases of said carrier wave and the output signal from said means for multiplying to produce an output signal when the phases of said signals bear a predetermined phase relationship to one another and means responsive to an output signal from said phase comparator for a specified length of time for performing a predetermined function.

15. A transmitter for remotely controlling a remote receiver comprising:

a source of a carrier wave;

means to derive a command signal from said carrier wave having a time parameter having a fixed relationship with the frequency of said carrier wave;

means to modulate said carrier wave with said command signal; and

means to transmit the modulated carrier wave;

wherein said means to derive a command signal derives a plurality of command signals from said carrier wave, each having a different time parameter, and comprises selector means for selecting a particular command signal for transmission for controlling a particular remote receiver.

16. The combination according to claim 15 further comprising a receiver for receiving the transmitted modulated carrier wave, said receiver comprising:

means to derive a reference signal from said received carrier wave having a time parameter which is a function of the frequency of said received carrier wave, means to detect said command signal modulated on said received carrier wave, comparison means for comparing said time parameters of said detected command signal and said reference signal and for providing a control signal in response to a predetermined relationship between said time parameters, and apparatus controlled by said control signal.