Independent security zones
The number of independent security zones provided in the alarm system.
Each independent zone has its own set of sensors — for example, one zone can cover the doors, the second — the boot, the third — the hood, etc. This, in particular, makes it possible to determine in which place an attempt was made to penetrate, a blow occurred, etc., and to give an appropriate signal — up to showing a specific place of operation on the display of the key fob with two-way communication (see "Type of communication"). In addition, separate activation / deactivation or a time difference can be provided for individual security zones. For example, upon auto-arming (see "Security and Protection"), the alarm for the doors can be activated immediately, and for the boot — for some time later, which will make it possible to calmly pick up things from there.
The simplest modern car alarms have 1 – 2 security zones, in advanced models this number can exceed a dozen (which, in particular, allows you to provide your own security zone for each individual door).
Autorun
Features for automatic start and shutdown of the engine, provided in the alarm. In some cases, using automation is much easier, more convenient, and even more reliable than starting and stopping the engine manually.
— Autostart
by timer. Alarms with this function are able to automatically start the car engine at a certain time set by the driver. This feature allows, in particular, to provide additional comfort and save time on warming up: since the owner does not need to be in the car to start the engine, he can come later, get into an already warmed up car and drive right away.
— Autostart
by temperature. The ability to use an alarm to automatically start the engine for warming up — in the event that its temperature drops below certain values. This function is intended for the cold season, when the machine has to stand outdoors for a long time (for example, all night). Starting a cold, and even more “frozen” engine is associated with a number of problems: the oil becomes thicker, and the battery can “sit down” and produce a weaker current than expected. To avoid such problems, some car alarms are equipped with an auto start function based on temperature: when the engine temperature drops below a certain level, the system automatically starts it to warm up. This ensures that the temperature is maintained sufficient for a comfortable start of the engine at any time. On the other hand, fuel
...is spent on regular warming up of the engine, and in enclosed spaces and other places where exhaust gases are undesirable (and even dangerous), this function is poorly applicable. Thus, most alarms with this feature have limitations related to fuel economy — for example, starting less than a certain number of times during one idle time, or the maximum engine warm-up time.
— According to the voltage of the on-board network. Automatic start of the car engine in the event of a voltage drop on the on-board network (in fact, the car battery) to a certain level. By using this function, you can avoid a decrease in battery charge and related troubles — including not only starting “with a pusher” or “lighting up”, but also completely turning off the alarm (if it does not have an autonomous power supply). Of course, the operation of autorun requires additional fuel costs, but usually such alarms have a number of restrictions aimed at minimizing such costs. But when parking a car in a closed room, this function should be used with caution — it requires good ventilation, otherwise the periodic engine start will lead to the accumulation of exhaust gases.
— Turbo timer mode. Possibility of operation of the alarm as a shutdown timer for an engine equipped with a turbocharging system. During driving, the turbocharger can reach high temperatures, and the oil circulation necessary for effective cooling is ensured by the operation of the engine. If you immediately turn off the car after driving, the heated compressor will actually lose the main cooling system, which can lead to damage and even failure. Therefore, the rules for operating turbocharged engines prescribe, after stopping, to allow the engine to idle for a while to cool the turbocharging system. However, the driver does not always have time to wait for the compressor to cool down. The turbo timer "simplifies life" for drivers of turbocharged cars: it keeps the engine running for some time after the ignition key is removed, after which it automatically turns off the engine. This eliminates the need to wait without removing the key from the ignition and manually control the idling time.
— Webasto support. Car alarm support for Webasto equipment, more precisely, the proprietary W-bus protocol. Webasto is known primarily as a manufacturer of starting heaters for cars, however, in addition to this, the company produces many other components, mainly for “climatic” purposes — air conditioners, sunroofs, etc. Accordingly, Webasto support allows you to connect an alarm to equipment under the W-bus and control this equipment through it. Note that W-bus controllers are also available separately, but it is usually easier and more reliable to buy a compatible signaling right away. — Support of the signaling of the Start/Stop function. This function is mainly intended to give the driver the ability to start the engine without using a key, simply by pressing a special button. At the same time, some models are designed for installation in a car where such a button was originally provided, and we are only talking about compatibility with a keyless start system; others are equipped with their own button and can even be installed in cars that were initially started only with a key.
In addition, models with the "Start / Stop" function can have the function of remote engine start on command from the key fob. This can be useful, for example, to save time on warming up the car before driving in cold weather: you can start the engine without leaving your home, and then get into an already warm car.
— Automatic transmission support. Signaling compatibility with automatic transmissions.
Such systems are structurally more complex than traditional mechanical boxes, they are closely related to the electronics and controls of the car. Therefore, for the correct operation of the autorun functions on a car with automatic transmission, it is necessary that this type of transmission is initially supported by the alarm system. If the “signaling” covers only locks and other functions that are not actually related to the engine, this feature is not mandatory.
— Support for diesel engines. This feature is indicated for car alarms that have a specialized mode for starting diesel engines. One of the differences between such engines and gasoline engines is that they use the so-called. glow plugs. For normal operation of the diesel engine, it is necessary that such candles warm up to operating temperature; heating starts immediately when the ignition is switched on, but it takes time. These moments are taken into account in the "diesel" mode: the alarm first turns on the ignition, and gives the start command only after the candle warm-up indicator goes out.Anti-scan
Availability of alarm
protection from scanning ; if the characteristics specify the type of such protection, it is also given in this clause.
Scanning is used by attackers to intercept the control signal from the key fob; by forging such a signal, the hijacker can safely open the car. Accordingly, this protection is aimed at preventing such hacks. And its main types nowadays are
dynamic code and
dialog code, here are the features of each of these methods:
— Dynamic code. The general principle of dynamic coding is that each time you press the button to turn on or turn off the alarm, the key fob gives a new, unique signal. Most often, the Keelog algorithm is used for this; it assumes that the signal from the key fob contains data on the serial number of the device, the number of clicks and the secret code that the central unit also “knows” (this code is written at the factory and is unique for each alarm). Based on the serial number, the system performs general identification of the key fob, the click counter confirms that the signal has not been sent before, and the secret code acts as an encryption key. Thus, even if an attacker intercepts and copies the signal from the key fob, this signal will be outdated and, accordingly, useless; and it is impossible to decipher this signal and reproduce the desired version without a secret code.
The main advanta
...ge of systems with dynamic coding is simplicity and, accordingly, low cost. However, this method in itself is less perfect than the dialog code, it provides a lower degree of protection against interception and hacking — with the help of the so-called dynamic code grabber with a jammer, an attacker can still intercept the control code under certain conditions and open the machine. However this procedure is quite complicated and does not give a guarantee; so in general, dynamic code is a good option for inexpensive cars that are not particularly attractive to professional crackers. But for maximum protection, it is still better to use dialogue systems.
— Dialogue code. Protection operating on the principle of “friend or foe” recognition: before giving a control signal, the key fob and the central unit exchange service data, identifying each other and making sure that the signal comes from the rightful owner. This is done in the following way. When you press a button on the key fob, it sends a connection request with data about its serial number. The central unit checks the serial number and, if the result of the check is positive, sends a randomly generated number to the key fob. The keyfob processes this number according to a certain algorithm and sends the result (together with a request for action) to the central unit, which performs calculations according to the same algorithm; if the results agree, the defense gives the go-ahead to execute the command. The algorithm used for calculations is unique in each individual signaling, and so-called hash algorithms are used to encrypt the transmitted data. Due to this, the dialogue code is almost impossible to crack: for this, the attacker must intercept 3 data packets (request, riddle, guess) and decrypt 2 of them, while without knowing the key (embedded in the alarm itself and inaccessible without physical access to the device), such a decryption nowadays is inaccessible even to the most powerful computers.
Dialogue systems are naturally somewhat more expensive than dynamic ones, but this is more than offset by a high degree of security.
