Comparison Alpine CDE-178BT vs Alpine CDA-137BTi

Media types supported by the car radio.

— CDs. Support for optical discs usually assumes at least compatibility with CD, the ability to work with DVD is somewhat less common . For more information about these types, see "Disk Types". Here we note that nowadays, disks are gradually being replaced by more compact and functional media — in particular, memory cards and USB devices; so many modern radio tape recorders, including high-end ones, do not have optical drives at all.

— Memory cards. Ability to work with removable memory cards, usually SD or microSD; the module for reading them is called a card reader. This feature is convenient primarily because such cards are supported by many other devices — in particular, laptops and photo / video cameras. The card reader facilitates the exchange of data between these devices: for example, a selection of music from a laptop can be written to a memory card. Note that the specific type of supported cards needs to be specified separately — the (micro)SD format includes several varieties that are not quite compatible with each other.

— USB drive (front). The ability of the radio to work with external USB-drives — " flash drives ", hard drives, MP3 players, etc. — to pla...y content directly from them. In this case, it means connecting such media to the USB connector located on the front panel of the radio — it is convenient because the connector is in close proximity, right at hand.

— USB drive (rear). Connecting USB drives (see above) through the rear panel. However, the external device is connected not directly to the rear panel, but to an external USB connector, which, in turn, is connected to the rear panel with a cable. Such a connector does not take up space on the front panel, but you can place it on a shelf under the dashboard — and the connected drive will not stick out of the radio, but lie neatly on the shelf. But in standard radios (see above), the “rear” connection can be carried out a little differently — there the cable from the rear panel can be connected to the standard USB socket on the instrument panel using a special connector.

— Connecting an iPod/iPhone. The ability to connect portable devices from Apple to the radio — primarily iPods and iPhone smartphones — through a special docking connector. Even the simplest options for such a connection, in addition to playing music, provide a number of additional features — in particular, control of the player's functions (for example, switching a track) from the control panel or remote control of the radio itself. And the most advanced models have a proprietary CarPlay system; for more information about it, see "Control functions".

— Android connection. The ability to connect smartphones and other devices based on the Android operating system to the radio. Connection methods may vary: for example, some radio models support only a wired connection, others can use Bluetooth (see "Multimedia"). The same applies to the set of functions available in each case, this point should be clarified according to the manufacturer's official data. Specific features include direct playback of music from the phone (with control through the radio), working with the contents of its drive, watching videos, using the radio as a car kit for receiving calls, etc. And in high-end models, there is support for Android Auto smartphone integration technology; for more information about it, see "Control functions".

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.

The number of fixed settings (presets) provided in the car radio equalizer.

The presence of such settings can greatly simplify the adjustment: choosing the right preset is easier than manually adjusting each EQ band. At the same time, presets are often selected by the manufacturer for certain genres of music and have the appropriate names — "Rock", "Pop", "Jazz", etc.; this simplifies the task even more. And the more fixed settings in the device, the wider the choice of the user. In some radio tape recorders, in addition to pre-flashed ones, user presets are also provided — they can be programmed in advance and turned on in the same way as the preset ones.

The ability to adjust the high cut without affecting other frequency ranges. Thanks to this, you can improve the overall timbre of the sound by completely removing the high frequencies, if necessary (for example, for a subwoofer). Moreover, this method of adjustment is much simpler than adjusting individual equalizer bands (see above). Typically, this function is combined with bass control (see below).

The presence of a line input (see Line input) directly on the front panel of the car radio. Such an input can also be located behind the panel (folding or removable), however, with its external location, it is much more convenient to connect external signal sources (for example, an MP3 player) to the radio, since this does not require folding or removing the front panel.

Additional outputs provided in the design of the radio in addition to those described above. These are, usually, rather specific connectors that are rare, for example:

— Control bus input. Input for connecting the control bus — CAN, 5L-Bus, etc. The general idea of the control bus is to combine all the electronics of the car using the simplest single or double wire — instead of complex and bulky multi-wire bundles. Connection to the control bus allows, in particular, to display various data on the radio screen — speed, fuel consumption, tyre pressure, engine temperature, etc.

— Coaxial. Digital input for audio transmission (including multi-channel) through a single connector via an electrical coaxial cable. It is used to connect various advanced audio equipment.

— For the microphone. Input for connecting an external microphone. The microphone itself can be useful, for example, when using the radio as a car kit for a mobile phone, or for voice control. And the input for this accessory in different models can use different types of connectors, this point (as well as additional connection features) should be specified separately.

— For GPS antenna. Input for connecting an external GPS antenna. For more information about GPS navigation itself, see "Multimedia", here we note that an additional antenna provides more reliable reception, improving positioning accuracy and reducing the start time of the GPS receiver after a break in oper...ation.

— For DVD changer. Service connector for connecting a DVD-changer — an external player for several DVD (or CD) discs. The presence of such an input allows not only to play music from the changer, but also to control its settings from the radio: switch between discs, manage playlists, etc. Note that the compatibility of the connector with a specific changer will not hurt to clarify separately.

— For Bluetooth-adapter. Input for connecting an external Bluetooth adapter. For more information about Bluetooth, see "Multimedia", here we note that in some radio tape recorders, instead of the built-in module, this option may be provided. It is convenient in cases where there is no certainty that Bluetooth will be needed in fact: you can buy a radio without overpaying for additional equipment, and purchase an adapter separately if necessary. However, note that the radio, usually, is compatible only with certain models of adapters; the list of compatible accessories in each case must be specified separately.

— FM. This term refers to the part of the ultra-short wave (VHF) range ranging from 87.5 MHz to 108 MHz. It uses frequency modulation, which allows you to broadcast music in stereo with a fairly high sound quality, as well as transmit RDS signals (see RDS support). At the moment, most music radio stations in the CIS are broadcasting in this range. The disadvantage of FM is the limited reception area — a maximum of several tens of kilometers from the broadcasting station — so they can usually be listened to within the same city and surrounding areas.

— AM (English amplitude modulation — amplitude modulation) — broadcasting using amplitude modulation. It can be carried out in different bands, but most commercial broadcasts are carried out on medium waves in the range of 520-1610 kHz; most consumer AM receivers, including those in car radios, are designed for the same frequencies. AM broadcasting has a much longer reception range than FM (it can be hundreds of kilometers), but the sound quality is lower, so this format is broadcast mainly by “talk” and news radio stations.

— LW (English long wave) — broadcasting on long waves in the range of 148-408 kHz. Such broadcasting has a reception range of hundreds and even thousands of kilometers, and is almost independent of the time of day and atmospheric interference. It is used mainly at stations of national importance.

— MW (English medium wave) — broadcasting on medium waves in the range of 522-1...720 kHz, in fact — the same as AM (see above).

— SW (English short wave) — broadcasting on short waves, is carried out in a whole set of bands, the lower limit of which is at the level of 2.5 MHz, and the highest — 26.1 MHz. The features of the propagation of short waves are such that they can be received on the opposite side of the globe, but it is not always possible to hear within a few tens of kilometers from the transmitter. Therefore, shortwave broadcasting is mainly used for foreign broadcasts.

— VHF. In this case, not the entire VHF band is meant, but the sub-band 65.9-74 MHz, using the so-called OIRT modulation. In this format, VHF broadcasting was originally conducted in the countries of the Soviet Union and Eastern Europe, but at the moment it is not very popular due to the development of FM. VHF OIRT is technically similar to FM (see above); the main differences are the bandwidth occupied and the inability to transmit RDS signals in OIRT (see RDS support).

The colour of the backlight plays primarily an aesthetic role, allowing you to choose a radio for the design of the dashboard and user preferences. In addition, some colours have a practical meaning. So, the red backlight is extremely popular nowadays also because it is almost perfect for the dark time of the day: this shade does not knock down "night vision" and has a stimulating effect on the nervous system. And green, on the contrary, relieves excessive nervousness and promotes peace of mind. Other popular colours in modern times include white, blue, orange, yellow, purple ; they do not have such pronounced effects, here the main selection criterion is “like or dislike”.

Also note that in many models several backlight colours are indicated at once. This means that the device has a backlight with adjustable colour selection. At the same time, there are models with a choice of a full range of RGB colours.