GB2349293A - Alarm sensor - Google Patents

Abstract

An alarm sensor unit which responds to an audible sound and automatically calls a user programmable telephone number when combined with an adapted telephone system. The audible sound would normally take the form of an annunciator indicating the existence of a fire or a burglar alarm but could be derived from other sources such as a dog barking or a voice or pre-programmed sounds. The adapted telephone system could take the form of a conventional land line or a mobile or portable device. As such the invention provides a means for the warning of remote and mobile installations including vehicles and temporary installations such as building sites, camp sites and unattended vehicles.

Description

Alarm Sensor This invention relates to an alarm sensor device which in response to an audible sound automatically phones a user pre-programmable telephone number or activates another device.

Remote alarm devices that respond to a change in electrical state due to the operation of an alarm are well known. Such devices usually form a part of a burglar/fire alarm system and automatically make a phone call in response to the alarm system being tampered with. The operation and installation of these devices is complex requiring wiring or the use of radio frequency to activate the call to the remote user.

Extensive use is now made of stand alone fire, burglary, and other annunciators which make a loud sound in response to smoke or fire detection or other event in both mobile and static situations such as vehicles and fixed installations including houses and business premises. These devices do not provide an indication of a fire or burglary or other event if the interested party is outside the audible range of the annunciator.

According to the present invention there is provided an alarm sensor unit comprising a microphone, a noise filter to distinguish between normal day to day background noise and that of the sound sensed, an interface unit for connection to a conventional telephone line or a mobile wireless or other adapted telephone system, a means for programming the telephone or other contact number or system, and an enclosure. The invention comprises electronic circuitry which in response to an audible sound automatically connects the adapted phone to a pre-programmable number.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which Figure 1 shows the electrical functional blocks; Figure 2 shows a microphone and amplifier circuit; Figure 3 shows a filter and rectifier circuit ; Figure 4 shows a level comparator and telephone activation circuit; Figure 5 shows an active memory recall interface circuit; and Figure 6 shows the electrical interface to a telephone.

Referring to the block schematic Fig 1 the microphone and sound amplification circuit 1 is connecte to input filter circuit 2 which would typically be in the form of a band pass filter to attenuate unwanted random noise and speech. The output from the filter circuit 2 is fed to a comparator circuit 3 which at a predetermined level via the phone activation circuit 4 activates the adapted phone system 5.

Figure 2 details the microphone and amplifier circuitry which consists of a class A type amplifier which converts the sound waves to electrical signals and increases the level via Q1, 2, and 3 to an amplitude which is immune to background electrical noise.

The output from the amplifier Fig 2 is then filtered using the band pass filter Fig 3 consisting of C20, R24, C21, R23, and C13 and the signal is then peak rectified by D1 in combination with C14. The component values and style of filter being selected to maximise the amplified signal level at frequencies around that of audible alarm systems and rejecting frequencies around the telephone bell/buzzer range.

The filtered output is then fed to the level Comparator and telephone activation circuit Fig 4 which by using the comparator circuit of Q4,5, and 6 switches on the relay RLB when the DC level of the signal at the junction of R27 and Q4 exceeds the voltage at the junction of R25, R26 and Q5's base.

The output from the level comparator and telephone activation circuit Fig 4 is fed to the activate memory recall circuit Fig 5 and by differentiating the falling edge of the output from the level comparator and telephone activation circuit, using R17, D2 and C5, Q9 is momentarily turned on to switch on RLC/2 which simulates the operation of the Memory recall button on the adapted telephone.

Figure 6 shows how the circuitry interfaces with a telephone that incorporates a Memory Recall feature.

Operation is as follows : The adapted telephone is used as a normal telephone in every respect except the user programmes the designated Memory recall button with his preferred call number such as his mobile or any other telephone number.

Each time the phone is used to make or receive calls the act of lifting or simulating the lifting of the handset (e. g. with a hands-free phone system) causes the pick up sense relay RLA to disconnect the Sensor supply line. This results in the alarm sensor circuitry becoming disconnected from its power source preventing it from being affected by normal use of the adapted telephone and visa-versa.

In the event of a fire or burglar alarm annunciator sounding RLB operates closing the contacts in parallel with the telephone hook switch Sl and simultaneously overrides the effect of RLA by closing contacts RLB/2. After a short delay RLC momentarily closes its isolated contacts simulating the effect of operating the memory recall button MO on the adapted phone.

When the remote phone is answered by the user he is able to hear the background noise of the alarm and can take appropriate action.

A second specific embodiment would be similar to the aforementioned but would use solid state amplifier circuitry enclosed within integrated circuits. Figure 7 shows the implimentation of an example circuit. The opto-isolated solid state switches replace the relays.

A third specific embodiment would be similar to the aforementioned but be integrated within a mobile phone.

A fourth specific embodiment would be similar to the aforementioned but be configured for use within or on a vehicle. eg. motorbike, car, aircraft, or boat.

A fifth specific embodiment would be similar to the aforementioned but contact to the remote user would be implelmented by the transmission of a radio frequency which may be encoded.

A sixth embodiment would be similar to the aforementioned but contact a dedicated annunciator.

Claims (8)

1. CLAIMS 1 An alarm sensor unit which responds to a noise comprising a noise filter to distinguish between normal day to day background noise and that of the annunciator sensed, an interface unit for connection to a conventional telephone line or a mobile wireless or other adapted telephone system, a means for programming the telephone or other contact number or system, and an enclosure.

   The invention comprises electronic circuitry which in response to an audible sound automatically connects the adapted phone to a pre-programmable number.
2. 2 An alarm sensor unit as claimed in 1 wherein the enclosure is a stand alone device.
3. 3 An alarm sensor unit as claimed in claim 1 or claim 2 whereby programmable frequencies are selectable and de-selectable.
4. 4 An alarm sensor unit as claimed in claim 1 or claim 2 whereby the device can be programmed to respond to any pre-recorded sound.
5. 5 An alarm sensor unit as claimed in claim 1 or claim 2 whereby the device can be programme to respond to a specific range of noises.
6. 6 An alarm sensor unit as claimed in claim 1 or claim 2 whereby the device is combined with other sensors.
7. 7 An alarm sensor unit as claimed in claim 1 or claim 2 whereby manual adjustments can be made.
8. 8 An alarm sensor unit substantially as described herein with references to Figures 1 to 7 of the accompanying drawings.