Car alarm: types, structure and principle of operation

Purpose and functions of the alarm

A car alarm cannot be called a specific device. It would be more correct to say that this is a complex of devices consisting of different sensors and control elements and representing a single system.

In Russia there is an approved frequency for all alarms - 433.92 MHz. But many manufacturers on the market produce systems with different frequencies from 434.16 MHz to 1900 MHz (GSM - band for mobile communications).

Anti-theft systems perform several main functions:

warn of intrusion into the vehicle interior with sound and light signals;
warn of an attempt of external influence and suspicious approach to a car in a parking lot (removal of wheels, evacuation, impact, etc.);
notify the driver of intrusion and track the further location of the car (if this function is available).

Various anti-theft systems have their own configuration and functions - from basic to advanced. In simple systems, only the signal function (siren, flashing headlights) is often implemented. But modern security systems are usually not limited to this function.

The composition of a car alarm depends on its complexity and configuration, but in general terms it looks like this:

Control block;
various types of sensors (sensors for door opening, tilt, shock, motion, pressure, light and others);
signal receiver (antenna) from the key fob;
signaling devices (siren, light indication, etc.);
control key fob.

Alarm elements layout diagram

All anti-theft systems can be divided into two types: factory (standard) alarm and optionally installed.

The factory alarm system is installed by the manufacturer and is already included in the basic configuration of the car. As a rule, the standard system does not have a variety of functions and is limited only to a warning about hacking.

A wide variety of additional functions can be implemented in the installed systems. It depends on the model and cost.

How does the alarm work?

Let's figure out what the vast majority of car alarms that can be found on the security systems market consist of. The figure schematically shows the main elements of such a system. Let's consider the purpose of each of them.

The heart of the car security system is the central unit. No system can operate without an electronic control unit with a central processor. This device receives encoded signals sent by the remote control - key fob. It's that cute little button device that drivers carry on their car key ring. We will return to it below. So, this central unit controls the operation of the alarm system - it receives information from sensors, analyzes it and sends signals to actuators and signaling devices, informs the owner about problems in the system, open doors, headlights not turned off, etc. . The central unit has a hard memory, and even when the power is turned off, it remembers the program settings and code combination data received from the key fob.

In terms of design, car alarms can be implemented either as a monoblock design, that is, a central unit with a siren and one of the sensors are assembled in one housing, or as a separate one, such as in the figure. European manufacturers often prefer a monoblock layout. Italians are especially guilty of this. American companies, on the contrary, try to make all systems according to a spaced pattern.

Of great importance is the power supply of the system, that is, the voltage (its value and fluctuations) that is supplied to the central unit. A car, especially a modern one, is a complex system. It contains a huge number of energy consumers, blocks and wires. At different operating modes of the vehicle, voltage fluctuations and sags occur in the electrical circuit. A lot depends on how the alarm system is installed (how competently the installer supplied power to it), how the central unit and the system memory perceive these vibrations. There are many subtle points in this problem, but the car owner does not need to know them - it’s all on the installer’s conscience. One has only to say that, for example, the Clifford Cyber 5 system forgets all previously programmed settings at a voltage below 10 Volts. And in a VAZ car - 2108-09 Clifford Cyber 5 generally works very poorly, since the on-board network of this car is replete with interference and voltage surges. Python 100 system from Derected Electronic Inc. In contrast, it can operate on a regular Krona battery - 9 Volts - it is so unpretentious to the power source. This does not mean that the Clifford Cyber 5 system is worthless. It behaves well in foreign cars where the on-board network is “clean”. When determining protection for your car, the owner of a “nine” should not insist on installing Cyber 5. It is necessary to listen to the recommendations of specialists who have extensive experience in this matter.

The alarm system is controlled, most often, using a remote control - a key fob. It transmits the car owner’s commands to the central unit, which, using an antenna, receives and decrypts the radio signal. The key fob is a miniature remote control radio transmitter. In order to prevent the alarm from being turned off by unauthorized persons, the key fob sends encoded radio signals. The level of secrecy, types of codes, and the number of their combinations in different alarm systems are different. The key fob is equipped with one or more control buttons, pressing which generates a particular signal. If this signal belongs to the owner of the car, the car alarm normally responds to control signals and turns the alarm on or off and controls the unlocking or locking of doors, as well as many of its other functions.

Here it is worth taking a closer look at how the encoded signal is transmitted from the key fob to the central unit of the security system. The very first key fobs had a 5-10 digit permanent code, which was set using switches on the key fob and in the central car alarm unit. Any person more or less familiar with radio technology was able to assemble a circuit based on a key fob from an alarm system, with the help of which he could select a code for your security system in a few hours. In general, it is worth saying that the struggle to decipher the code has been waged between manufacturing companies and car thieves since the first models of car alarms. Manufacturers have always found an opportunity to move a little ahead, but car thieves have always been breathing in their backs. As soon as it became clear that the primitive key fob code had no future, an anti-scanner appeared. It could be made in various versions. For example, companies have gone to increase the bit depth of codes transmitted by key fobs. The code began to have so many combinations that it became pointless to search through it, since it would take centuries. Another way is to monitor the transmitted codes and, if these codes (for example, 5 consecutively transmitted codes) do not correspond to the code of the system key fobs, then the central unit became “deaf” to the transmitted signals for 15 - 20 minutes, after which it again switched to receiving mode, or immediately sounded an alarm, informing the owner that the car was being scanned. The hijackers began to catch up. They made a device capable of setting the frequency at which the code is transmitted, recording the code itself, and then transmitting it, disarming the car. The anti-scanner is powerless against this. The new device began to be called a code grabber. It should be noted that a code grabber is a very expensive device, the cost of which is comparable to the cost of an inexpensive car. Such a device will most likely be used to steal expensive and complex cars rather than “fives” or “sixes”. Manufacturing companies had to look for a new solution. Such a solution was soon found. Systems with a floating code or anti-code grabber have appeared. Its principle is that the code transmitted by the radio key fobs to the central unit changes after each code transmission, which means the caught and recorded code will be useless. It will not disarm the alarm system. The next time you access the central unit, the key fob will send a completely different code, and so on every time. The principle by which this code changes is different, even in two identical systems running side by side on the assembly line. Clifford and Derected Electronics Inc. have succeeded in using such tricky code. (Viper, Python). Their systems use floating code that never repeats. Other companies use simpler floating code algorithms, but this is still very serious protection. There are cases where floating code was hacked by hijackers, but this requires even more expensive equipment and the use of special computer programs specially written for this case. A car thief with a code grabber must relentlessly follow the vehicle targeted for theft for several days, writing down each code without losing a single one. Only in this case does he have a ghostly chance (about 50/50) of finding the algorithm by which the system code is changed. Now you can imagine the amount of work that needs to be done by a person who plans to disarm an alarm with a floating code, and this despite the fact that he may not achieve a positive result.

The design of the key fob is constantly being improved. Many manufacturing companies pay great attention to the appearance - the design of the key fob. The result of such searches can be considered a Prestige 150 (bean-shaped) or Prestige 400 (multi-colored boomerang-shaped) or Ungo (hourglass-shaped) system keychain. And the design of the Spy Ball system key fob was even specially ordered from the famous car body shop Peninfarina, the main designer of most sports models (such as Ferrari). The keychain is convenient and easy to use. It easily fits in the palm of your hand, and its weight usually does not exceed several tens of grams.

The energy source for the remote control is 12 V batteries. Such batteries are now sold in any store. The range of the key fob, that is, the maximum distance from which you can, for example, disarm or arm a car, is different for each system. Most often, this distance ranges from 30 to 50 meters. More accurate information can only be obtained from the technical manuals supplied with the specific car alarm. A system such as Clifford provides, as additional equipment, the installation of a special unit for receiving the key fob signal. At the same time, the range increases to 100 meters. Depending on the operating mode of your car, the battery in the key fob will last from six months to a year. Most often, you can replace it yourself, but in some complex security systems, when replacing the battery, synchronization of the key fob and the central unit is necessary. This process is described in the operating instructions, which should be given to you by the installer. To increase the service life of the batteries in the key fob, Audiovox has used an energy saving system in the latest models of Excalibur car alarms. If you accidentally placed the key fob in such a way that some foreign object pressed its button and it began to “waste” emit a radio signal, then after a few seconds the emission of the signal will artificially stop. Any other system will emit a signal until the battery runs out. Some security systems installed as standard on cars, especially German ones (a striking example is Bosch alarms) are controlled using an infrared beam. The same principle is used in television control panels, therefore, unlike a key fob that emits a radio signal, it must be directed strictly at the receiving antenna and from a short distance.

In addition to the traditional key fob, the security system can be controlled from a transponder - a plastic card (resembling a driver's license coupon) or a small key fob containing highly complex electronic components. The transponder does not require power. There is no need to press buttons. All you have to do is get into the car and ensure that the card or key fob falls within the antenna’s field of action and the system will cancel the car’s security mode.

The most important part of any car alarm system are sensors. Any car alarm system contains them. These are the original eyes and ears of the system. During any impact on the car, they transmit information to the central unit about the degree of danger of the impact and its time. Considering that these impacts can be very diverse, the sensors must ensure high reliability and reliability of the monitored parameters, leaving out everything that can be attributed to false disturbances: vibrations and oscillations from a heavy vehicle passing nearby, the impact of climatic and atmospheric phenomena, electromagnetic interference .

Car alarms use a variety of sensors that operate on different principles, and each of them protects the car from a particular danger. From impact, from opening doors, windows, from touching the car, from entering the interior. It happens that a thief suddenly doesn’t need the entire car, but only a chrome bumper or wheel caps. Each sensor must inform the alarm system about the plans of criminals or naughty teenagers.

The very first sensor that security systems began to be equipped with at the dawn of their appearance were “pitch sensors”. They reacted to the rocking of the car body, which could occur when the wheels were removed or another similar impact. I rocked the car and the alarm went off. The boys often brought car owners to nervous stress, especially considering the increased sensitivity of these sensors. However, if an attacker broke the glass, then most often the alarm was silent.

Gradually, “pitch” sensors replaced shock sensors (shock sensors). They reacted somewhat worse to the rocking of the car, but, on the other hand, they very clearly tracked impacts on the body. It has become almost impossible to break glass with impunity. And if a housemate, not very carefully maneuvering around your car, accidentally hits your bumper with his bumper, the alarm will immediately notify the entire yard about this, drawing everyone’s attention to the culprit of the “mini-accident.” The first shock sensors had only one sensitivity threshold. This sensor is not very convenient. Either its setting was very coarse so that the alarm would not be triggered by a ball accidentally hitting the wheel, and then there was a chance of missing a more important intrusion, or the sensitivity was set very high, in the hope of keeping track of every more or less small impact on the car, and the alarm was accompanied by a prolonged howl of the siren every dog that passes by.

Two-threshold shock sensors do not have all of the above disadvantages. In such a sensor, the force of influence at which the first threshold and the second threshold will operate is separately adjusted. If a passer-by accidentally leans on your car, the system will simply warn the uninvited guest with a brief beep of the siren that he has invaded someone else's property. But if someone tries to break the glass or tear off the emblem from your hood, the car alarm will announce the presence of an enemy near the car with the sound of a siren.

I would especially like to highlight the Omni Sensor - a shock sensor used on expensive models in Clifford car alarms. This microprocessor sensor itself is a small system. It separately records longitudinal and transverse vibrations of the car body. This operating principle makes it possible to virtually eliminate false positives. Omni Sensor has another distinctive ability. The impact force of the first and second thresholds is adjusted from the alarm panel. The system is entered into programming mode, and a blow of a certain force is applied to the car body. The sensor itself remembers it. Now this will be the first threshold. The second threshold is configured in the same way. If it is necessary to reconfigure the sensor, this can be done by the owner himself, depending on his needs.

Ultrasonic sensor. Or as it is also called ultrasonic. Its task is to detect the thief if he managed to get into the salon. Two remote microphones constantly monitor the interior in security mode. This highly sensitive sensor consists of an ultrasonic wave emitter that sends a signal and a receiver that receives this signal. If the received signal is interrupted or distorted, the alarm is triggered. Any body of sufficiently large volume moving in the cabin will be immediately detected and the alarm system will raise the alarm. However, its sensitivity is such that it is able to detect air movement in the cabin caused by temperature changes when the car cools down in winter and even acoustic noise. The disadvantage of these sensors is false alarms due to sudden temperature fluctuations and strong external sound vibrations. You probably noticed that when a salvo of fireworks went off, the alarms went off for two or three cars parked in your yard. Or a loaded KAMAZ will rumble past your car - and the cars standing along the road will raise the alarm every other time.

The microwave sensor does not have all the disadvantages of ultrasonics. It was invented and used to protect open cars - convertibles. The operating principle is as follows. The sensor covers the car with two fields. The first field can also end outside the car body (at a distance of 20 - 15 cm). This is the first threshold. The second field takes control of the car interior. This is the second threshold. If a person comes too close to the car and crosses the first field, then, as in the case of the shock sensor, the system will warn the ill-wisher by beeping the siren. If the thief gets inside the car, he will be in the range of the second field, and then the system will raise the alarm. No matter how carefully the thief behaves inside the cabin, the microwave sensor will still detect him. Both fields can be adjusted up or down depending on the wishes of the car owner and operating conditions.

There is one interesting type of microwave sensor that deserves a separate comment. Clifford systems use, so to speak, a “pseudo-two-threshold” sensor. It covers the car with only one field. If the sensor detects a moving body in the controlled area 2 times in 2 seconds, the alarm system will give warning signals as in the case of the first threshold of the sensor described above. If the sensor detects a body in the security zone, for example, 5 times in 5 seconds, the system will raise an alarm, as in the case of the second threshold.

Voltage drop sensors. There is a formula for theft when a car battery is punctured, and when all the electrolyte has flowed out of it, the thief can calmly disarm the de-energized alarm. In many cars, the layout of the units under the hood is designed in such a way that you can simply bite the wires coming from the battery. To ensure that this fact does not go unnoticed, such sensors exist. They come in two main types. The first type of sensor is triggered when the voltage drops below a threshold preset at the factory (for example, 8 Volts). The second type of sensor is triggered when the voltage jumps down by a specified amount (for example, 1 Volt). Such a sensor will react even if the thief opens the door, the interior light comes on, and a slight voltage drop occurs, which is immediately registered. Problems with such a sensor may arise if the vehicle's electrical wiring has significant flaws, leaks, short circuits, etc. In other cases, the sensor turns out to be very useful.

Glass break sensor. It is used quite rarely in modern systems. Reacts to the sound of breaking glass (the microphone is specially tuned to this frequency). A properly configured shock sensor will replace the glass break sensor almost completely. SUBSONIC SENSOR. This sensor evaluates the noise level both inside and outside the cabin. It reacts to an attempted intrusion by an unknown person - at this time the noise level inside the cabin changes. It is used quite rarely and only as part of expensive systems.

Contact type sensors (limit sensors). These are ordinary buttons that control the status of the doors, hood and trunk. Most often, standard car buttons are used. The hood and trunk are equipped with buttons when installing a security system. Modern systems have separate inputs for connecting limit sensors. This is done so that, firstly, when opening the hood or trunk, the interior lighting does not come on, and secondly, so that in alarms that have a trigger memory, it is clear why exactly the system raised the alarm. Since the car buttons, both standard and installed additionally, are in the zone of influence of the active environment - dirt, salt, water, electrolyte, they require careful care. This is one of the few preventive measures that can be performed by the car owner or in any car service center. Buttons that have oxidized during use account for up to 50% of customer complaints to our company. Moreover, developed alarm systems with self-testing in the event of problems in the limit switch circuit will turn off this sensor completely until the problem is resolved. The car alarm, of course, will tell its owner about a malfunction, but he may not hear this hint, or even ignore it altogether. Such an owner puts his car at serious risk.

Light-emitting diode. Usually made in the form of a red light bulb, which is installed in a visible place. An LED has many responsibilities. The simplest and most common function is to signal that the car is armed. This is usually flashing mode. The LED can warn about malfunctions of the alarm system sensors, which sensors were triggered in the absence of the car owner. In some systems, the LED will signal for several days that another key fob has been recorded in the system memory. This can happen at a car service center where you take your car for repairs. There, another key fob can be programmed into the memory of your security alarm, so that they can then disarm the car and steal it.

Siren. It is a “bell” that emits a sound signal with a power of up to 135 dB. The tasks of a siren are varied. Firstly, it turns on during an alarm, but for no more than 45 seconds, which corresponds to the European standard. Secondly, it emits sound signals when arming and disarming the vehicle. These signals can be turned off if necessary using the remote control if the car owner does not want to disturb the residents of his house at night. Third, it provides short-term warning signals when the first threshold of the microwave or shock sensor is triggered.

Sirens are divided into autonomous and non-autonomous. An autonomous siren differs from a non-autonomous one by the presence of nickel-cadmium batteries in its body, which, in the event of a car battery disconnection, will power the autonomous siren in alarm mode. In order for the owner to freely remove his battery and not listen to the howling of the siren, there is a key in its case with which the owner can turn off the siren during work. The nickel-cadmium battery will be recharged from the generator while driving. Even if a thief cuts off all the wires coming from the siren and rips it out by the roots, it will still sound alarms. The siren can be multi-tone or single-tone. Depending on the client’s wishes, one or the other model can be used. This was done to make it more convenient for the owner to identify his car in the polyphony of other sirens.

Light indication. Different installers implement this feature differently. You can make it so that in alarm mode the car will blink its dimensions, or you can use emergency signals. It depends on the commitment of the master and the needs of the owner of the car. We recommend using an emergency signal as a warning light. In this case, the owner standing to the side of the car at the time of arming and disarming will clearly see whether his car is armed or not (especially if he uses silent arming).

Valet switch. This name translated from French means servant. Ensures that the car alarm is set to service mode, when the alarm is completely turned off and the car in this state can be sent for service by removing all key fobs from the key ring. You don’t have to teach a locksmith you see for the first time all the intricacies of a car security system. Why does he need this! Thus, no one except you will know where and what security systems are installed on your car. Another function of the “Valet” switch is that it can be used to disarm a car without a key fob. Let's say you forgot or lost your keychain. Then you need to open the door with the key, get behind the wheel, insert the key into the ignition and turn it there to the position where the dashboard “comes to life”, and then click the “Valet” switch. Just. It may be objected to me that if it is so simple, then anyone who can turn on the ignition of your car can steal it? This is far from true! First, when a car thief breaks into a car, the siren immediately sounds the alarm. Secondly, the “Valet” switch is usually hidden quite far away, since it is not used often (for example, under the panel or far into the glove compartment). The car owner should definitely ask the installer about its location and discuss this location with him if something is not satisfactory. Using the “Valet” switch on some alarm systems, initial settings are entered when installing the system. In order to make it safer to work with the Valet switch, in Clifford systems it is installed openly, but made three-position - almost like a key light switch in our home. Using such a three-position switch, before entering the alarm into service mode, you need to dial a three-digit code, which can be set by the car owner himself. He can quickly change it at any time.

Ignition switch signal wire. Every modern alarm system has it. Its task is to inform the central unit that the car’s ignition is on (indirect information that the engine is running). This is necessary in order, for example, to protect the car and its owner while driving. If the system, which has an ignition break, is accidentally armed while driving, then an emergency situation may arise on the road, and the automatic transmission may even fail. You also need to have a signal from the ignition switch in order to know when to lock the door locks, and when to unlock them when using certain service functions (this will be described in more detail below), etc.

Channels for controlling additional devices (conditional name). Car alarms, especially mid- and high-level ones, have the ability to control additional devices using separate outputs. Such devices can be: a second siren, a pager or pager system, an engine starting module (for starting the engine without leaving the apartment, from the key fob and pre-warming the car before driving). Using such a channel, you can send a command to close the electric fuel valve, which completely blocks the supply of fuel to the power system, etc.

Additional control channels (conditional name). The more complex the car alarm system, the more such outputs it has. What are they used for? For example, the simplest thing is the implementation of “polite car interior lighting.” Let's say you approach your car, standing in the corner of a dark yard, and disarm it. When you get into the car, there is a possibility that the criminal has already gotten there before you, or has planted something in the car. To ensure that the situation is clarified before entering the car and the owner does not have any unforeseen complications, the alarm systems implement the function of “polite illumination of the car interior.” This means that when the alarm is disarmed, the headlights in the cabin light up for 20-30 seconds, giving you the opportunity to look around before getting into the car. Or here's another example. You arrive at your house at night, park your car, and to the entrance you still have to walk about 100 meters through the dark yard. In order to protect yourself from any surprises, you press an additional button on the key fob and the car turns on the low beam headlights, illuminating the owner’s path to the house. The headlights will remain on until you release the key fob button.

The Clifford Intelliguard 900 IQ system has a light sensor. With its help, the above function is implemented automatically whenever it is already dark outside. You don't even need to press a button.

Service channels (conditional name). These are the outputs of the central unit, which allow you to control various devices that do not perform security functions, but are very necessary to make the life of the car owner easier. For example, when approaching a car and disarming the car alarm system, your four-wheeled friend will not only greet you with a squeaking siren and blinking lights, but will also unlock the doors. This is especially pleasant in winter, when many drivers freeze their car locks almost every day. When you get out of the car and set the car alarm using the key fob, all the locks will be locked automatically. Thus, there is no need to check that the lock buttons are properly closed every time before leaving the car. The security system will do this for the owner. The owner can equip his car with all four door lock drives, or with one or two, at his discretion. Another version of the same case. It is dangerous to unlock all the doors at once when getting into a car. A criminal can get in on you by opening any car door while you are distracted by starting the car or doing something else. To prevent this from happening, many car alarms are capable of implementing the above-described function in another way. When disarming the car, only the driver's door is unlocked, because the lion's share of the time the driver moves alone in the car. If there is a need to unlock all doors immediately after disarming the car, then you need to press another, adjacent button. At the same time, during arming, all door locks equipped with drives are always closed. Another use of service channels. If there is a need, say, after leaving the store, to put things in the trunk and go shopping again, then on cars equipped with an electric trunk lock (for example, Mersedes), the following situation is possible: The owner of the car approaches the trunk and presses the button and only the trunk is unlocked ( in this case the car is disarmed). The trunk will open itself in front of the owner. There is no need to press or turn the lock cylinder. All doors will remain locked. Then the owner closes the trunk, puts his car on guard and goes shopping again. Or this example. You get out of the car and arm it. The alarm system itself will lock the locks, close the unlocked windows, and batten down the hatch. And all this from one key fob button. Fantastic? No, it's real. You just need to install connecting modules between the alarm system and electric windows with an electric sunroof.

Not all of the above can and should be included in a standard installed car alarm. The implementation of many functions requires additional labor and material costs, and as a result, separate payment. All system capabilities, including service ones, must be separately discussed with the consulting manager when placing an order.

Design and principle of operation of the alarm system

All elements of any alarm can be divided into three types:

actuators;
reading devices (sensors);
Control block.

The alarm is turned on and off (arming) using the control key fob. In standard systems, alarm control is combined with central locking control and is implemented in one device together with the ignition key. It also contains the immobilizer tag. However, these are completely different systems and operate independently of each other.

The radio receiver (antenna) receives the signal from the key fob. It can be static and dynamic. Static signals have a permanent encryption code and are therefore susceptible to interception and hacking. At the moment they are almost never used. With dynamic encoding, the packets of transmitted data are constantly changing, creating high protection against interception. The principle of a random number generator is used.

The next development of dynamic is conversational coding. Communication between the key fob and the receiver is carried out via a two-way channel. In other words, the “friend or foe” function is implemented.

A variety of sensors are classified as input devices. They analyze changes in various parameters (pressure, tilt, impact, light, movement, etc.) and send information to the control unit. In turn, the unit activates actuators (siren, beacons, flashing headlights).

Car alarm components diagram

Shock sensor

This is a small sensor that picks up mechanical vibrations of the body and converts them into an electrical signal. The piezoelectric plate produces an electrical signal. Triggering occurs at a certain level of vibration. Sensors are installed around the perimeter of the car body. Shock sensors can often trigger false alarms. The cause may be hail, strong sound vibrations (thunderstorm, wind), or a blow to the tires. Adjusting the sensitivity may help solve the problem.

Tilt sensor

The sensor reacts to unnatural tilt of the car. For example, this could be lifting the car with a jack to remove the wheels. It will also work when towing a car. The sensor does not respond to wind tilt, vehicle position on the ground, or different tire pressures. This is achieved by adjusting the sensitivity.

Motion Sensor

These types of sensors are common in various fields (turning on lights when moving, perimeter security, etc.). When the alarm is on, the sensor reacts to extraneous movement in the cabin and near the car. Dangerous proximity or movement will trigger the siren. Ultrasonic sensors and volume sensors work on the same principle. All of them detect various changes in the volume of the car interior.

Door or hood sensor

Often built-in door limit switches are used as sensors. If you open the door or hood, the circuit will close and the siren will sound.

Safety

After arming the car, the car alarm is constantly ready to respond to an external signal received from the sensors. The most obvious function is to respond to sound or impact on the car ; the built-in sensor is responsible for it. If sufficiently strong irritation occurs, the alarm will send a notification to the key fob via its own communication channel, start the engine compartment siren and start signaling with the car's lighting equipment.

The next line of security is protection against entry into the car through opening the doors or trunk . To read the status of the lock and the state of the doors, as we noted earlier, the alarm is connected to a connector switch or CAN bus. Thanks to this, it can monitor most vehicle systems and also trigger an alarm mode in the event of emergency situations.

Even if intruders get inside the car and try to start it, then we still have one more ace up our sleeve - blocking the car's systems . The most common blockage is monitoring the operation of the car’s fuel pump. While the alarm is in alarm mode, it will not allow the fuel pump to function normally, as a result of which the car simply will not start . This effect is achieved by “inserting” the alarm wiring into the standard circuit. You can come up with a wide variety of locks, and their options are limited only by the imagination of the master.

But what if attackers are able to open the hood and remove the terminal from the battery ? Then the alarm will not function? Not certainly in that way. Most modern car alarms have a backup power line on which you can hang an additional battery . It will connect only when contact with the main battery is lost, and will support the operation of the alarm and siren.

But is it possible to turn off the siren? Yes, the siren is powered by a simple wire, it can be cut, but the alarm will not stop blocking the car's systems ; it will still take a lot of time to completely turn it off.

What if the car is simply loaded onto a tow truck ? This situation is also foreseen. Pandora alarms can be equipped with a GPS antenna , which will monitor the location of the car. If it starts moving in security mode, it will be regarded as an emergency situation, and the owner will receive a notification on the key fob or smartphone.

Additional alarm functions

In addition to the main security function, some useful additions can be implemented in car alarms. For example, such as:

Remote engine start. The engine warm-up function is especially convenient in winter. You can start the engine remotely and prepare it for the trip in time.
Remote control of power windows. The windows are automatically raised when the car is armed with an alarm system. No need to remember if all the windows are closed.
Car protection when the engine is running. This function is useful when leaving the car for a short time.
Satellite tracking (GPS/GLONASS). Many anti-theft systems are equipped with active tracking systems via GPS or GLONASS satellite systems. This is an additional level of protection for the car.
Engine blocking. Advanced versions of security systems can be equipped with a remote engine stop system. Additional vehicle security against theft.
Control the alarm and other functions from your smartphone. Modern systems allow you to control all functions from your mobile phone. The availability of this option depends on the configuration and model of the alarm. Management occurs through a special application.

Types of models

In most cases, the package for new cars does not include an alarm system with automatic start. The car enthusiast needs to select and purchase such a device himself.

Let's consider the types of such anti-theft devices:

Type of interaction between the key fob and the central unit

Nowadays, two common types are used: one-way and feedback alarms.

The first type has been used for a long time, but does not allow the car owner to know what is happening and is therefore not effective.
The second model declares itself to be reliable. The two-way alarm system has feedback and is made in the form of a liquid crystal display on a key fob, reflecting all the necessary information about the car online.
GSM alarm systems and car security systems connected to the satellite are practiced.

Their main advantage is their unlimited range of action, due to this they gain complete control over transport.

Type of protocol for radio communication

Dialogue code is considered the most used and reliable. Hijackers often use code grabbers, but they are not effective against this type of protection due to changes in frequencies and bandwidth.

The difference between a car alarm and an immobilizer

Car alarms and immobilizers have similar security functions, but several significant differences. These two concepts are often confused, so some clarity is needed.

A car alarm is a whole security complex that warns the owner about theft or an attempt to break into the car. There are also many other features such as satellite tracking, auto start, etc.

The immobilizer is also an effective anti-theft system, but its functions are limited to blocking the engine from starting if you try to start the car with an unregistered key. The device reads the access code from the chip (tag) in the key and recognizes the owner. If the thief tries to start the car, it will not work. The engine will not start. As a rule, an immobilizer is standardly installed in all modern car models.

The immobilizer will not protect the car from breaking and entering in a parking lot. It only protects against car theft. Therefore, they cannot do it alone. We need a full-fledged car alarm.

Daily use

Using the alarm is very simple. You have a keychain , and optionally a tag . The key fob has buttons (“Remove”, “Put on”, “Service”) and a small screen. The mark is a small plastic thin rectangle, inside of which there is a circuit. If the alarm is configured correctly, the car will not start, or even open, if the alarm does not sense a mark within a radius of 5-10 meters from the car.

If the alarm is triggered, the key fob will begin to make sounds and vibrate, and additional information will appear on the screen.

Many Pandora alarms support GSM channel operation . This means that a SIM card is installed inside the alarm unit, and when an alarm is triggered, an automatic call will be made to the car owner’s phone. The GSM module also allows you to use the Pandora Online mobile application , in which you can monitor all the parameters of the car, disarm it or start it remotely, all without leaving the couch.

Major alarm manufacturers

Model of a security complex from the StarLine company
There are several companies on the market that have proven themselves well and their products are in demand.

StarLine. The company is one of the leaders in the production of security systems. It produces not only budget models, but also fifth-generation models. The cost varies from 7,000 to 14,000 rubles.
Pandora. Popular Russian manufacturer of security systems. Wide range of models. Prices range from 5,000 to 48,000 for new advanced models.
"Scher-Khan". Manufacturer – South Korea, developer – Russia. The cost is in the range of 7-8 thousand rubles. Connection via mobile phone and Bluetooth is possible.
"Alligator" American security system. Cost up to 11 thousand rubles. Diverse model range.
"Sherriff". Manufacturer – Taiwan. Budget models are presented, costing 7-9 thousand rubles.
"Black Bug" Russian manufacturer. The lineup includes both budget and premium models.
"Ghost" Russian manufacturer of alarm systems with a wide range of models. Prices range from 6,000 to 27,000 thousand rubles.

A car alarm helps protect your car from theft and burglary. Modern security systems provide a fairly high degree of protection. The driver also has many other useful features. An alarm system is a necessary and mandatory thing for every car.

How to choose the best car alarm

Retail outlets provide a large number of car alarm models with different prices, so you don’t have to pay a high price to choose the best one.

All anti-theft devices are divided into classes, based on which the following categories can be distinguished:

With an immobilizer. These devices stop the engine, making it impossible for the thief to start the car. Many manufacturers include immobilizers in a regular alarm kit;
with CAN buses. Thanks to the bus, the security system can be integrated into the overall machine control system. This detail does not affect the protected properties, only the installation of the system;
With motion blocker. This includes special relay immobilizers. When the alarm is triggered, the electrical supply circuit is broken, which stops the supply of fuel to the engine;
With GPS module. Such devices are capable of transmitting a signal about the location of the car to the key fob and to the owner’s smartphone. This is convenient because if the car is stolen, the owner can send the location data to the police and it will be quickly found;
With starting the engine from a distance. Car alarm systems with auto start are recognized as the most modern, because in addition to their main function, these devices can warm up the car and for this you do not have to go outside, especially in winter this is convenient. Also, a running engine will attract the attention of pedestrians and other drivers when attempting to steal;
With different notification methods. According to this parameter, the alarm is divided into one-way and two-way models. The first ones are not connected to the car owner and can only scare away the thief with a sound signal. In addition to the usual signal, double-sided products provide information to the key fob. The distance can be up to 2000 m.

Alarm systems for vehicles with feedback are recognized as the best, so it is recommended to choose just such products.

How does an alarm work and what should you add to your car?

No one seems to be under any illusion that a steering wheel lock or ignition switch is an effective deterrent to car thieves. The main obstacle for a lover of other people's property is the appearance of protection against breaking the door, breaking the steering lock and turning off the ignition. The thief made a hundred manipulations, the starter works, but the engine does not want to rotate.

Fuel does not flow from the tank, the ignition system does not work, and the computer that controls its operation is completely thinking about something of its own. The operation of all anti-theft devices is similar: when we turn them on, they disable at least one of the elements necessary for driving. In theory, only an authorized person can disable this protection.

A transmission lock, like other mechanical security measures, is only a deterrent for some thieves. Professionals are capable of stealing a car in which both the gearbox and clutch are locked.

Medium set (medium level of protection)

It is recommended to supplement the anti-theft system with a hood lock and an immobilizer.
These two devices “cover” each other according to the principle of mutual responsibility - the hood lock prevents access to the immobilizer, and the immobilizer blocks the engine and prevents unauthorized opening of the hood. The immobilizer and alarm system can interact in different ways. The most advanced models can “communicate” with each other via a wireless encrypted communication channel, making it even more difficult to track the position of the immobilizer. However, the most commonly used immobilizers are those that are controlled by a wired alarm.

The hood lock communicates with the immobilizer via a wire and receives opening/closing signals from it. The absence of a direct connection between the hood lock and the alarm system provides a higher level of security, since an attacker will not be able to open the hood even if the alarm head unit is removed.

Car alarm price with installation

How much does a car alarm cost? The cheapest, but at the same time the simplest car alarms can be bought for only 1.5 thousand rubles. They include a switchboard and several sensors located in the vehicle. You must add the cost of assembly to this amount, but since the system is quite simple, the total cost of such a system will be no more than 3-3.5 thousand rubles.

Inexpensive car alarm kit

A top-class alarm system with many additional elements costs about 20-30 thousand rubles. Experts advise choosing alarm systems from lesser-known companies with unusual designs and installing them in hard-to-reach places. Due to this, there is a high chance that the person trying to hack will not know how to deal with this type of security. If you bought a new car that is equipped with a factory security system, you should invest in it and install another alarm system.