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1. WO2009013549 - INFRASONIC INTRUDER ALARM

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

CLAIMS

1. An infrasonic intruder alarm system adapted to detect changes in infrasonic frequency in a defined space comprising:
- a transducer for sensing infrasonic frequency variations, adapted to produce an analogue signal;
- a signal amplifier;
- an analogue to digital converter adapted to convert a portion of the analogue signal which crosses at least one predetermined threshold into a digital signature;
- a processor adapted to compare the digital signature against known digital signatures, and to trigger an alarm event if the digital signal produced matches a said known signature; and
- alarm means activated by the alarm event.
2. An infrasonic intruder alarm system as claimed in claim 1 wherein multiple thresholds are provided, at least one threshold being positive and at least one threshold being negative relative to a mean signal.
3. An infrasonic intruder alarm system as claimed in claim 2 wherein there is a first positive threshold, a second positive threshold set at 33% of the first positive threshold, a first negative threshold and a second negative threshold set at 33% of the first negative threshold.
4. An infrasonic intruder alarm system as claimed in claim 3 wherein the processor can differentiate between a positive and a negative threshold crossing.

5. An infrasonic intruder alarm system as claimed in claim 4 wherein the processor will assign an "UP" code to positive threshold crossings, and a

"DOWN" code to negative threshold crossings.
6. An infrasonic intruder alarm system as claimed in any of claims 3 to 5 wherein the alarm event will be triggered when the analogue signal crosses four thresholds.
7. An infrasonic intruder alarm system as claimed in any of claims 2 to 6 wherein the time between each threshold crossing is measured.
8. An infrasonic intruder alarm system as claimed in claim 7 wherein if the time between two threshold crossings is above a set time limit, an alarm event will not be triggered.
9. An infrasonic intruder alarm system as claimed in any of the preceding claims wherein the analogue signal is processed to remove unwanted frequencies.
10. An infrasonic intruder alarm system as claimed in any of the preceding claims which further comprises a pre-amplifier, a digital low pass filter, digital high frequency roll off control, automatic background control and a low cut-off filter.

11. An infrasonic intruder alarm system as claimed in any of the preceding claims wherein the sensitivity of the alarm system may be adjusted.
12. An infrasonic intruder alarm system as claimed in any of the preceding claims wherein the alarm means comprises an audible signal.
13. An infrasonic intruder alarm system as claimed in any of the preceding claims wherein the alarm means is coupled to a telephone or ADSL line to notify an address book when an alarm event is triggered.
14. An infrasonic intruder alarm system as claimed in any of the preceding claims wherein the alarm means is coupled to a GPRS or other mobile phone network to notify an address book when an alarm event is triggered.
15. An infrasonic intruder alarm system as claimed in any of the preceding claims wherein the infrasonic intruder alarm system is adapted to be networked with other infrasonic intruder alarm systems via a central hub.
16. An infrasonic intruder alarm system as claimed in any of the preceding claims wherein the infrasonic intruder alarm system further comprises an auxiliary input port to which may be connected one or more secondary devices.
17. An infrasonic intruder alarm system as claimed in claim 16 wherein the secondary device is one or more health monitors attached to a user.
18. An infrasonic intruder alarm system as claimed in any of the preceding claims wherein the transducer is a microphone.
19. An infrasonic intruder alarm system as claimed in any of the preceding claims wherein the processor includes an adaptive self learning protocol to allow self adjustment.
20. An infrasonic intruder alarm system as claimed in any of the preceding claims wherein the processor incorporates a data logging protocol.
21. An infrasonic intruder alarm system as claimed in claim 20 wherein the data logging protocol can be updated from the Internet.