GB2471410A

GB2471410A - Handheld signal detector used for monitoring signal strength in a wireless alarm system

Info

Publication number: GB2471410A
Application number: GB1015887A
Authority: GB
Inventors: Gerard Kelly
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-03-13
Filing date: 2009-10-23
Publication date: 2010-12-29
Anticipated expiration: 2029-10-23
Also published as: GB2466546B; GB2466546A; GB201015887D0; GB0918658D0; IES20090200A2; GB2471410B

Abstract

A handheld signal detector is disclosed used with an alarm system of the kind comprising a central control unit (10,fig.1) and a plurality of remote devices (12,14,18,22,fig.1) in two-way RF communication with the control unit. The signal detector comprises a handheld housing 30 having an antenna (36,fig.3) and RF transmit/receive circuitry (38,fig.3) operable under manual control to cause the antenna to transmit a test signal to, and receive a response signal from the control unit (10,fig.1). The response signal indicates the strength of the test signal as received at the control unit. The signal detector further includes a means to select the characteristics of the test signal to correspond to transmission characteristics of different types of remote devices. The signal detector has LEDs and/or a loudspeaker (40,fig.3) for indicating to a user the strength of the test signal received at the control unit.

Description

An Alarm System This invention relates to an alarm system of the kind comprising a central control unit and a plurality of remote sensors in two-way RF communication with the control unit. The invention also relates to a signal detector for use with such system.

According to the present invention there is provided a signal detector used with an alarm system of the kind comprising a central control unit and a plurality of remote devices in two-way RF communication with the control unit, the detector comprising a hand-held housing having an antenna, RF transmit/receive circuitry operable under manual control for causing the antenna to transmit a test signal to the control unit and receive a response signal from the control unit, said response signal indicating the strength of the test signal at the control unit, and means for indicating to a user the strength of the test signal at the control unit as indicated by the response signal including means to select characteristics of the test signal to correspond to transmission characteristics of different types of devices.

In a preferred embodiment the signal detector housing further also includes a voice recording and playback device.

The invention also provides an alarm system comprising a central control unit and a plurality of remote sensors in two-way RF communication with the control unit, the control unit being operable in a test mode to receive a test signal from a remote device and upon receipt of said test signal to transmit a response signal to said device indicating the strength of the test signal at the control unit.

The invention further provides an alarm system comprising a central control unit, a plurality of remote sensors in two-way RF communication with the control unit, and at least one alarm sounder coupled to the control unit for sounding an alarm when a sensor signals an alarm condition to the control unit, the control unit being operable in a test mode to receive a sounder test signal from a remote device and upon receipt of said sounder test signal to test said sounder.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of an embodiment of an alarm system according to the invention.

Figure 2 is a perspective view of an embodiment of signal detector (hereinafter referred to as a!vtest wand") for use with the system of Figure 1.

Figure 3 is an exploded view from above of the test wand.

Figure 4 is an exploded view from below of the test wand.

Referring first to Figure 1, an alarm system comprises a central control unit, or control panel, 10 and a plurality of remote sensors 12-22. The sensors may be of various types, such as passive infrared (PIR) sensors, ultrasonic sensors, movement detectors, window/door contact sensors, or any combination of these. Some of the sensors, such as the sensors 12, 14 18 and 22, communicate with the control panel 10 by two-way RF communication, for example using packeted data. These sensors are typically battery-operated and of course power consumption is critical in terms of prolonging service life and reducing maintenance. In such a case the sensors communicate with the panel by periodically sending a message to the panel and listening for a response. In the interim, their RX and TX antenna circuitry is switched off. It is particularly advantageous to employ sensors of the type described Irish Patent No. S85245 (Attorney Ref: P929611E00) . Other sensors, such as the sensors 16, 20, may be connected by wires to the control panel 10 and are typically powered from the control panel 10. The system may also include one or more audible sounders, such as alarm bells or sounders 24, 26. Again, the alarm bells may be connected wirelessly to the control panel 10, e.g. alarm bell 26, or by wires, e.g. alarm bell 24. While wireless alarm bells are typically battery powered, wired bells usually include a back-up battery.

In operation, each sensor, if its monitoring circuitry is switched on, monitors its environment according to the type of sensor it is, and signals an alarm condition to the control panel 10 if certain criteria are met indicative, for example, of an intruder. When the control unit 10 receives an alarm condition it may sound a local alarm bell 24, 26 and/or signal a remote monitoring service and/or to the police via a network 28.

The network 28 may be a telephone network or the internet, for example. Not all sensors need be switched on all the time. For example, when a building is occupied at night it may be desired only to switch on the sensors monitoring doors and windows, while leaving internal sensors switched off to allow for movement around the building. During periods of unoccupancy, however, it might be desired to switch all the sensors on. The switching of sensors on and off is controlled from the control unit 10, either wirelessly or through wires, according to the connection of the sensor. The control unit is also operable in a test mode to allow the sensors to be tested without raising an alarm, e.g. using a so-called walk test.

The principles of construction and operation of such systems are well-known.

According to the embodiment of the invention, the system has two additional test modes referred to herein as a signal strength test (SST) mode and a bell test (BT) mode. The nature of these test modes will become clear in the following description of Figures 2 to 4, which show a test wand for use with the system of Figure 1.

The test wand comprises a housing 30 having an elongated main body portion 32 and an elongated head portion 34 inclined at an obtuse angle to the body portion. The head portion 34 contains an RF antenna 36 aligned in the longitudinal direction of the head portion. The body portion 32 contains a printed circuit board (PCB) 38 on which is mounted RF transmit/receive circuitry for the antenna 36 and control circuitry to control the operation of the transmit/receive circuitry. The main body portion 32 also includes a row of LED5 40, a set of manually operable buttons 42, a loudspeaker and cover 44 and a microphone 46. The purpose of these will be described below. The wand is powered by batteries (not shown) contained in a battery compartment 48.

The function of the wand is to determine the signal strength at proposed locations for different sensor types, when the site is being assessed and system specified prior to installation. Thus the head portion 34 of the wand is angled relative to the body portion 32 such that if the wand is held with its body portion 32 extending vertically upwards against a vertical wall, the antenna 36 housed within the head portion 34 is in an orientation corresponding generally to the orientation of an antenna within a PIR, inertia sensor, contact or internal/external bell when mounted in an in-use position.

In use of the wand, the control panel 10 is first placed in SST mode which enables the panel to respond to the wand in the following manner. Each of the buttons 42 corresponds to a different type of sensor such as a PIR sensor, ultrasonic sensor, movement detector, window/door contact sensor, etc. When the wand is held against a vertical wall in a test location, i.e. a location where it is desired to fix a sensor, the particular button 42 is pressed corresponding to the type of sensor proposed to be mounted at that location.

Pressing a particular button 42 causes the control circuitry on the PCB 38 to drive the transmit/receive circuitry to transmit a test signal via the antenna 36 having the same transmission characteristics as the particular type of sensor associated with that button, i.e. the sensor type proposed to be mounted at that location. In other words, the wand mimics the type of sensor proposed to be mounted at that location.

Upon receiving the test signal from the wand, the control panel 10, in SST mode, transmits a response signal to the wand which indicates the strength of the test signal as received at the control panel. For example, where communication is via packeted data, the received test signal strength may be encoded in the payload of the response signal.

The wand receives the response signal via the antenna 36 and the control circuitry on the PCB 38 decodes it to determine the strength of the test signal as received at the control panel.

If the received test signal strength is sufficiently high to permit a sensor of the type concerned to be mounted at that location, i.e. the signal strength is adequate to provide good communication between the sensor and the control panel, this fact is communicated to the user.

This may be by lighting one or more green LED5 40, the number being lit indicating the strength of the signal, and/or by a voice message from the loudspeaker, e.g. 25!vlocation suitable for (type) sensor!!. On the other hand, if the received test signal strength was insufficient to provide good communication between the sensor and the control panel, this fact too is communicated to the user. This may be by lighting one or more red LED5 40, and/or by a voice message from the loudspeaker, e.g. "location not suitable for (type) sensor!!.

The wand can also be used near in situ sensors to assess the signal level at that location and so to assist in determining whether a sensor or its location may be causing problems.

The wand also includes a non-volatile storage which, in association with the loudspeaker and microphone 46, provides a voice recording and playback device. This is most typically used before a system is installed and when the site is being assessed and the system specified. Here the wand can be used for recording voice memos to record system specification details including placement of sensors and sounders, etc., the voice memos being played back at the office by the surveyor. Alternatively, the wand could provide either a socket or wireless communication for uploading a stored sound file to a computer.

As mentioned above, the control panel 10 is also operable in bell test (BT) mode. In this mode the control panel is operative to receive a bell test signal transmitted by the wand in response to the user pressing a button 50, and upon receipt of the sounder test signal to test the bell. Where several bells are to be individually tested, the bell test signal will differ according to the bell to be tested, the relevant signal being selected for transmission by holding down the button 50 while simultaneously pressing a selected one of the buttons 42 which, in this mode, corresponds to a selected one of the bells. Both wired and wireless bells 24, 26 can be triggered from the wand in this way. This enables the user to be in the vicinity of the bell under test and so saves having to walk to and fro between the control panel and bells being tested while they are ringing.

The invention is not limited to the embodiments described herein which may be modified or varied without departing from the scope of the invention.

Claims

Claims 1. A signal detector used with an alarm system of the kind comprising a central control unit and a plurality of remote devices in two-way RF communication with the control unit, the detector comprising a hand-held housing having an antenna, RF transmit/receive circuitry operable under manual control for causing the antenna to transmit a test signal to the control unit and receive a response signal from the control unit, said response signal indicating the strength of the test signal at the control unit, and means for indicating to a user the strength of the test signal at the control unit as indicated by the response signal including means to select characteristics of the test signal to correspond to transmission characteristics of different types of devices.
2. A signal detector as claimed in claim 1, wherein the indicating means comprises lights and/or sounds.
3. A signal detector as claimed in any preceding claim, wherein the transmit/receive circuitry further includes means for transmitting an alarm actuating signal to the control unit.
4. An alarm system comprising a central control unit and a plurality of remote sensors in two-way RF communication with the control unit, the control unit being operable in a test mode to receive a test signal from a remote device comprising the signal detector of any one of claims 1 to 3 and upon receipt of said test signal to transmit a response signal to said device indicating the strength of the test signal at the control unit.
5. An alarm system comprising a central control unit, a plurality of remote sensors in two-way RF communication with the control unit, and at least one alarm sounder coupled to the control unit for sounding an alarm when a sensor signals an alarm condition to the control unit, the control unit being operable in a test mode to receive a sounder test signal from a remote device comprising the signal detector of any one of claims 1 to 3 and upon receipt of said sounder test signal to test said sounder.