Security system using sensors

• US 20030102963A1
• Filed: 11/08/2002
• Published: 06/05/2003
• Est. Priority Date: 11/09/2001
• Status: Active Grant

• Current Assignee: Nihondensikougaku Company Limited
• Original Assignee: Nihondensikougaku Company Limited
• Inventors: Orita, Takehiro, Orita, Kouji, Kuriuchi, Kimito
• Granted Patent: US 6,831,550 B2
• Time in Patent Office: Days
• US Class Current: 340/310.01
• CPC Class Codes: G04G 5/00 Setting, i.e. correcting or changing, the time-indication radio-controlled time-pieces G04R
• CPC Class Codes: G08B 25/06 using power transmission lines
• CPC Class Codes: G08B 29/12 Checking intermittently signalling or alarm systems

Abstract

In a security system using sensors that includes clock-equipped surveillance terminals for sending security data to a surveillance center, one surveillance terminal uses a power supply line to send a time calibration signal to the other surveillance terminals at appropriate times, the surveillance terminals use the signal to eliminate time error among their clocks, the other surveillance terminal use the power supply line to send to the one surveillance terminal time-stamped data, and the one surveillance terminal discriminates operating states of the other surveillance terminals by comparing the receive time and send time of time-stamped data.

Claims

1. A security system using sensors comprising:

multiple surveillance terminals each equipped with a clock and adapted to send security and other data over a power supply line; and

a surveillance center for performing security surveillance utilizing security data received from the surveillance terminals,

wherein;

at least one surveillance terminal among the multiple surveillance terminals uses the power supply line to send a time calibration signal to required ones of the other surveillance terminals at appropriate times,

the surveillance terminals receiving the time calibration signal use the signal to correct their clocks to eliminate time error among the clocks of the multiple surveillance terminals,

each surveillance terminal uses the power supply line to send to a prescribed surveillance terminal time-stamped data created by adding to the security and other data it sends send-time data indicating the time at which the data was sent, and

the prescribed surveillance terminal discriminates operating states of the surveillance terminals by comparing receive time and send time of time-stamped data.

2. A security system as claimed in claim 1, wherein a standard time data is received in at least one of the multilple surveillancance devices of tne securituy system, and the standard time data received is sent over a distribution line to required surveillance devices.

3. A security system as claime in claim 2, wherein each of said surveillamce devices has a power-line carrier transceiver and the standard time data is send throiugh the power-line carrier transceiver to the required surveillances.

4. A security system as claimed in claim 2 or 3, wherein a time calibration is performed by overwriting the time data of the clock with the standard time data.