Comparison Motorola TLKR T82 Extreme vs Xiaomi Mijia Walkie Talkie

According to the type of communication, all modern walkie-talkies are divided into analogue and digital. Here is a detailed description of each option:

— Analogue communication. The simplest, from a technical point of view, way of working: the sound received by the walkie-talkie microphone is "embedded" into the radio signal directly, without converting to digital format. Accordingly, the main advantages of analogue radios are the simplicity of design and low cost. The key disadvantages of this option are the relatively low sound quality, which, moreover, strongly depends on the actual signal power: the weaker the signal, the worse the audibility and the higher the level of interference. In addition, the connection itself is not protected from eavesdropping: any user in the range of the walkie-talkie, having tuned in to your range and channel, will be able to hear your conversations. On the other hand, this can be both a disadvantage and an advantage — for example, if we are talking about a CB range car radio, often used to communicate with unfamiliar people. And you can protect the channel from listening, for example, using a scrambler.

— Digital communication. With this communication format, the analogue audio signal (electrical oscillations) is first converted to digital (a sequence of zeros and ones), and only then is sent to the transmitter. In the receiver, accordingly, everythin...g happens the other way around: the digital-to-analogue converter restores the original sound from the stream of numbers. Digital walkie-talkies are noticeably more complicated and more expensive than analogue ones, but they have a number of advantages over them. First, the signal is much better protected from interference. Secondly, its quality does not change when the power changes: the receiving party either hears the sound in its original quality (even at the minimum signal level), or hears nothing at all. Thirdly, the digital format allows the use of various additional features, such as text messages. And fourthly, in such walkie-talkies it is much easier to implement eavesdropping protection. So, within the same range, hundreds or even thousands of channels can be provided, with random selection and periodic switching between them (a similar technology is used in mobile networks and Wi-Fi equipment). And interconnected devices can "agree" on a common unique encryption key — as a result, an outsider will not be able to decrypt digital data, even if he finds a communication channel.

The frequency range supported by the radio for both reception and transmission.

— CB (27 MHz). Abbreviation for "Citizens' Band" (sometimes spelled "Civil Band"), i.e. "civil range". One of the most widely used modern ranges, in particular in the CIS, in many countries CB radios do not require licensing. The technical features of the range are such that it is poorly suited for urban development, but provides good communication outside the city. As a result, such walkie-talkies are widely used in vehicles, especially among truck drivers — they allow you to exchange information at a distance of up to 5 km and warn other drivers about the traffic situation in advance. Also this range is used by many emergency services for direct reception of information.

— LPD (433 MHz). An abbreviation for "Low Power Device", which fully describes the features of walkie-talkies for this range. They have low power consumption and often do not require special batteries (ordinary batteries will do). At the same time, due to the high frequency, LPD models behave well in urban conditions, with dense buildings and an abundance of other sources of electromagnetic interference — the communication range can reach 2-3 km. This range is used mainly in Europe and the CIS, in many countries models for it do not require licensing.

— PMR (446 MHz). Abbreviation for "Private Mobile Radio" — "private walkie-tal...kie". This range is in many ways similar to LPD (see above): in particular, it is intended primarily for urban conditions, it is used mainly in Europe and the CIS, and walkie-talkies under PMR can be used without a license in many countries.

— FRS (462-467 MHz). It stands for "Family Radio Service", which is "walkie-talkie for family use." It is one of the varieties of the UHF band (see below), it has low power consumption on the one hand and relatively short range on the other. Generally refers to the "urban" bands, similar to LPD and PMR (see above), however, unlike them, it is used mainly in North and South America; in Europe and the CIS, such walkie-talkies require licensing at best, and in some countries they are generally prohibited for use.

— VHF. Abbreviation for "Very High Frequency" — "very high frequency", this range covers frequencies 134 – 174 MHz. VHF radios have good range and signal penetration, suitable for both urban and rough terrain, but such devices require a rather long antenna for reliable operation. As a result, VHF is widely used in professional radio communications, in particular maritime and taxi services, but in many countries such walkie-talkies can only be used after registration and/or obtaining a license.

— UHF. The "Ultra High Frequency" range is "super high frequency", most often this definition means frequencies of the order of 400 – 470 MHz. It is a kind of analogue of VHF: it is widely used in professional walkie-talkies and requires licensing in many countries. At the same time, UHF, due to its high frequency and short wavelength, has good penetration and does not require long antennas, which makes it more suitable for compact "city" type radios.

In addition to the above, it is worth noting two points regarding the licensing and registration of walkie-talkies of all ranges. Firstly, license-free conditions often describe not only the range, but also a number of other technical specs (primarily this concerns the power of the transmitter and the type of antenna, see more about both below). Secondly, in different countries (even within the same region), the legislation relating to radio communications can differ significantly — as a result, a model that is freely sold in one country may be subject to registration or even be banned from use in another. And for professional models, a license may be required not only for a walkie-talkie, but also for a specific frequency. Therefore, before purchasing a walkie-talkie, it makes sense to separately clarify the relevant provisions of the law.

The maximum power at which the radio transmitter is capable of operating. This parameter is one of the most important: it determines both the range of the device (see above) and the features of its use and registration (for more details, see "Frequency range"). For most models of the "amateur" (conditionally) class, the power level does not exceed 2.5 watts. More powerful walkie-talkies are, usually, professional models of the VHF and UHF bands (for more details, see "Frequency range").

Many modern walkie-talkies have several power settings, most often two — low (Low) and high (High). The first option is useful if the the other walkie-talkie is at a short distance: the transmitter will not consume excessive power, respectively, the battery will last longer. If the distance is large, you may need the “High” mode, in fact, the full power of the transmitter.

The number of channels on which the radio can operate. Each channel is essentially a fairly narrow subband within the main operating band (see "Frequency range"). The division into channels allows several groups of users to work simultaneously on the same territory and in the same range so as not to overlap on the air and not interfere with each other. The more channels provided in the design of the walkie-talkie, the more likely it is to find a free channel and the better it is suitable for working in conditions of intense extraneous radio traffic. This is especially important for powerful "long-range" models. At the same time, simultaneous operation of several groups on one channel is also possible thanks to subcodes (see below).

Subsonic signals to reduce short-term interference on the air or to ignore radios broadcasting in the same frequency channel without a subtone included. The parameter is set by a special code, which indicates the frequency of the tone mixed with the useful signal. A similar subtone must be set on the receiving device. The sounds of subtones are removed from the signal before being fed into the amplifier and further into the sound system of the walkie-talkie.

— CTCSS. An analogue tone transmitted with a call to separate walkie-talkie users on the same channel and to filter out interference. Various radios may use 38, 39, or 64 CTCSS tones at frequencies from 33 to 254.1 Hz. The serial numbers of specific tones are determined by special charts.

— DCS. Radios with the DCS digital subtone system "hear" each other when set on the transmitting and receiving side of the same code. The DCS system offers over a hundred standardized digital codes, which are a three-digit number of zeros and ones at a carrier frequency of 133 Hz. DCS subtones effectively divide the communication frequency according to the "friend or foe" principle, cutting off unauthorized users, interference or noise on the air.

— CTCSS\DCS. Walkie-talkie models that combine analogue and digital formats for introducing subtones with the ability to switch between them.

The number of subcodes provided in the design of the walkie-talkie. Subcodes are used to create separate subchannels with different coding within one channel (see "Number of channels"). This allows several groups of users to communicate simultaneously on the same frequency channel without interfering with each other. Thanks to the combination of channel and subcode, the number of subchannels available for communication can be in the hundreds — which is more than enough even in a busy air. In entry-level models with low power, the possibility of using subcodes may not be provided at all as practical uselessness — there are not too many users within their range. But for powerful radios with a long range, the presence of subcodes is very important.

The type of antenna used in the radio.

— Non-removable. As the name implies, such an antenna is permanently attached to the body of the radio. Technically, it is most often possible to remove it, but for this you will need to disassemble the radio; replacement for such an antenna with another, of a different type, is not provided at all.

— Removable. The detachable antenna was originally designed to be quickly detached from the body of the radio, most often without the use of any tools. In addition to ease of transportation and storage, this design often provides the ability to change the stock antenna to a more powerful one, or even connect the walkie-talkie to a separate external antenna — to increase the range.

Note that the legislation of some countries refers the design of the antenna to the parameters that determine the conditions for licensing and registration: for example, walkie-talkies with removable antennas may be subject to licensing, while for completely similar models with non-removable antennas, it will not be required.

— Headset connection. The ability to connect a headset to the walkie-talkie — an earpiece (or headphones) with a microphone. The main purpose of the headset is to free your hands during a conversation. In addition, in noisy environments, an earpiece is often more convenient than an external speaker.

— Bluetooth. Medium-range wireless technology (10 to 100 m, depending on version) for direct communication between different devices. The main and almost the only way to use this technology in walkie-talkies is to connect wireless headsets that allow you to free your hands when talking. Bluetooth can be provided in both portable and fixed radios.

— Speech masking (scrambler). The presence of a speech masking feature in the radio: the built-in encryption module (scrambler) encodes the sound and broadcasts an encrypted signal, which is decrypted by the similar scrambler at the receiving end. The main purpose of this feature is to protect against unauthorized listening and interception of “sensitive” information: even if an outsider tunes the radio to the appropriate channel (or subchannel, see “Number of subcodes”), he will hear only a set of meaningless noises. For correct operation in this mode, the scrambler modules for all users must be identical. Also note that speech masking walkie-talkies may be subject to licensing in so...me countries.

— Voice activation (VOX). The ability to control the walkie-talkie with the help of voice: during the silence of the user, the device works for reception, and when the microphone captures the voice, it switches to transmission mode. Usually this feature is implemented through a headset (see above), which allows you to completely free your hands and makes the use of the walkie-talkie as convenient as possible: you do not have to press the button every time to switch to transmission mode. And to avoid accidental activation due to extraneous sounds, many models with VOX have a sensitivity control that allows you to set the volume level for triggering the switch.

— Volume control. The ability to adjust the volume of the speaker, which allows you to choose the optimal volume level depending on the environment. This feature is present in most modern walkie-talkies, with the exception of only the most inexpensive models.

— Auto noise reduction. The function of suppressing noise generated on the air by extraneous sources of interference, when the radio is receiving. Such noises create a signature hissing sound in the speakers (the same one that is heard when the radio is not tuned). It's useless "ethereal garbage", because when talking, it reduces the intelligibility of speech, and when silent, it wastes the battery charge to reproduce a meaningless hiss (which is also unpleasant to hear). The noise suppressor blocks these noises, thus increasing speech intelligibility and providing silence between phrases. Usually, walkie-talkies with this feature provide setting the level of noise suppression — for optimal separation of the useful signal and background noise.

— Channel autoscanning. The ability to operate the radio in automatic channel scanning mode (for more details on the latter, see "Number of channels"). In this mode, the walkie-talkie independently tunes in turn to each channel in search of a transmission signal. Channels without transmitters are skipped, and when a signal is detected, scanning is suspended — for a while or until a special user command. Thus, the user can listen to all active channels and select the desired one.

— Channel monitoring. The ability to operate the radio in the channel monitoring mode. In this mode, noise reduction is completely disabled (see above), and the user can listen to the unfiltered signal on each selected channel. This allows you to evaluate both the traffic load of the channel with calls and the overall level of interference, and select the optimal communication settings.

— Roger-Beep signal. The presence of an automatic end-of-transmission signal on the radio, the so-called Roger Beep. Such devices, when switching from transmit mode to receive mode, broadcast a special sound signal (usually in the form of a short squeak, hence the name), indicating the end of the transmission. This eliminates the need for the user to specify the change of modes himself (for example, with the traditional word "over") — his interlocutors will receive a signal about this automatically.

— Power saving mode. The walkie-talkie has a special mode designed to maximize power saving and allow you to extend the work without recharging the battery (or changing batteries). This feature is especially useful if you have to carry the radio with you for a long time, only occasionally getting in touch. Specific features in different models may vary: for example, some walkie-talkies in this mode are almost completely turned off, only periodically “waking up” and scanning the channel for activity; in others, specific power saving features can be selected as desired by the user.

— Vibration. The walkie-talkie has a vibrating call feature similar to that used in mobile phones: when a signal is received on the selected subchannel, the body of the walkie-talkie starts to vibrate. This feature can be useful in noisy environments where it is difficult to hear the sound signal from the speaker — or vice versa, in silence, when any extra noise is undesirable.

— Keypad lock. The ability to block the keys of the radio from accidental pressing. This allows you to carry the device in your pocket or tight case, without fear that due to an accidental movement, the settings will go wrong, the transmission will turn on, etc. The lock itself is usually controlled in a way that excludes as much as possible the possibility of its accidental release — for example, by simultaneously pressing two buttons.

— On/off button sound. The ability to turn on and off the beep that sounds when each button is pressed. An audible signal serves as a convenient confirmation of a full press; on the other hand, it may not be appropriate in some situations.

— GPS module. It implies the presence of a built-in module for receiving GPS data from satellites, which allow you to determine the exact location of the user. The accuracy of work largely depends on the number of satellites that see the receiver at a particular moment, and weather conditions, but, usually, it ranges from one to ten metres. The functions of the portable radio with built-in GPS may vary depending on the specific model. So, the device can simply display the exact position at the moment on the screen (latitude, longitude, altitude), as well as the direction and speed of movement. More advanced models with a large screen can show locations on a map or, for example, transmit the user's coordinates to the dispatcher.