GB2177797A - An environmental interference detection device - Google Patents
An environmental interference detection device Download PDFInfo
- Publication number
- GB2177797A GB2177797A GB08517670A GB8517670A GB2177797A GB 2177797 A GB2177797 A GB 2177797A GB 08517670 A GB08517670 A GB 08517670A GB 8517670 A GB8517670 A GB 8517670A GB 2177797 A GB2177797 A GB 2177797A
- Authority
- GB
- United Kingdom
- Prior art keywords
- detection device
- environmental interference
- led
- signal
- audio frequency
- 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.)
- Granted
Links
Classifications
-
- 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
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/02—Mechanical actuation
- G08B13/04—Mechanical actuation by breaking of glass
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Burglar Alarm Systems (AREA)
Abstract
In an alarm comprising:- an acoustic transducer (1); a sensitivity control (2); various signal processing circuits (3)-(7); and an alarm indicator (8)-(9); a test circuit 6 (which does not influence the operation of the alarm) monitors the signal between the sensitivity adjustment (2) and the alarm indicator (9), the test circuit 6 including a transient suppressing circuit and a display (eg light). In use, the test circuit enables the sensitivity to be adjusted so that the alarm is unaffected by environmental noise. Detailed circuitry is disclosed. <IMAGE>
Description
SPECIFICATION
An environmental interference detection device
This invention relates to An Environmental Interference Detection Device, particularly for audio frequency detection.
An audio frequency detection device is usually installed in a protected area in order to sense instrusion and subsequently trigger an alarm unit by detecting high-frequency sound such as that of breaking glass. The traditional audio frequency detection device has a major defect in adjustment of the device's sensitivity. If the sensitivity is set too low, a thief can easily enter the protected area undetected; if the sensitivity is set to high, ordinary environmental noise may be picked up by the device and generate a false alarm. The user must usually therefore opt to set the sensitivity of the device at an intermediate position, which is frequently not the ideal setting.
In order to eliminate the above defect, the invention has created an environmental interference detection device to allow the audio frequency detection device to be adjusted to optimum sensitivity level.
The invention provides an environmental interference detection device-consisting of IC4, D6, C13, R", Q1, and a display unit (LED or indicating Mater)-which allows users to ascertain the environmental interference status, and, through the utilization of this status, to adjust the sensitivity of the audio frequency detection device to a proper setting, thus maximizing the theft alarm function of the audio frequency detection device.
An embodiment of Environmental interfer- ence Detection Device according to this invention is described by way of example, with reference to the drawings in which:
Figure 1 is a block diagram of the invention as it is applied to an audio frequency detection device;
Figure 2 is a control circuit diagram of the invention as it is applied to an audio frequency detection device.
Receiver (1), Sensitivity control (2), Amplifier (3), Band pass filter (4), Amplifier (5), Environmental interference detection device (6), Filter and Phase inverter (7), Driving amplifier (8),
Alarm circuit (9).
Fig. 1 is a block diagram of the invention as it is applied to an audio frequency detection device. An ordinary audio frequency signal is picked up by a receiver (1), and after being first selected by the sensitivity control (2), then is amplified by the amplifier (3), and
passed through the band pass filter (4). The
picked-up signal is processed in this way to suppress unwanted noise and to leave a required uniformly amplified signal with a band width of aboutn 5 KZ. This signal is then amplified by the amplifier (5) again. Because this second amplification stage is used to compensate for the influence of the environmental interferencnce factor, the environmental interference detection device (6) of the invention is connected to the output side of the second amplification stage for detection of the size of the environmental interference factor.If the interference factor is too large, the sensitivity can be reduced accordingly to the optimum required setting for aboiding environmental interference and allowing the detection device to developing to perform its proper monitoring function. The theft alarm circuit (9) of the audio frequency detection device of the invention is driven by an audio frequency signal after it passes through the second amplification stage (5), filter and phase inverter (7) (to remove its negative half wave and to make a phase reversal), and driving amplifier (8).
Fig. 2 shows the invention as it is applied to the control circiut of an audio frequency detection device. MIC as shown in Fig. 2 is a microphone receiver, VR1 is a sensitivity control, IC1 is an amplifier and IC2, C4, C5, C6, C7, Cs, R4, R6, R6 consists of a Band pass amplification circuit (4). IC3, R7, R9 and R10 form an amplifier circuit (5). The amplified signal is sent to the filter and phase inverter (7), the input signal of the filter and phase inverter (7) comes from R14 and feeds to 1C6 etc., while
R,3 and R,4 are used as a voltage divider, and Cg, C,O are used for instantaneous voltage delay.The signal after phase inversion by IC5 and 1C6 is used to drive Q3 and Q3 and is displayed by D6, because this invention allows the input of the environmental interference device to be connected to the output side of the amplifier (5); therefore, D3 is connected to IC4, (IC4 is a phase inverter). R", C,3 consists of a time delay circuit. In detection of the environmental interference factor, a sudden outbreak signal is not considered important as it will
reflect disproportionately on the optimum sensifivity level of the detection device. The envi
ronmental interference detection device (6) of the invention consists of IC4, D5, R", C,3. Q1, and a display.Also, the time delay circuit con
sisting of R", C,3, of the invention provides for the elimination of the sudden outbreak type of signal. Q is a driving transistor. If an
LED is used as an environmental interference
status display, then Q, is used to drive the
LED, but an indicating meter can be used in
stead of an LED.
In this invention, IC4 abnd 1C6 have the same
transfer voltages. After rectification at D3, the
signal gained by IC4 and Ices, having passed
through the voltage divider R,3, R,4, starts a
voltage change so that micro-environmental in
terference can be detected easily by IC4. The
environmental interference signal, after under
going ampilification and voltage transfer at IC4,
is delayed and amplified by D6, C,3, R11, Q,
and displayed by D7 (LED).
The special function of the invention is to allow the audio frequency device to reach its highest detection function; the circuit structure of the invention is also very simple.
Claims (4)
1. An environmental interference detection device, which is installed in an audio frequency detection device, and consists of IC4, D5, C,3, R1l, Q1, and an LED display unit etc.
The amplified audio signal is phase invested by IC4, filtered by D5, and delayed by R1l, C13, then this signal is used to drive an LED through Q1. this LED display can be used in setting the sensitivity of the audio frequency detection device so as to avoid false alarms and allow the detection device to perform its proper monitering function.
2. An environmental interference detective device as claimed in Claim 1 above, after rectification at D3, the signal gained by IC4 and Ices, having passed through the voltage divider
R13, R14, starts a voltage change so that microenvironmental interference can be detected easily by IC4. The environmental interference singal, after undergoing ampilification and voltage transfer at IC4, is delayed and amplified by D6, C13, R1l, Q1 and displayed by D7(LED).
3. An environmental interference detection device as stated above, in which the LED is used for detection display but can be replaced by an indicating meter.
4. An environmental interference detection device constructed and arranged. Substaintially as herein described with reference to any of the drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8517670A GB2177797B (en) | 1985-07-12 | 1985-07-12 | An environmental interference detection device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8517670A GB2177797B (en) | 1985-07-12 | 1985-07-12 | An environmental interference detection device |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8517670D0 GB8517670D0 (en) | 1985-08-21 |
| GB2177797A true GB2177797A (en) | 1987-01-28 |
| GB2177797B GB2177797B (en) | 1989-07-26 |
Family
ID=10582207
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8517670A Expired GB2177797B (en) | 1985-07-12 | 1985-07-12 | An environmental interference detection device |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2177797B (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1446925A (en) * | 1972-09-15 | 1976-08-18 | Kidde & Co Walter | Method and apparatusfor adjusting sesitivity of an ultrasonic detection system |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2137749A (en) * | 1983-04-07 | 1984-10-10 | Healey Meters Limited | Intruder Detection System |
| GB2175425B (en) * | 1985-05-17 | 1988-10-19 | Gec Avionics | Intruder alarm system |
-
1985
- 1985-07-12 GB GB8517670A patent/GB2177797B/en not_active Expired
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1446925A (en) * | 1972-09-15 | 1976-08-18 | Kidde & Co Walter | Method and apparatusfor adjusting sesitivity of an ultrasonic detection system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2177797B (en) | 1989-07-26 |
| GB8517670D0 (en) | 1985-08-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20000712 |