Security system

• US 4,477,800 A
• Filed: 12/07/1981
• Issued: 10/16/1984
• Est. Priority Date: 12/07/1981
• Status: Expired due to Term

• Current Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Original Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Inventors: O'Brien, Thomas E.
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US06/328,304
• Time in Patent Office: 1,044 Days
• Field of Search: 340/533, 340/531, 340/532, 340/518, 340/505-507, 340/536, 340/825.21, 340/825.06-825.13, 340/825.29, 340/825.52, 340/825.54 , 340/870.09, 340/870.16, 340/870.18, 340/870.26, 179/5 R, 179/5 P, 178/63 R, 178/63 A-63 C, 358/10, 358/139, 358/122, 358/86, 375/36, 375/7
• US Class Current: 340/533
• CPC Class Codes: G08B 25/007 Details of data content structure of message packets; data protocols
• CPC Class Codes: G08B 25/014 Alarm signalling to a central station with two-way communication, e.g. with signalling back
• CPC Class Codes: G08B 25/08 using communication transmission lines G08B13/19658, G08B21/0286, G08B25/016 take precedence
• CPC Class Codes: G08B 26/00 Alarm systems in which substations are interrogated in succession by a central station
• CPC Class Codes: G08B 26/003 replying the identity and the state of the sensor

Abstract

A cable TV security system utilizes three radio frequency signals as three data communication channels. One downstream channel is provided as a polling channel in available spectrum space in the standard FM band. Two upstream channels are provided in the return portion of the cable spectrum. One of the upstream channels is a polling response channel, and the other is an alarm channel. Subscriber security units transmit on the polling return channel in response to downstream command messages on the polling channel. Alarm conditions are immediately transmitted on the alarm channel so that system response to an alarm condition is fast and substantially independent of the number of subscribers.

Claims

1. A subscriber security apparatus for use in a cable communication system having a headend alarm processor for providing polling messages modulating a first radio frequency signal propogating over said cable communication system from said headend alarm processor, said cable communication system also propogating second and third radio frequency signals to said headend alarm processor, said security apparatus comprising:

means responsive to said polling messages modulating said first radio frequency signal for providing polling return messages modulating said second radio frequency signal; and

means responsive to an alarm condition for providing an alarm message essentially when said alarm condition is first detected, said alarm message modulating said third radio frequency signal.

2. An alarm system comprising:

a headend alarm processor including means for providing polling messages modulating a first radio frequency signal;

a two way cable TV communication system for propogating said first radio frequency signal in a direction from said headend alarm processor, and for propogating second and third radio frequency signals to said headend alarm processor; and

a plurality of subscriber alarm processors, each comprising means responsive to said polling messages modulating said first radio frequency signal received from said headend alarm processor over said cable system for providing respective reply messages modulating said second radio frequency signal to said headend alarm processor over said cable system, and means responsive to an alarm condition for providing an alarm message essentially when said alarm condition is first detected, said alarm message modulating said third radio frequency signal to said headend alarm processor over said cable system.