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Bluetooth. A wireless communication technology designed to directly connect various devices to each other over a relatively short distance — on the order of several metres (although in specific cases the range can reach up to 100 m). There are many Bluetooth protocols, each of which is responsible for certain functions of a given connection; the set of these protocols (and, accordingly, functions) in different models of automonitors may be different. So, a fairly popular option is to use it as a hands-free car kit: for this, a mobile phone is connected to the monitor via Bluetooth, and the microphone and monitor speakers (or external speakers to which it is connected) are used during a conversation. This allows you to have a conversation without holding the phone in your hand, which makes it easier to drive. In addition, audio can be broadcast from a car monitor to wireless headphones / headsets (or vice versa, from an external device to a monitor), remote control from a smartphone, etc.
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FM transmitter. The car monitor has a built-in FM transmitter. If you have a car radio with an FM tuner (and it is installed in almost all radios), the transmitter makes it easy to output sound from the monitor to the car's speaker system: just set the radio's FM tuner to the frequency of the transmitter. Another option is to use a portable FM receiver or other gadget with an FM tuner (MP3 player, mobile pho
...ne) as wireless headphones. The power of the FM transmitter is small (so as not to interfere with others), but it is enough for a distance of several metres.
— Built-in speakers. The car monitor has its own speaker or speakers. This function eliminates the need to connect the device to an external speaker system or use headphones, portable speakers and other similar equipment — you can play sound on the monitor itself. At the same time, the power of own speakers is usually low, which should be taken into account when installing in large vehicles such as buses.
— Plafond with backlight. The presence in the design of the automonitor of its own lighting lamps. This function is found only in ceiling type models (see "Installation"), as for their installation, it may be necessary to remove the regular lighting cover of the car. In this case, the monitor's own ceiling will replace it.
— Remote control. The presence of a remote control in the delivery set of the car monitor. This feature is useful primarily for passengers in the back seat: to control them, they do not have to reach for the buttons on the monitor case. Also note that if there are additional functions, it is often more convenient to control them on the remote control, and leave only basic adjustments on the panel of the monitor itself; this principle is often used in mid-range and top-end models.
— Connecting IR headphones. Possibility of using wireless headphones connected via infrared channel with the automonitor. The purpose of such headphones is similar to conventional wired ones (see "Outputs — Headphones"), however, they do not have the actual wire, which limits mobility and gets tangled under the arms, which makes it much more convenient. The range of the IR transmitter installed in the monitor is usually several metres. Among the disadvantages: IR headphones work only with line of sight, and also require their own power supply from batteries or accumulators, which have to be periodically changed or recharged. The headphones themselves most often need to be purchased separately, although in some models they may be included in the package.
— Auto-dimming mirrors. The presence in the car monitor of an automatic system that automatically dims the rear-view mirror if necessary. For obvious reasons, this feature is only found on mirror-mounted models (see "Installation"). The meaning of auto-dimming is to reduce the brightness of the intense light flux that enters the driver's eyes — for example, "dim" the powerful headlights of a car coming behind. In this way, not only can overall driving comfort be improved, but glare that could lead to an accident can also be avoided. This function is found in separately produced rear-view mirrors, but it is often more convenient (and cheaper) to equip a standard mirror with a monitor overlay.
— Connecting a remote antenna. An external antenna significantly improves the quality of radio and terrestrial TV reception. It should be taken into account that antenna designs differ not only for radio and TV, but also for different bands and formats in both cases. Therefore, you need to choose an external antenna, taking into account its intended purpose.
