Comparison Motorola DP4801 EX MA vs Motorola DP4801

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, eve...rything 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 over which the walkie-talkie is capable of transmitting. This parameter is usually indicated if it does not completely match any of the standard radio operating ranges (see “Frequency Range”). For example, the transmission range is often specified for VHF and UHF models, as these bands themselves are quite wide, and individual walkie-talkies can only use a subset of these frequencies. The opposite option is also possible - wide-range models, whose specs go beyond the standards.

The frequency range in which the radio can receive transmissions. It is usually indicated if it does not coincide with one of the standard ranges of the radio; see "Transmission frequency range" for details.

— 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 lic...ensing in some 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.

The maximum operating time of the radio in talk mode — i.e. with continuous radio traffic and approximately equal distribution of time between work for reception and transmission. You should pay special attention to this parameter if you plan to communicate intensively. Note that when receiving, much less energy is consumed than when transmitting. And therefore, in fact, the time in the talk mode, even with continuous radio exchange, may differ from the claimed one both downward (with large volumes of transmissions) and upward (when working mainly for reception).

Walkie-talkies with this feature have a special protected housing that prevents dust and moisture from getting inside and damaging sensitive electronic components. If you often have to be in adverse conditions, you should pay attention to such walkie-talkies. At the same time, note that the specific degree of protection in different models can vary markedly, and here it is most convenient to evaluate it by IP marking. This marking consists of the letters IP and two numbers; resistance to dust — the first digit, resistance to moisture is described by the second, last digit. You can find the following options for protection against moisture:

— 4. Protection against splashes from any direction. Thus, the walkie-talkie will be fine during rain of medium intensity, regardless of the strength of the wind
— 5. Protection against water jets from any direction. Allows walkie-talkie to endure a combination of strong wind with a downpour.
— 6. Protection against strong water jets and sea waves. It is considered the minimum level of protection that allows use near water.
— 7. The possibility of short-term (less than half an hour) immersion under water to a shallow depth (less than 1 m); continuous operation in immersed mode is not expected.
— 8. The highest level of water protection. Allows long-term (more than 30 minutes) immersion under water to a depth of 1 m or more, and even permanent work in a submerged position. However, note that specific restr...ictions on the use in such walkie-talkies may be different, they must be clarified according to the manuals.

Dust protection values are presented more modestly:
5 — dust resistance without full closure (a certain amount of dust can get inside, but it is small and does not affect the operation of the device)
6 — full protection (dust is not able to penetrate inside the case).

At the same time, there are situations when the manufacturer did not test the device for dust resistance, but limited itself to water protection. In this case, instead of the dust protection number, there is an X, for example IPX7.

Special protection against explosive impact.

Availability of explosion protection means that the walkie-talkie well resists not only blows and concussions, but also high temperatures. Thus, such devices are indispensable in conditions of increased explosion and fire hazard, where conventional moisture and shock protection is no longer enough. Walkie-talkies with this feature are widely used in hazardous industries (chemical, oil), in rescue services, the armed forces, etc.

Also note that most of the explosion-proof models presented on the local market comply with the European ATEX standard (safety in an explosive atmosphere). Details regarding ATEX criteria can be found in specific sources.