Number of bands
The number of bands in the radio equalizer.
In this case, the band means a separate part of the frequency range, the volume of which can be adjusted using the equalizer independently of the other parts. The more bands the equalizer has, the more accurately it allows you to adjust the overall sound of the car radio acoustics. However, note that multi-band equalizers are quite difficult to set up, therefore they are recommended primarily for experienced users.
DSP
The presence in the radio built-in
DSP — digital sound processor.
Such a processor improves the overall sound quality and provides additional options for its adjustment. One of the most important DSP functions is time correction: it allows you to adjust the acoustics so that the sound from speakers located at different distances from the user reaches it at the same time. Such coordination significantly improves the impression of the sound. In addition, radios with DSP necessarily have a digital crossover (frequency separation) and an equalizer with a fairly large number of bands.
The presence of a processor significantly affects the price of the radio, but in most cases this is a justified payment for the sound quality. But the unequivocal disadvantage of "processor" models is the difficulty in installation and configuration, for this it is best to contact a specialist.
Control functions
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Remote control. The radio has a remote control. This function will be convenient primarily for passengers behind the driver — from the rear seats you can’t reach the radio itself. In addition, remotes often have more keys than the stock control panel, which allows you to access various additional functions on the go without digging through the settings.
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Remote control on the steering wheel. Remote control (see above) with the ability to mount on the steering wheel. Such a remote control allows the driver to control the functions of the radio without removing his hands from the steering wheel and thus not being distracted from driving the machine.
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Control from regular steering wheel buttons. The ability to control the radio from standard buttons, originally provided on the steering wheel for this very purpose. This function is similar to the steering wheel remote control described above, with the adjustment that the "remote" in this case is built directly into the steering wheel. Before buying such a radio, you must definitely check its compatibility with a particular model of car.
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Smartphone control. The presence of software (application) that allows you to control the radio using a smartphone, tablet, etc. This is not just about switching songs on the phone, but a full adjustment of all device functions.
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— Voice control. The ability to control the radio using voice commands. The implementation of such control can be different: in some models, to activate it, you need to press a button, others constantly “listen” to the environment and immediately respond to code words. Anyway, this function allows the driver to control the radio without taking his eyes off the road, which has a positive effect on traffic safety. Note that in its pure form, voice control in modern radio tape recorders is becoming less and less common, being replaced by advanced technologies like CarPlay and Android Auto (see “Control Functions”), which also include voice functions.
— Apple CarPlay system. Support for car radio technology CarPlay. This technology is designed to connect portable devices from Apple to the radio, primarily the iPhone, although it is technically possible to work with any “apple” gadget that has iOS 7.1 or later firmware, as well as a proprietary 8-pin Lightning connector. Thanks to this technology, many smartphone functions (including the Siri voice assistant, navigation, call and message management, as well as music) are integrated into the radio; using them through on-board electronics can be much more convenient than holding the iPhone in your hands. At the same time, CarPlay puts special emphasis on safety: it is designed with the maximum use of voice control, so that the driver has to be distracted by the radio screen as little as possible. For example, the mentioned messages can be dictated by voice and listened to "performed" by Siri. The connection itself is carried out by wire, through the mentioned Lightning connector.
— Android Auto system. Car radio support for Android Auto technology. Similar to the CarPlay described above, this technology is designed to combine portable devices with on-board electronics of a car — only, as you might guess from the name, in this case we are talking about gadgets running the Android OS. When you connect such a gadget, the radio actually plays the role of an external display for a mobile device, with its optimized interface and related capabilities. Features available through Android Auto include navigation (including mobile device access to external GPS antennas and modules), music control, receiving and making calls, listening to and composing SMS, and searching the Internet. Android Auto is only available for Android 5.0 Lollipop and later; in addition, if the mobile device uses proprietary firmware, its compatibility with the radio needs to be specified separately.Other outputs
Additional outputs provided in the design of the radio and not related to those described above. These can be, in particular, such interfaces:
— Coaxial. Digital output for audio transmission (including multi-channel) via RCA cable, electric version of S/P-DIF interface. Do not confuse this standard with analogue RCA (see "Connecting speakers"): firstly, it uses a digital data transmission format; secondly, the entire signal is transmitted over one cable; thirdly, conventional RCA cables for coaxial connection are poorly suited, it is desirable to have shielded ones. Unlike optical S/P-DIF, this variant is subject to some degree of electrical interference; on the other hand, it does not require special care when handling the wire.
— Optical. A variation of S/P-DIF that uses a TOSLINK fibre optic cable to transmit the signal. Like the coaxial version described above, it supports multi-channel audio. At the same time, optical fibre, on the one hand, is completely immune to electrical interference, on the other hand, it requires rather delicate handling (in particular, it does not tolerate sharp bends).
— On the regular display. Output for connecting one or another regular display. This can be a screen that is originally installed on the dashboard of a car, or a monitor purchased separately; specific models of compatible screens should be specified in the documentation for the radio.
— High voltage. Speaker output with increased op...erating voltage of 4V instead of the traditional 2V. This improves the signal-to-noise ratio and improves the overall sound quality. On the other hand, connecting speakers to such an output can be associated with additional difficulties.
