GB2295230A - Shock sensor apparatus and method - Google Patents
Shock sensor apparatus and method Download PDFInfo
- Publication number
- GB2295230A GB2295230A GB9520294A GB9520294A GB2295230A GB 2295230 A GB2295230 A GB 2295230A GB 9520294 A GB9520294 A GB 9520294A GB 9520294 A GB9520294 A GB 9520294A GB 2295230 A GB2295230 A GB 2295230A
- Authority
- GB
- United Kingdom
- Prior art keywords
- shock
- time window
- amplitude
- shocks
- received
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/02—Mechanical actuation
- G08B13/06—Mechanical actuation by tampering with fastening
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/16—Actuation by interference with mechanical vibrations in air or other fluid
- G08B13/1654—Actuation by interference with mechanical vibrations in air or other fluid using passive vibration detection systems
- G08B13/1663—Actuation by interference with mechanical vibrations in air or other fluid using passive vibration detection systems using seismic sensing means
Abstract
The present invention relates to detecting either a single large shock or an accumulation of smaller shocks within a predetermined time window to establish an alarm condition in an intruder detection system. The apparatus of the present invention is intended to be mounted on a surface to be protected and its sensitivity may be adjusted so as to effectively protect said surface by detecting shock events individually and/or accumulatively to establish an alarm condition whilst avoiding false alarms which may be caused by passing traffic or wind or the like. <IMAGE>
Description
SHOCK SENSOR APPARATUS AND METHOD
The present invention relates to a shock sensor apparatus and method, in relation, in particular, to the security art, which shock sensor apparatus is intended to form part of a security system.
At present, many security systems rely upon a combination of magnetic switches and passive infra-red (PIR) detectors protecting primary access routes and designated areas within a building and will only trigger an alarm after entry of an intruder has occurred. In order to detect an attemped break-in, e.g. when an intruder is attempting access by breaking a window or forcing a door, shock sensors have been developed endeavouring to detect the act of breaking-in and thereby trigger an alarm prior to the intruder having gained entry. With existing sensors, such are either set to detect a single large shock occurring due to the structural failure of a building component, or according to "double knock" criteria according to which a second subsequent shock of a predetermined level must be detected within a predetermined time of sensing a first shock, in order to trigger an alarm condition.Such "double knock" criteria are used primarily to reduce the likelihood of false alarms thereby providing a more reliable system. However, such arrangements are unsatisfactory in that they only allow for significant events triggering an alarm and are still liable to false alarms. For example, such prior art arrangements would not be triggered by a succession of small shocks, for example, by an intruder endeavouring to remove putty from around a window and might not, for example, be able to detect the breaking of a single pane of glass in a multi-framed, e.g. Georgian, window if located at some distance from the sensor, due to the effects of dissipation of the energy of the impact through the frame structure.
It is an object of the present invention to seek to provide a sensor apparatus and method which, whilst being able to detect large shocks sufficient to cause the failure of a structural component, is also capable of detecting cumulative shocks within a time window, the accumulated amplitude of which exceeds a predetermined level, or a combination of a single shock and smaller shocks exceeding such level.
According to the present invention, there is provided an analysis method comprising, detecting vibrations due to a mechanical shock detected by a shock sensor, establishing a variable time window, monitoring the cumulative amplitude of such shock signals within said time window and issuing an alarm condition if, either a single shock of a predetermined amplitude is received during said time window or a cumulative amplitude is received, comprised of a number of small shocks within said time window, or the combination of a single large shock and accumulated multiple smaller shocks exceed said predetermined amplitude within said time window.
Also according to the present invention there is provided a shock sensor apparatus comprising a shock sensing means for detecting mechanical shocks, means for monitoring the amplitude of a detected shock and establishing a variable time window, means for monitoring the cumulative amplitude of a series of shocks within said time window and means for issuing an alarm output signal when a predetermined amplitude level is reached, either when a single shock exceeds said predetermined amplitude or an accumulation of multiple shocks within said time window exceeds said predetermined amplitude or a combination of a single large shock signal and multiple small shocks exceeds said predetermined amplitude within said time window.
The shock sensor apparatus of the present invention is a digital device, the analog shock signals being converted to a digital signal for the purpose of the analysis process. When a shock is received a variable time window is established according to the size of the shock, i.e. if the smallest detectable shock is received, the time window will be set to 15 seconds and the analyser will wait for 15 seconds to receive further shocks. If no such shocks are received within such time window, the apparatus will be reset. However, if a further shock is received within the time window, the time window is then reset dependent upon the amplitude of said further shock. If further subsequent shocks are received within said new time window, the cumulative level of the received amplitude is increased and again the time window is increased allowing for the accumulation of further shocks.
The maximum duration of the time window would normally be set at 60 seconds, so that if the predetermined amplitude for an alarm condition is achieved within said time window then an alarm signal is issued, otherwise if the amplitude is not reached within said time window, the system is reset. It can be seen that either a number of small signals or a signal large signal or a combination of small and large signals can combine to achieve the predetermined level within a variable time window and thereby signal an alarm condition.
It will be appreciated that, for example, a single large signal may be sufficient to achieve said predetermined level, or if such is just below said predetermined level, then a large time window of the maximum 60 seconds would be set and a further small signal received within said time window could trigger the alarm condition. Thus, a variety of combinations of signal sizes can cumulatively trigger an alarm condition.
The main benefit of this arrangement is that small nuisance shocks, such as passing traffic, which could cause false activation are quickly ignored, and similarly, a bird flying into a window, or branches hitting the window, would also be unlikely to trigger an alarm condition. However, increasingly larger shocks, which are more likely to be actual entry attempts produce a longer time window and therefore a higher level of security since a longer time window is established within which to monitor the shock signals.
A further aspect of the invention concerns the provision of an auto-ranging sensitivity control which addresses the uncertainty of adjusting sensitivity in the analyser by giving the engineer an accurate recommendation as to what setting to make in each installation. This is compared with conventional arrangements in which adjusting sensitivity consists of adjusting a variable resistor by means of a screw-driver on a trial and error basis.
With the arrangement of the present invention, upon installation of the sensor at a suitable location on a structure to be protected, e.g. a window frame, after power up, the engineer would simply strike the protected surface, at a level approaching but not exceeding the breaking point of the structure, and the analyser indicates the sensitivity level for the engineer to set. Since this information is actually provided by the analyser, which calculates the sensitivity level required for the received shock to be 80% of an alarm signal, the engineer simply selects the appropriate setting by utilising a jump-link provided on the circuit board of the sensor apparatus.The recommended sensitivity level is indicated by means of a flashing LED in which, for example, a single flash will indicate 20% of an alarm level, two flashes would equal 40% of an alarm level, three flashes would equal 60% of an alarm level and four flashes would equal 80% of an alarm level.
Once the sensitivity level has been selected by the installing engineer, the device may be instructed to indicate via the LED, the amplitude of a test shock that does not exceed the set alarm level. This enables the engineer to accurately test the detection response over the entire detection area and, as such, make an assessment as to the performance of the detection system. It will be appreciated, that due to signal dissipation across the structure and since the detector is likely to be placed at one edge thereof, it is important to ensure that shocks occurring at the furthest distance from the detector can still be accurately detected and an alarm condition indicated when the required criteria are met.
In practice, if a building comprises a number of similar structures, i.e. windows of similar size and design, it may only be necessary for the engineer to test the installation on a single structure and then utilise the same set of criteria for other similar structures, although once the sensitivity has been set on such other structures, the test procedure, as indicated above, would then be followed to satisfy the engineer that the apparatus is working satisfactorily.
Thus, also according to the present invention there is provided a method for enabling sensitivity control set-up of a detector comprising establishing a detection event, calculating the required sensitivity for said detection event to equal 80% of a threshold level and indicating the required sensitivity level to be set on said detector.
Also is provided a method of testing the sensitivity of a detector, comprising establishing a test event, comparing said test event with a predetermined threshold level and indicating the magnitude of said test event relative to said threshold level.
According to the above two methods, more particularly when applied to the apparatus of the present invention, such enable an accurate and consistent sensitivity to be established and subsequently tested during the installation of a shock sensor apparatus according to the present invention, although such methods could also be applied to other types of detectors to enable an accurate and repeatable sensitivity thereof to be relatively readily achievable.
The present invention will be described further with reference to the accompanying drawings.
Fig. 1 illustrates the overall system of the present invention.
Fig. 2 illustrates the function layout of a device according to the present invention.
Fig. 3 is a table showing the various possible combinations of sensitivity settings for the device of the present invention.
Referring firstly to Fig. 1, this illustrates in general block diagram and form of the device of the present invention. The sensor module may, for example, be a shock sensor switch of the type described in U.K.
Patent No. 2164800 or any other suitable type of sensor switch and which is capable of differentiating between natural vibrations detected by the sensor, for example, due to wind or traffic generated vibrations. The output from the sensor module is preferably digital in form and is supplied to a micro-controller for analysis to determine whether a valid alarm condition has been established. The analysis comprises monitoring of variable size shocks (amplitude) within a variable time window which may be determined by the size of the shock received. For example, if a shock of the lowest amplitude is received, then the time window is set, for example, at 15 seconds, and the analyser will wait for 15 seconds to determine whether further shocks are received.If a further shock is received within the time window, then the time window is reset, its size being dependent upon the level of the new shock. As the size of the received shock signal increases, so too does the time window allowing for further shocks, up to a maximum of 60 seconds, in the preferred embodiment. By this means small nuisance shocks caused by passing traffic or the like which cause false activation are quickly ignored, whilst increasingly larger shocks, which are more likely to be actual entry attempts, produce a longer time window and therefore a higher level of security as the analyser waits longer to receive subsequent shocks. The micro-controller utilised is of a standard type, for example, the PIC16 micro-controller.
For adjustment of the sensitivity, this may be performed either automatically or manually utilising links 1, 2, 4 and Q indicated in Fig. 2 which shows the base assembly of the shock sensor device. For automatic sensitivity control, upon installing the shock detector at a suitable location on a structure to be protected, the links 1, 2, 4 and Q are all removed and the link E is removed and refitted to reset the memory of the analyser. The installer would then strike the protected surface at a level not exceeding the breaking point of the structure at a point furthest from the detector.
The shock signals received by the sensor will be remembered as 80% of an alarm signal and the LED will flash red between 1 and 7 times and the link positions are then established in accordance with the table shown in Fig. 3. For example, if the LED flashes three times, then links 1 and 2 are closed and link 4 is left open.
The link E is then removed and the detection level is now set. If the LED does not flash, then a sufficient shock signal has not been detected, either because the test shock was too small or the detection area is too large. Appropriate action can then be taken, either to increase the size of the test shock, or to install additional slave sensors to increase the detection area.
Alternatively, the sensitivity level may be set manually, in which case the links 1, 2, 4 and E are left in place and the link Q is removed. The engineer then strikes the outer limits of the protected surface and after 3 seconds the LED will flash amber to indicate the level of shock received, each flash indicating 20% of an alarm condition so that 1 flash equals 20%, 2 flashes equals 40%, 3 flashes equals 60%, 4 flashes equals 80% and flashing red indicates an alarm condition. Ideally, the LED should give three or four flashes assuming a single large shock almost sufficient to break the protected surface. If the LED shows red then the sensitivity must be reduced. If less than three amber flashes are given then the sensitivity must be increased using the jumper plugs.
In order to test the detection level, once the sensitivity control has been set by fitting the appropriate sensitivity links, according to automatic or manual sensitivity control, the link E is refitted and the protected surface is struck. After three seconds the LED will flash amber to indicate the level of shock received, as above, 1 flash equals 20% and 2 flashes equals 40%, etc.. The amber LED will continue to flash (with short pauses) to show the memory status. As more small shocks are applied, the LED will show the accumulated level of shock held in the pulse count memory of the analyser module. When the detection tests are completed, the link E must be removed.
Once the device has been set at the required sensitivity level, an alarm condition is detected when either a single large is applied which exceeds the threshold level set by the sensitivity control or an accumulation of smaller shocks or large and small shocks are detected within the time window. Upon detection of such an alarm condition, the analyser activates the alarm relay triggering the alarm sounder.
Claims (9)
1. An analysis method comprising, detecting vibrations due to a mechanical shock detected by a shock sensor, establishing a variable time window, monitoring the cumulative amplitude of such shock signals within said time window and issuing an alarm condition if, either a single shock of a predetermined amplitude is received during said time window or a cumulative amplitude is received, comprised of a number of small shocks within said time window, or the combination of a single large shock and accumulated multiple smaller shocks exceeds said predetermined amplitude within said time window.
2. A shock sensor apparatus comprising a shock sensor means for detecting mechanical shocks, means for monitoring the amplitude of a detected shock and establishing a variable time window, means for monitoring the cumulative amplitude of a series of shocks within said time window and means for issuing an alarm output signal when a predetermined amplitude level is reached, either when a single shock exceeds said predetermined amplitude or an accumulation of multiple shocks within said time window exceeds said predetermined amplitude or a combination of a single large shock signal and multiple small shocks exceeds said predetermined amplitude within said time window.
3. A shock sensor apparatus according to claim 2, in which the means for monitoring an amplitude of a detected shock signal is an analyser incorporating a digital micro-controller, said shock sensor converting the analog shock signals into a digital signal for the purpose of the analysis process.
4. A shock sensor apparatus as claimed in claim 2 or 3, in which the maximum duration of the time window is set at 60 seconds and if the predetermined amplitude for an alarm condition is achieved within said time window, then an alarm signal is issued to an alarm relay for enunciating an alarm.
5. A shock sensor apparatus as claimed in any of claims 2 to 4, in which the sensitivity of the device is adjustable in accordance with prevailing conditions according to its siting.
6. An analysis method as claimed in claim 1, in which the maximum duration of the time window is set at 60 seconds and when a shock is received a variable time window is established according to the size of the shock and the amplitude of the shock is retained in memory for a predetermined period awaiting further shocks.If no such shocks are received within said time window then the apparatus will be reset, but if a further shock is received within the first preset time window, a subsequent new time window is reset depending upon the amplitude of said further shock, if further subsequent shocks are received within said new time window, the cumulative level of said received amplitude is increased and again the time window is increased allowing for the accumulation of further shocks up to the maximum permissible time window, and if sufficient shocks are received to bring the amplitude of the shock signal to said predetermined level, then an alarm signal is issued, otherwise the system is reset at the end of said subsequent time window or the end of said maximum time window.
7. A method for enabling sensitivity control set up of a detector comprising establishing a detection event, calculating the required sensitivity for said detection event to equal 80% of a threshold level, indicating the required sensitivity level to be set on said detector.
8. A method of testing the sensitivity of a detector comprising establishing a test event, comparing said test event with a predetermined threshold level and indicating the magnitude of said test event relative to said threshold level.
9. A method as claimed in claim 8, in which said test event comprises a shock signal detected by a shock sensor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9420090A GB9420090D0 (en) | 1994-10-05 | 1994-10-05 | Shock sensor analysis |
| GB9423798A GB9423798D0 (en) | 1994-11-25 | 1994-11-25 | Shock sensor apparatus and method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9520294D0 GB9520294D0 (en) | 1995-12-06 |
| GB2295230A true GB2295230A (en) | 1996-05-22 |
Family
ID=26305744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9520294A Withdrawn GB2295230A (en) | 1994-10-05 | 1995-10-04 | Shock sensor apparatus and method |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2295230A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002035490A1 (en) * | 2000-10-26 | 2002-05-02 | Nordan As | Alarm chip and use of the alarm chip |
| GB2515678A (en) * | 2012-12-19 | 2014-12-31 | Tyco Fire & Security Gmbh | Automatic intrusion detector threshold controlling systems and methods |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112889093B (en) * | 2018-10-31 | 2023-01-24 | 亚萨合莱有限公司 | Method for classifying vibrations, vibration classifier and computer readable device |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB958865A (en) * | 1961-09-07 | 1964-05-27 | American District Telegraph Co | Electrical protection system |
| GB2080592A (en) * | 1980-07-03 | 1982-02-03 | Rca Security Systems Ltd | Vibration and/or impact detection system |
| GB2103406A (en) * | 1981-05-28 | 1983-02-16 | Bedford Printed Circuits Limit | Improvements in or relating to microprocessor alarm systems |
| US4386343A (en) * | 1978-11-20 | 1983-05-31 | Shiveley James T | Acoustic emission intruder alarm system |
| US4415979A (en) * | 1981-03-25 | 1983-11-15 | Ensco, Inc. | Method and apparatus for detecting the presence of an animate body in an inanimate mobile structure |
| GB2221990A (en) * | 1988-08-17 | 1990-02-21 | Shorrock Ltd | Vibration-sensitive intrusion detection system |
| US5194848A (en) * | 1991-09-09 | 1993-03-16 | Hitek-Protek Systems Inc. | Intrusion detection apparatus having multiple channel signal processing |
-
1995
- 1995-10-04 GB GB9520294A patent/GB2295230A/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB958865A (en) * | 1961-09-07 | 1964-05-27 | American District Telegraph Co | Electrical protection system |
| US4386343A (en) * | 1978-11-20 | 1983-05-31 | Shiveley James T | Acoustic emission intruder alarm system |
| GB2080592A (en) * | 1980-07-03 | 1982-02-03 | Rca Security Systems Ltd | Vibration and/or impact detection system |
| US4415979A (en) * | 1981-03-25 | 1983-11-15 | Ensco, Inc. | Method and apparatus for detecting the presence of an animate body in an inanimate mobile structure |
| GB2103406A (en) * | 1981-05-28 | 1983-02-16 | Bedford Printed Circuits Limit | Improvements in or relating to microprocessor alarm systems |
| GB2221990A (en) * | 1988-08-17 | 1990-02-21 | Shorrock Ltd | Vibration-sensitive intrusion detection system |
| US5194848A (en) * | 1991-09-09 | 1993-03-16 | Hitek-Protek Systems Inc. | Intrusion detection apparatus having multiple channel signal processing |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002035490A1 (en) * | 2000-10-26 | 2002-05-02 | Nordan As | Alarm chip and use of the alarm chip |
| US6989746B2 (en) | 2000-10-26 | 2006-01-24 | Nordan As | Alarm chip and use of the alarm chip |
| GB2515678A (en) * | 2012-12-19 | 2014-12-31 | Tyco Fire & Security Gmbh | Automatic intrusion detector threshold controlling systems and methods |
| GB2515678B (en) * | 2012-12-19 | 2015-05-27 | Tyco Fire & Security Gmbh | Automatic intrusion detector threshold controlling systems and methods |
| US9280891B2 (en) | 2012-12-19 | 2016-03-08 | Tyco Fire & Security Gmbh | Automatic intrusion detector threshold controlling systems and methods |
| US9691268B2 (en) | 2012-12-19 | 2017-06-27 | Tyco Fire & Security Gmbh | Automatic intrusion detector threshold controlling systems and methods |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9520294D0 (en) | 1995-12-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |