Sound annunciators of the security alarm system. Choosing a Good Burglar Sound Detector

The main requirements for all systems are to promptly inform people inside buildings and structures about gas contamination / smoke, and the detection of signs of open combustion.

Types

According to the technical device, principles of operation, as well as the time of invention, the appearance on the market of equipment, components of security systems, sound detectors fire alarm divided into 3 types:

Electromechanical. They form low frequency sound vibrations, well distinguishable from background noise, therefore immediately attracting the attention of others. As a rule, taking into account the characteristics, experience of use, they are installed in premises of a large area / building volume or on open technological sites, the territory of industrial facilities, warehouse complexes, motor transport enterprises, parking lots.
Electrodynamic. Such devices produce a powerful low-frequency signal with an unpleasant sound up to 110 dB with a wide sound pressure diagram.
Piezoelectric. Outstanding sound vibrations with the help of a piezoceramic crystal. Today, these are the most common products in the production of such devices, they are widely used in the design, are used in the installation, replacement of equipment for APS / AUPT installations, warning systems.

According to the design, execution of the body / shell, place, method of installation / installation of the product, sound fire detectors are:

Wall, ceiling, incl. mortise, installed in suspension systems.
Indoor / outdoor, as well as universal with a high degree dust/moisture protection.
Normal/explosion-proof execution.
Combined, combined with light signaling devices about the occurrence of a fire - various scoreboards, direction indicators.
Both wired and radio channel devices.

In terms of external dimensions of the case, piezoelectric sound PIs are the most compact / miniature.

For example here specifications several products from domestic companies that are in demand / common on the market of fire-technical products:

Sound fire alarms "Ton-1S-12" and "Ton-1S-24" manufactured by the IRSET-Center plant from St. Petersburg, differing only in the power supply voltage - 12 and 24 V. Otherwise, all technical characteristics are the same - the dimensions are the case diameter 105, height 67 mm, sound pressure level not less than 85 dB, signal frequency range 2500-3500 Hz, operating range - 40 to + 55℃.
"Mayak-12/24 ZM/M1" manufactured by "Elektrotekhnika i Avtomatika" from Omsk with a sound pressure level of 105 dB, dimensions 80x80x55/100x80x30, power supply 12 and 24 V, degree of protection IP56/IP 55, operating temperature range from -50 up to +55℃.
"Svirel-2". It is a security and fire sound annunciator from the most famous on Russian market equipment for security systems of the Bolid company. Issued various modifications of this product, operating from a low-voltage network of 12 or 24 V, with one / two piezocrystalline sound emitters, with an additional light annunciator, the volume level at a distance of 1 m is 100/105 dB. It is made in a waterproof metal case, designed for indoor / outdoor installation at temperatures from -30 to + 50℃. Dimensions - 66x92x118 mm with a product weight of not more than 0.6 kg.
"Flute-12" manufactured by Arsenal Security Group of Companies from Omsk is also intended for use as a sound annunciator in alarm systems. Case material - plastic. Power supply - 9-13.8 V. Signal volume level - 105 dB. The carrier frequency range of the sound is 200–5000 Hz. Dimensions - 134x134x50 mm, weight only 70 g. Protection against dust / moisture in indoor air - IP Temperature range of operation - from - 30 to + 55 ℃. This group of companies also produces the Grom-12M sonic launcher with similar technical characteristics.

In total, there are several dozen models of sound, light and sound transmitters from various manufacturing companies with similar parameters, but with different protection of products from the external environment, with performance from normal to explosion-proof, in metal / plastic cases.

Design and principle of operation

As already mentioned, sound fire detectors are three main types of devices in the body of which stimulating elements are mounted that create sound vibrations / signals.

They differ in design, principle of operation:

In an electromechanical fire sounder, it is an electromagnet with a movable core, whose oscillatory movements, when an electrical signal is applied from the alarm control equipment to the coil winding, lead to strikes on the bells installed in the product case. The result is a sound wave with a frequency that depends on the size/shape of the bell. There is no need to talk about particularly compact dimensions with this design of the product.
The acoustic fire detector of the electrodynamic type is equipped with a moving coil with a magnet. This type of device for converting an electrical signal into sound vibrations is used in most acoustic systems, incl. sound/voice warning of a fire.
The sound that a piezoelectric sound detector emits is formed when a metal plate, rigidly connected to a piezoceramic crystal, vibrates when an alternating electric current is applied to it. Such products are compact to miniature, and therefore are in demand for installation in rooms with high requirements for interior design.

These features are taken into account by specialists of design organizations when choosing the type / type of sound PI.

Application area

The obligatory use of sound fire detectors when constructing diagrams of any APS installations, the possibility of their use in separate rooms / zones in warning systems / evacuation flow control systems of types 3-5 is dictated by that establishes the requirements for the design of these security systems.

According to the norms, only sound notification is permissible to use:

In kindergartens / nurseries with the number of floors / places - in one-story / up to 100, in two-story / up to 150 children.
In the buildings of hotels / hotels, sanatoriums / rest houses - up to three floors / up to 50 residents.
In the halls of cinemas, concert halls, libraries - up to 100 visitors.
In museum/exhibition buildings - up to three floors high / up to 500 visitors.
In one / two-story buildings of trade organizations with an area of up to 3500 sq. m.
In school buildings with a height of 1, 2 floors with the number of students in them - up to 350 people.

In many respects, the use of such annunciators is due to the fact that their harsh / unpleasant for the hearing organs loud sounds - sirens, toned signals easily and quickly attract attention even in the premises of educational, administrative, entertainment institutions / institutions, where the level of everyday background noise is high.

In addition, a sound fire and security detector used as a universal device in installations / systems of fire alarm systems, SOUE 1, 2 types, according to the standards, is required for installation in the following industrial, warehouse buildings, parking lots for vehicles depending on the number of storeys of buildings / structures and:

One-story - from A to D.
From 2 to 8 floors - B.
From 2 to 10 floors - G, D.

Sound PI during installation / installation should:

Ensure the pressure level of the sound signal is not less than 75 dBA when located 3 m from the product, but not more than 120 dBA at any point in the space of the protected / premises. Interesting, but manufacturers stubbornly indicate data on sound pressure of their products, tested for some reason at a distance of 1 m.
Placed at a height of at least 2.3 m from the floor mark to the top of the product body, but with a minimum distance of 0.15 m from the ceiling to it.
The required number of both sound and speech PIs, their correct placement/arrangement should provide the necessary level of the alert signal in premises with permanent workplaces/temporary stay of workers/employees, visitors/customers, clients/patients in them.

When choosing specific products for the scheme / specification of the APS / SOUE project, important parameters are:

sound pressure level.
Power supply voltage.
The value of the current consumption.
Climate options.

There are quite a lot of questions, starting from the stage of surveying objects to be equipped with APS, SOUE installations; therefore, specialists from design institutes/bureaus, enterprises providing installation and maintenance services for such security systems should be involved in the creation of warning schemes, acoustic calculations, and the installation of sound PIs.

Designation

The sign of the sound annunciator of a fire alarm is located at the location of the sound annunciator or together with the sign “Button for turning on fire automatic installations (systems)”.

Shape: square Background: red Symbol: white

Pros and cons

The advantages of using sound fire detectors at facilities are obvious:

These are reliable, resistant to vibration, electromagnetic effects of the product.
They are compatible with all other APS / SOUE equipment - monitoring / control devices, uninterruptible / redundant power supplies with a power supply of 12-24 V,.
Their price is low, therefore, even the use in each protected room, at emergency exits, slightly increases the total cost of the APS / SOUE system.

There are no obvious shortcomings during their installation, operation, service. It is unlikely that they should include a loud unpleasant sound, the generation of which in the event of a fire is actually their direct purpose.

Development of microelectronics, use/implementation of inventions in production different types components of fire-fighting automation systems leads to the fact that sound PIs become an integral part of not only light and sound devices, but also multi-sensor sensors.

The most vulnerable area in the room are window openings. There is nothing easier for an intruder than to break glass and get inside the building. To protect them, roller shutters are installed, however, they are not very difficult to open.

Therefore, more and more often, a surface sound security type detector is used as protection against unauthorized entry. It can be installed on any type of glass and is triggered when it breaks.

What is a sound sensor?

In such a detector, a condenser microphone plays the role of a sensitive element, inside of which a preamplifier is built. The process of operation of the device consists in transmitting a signal from a microphone to an amplifier, converting it from an electric one, and from it to a microcontroller. The latter checks the supply voltage and generates warning signals.

Devices of this type appeared on the security systems market in the early 90s, but still remain relevant. Over the past time, they have become more advanced, the number of false positives has decreased and the accuracy of fixing the destruction of the glass surface has increased.

The sensor security superficial sound works on a certain signal, for example, on breaking glass. The principle of operation of such a device is not very complicated, it is as follows. Considering the device device, you can see that it has a microphone. All the main work is done by this part. It converts sound into an electrical signal. Also included in the sensor mechanism are other electronic devices responsible for dividing the signal into components with their subsequent analysis.

What is an acoustic sensor?

When the produced sound coincides with the existing standards, typical for breaking glass, a signal is generated, which is fed to the control panel. This principle of operation very often leads to false positives, so it was somewhat modified.

Now the received signal is divided into low and high frequency components, the analysis of which is performed separately. This made it possible to somewhat reduce the number of false signals, but it has not yet been possible to avoid them completely.

Depending on the fact that glass of different types can make different sounds during breaking, sound sensors have several types of markings corresponding to the type of glass in terms of thickness, density and surface type. In addition, most modern sensors have fine-tuned sensitivity, which makes them work efficiently.

Types of sound detectors

The classification of this type of security equipment depends on the principle of operation of the devices. They are divided into:

electro-contact - working to fix the mechanical integrity of the glass
shock-contact - are triggered when vibrations occur, which characterize the mechanical destruction of the surface
acoustic - defining sound vibrations arising in the process of breaking

Sensors of the first type are practically not used at present, since the installation of such devices has its own difficulties and is quite laborious. Another disadvantage is the fact that such detectors are too visible to intruders and are a strip of foil or wire located around the perimeter of the glass.

We look about the shock-contact sensor:

Shock-contact models react to the impact of any object. They form a signal when the inertial properties of the elements are triggered. The installation of such devices is carried out on the inner surface of the glass, which limits their use, especially for large buildings.

Acoustic devices are among the most effective. They successfully combine ease of installation and operation. One such device is installed for several window openings at the same time, which reduces the cost security system. The detector reacts to the sound of breaking glass, not only catching it, but also conducting a complete analysis of the situation.

Choosing the best brand of sensor - Svirel or Harp?

The surface security detector is produced by manufacturers of both domestic and foreign companies.

Among them, the most popular products of companies:

Argus-Spectrum (St. Petersburg)
STC Teko (Kazan)
Pyronix (UK)
DSC (Canada)
Crow (Israel)

It is impossible to consider the products of each manufacturer in one article, so we will focus on the review of only two models produced by domestic companies - the Harp and Svirel detectors.

The detector of the Arfa brand is a security surface sound, which is a miniature sensor that is used to fix glass breaking in windows or door leaf. In this case, a signal is generated by opening the relay contacts of the device.

The sensor can be installed on any vertical structure dividing space or a window opening. Depending on the location, you can change the sensitivity of the device.

Its main advantage is the ability to detect damage for 6 types of glass: from the most ordinary to reinforced or coated with a special film.

Moreover, having a high detecting ability, the device is able to record even the smallest damage to glazed fragments.

The Svirel detector belongs to security and fire equipment. It is most often used to give a “siren” signal when an unauthorized entry to an object is detected. Devices of this brand are available in 4 versions with one or two piezoelectric emitters for 12 or 24 V.

Watch a video about Crow products:

The use of security surface sound detectors of the Svirel type is allowed both indoors and outdoors, thanks to the waterproof design of the housing. They are able to provide effective joint work with various control panels having an output used for voltage supply direct current when the sensor is triggered.

What should not be forgotten when choosing?

A wide variety of modern models of security surface sound addressable detectors s2000 ST provides for the possibility of purchasing equipment taking into account the acoustics of the monitored object, which makes it possible to practically avoid false alarms.

However, when choosing, the most important parameters include the following:

type, thickness and area of the serviced surface
range of the device
the presence of anti-masking
power supply type

Given these indicators, you will be able to complete the security system with equipment that will ensure high efficiency of its work and, therefore, help to save property. It is very difficult to choose one sensor model and evaluate it as the best, because each of them has its own characteristics. It all depends on the parameters of the protected object and the desired result that the user expects.

Acoustic detectors burglar alarm designed to detect glass breakage. By the nature of the detection zone, they are superficial. The block diagram of the acoustic detector contains:

microphone;
signal processing board;
output relay (actuator).

It should be noted right away that all this refers to the classic wired version of the detector.

For address and wireless sensors relay is not used. In the first case, instead of it, a matching device with an alarm loop is used, which generates a code corresponding to the state of the sound detector. For wireless version, a radio transmitting module is added.

However, these differences are not fundamental for understanding the principle of operation of the described devices. Below we will discuss how this type of burglar alarm detectors work.

PRINCIPLE OF OPERATION

The algorithm of operation of modern security acoustic detectors is as follows:

sound broken glass the microphone is converted into an acoustic signal;
the electronic circuit performs its processing and analysis;
according to the results, the executive device generates the necessary notification.

With the first point, everything is quite obvious, the most interesting begins at the stage of acoustic signal processing. Electronics in without fail takes into account the following factors that accompany the sound of broken glass:

Audio signal level.

First of all, this is necessary in order to cut off possible interference, thereby eliminating false positives. Since the acoustic situation at each specific object is quite individual, manufacturers provide for the possibility of adjusting the sensitivity of the security sensor.

Spectrum analysis.

An additional and more effective way to protect against false positives. The fact is that without this option, the acoustic detector can be triggered by the sound of a car passing by, a phone ringing, etc. Analysis of various frequency components allows you to more accurately identify the nature of the sound effect.

In this case, there is one parameter that should be taken into account when choosing a detector - the thickness of the glass of the monitored surface. Yes - glass of different thickness gives a different sound when broken. Moreover, the signal spectrum when split, for example, normal and tempered glass is also different. Please note that this characteristic must be indicated in the passport and characteristics of the detector.

The presence of a low-frequency component.

Another way to get rid of unnecessary positives. When the glass is broken, first comes a blow that gives a low-frequency sound, and then a characteristic ringing is heard. So here it is security detectors with microprocessor signal processing, this moment is taken into account and the desired sequence of sounds is tracked.

This triad makes it possible to high level reliability and quality of protection of glass surfaces. We will talk about the differences in the principles of operation of various types of sound sensors (wireless and addressable) below.

SECURITY SURFACE SOUND DETECTORS

We have considered the principles of signal processing by acoustic security sensors, now let's move on to the methods of transmitting notifications. Basically there are two of them:

wired;
and wireless.

In the first case, the operation of the detectors as part of the intrusion alarm system requires a physical connecting line. Sensors with relay output and addressable devices can be connected to it. The former have minimal information content, since the relay has two positions - closed and open.

Thus, we get the "normal" state, corresponding to the security mode and, as I would call it, "everything else". There can be disarming and malfunction of the device and alarm mode. It is not possible to identify the reason for the activation of the relay on the sensor side. In addition, if there are several surface sensors in the alarm loop, we also have no way to quickly determine the triggered one.

Free from these shortcomings addressable sound detectors surface type.

The principle of their operation lies in the name itself - each device has its own individual address, by which it is identified in the alarm system. All information is transmitted in a digital code, so it becomes possible to generate more than two notices, for example:

norm;
malfunction;
anxiety.

An additional plus is the possibility of using one line for a significant number of detectors.

If there is a desire for one reason or another to get rid of the wires, then you should use wireless acoustic detectors. By the way, everything wireless devices by definition, they are targeted, but you can read about their advantages and disadvantages.

Now let's see what specific models of surface sound sensors the modern security systems market can offer us. We restrict ourselves to the most popular models, which today are:

Astra-s - manufacturer ZAO NTC "TEKO", Kazan;
Glass-3 - manufacturer CJSC "Rielta", St. Petersburg;
Harp - manufacturer "Argus Spectrum", St. Petersburg.

All of them are wired, generating an alarm signal by opening the relay contacts.

Astra-S.

One of the most popular acoustic surface detectors. With a range of up to 6 meters allows you to control different types glazed surfaces (conventional and protected with a polymer film, reinforced, multi-layered and hardened).

Execution is wired, so to speak "classic of the genre". The price is average compared to other models. It has been produced for a long time, so many installers are familiar with it. However, it does not differ in any extraordinary parameters. There are cheaper models of the same manufacturer that are similar in characteristics, for example: Astra 531AK, Astra-612.

Glass-3.

More expensive than Astra, let's see why. Firstly, the range is 9 meters versus 6. Secondly, it has better declared signal processing algorithms and somewhat wider functionality, which is far from always critical.

By the way, this trademark It has also been known for a long time and has a number of modifications: Steklo-2 (powered by an alarm loop), Steklo-3M.

Harp.

The price is also more expensive than Astra, the main technical characteristics (range, temperature, power consumption) are similar. It has more "fancy" functionality (in my opinion, Argus Spectrum generally likes to be smart), which not everyone needs. It has also been on the market for a long time, also "on hearing".

It seems to me that the Astra line of models is still optimal for a home or a summer residence, since it is more budgetary, but, I emphasize, this is my personal opinion, though based on sufficient experience.

INSTALLATION, INSTALLATION AND CONNECTION

Acoustic detectors are installed on walls, ceilings or window opening slopes. This placement is possible for all models, you only need to consider the following points:

the distance to the farthest point of the controlled structure should not exceed the detector’s passport operating range;
between the sensor and the controlled surface there should be no foreign objects such as curtains and blinds;
access to the detector should be convenient, the indicators are clearly visible - it still has to be serviced.

A little advice - if the detector cover is fixed with a latch, then provide for the possibility of subsequent convenient access to the latch. This is not a trifle, because, for example, by installing the sensor on the wall with a latch close to the ceiling, you will cause quite serious problems for yourself or those who will subsequently service the alarm system.

When connecting a wired sensor to the alarm loop, ensure a small supply of wires - if you connect them "in tightness" then:

firstly, when disconnecting / connecting the sensor, it will be inconvenient to do this;
secondly, if the wire breaks off during installation or operation, then its extension will take you a lot of time and nerves.

Of course, everything can be done, but at what cost.

Another thing to pay attention to when installing wired detectors is their type. When connecting addressable sensors, as well as devices that receive power through the alarm loop, the polarity of the loop must be observed.

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The site materials are for informational purposes only and cannot be used as guidelines or official documents.

Sound or acoustic detectors used in burglar alarm systems are designed to detect glass breakage of windows, shop windows, decorative doors. They have a surface detection zone and use an addressable, wired or wireless data transmission method.

Sometimes security detectors are called sensors. This is not entirely correct, but it is quite acceptable, if you do not find fault with the severity of the wording.

The structure of any acoustic detector includes:

microphone;
signal processing unit;
executive device.

The principle of its operation is to convert an acoustic signal (the sound of broken glass) into an electrical one. Wired sensors are included in the security loop. Radio channels are used in wireless signaling systems. The difference between these versions is in the design of the actuator.

Wired ones form a notification of their status by switching relay contacts. There are two options here: on-off, respectively, the information content is minimal. However, there are address executions. They can also use wires, but the signal is digital.

You can pass more status information:

taken;
withdrawn;
anxiety;
malfunction.

As a rule, this is enough to organize reliable protection.

Wireless sound detectors for data transmission use a radio channel in a specially allocated frequency spectrum. They are addressable with all the advantages of such data transfer technology.

Wireless versions are powered from a built-in autonomous source (battery, accumulator). Wired ones are connected to the power supply through a separate input, addressable ones receive voltage via a loop.

TECHNICAL SPECIFICATIONS OF ACOUSTIC DETECTORS

Since we are dealing with the surface principle of detection, one of the main parameters is the area of the controlled surface. As a rule, its minimum value is indicated in the passport data, below which the reliability of glass break detection is not guaranteed.

The upper limit is determined indirectly, based on two values:

range of acoustics;
viewing angle.

As a rule, their values are 6 meters and 120 o, but there may be exceptions.

The sound of broken glass (spectrum and frequency) depends on its brand, thickness, presence of reinforcement, etc. The device passport must contain information on the types of glass sheets for blocking which a particular detector model is suitable for.

To reduce the level of false alarms, manufacturers implement the principle of analyzing two components of the breaking audio spectrum:

low-frequency component corresponding to the impact on the web;
high-frequency, accompanying the stage of destruction and shedding of fragments.

On the one hand, this is good, on the other hand, you can paste over the window with a film that will prevent glass residues from falling out and muffle the high-frequency component of acoustic vibrations. An alarm may not be generated in this case. It is possible to increase the effectiveness of protection through the use of a combined detector that combines sound and surface infrared detectors.

Acoustic security detectors may have additional options for adjusting sensitivity, microphone position (two-position versions).

The following are the parameters that determine electrical characteristics and operating modes of the product: voltage and current of switching relay contacts (for wired), operating frequency (for wireless), supply voltage, temperature range, climatic version.

INSTALLATION AND CONNECTION OF GLASS BREAK DETECTORS

Most often, sound detectors are used to block windows. The place of their installation should be chosen so that all points of the protected surface are at a distance not exceeding the passport value of the range. The direction of the acoustic axis of the device must ensure that the glazing is in the viewing area declared by the manufacturer.

Possible installation locations:

ceiling;
walls;
window slopes.

Each has pros and cons. For example, ceiling mounting makes it possible to block several windows with one sensor (if the range allows). In addition, at suspended ceilings type "Armstrong" behind them it is convenient to hide the wires of the loop - the design does not suffer. On the other hand, if blinds (curtains) are installed on the windows, they can attenuate the sound of broken glass so much that the detector does not work.

This is prevented by installing the device on a slope. But at the same time:

there may not be enough space for convenient installation and maintenance;
the sensor may interfere with the free opening of the frames;
part of the surface may be in the "blind zone" outside the viewing angle.

In most cases, the last moment is not critical. As for the wall installation, this option is similar to the ceiling. Only there is a problem with the wiring and connection.

At one time, private security used acoustic detectors in alarm loops to promptly transmit a signal about a robbery. For example, breaking a jewelry store window. This was called a means of alarming, which works regardless of the actions of the personnel.

Since the system was activated during working hours, the alarms occurred on phone calls, the ringing of dropped keys, despite the declared microprocessor signal processing. Thus, the acoustic background of the room affects the stability and reliability of the detector.

The choice of installation location for the wireless version of the sounder is no different. The only thing is that you need to take into account the presence of interior items, building structures that contribute to signal attenuation, and also provide for ease of access to replace batteries.

Sabotage protection.

There are several ways of sabotage (depriving the detector of the ability to perform the functions assigned to it):

changing the electrical part of the loop (more often - installing jumpers);
sealing the microphone hole with soundproof material.

The first option is prevented by a hidden laying of the loop, making connections inside the detector housing, connecting the detector to a separate specially dedicated round-the-clock loop of the tamper (tamper sensor) of the detector (if any, of course). This is a reliable solution, but in practice, few people do this - it complicates installation.

In addition, there remains the second method, which can only be combated by restricting unauthorized access to the detector. This automatically solves the first problem. To be honest, there are many ways to sabotage a security alarm. There are also enough ways to deal with this, so with proper design and installation of the system, reliability can be brought closer to 100%.

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