MONITORING METHOD

• US 20100085195A1
• Filed: 04/24/2008
• Published: 04/08/2010
• Est. Priority Date: 04/27/2007
• Status: Abandoned Application

• Current Assignee: Thorn Security Limited (Johnson Controls International plc)
• Original Assignee: THOM Security Limited
• Inventors: Bennett, Steven Ian
• Application Number:
  US12/596,802
• Publication Number:
  US 20100085195A1
• Time in Patent Office: Days
• US Class Current: 340/577
• CPC Class Codes: G08B 29/10 Monitoring of the annunciator circuits
• CPC Class Codes: H04R 29/007 for public address systems public address systems per se H04R27/00

Abstract

A method of monitoring an alarm system comprises transmitting a sound alert signal, receiving the transmitted sound alert signal, comparing the received sound alert signal with a reference signal having parameters dependent upon equivalent parameters of the transmitted sound alert signal, and outputting a signal indicating whether or not the equivalent parameters of the received sound alert signal have a predetermined relationship with said parameters of the transmitted sound alert signal.

Claims

1. A method of monitoring an alarm system, the method comprising transmitting a sound alert signal, receiving the transmitted sound alert signal, comparing the received sound alert signal with a reference signal having parameters dependent upon equivalent parameters of the transmitted sound alert signal, and outputting a signal indicating whether or not the equivalent parameters of the received sound alert signal have a predetermined relationship with said parameters of the transmitted sound alert signal.

2. The method as claimed in claim 1, wherein a single tone is transmitted, and the comparison step is to check that the level of the received tone is above a predetermined reference level.

3. The method as claimed in claim 1, wherein a series of tones are transmitted, and the comparison step is to check that the level of the received tone of the lowest intensity is above a predetermined reference level.

4. The method as claimed in claim 2, wherein the reference level is provided by a reference signal generator.

5. The method as claimed in claim 1, wherein a waveform signal is generated, and the comparison step compares parameters of the received waveform signal with equivalent parameters of a reference waveform signal, said equivalent parameters being dependent upon corresponding parameters of the transmitted waveform signal.

6. The method as claimed in claim 5, wherein the comparison step is to compare the repetition rate of the received waveform signal as it crosses a reference threshold with the expected repetition rate of a waveform signal provided by a reference signal generator.

7. The method as claimed in claim 5, wherein the comparison step comprises:

b) sampling the received waveform signal at a plurality of sample points; and

c) checking whether or not the received waveform signal is within maximum and minimum thresholds for each sample point.

8. The method as claimed in claim 7, wherein the maximum and minimum thresholds for each sample point are determined in dependence upon the maximum and minimum levels of the received waveform signal.

9. The method as claimed in claim 8, wherein the maximum and minimum levels of the received waveform signal are proportional to the maximum and minimum levels of the transmitted waveform signal.

10. The method as claimed in claim 5, wherein the comparison step comprises carrying out a cross-correlation between the received waveform signal and the reference waveform signal.

11. A system for monitoring an alarm system, the system comprising:

d) transmission means for transmitting a sound alert signal;

e) receiving means for receiving the transmitted sound alert signal; and

f) comparison means for comparing the received sound alert signal with a reference signal having parameters dependent upon equivalent parameters of the transmitted sound alert signal, and for outputting a signal indicating whether or not the equivalent parameters of the received sound alert signal have a predetermined relationship with said parameters of the transmitted sound alert signal.

12. The system as claimed in claim 11, wherein the transmission means is such as to transmit a single tone, and the comparison means is such as to check that the level of the received tone is above a predetermined reference level.

13. The system as claimed in claim 11, wherein the transmission means is such as to transmit a series of tones, and the comparison means is such as to check that the level of the received tone of the lowest intensity is above a predetermined level.

14. The system as claimed in claim 12, wherein the reference level is provided by a reference signal generator.

15. The system as claimed in claim 11, wherein the transmission means is such as to transmit a waveform signal, and the comparison means such as to compare parameters of the received waveform signal with equivalent parameters of a reference waveform signal, said equivalent parameters being dependent upon corresponding parameters of the transmitted waveform signal.

16. The system as claimed in claim 15, wherein the comparison means is such as to compare the repetition rate of the received waveform signal as it crosses a reference threshold with the expected repetition rate of a waveform signal provided by a reference signal generator.

17. The system as claimed in claim 15, wherein the comparison means is such as to sample the received waveform signal at a plurality of sample points, and to check whether or not the received waveform signal is within maximum and minimum thresholds for each sample point.

18. The system as claimed in claims 17, wherein the maximum and minimum reference thresholds for each sample point are determined in dependence upon the maximum and minimum levels of the received waveform signal.

19. The system as claimed in claim 18, wherein the maximum and minimum levels of the received waveform signal are proportional to the maximum and minimum levels of the transmitted waveform signal.

20. The system as claimed in claim 15, wherein the comparison means is such as to carry out a cross-correlation between the received waveform signal and the reference waveform signal.

21. A sounder module for incorporation in an alarm system, the sounder module comprising:

g) transmission means for transmitting a sound alert signal;

h) receiving means for receiving the transmitted sound alert signal; and

i) comparison means for comparing the received sound alert signal with a reference signal having parameters dependent upon equivalent parameters of the transmitted sound alert signal, and for outputting a signal indicating whether or not the equivalent parameters of the received sound alert signal have a predetermined relationship with said parameters of the transmitted sound alert signal.

22. The sounder as claimed in claim 21, further comprising a reference signal generator for supplying a reference signal to the detector.