Pulse code modulation responsive alarm system

• US 4,260,982 A
• Filed: 10/25/1979
• Issued: 04/07/1981
• Est. Priority Date: 10/25/1979
• Status: Expired due to Term

• Current Assignee: Angelo P. Debenedictis, Plato Zorzy
• Original Assignee: Angelo P. Debenedictis, Plato Zorzy
• Inventors: Zorzy, Plato, DeBenedictis, Angelo P.
• Primary Examiner(s): Waring, Alvin H.
• Application Number:
  US06/088,034
• Time in Patent Office: 530 Days
• Field of Search: 340/32, 340/52 R, 340/53, 340/56, 340/63, 340/539, 340/568, 340/673, 340/695, 455/26
• US Class Current: 340/539.24
• CPC Class Codes: G08B 13/1427 with transmitter-receiver for distance detection
• CPC Class Codes: G08B 21/0222 Message structure or message content, e.g. message protocol
• CPC Class Codes: G08B 21/0247 System arrangements wherein the alarm criteria uses signal strength
• CPC Class Codes: G08B 3/10 using electric transmission; using electromagnetic transmission

Abstract

A system for producing an alarm whenever the distance between a transmitter and a receiver exceeds a predetermined distance. The transmitter includes circuitry for generating a signal having a preselected pulse code modulation pattern. The receiver includes circuitry for responding to the particular pulse code pattern and for sounding an alarm when the signal from the transmitter is so weak that pattern is not received.

Claims

1. A system for detecting the displacement of two objects comprising:

A. a transmitter associated with one object, said transmitter including;

(i) power supply means;

(ii) means connected to said power supply means for generating a constant frequency signal having a preselected pattern of pulse code modulation; and

(iii) antenna means connected to said generating means for radiating said constant frequency pulse code modulated signal; and

B. a receiver associated with the second object, said receiver including;

(i) receiving means for receiving the pulse code modulated, constant frequency signal and for detecting the pulse code modulation signal portion thereof;

(ii) presence detecting means connected to said receiving for generating a presence detected signal in response to the presence of a constant frequency signal characterized by the pulse code modulation pattern;

(iii) alarm means connected to the presence detecting means for generating an alarm signal in response to the absence of a presence detected signal.

2. A system as defined in claim 1 wherein the presence detecting means comprises a phase locked loop detector.

3. A system as defined in claim 1 wherein the alarm signal generating means includes:

(i) oscillator means connected to the presence detecting means for generating an electrical signal in response to the absence of the presence detected signal; and

(ii) transducer means connected to said oscillator means for generating an alarm in response to the electrical signal from said oscillator means.

4. A system as defined in claim 3 further including means connected to said presence detecting means for generating an indication when said presence detecting means asserts the presence detected signal.

5. A system as defined in claim 4 wherein said indicating means constitutes a light emitting diode.

6. A system for detecting the displacement of two objects comprising:

A. a transmitter associated with one object, said transmitter including;

(i) power supply means;

(ii) means connected to said power supply means for generating a constant frequency signal having a preselected pattern of pulse code modulation, said means including;

(a) means for generating a pulse code envelope signal,

(b) means connected to the envelope signal generating means for generating a pulsed audio frequency signal modulated by the envelope signal, and

(c) means connected to the pulsed audio frequency signal generating means for generating a radio frequency signal modulated by the pulsed audio frequency signal,

(iii) antenna means connected to said generating means for radiating said constant frequency pulse code modulated signal; and

B. a receiver associated with the second object, said receiver including;

(i) receiving means for receiving the pulse code modulated, constant frequency signal and for detecting the pulse code modulation signal portion thereof;

(ii) presence detecting means connected to said receiving means for generating a presence detected signal in response to the presence of a constant frequency signal characterized by the pulse code modulation pattern;

(iii) alarm means connected to the presence detecting means for generating an alarm signal in response to the absence of a presence detected signal.

7. A system as defined in claim 6 wherein the presence detecting means comprises a phase locked loop detector.

8. A system as defined in claim 6 wherein the alarm signal generating means includes:

(i) oscillator means connected to the presence detecting means for generating an electrical signal in response to the absence of the presence detected signal; and

(ii) transducer means connected to said oscillator means for generating an alarm in response to the electrical signal from said oscillator means.

9. A system as defined in claim 8 further including means connected to said presence detecting means for generating an indication when said presence detecting means asserts the presence detected signal.

10. A system as defined in claim 9 wherein said indicating means constitutes a light emitting diode.