This article provides an opportunity to get information about how an autonomous GSM alarm system is assembled, installed and maintained. Each device of this type almost always works on the basis of a special module. In fact, this is the same mobile phone, but without keys, screen and case. Instead of these devices, connectors for sensors are attached to the main board. GSM modules are provided by such leading corporations in the mobile phone market as Siemens and Motorola.
A large number of high-quality professional security systems of foreign manufacturers are being developed, the purchase of which is limited for a wide range of consumers. There are practically no descriptions of the principles of assembling such devices.
DIY GSM module
Understanding the basic principles of operation of this type of signaling is necessary at the beginning of the arrangement of any object with a GSM installation. The devices consist of a control unit withcorresponding outputs for sirens and detectors. When an alarm occurs, the device can be programmed to perform certain actions. Such control units are able to process voice messages, send SMS notifications to owners of protected premises or appropriate alerts to security systems controlled by law enforcement officers.
In addition to the above, GSM-alarm systems are able to activate light warning systems, sound sirens, and carry out mass mailing of messages to several subscribers at the same time. You need to decide on the components that you plan to install. The quality of functioning and signaling capabilities will depend only on the developer.
Preparing for installation
As an example, we consider an assembled and configured home-made GSM (burglar alarm) in an ordinary apartment in a multi-storey building. The first step is to select all the necessary sensors. The ability to control hired workers, such as nannies, is often in demand. If it is planned to develop a GSM alarm system for the protection of industrial or commercial facilities, in addition to a noise recognition device, you will also need a motion detector and devices that are sensitive to shock and glass breaking, as well as sensors to control smoke and interact with magnets.
Sensitive elements transmit a signal to the GSM-module in case of opening the entrance doors, damaging the windows or attempting to enter the guardedpremises in any other way. Then, depending on the settings, the siren is activated, notifications are sent to the programmed numbers, the lighting equipment is turned on, or several functions are performed simultaneously. If the do-it-yourself GSM-alarm system has been assembled and correctly installed, you must activate it every time before leaving the territory of the protected facility.
Glassbreak sensors
At this stage, you have to make a choice between reliability and aesthetic design. When you select the first property, the appearance of the window can change significantly. After mounting the sensitive device, a transparent grid will appear on the glass, which can be seen if you look closely.
When an entire glass surface is damaged, the sensor transmits a signal to the control unit, which will instantly begin to perform all of the above possible actions. In order not to spoil the appearance of the surface with the mesh, new internal audio detectors are used for installation, which are directed to the windows. Such devices are characterized by an unmistakable distinction between the sound of breaking glass and any other objects.
Smoke detectors
Setting up a GSM alarm using smoke detection devices will always be relevant for any types of protected objects. It is advisable to install additional devices to neutralize the fire. When creating an alarm with your own hands, you can add to the systema wide variety of devices. You need to understand that the number of connectors on the GSM module is limited, and the choice should always be made wisely.
Device distribution
In a residential area, movement sensors can be installed in the kitchen, rooms or corridor. The actions of any person who tries to enter the building without the knowledge of the owner of the apartment or the responsible employee of the enterprise will be immediately detected by special security devices.
Do-it-yourself GSM-alarm system always requires choosing a location for the control unit and antenna. If integrated, the detector should be placed as close as possible to the window. If the antenna is portable, its installation will have to be carried out in the zone of the best signal reception from the main station. In this case, the control unit can be installed in the most convenient place. Mounting on wall areas out of reach of small children is recommended.
Using an old cell phone
The development technology is very simple. Button 1 of the mobile phone has a tape recorder icon. If you hold it for a long time, you can call the number specified in advance. The GSM alarm works according to this principle.
Instructions for installing a mobile device is not difficult. The processor scans the state of the button. To close the contacts, some low-power optocoupler will do.
The output pulse is applied to the middle contact, it is checkedsignal level. The galvanic discharge from external elements is remarkably consistent with the phone's circuits. The optocoupler is soldered to the contacts with short conductors and fixed on the mobile phone.
Small-sized remote button is used to perform the function of key 1. When an impulse is received, a call is made. The subscriber can listen to everything that happens in the room by pressing the call receive key. An ordinary charger is suitable for powering an integrated mobile phone.
GSM - burglar alarm with installed interface scheme
This method makes it possible to use a signal that is sent to sound warning devices. The output of the LM311 comparator will open some time after the capacitor gains 7 volts of power. After the start of the comparator, current is supplied in the direction from the resistor to the optocoupler. This is how the call is made.
Using a resistor, you can adjust the duration of the delay to activate the comparator. This is provided to prevent false calls during short-term signaling. The interface circuit is placed on a small board and installed together with the autoloader in one housing.
Connecting the secret
Situations may arise when a password is scanned, a key fob is stolen from the owner, or the GSM alarm is hacked so that the GSM alarm never goes off. With their own hands, anyone can create a so-called secret. Connecting it is easy. The contact of the device to power the LED is outputto the connection diagram. If, after starting the engine, while the capacitor is gaining power, the secret button is not pressed, a call is made.
Full handsfree
This technology is only used for car alarm circuits. A complete HF system can be used in place of the charger. Such devices provide power and mount phones, improve the quality of communication due to the antenna, two-way speakerphone.
For Nokia, the original CARK91 system can be used. The installed GSM-alarm system with your own hands will be improved thanks to such a device. Added the ability to auto-reply. When you set the minimum volume, everything will be heard clearly. The microphone is installed in the cabin. The system itself can be placed in the fire extinguisher compartment.
Conclusion
Finally, it is worth adding a few words about how the assembled GSM-alarm system should look like with your own hands. The circuit necessarily includes all of the above sensors. Detectors and sirens must be properly connected to the ports of the software module.
It is necessary to install the system at home before the completion of the repair work. In another situation, you should resort to the help of specialists so as not to create additional problems for yourself. After chasing the walls, there is always a lot of construction debris, dirt and dust in the living room.
