Frequency range pmr. LPD and PMR ranges. Headsets - PTT

12/17/2017 According to Russian legislation, there are two license-free bands in the UHF range for everyone who needs radio communications: LPD and PMR. They are close to each other on the frequency grid - LPD channels are located from 433.075 to 434.750 MHz, and PMR from 446.000 to 446.100 MHz.
The best thing to do is to use both, since each range has its own advantages. Moreover, Argut radios allow you to do this.
The main advantage of PMR radios is the power level. The permissible power in this range is 0.5 W. In LPD - much less. But on the other hand, PMR has only 8 channels. In a big city this is not much, the channels may be busy. Of course, CTCSS and DCS coding saves you, but it is often easier to switch to LPD channels and use them.
In LPD, the problem is the low level of permitted power. In addition, some of the channels are filled with telemetry and alarm systems, as well as various remote controls. But since there are many channels, the problem is always solvable. LPD has such useful things as auto channels where you can contact and chat about the situation on the roads.
But in terms of communication range, both ranges are approximately the same. In a line of sight zone of several kilometers, communication is provided without problems. Moreover, the connection is very high quality and legible. Sometimes long passages happen. But this requires special conditions and this rarely happens. But 3-5 km in open areas is always possible, and more is usually not required.

What connection do we use when engaging in active sports and recreation?

A cell phone is not always convenient and does not always work.

Satellite, and in some cases this is the only connection with the “greater land”.

Now about everyday realities.

Someone bought point-and-shoot radios, others snatched something more impressive, some had amateur radio, multi-band stations.

When everyone has the same stations, there are usually no problems, everyone can hear each other. And when the stations are different, how to “make friends” between them. After all, not all people engaged in the same type of activity have the same radio stations.

There can be many situations requiring the construction of different stations:

— You’re skiing and want to build a walkie-talkie with a guide.

— You are driving several cars on vacation, in a large group.

— You communicate in the mountains with other groups of climbers.

- If you are in trouble, ask for help.

— Interact with other groups during rescue operations.

Let's first look at what types of radio stations there are.

From simple to complex 😉

"Soapboxes"

“Soapbox” - “soapbox” ®

n so they are done according to transmitter power and frequency.

You've probably noticed that walkie-talkies have different numbers of channels: 69 channels, 22 channels, 8 channels. n with a different number of “subchannels”, remember, subchannels do not exist, in most cases you call this terrible word CTCSS tone or digital DCS noise suppressor. What this is, see the appendix at the end of the material.

There are also different markings on boxes, walkie-talkies, or under batteries: LPD, PMR, FRS/GMRS.

Let's figure out what's here and why.

FRS/GMRS is an American standard for household transmitting devices that operate on frequencies that are not allowed for use by the common man in Russia. It is not possible to use these radios legally.

PMR (“Personal Mobile Radio”), 8 channels are allocated for walkie-talkies with a transmitter output power of no more than 0.5 W. The European standard for household transmitting devices (446.00625-446.09375 MHz) due to the grid step of 6.25 kHz, they are not built with practically anything other than the same PMR standard radios. On amateur radio stations, where there is no 6.25 kHz step, you can build by slightly deviating from the given frequency. Registration of radio stations is not required.

LPD (Low Power Device) can be used freely - no radio station registration is required. They operate in the range 433.075-434.775 MHz. The most successful household radio stations for active pastime, especially if you bought the “correct” models that can be tuned to a slightly higher power (up to 3 W), compared to the allowed 0.01 W. There are models with a screw-on antenna; you can replace it with a longer antenna from a professional or amateur radio station, which will greatly increase its receiving and transmitting characteristics.

For a table of frequency correspondence to channel numbers and squelch tones, see the appendix.

P.S. The use of LPD (SRD) radios is not permitted in the following countries: Belgium, Denmark, Finland, Portugal, Luxembourg, Portugal, UK, Spain, Lithuania, Latvia, Estonia, Croatia, Turkey.

There are no such restrictions for PMR radios; you can safely travel abroad and use them freely.

As for FRS/GMRS, this range is prohibited primarily in Russia. 😉

Amateur radio stations.

How not all apples are created equal®

So not every Kenwood is a Kenwood.

(radio amateur wisdom)

Good communication doesn't come cheap. With these words I want to start the story about mid-level equipment.

Chinese KENWOOD TK-K2AT, TH-K2AT and TK-150S range 137-174 MHz, or TK-K4AT, TH-K4AT and TK-450S range 420-470 MHz work with any LPD/FRS/GMRS point-and-shoot cameras price less than 100 $ piece. These and other similar devices are sold quite widely in our country.

BUT! Oh, if you only knew how much I myself don’t like such “buts”. Walkie-talkies in this price range, with the stated characteristics, are a pig in a poke.

Reliability = reliability, durability, maintainability.

It’s precisely the reliability in these kitaKenwoods that is lacking.

How quickly it will stop working is also unknown. This equipment is class, whether you're lucky or unlucky, tested from your own experience.

Kenwood is a good manufacturer of professional equipment at reasonable prices. If your Kenvod kit breaks down, remember Kenwood has nothing to do with it, it has never even seen these stations.

There are so-called “two-bend” radio stations that combine the ranges that interest us, the so-called two-meter range and the 70cm range, they are named so not by chance, this is a display of the wavelength in the name. These are frequencies of 137-174 MHz and 420-470 MHz, the second, as you remember, includes household radios “soap boxes”.

So why do you think the 2-meter range is interesting to us? And in fact, very many.

The first and very important argument is that the rescuers of the Ministry of Emergency Situations work on it.

Secondly, a huge “army” of radio amateurs communicates in this range.

Third, it has good coverage in mountainous and wooded areas; the 70cm range benefits only in dense urban areas.

When engaging in active sports and recreation, it is very foolish to assume that you, your friend or other people around you will not need any outside help in your sport. You can’t rely on a mobile phone everywhere, and you’ve experienced this yourself. Therefore, being able to ask for help in a timely manner can be very important. When arriving in a new area, find out the frequencies of radio stations: guides, voluntary rescue teams and the Ministry of Emergency Situations. For the Ministry of Emergency Situations, this is the usual frequency of 164.450 MHz, but you must find out on your own what frequency the local rescue services’ receivers and their call signs are tuned to.

The calling frequency of radio amateurs (usually 145.500 MHz), all surrounding radio amateurs conduct their communications here, and many have stationary equipment of much higher quality and finely tuned than in the Ministry of Emergency Situations. You understand, some people are so addicted to their hobbies that they are ready to spend a lot of money and all their free time on their hobby in order to achieve good results. It should also be noted that radio amateurs repeatedly received distress signals and transmitted information to rescuers, which is how many lives were saved at different times.

Taking this into account, we can conclude that having a 2-meter range in your walkie-talkie is not superfluous. Radio stations at this level require registration if you are going to use them legally. There is nothing complicated about this, but more on that later.

Yaeski-yaeski.

Yaesu– a well-known brand

among radio amateurs

and is synonymous with high quality

amateur radio stations.

The good combination of price = quality simply forces us to take a closer look at the models of this manufacturer. Here are three models of portable stations that are worth paying special attention to.

YAESU FT-60R

YAESU VX-3R

YAESU VX-6R

All three two-band stations are priced in ascending order.

Briefly about the advantages and disadvantages of these. They are all very similar in their characteristics.

YAESUF.T.-60 R

Pros: Full 5W transmitter power, price, ability to use: lithium, metal hydride and nickel-cadmium branded batteries, ability to operate on batteries. Dustproof, waterproof.

Minus: a bit large and heavy compared to the other two. The headset connector is not very well thought out; you have to press it with a rubber band to keep it from falling out.

YAESUVX-3 R

Pros: Very compact and light, 130g. Dustproof, waterproof.

Cons: Weaker transmitter, no more than 3W. Only lithium brand batteries.

YAESUVX-6 R

Pros: Full 5W transmitter power, compact, average size between FT-60R and VX-3R. In terms of water resistance requirements, the station complies with the JIS-7 standard (immersion to a depth of 1 meter for 30 minutes). Only lithium brand batteries.

The Yaesu VX-120 stands apart; it can be described as “reliable.”

This walkie-talkie has only a two-band range, but its merits are not in a wide reception range but in reliability. Waterproof and shock resistant to military standard MIL STND 810 C/D/E.

Radio Options

The antenna is the best amplifier.

Whatever “cool walkie-talkie” you have

with a bad antenna it doesn't matter.

Antennas.

All antennas that come with radio stations have very weak characteristics due to their broadband. Since we need antennas for very narrow ranges, we can purchase them and gain in communication quality and range.

Yaesu ATU-6B (420-470 MHz) is a good antenna for seventy, if you install it at an LPD station, for example, four hundred Midland, you will benefit greatly in communication quality.

Yaesu /Vertex ATV-6XL Antenna for the range 136-174 MHz, adjusted to the required frequency by trimming. A cutting map is included in the kit.

Cut it to a frequency of 145 MHz and the second to 164 MHz and get the most efficient antennas for these frequencies.

Opek 601HV antenna for two bands 136-174 MHz-420-470 MHz. Has slightly higher gain than a standard antenna. It is a little flimsy, requires careful handling, and breaks badly at the junction with the reel. Lately the quality has been very unstable. With minor home modifications, it shows slightly better results than standard antennas for the FT-60 or VX-6.

When using radio communications at a considerable distance from each other, the use of antennas tuned exactly to the frequency on which you are working is mandatory, since when using standard multi-band antennas there is a chance of being without communication or receiving only fragments of phrases.

Headsets - PTT

Headsets or also handsfree are very convenient, as they free your hands from the radio station, but you can also quickly receive information transmitted to you.

Push-to-talk is a remote unit on a wire that connects to your walkie-talkie with a microphone, speaker and transmit button. In most cases it also has a headphone jack.

A very convenient thing, regardless of the type of station. The radio can be in an internal pocket (for example, so as not to freeze) or in a backpack, and the push-to-talk button is brought to a convenient place and connected to the station with a twisted wire.

Batteries

There are different types of batteries: lithium, metal hydride and nickel-cadmium. Briefly about the pros and cons of using them in radio stations.

Lithium - have the largest capacity, with a modest battery size. Accordingly, long-lasting energy output. Their disadvantage is that they are very afraid of negative temperatures, they quickly lose tension and the ability to continue working.

Metal hydride batteries have a lower capacity with the same dimensions, and are not as afraid of negative temperatures as lithium ones. They do not have a “memory effect” and can be recharged without waiting for complete discharge. But they have a relatively high self-discharge current. This means that they lose charge when they are simply sitting in storage awaiting use. In one week of storing a charged battery, you will lose somewhere around 20% of the capacity, respectively, 20% of the operating time.

Nickel-cadmium batteries have the lowest capacity of those listed above. They can deliver the highest current. They have a “memory effect” and require complete discharge before charging again. But their advantages are low self-discharge current. Therefore, they still enjoy the attention of operational services.

Battery cassettes

Convenient devices for AA batteries. They can help out a lot when you can’t find an outlet to charge the station.

Disadvantages: due to the many intermediate contacts between the power elements (batteries), micro resistances are obtained that prevent normal current output; the station will not operate at full power and for as long as on a standard battery. Inserting higher-capacity AA batteries there and using it instead of a standard battery is also not profitable due to micro resistances. All connections need to be wired with short (about 10-15mm) and thick wires. Well, that's a completely different story.

Increasing the radio communication range within a group in a given area.

If your area of ​​interest is around a static object (house, lodge, tent camp, etc.), then there you can install a stationary base antenna with good reception characteristics (for example Diamond X-50) and receive reception to a small portable station connected through an adapter. or install a station with a high transmitter power and a more sensitive receiver, which equals better reception of weak signals (for example, a car FT-2800 on “deuce” or FT-7800, FT-8800 on both bands), but in both cases use thick wires (7 -10mm) with a small attenuation coefficient for the range you select.

If there is such a “base”, but there is no person in it, everyone is scattered around the bush, and it is impossible to shout from one portable station to another due to the range or terrain. You can connect an Echo Repeater (Parrot), which is a small digital tape recorder, with an average recording time of 60 seconds, to the “base” station. connected instead of a push-to-talk switch to the station.

It works very simply, it records the voice received at the base station, when the reception is complete, it switches the station to transmit mode and plays your words on the air. This is heard by you yourself and the correspondent who is not available in direct radio visibility. He answers you and the cycle is repeated the required number of times. The cost of such devices is comparable to the cost of two simple ones or one good point-and-shoot camera.

Frequencies for broadcasting.

2 meters - 144-146 MHz

Here is a small illustration explaining the frequency distribution in the range 144-146 MHz.

Let's start with what frequencies you should NOT work at, say, while skiing or boarding. Do not operate on frequencies that are marked with a color other than green in the labels above. With your negotiations, you can interfere with other broadcast participants, and they, in turn, will interfere with you. Don't make each other uncomfortable.

Where you can, as you probably guessed, at those frequencies marked in green, but there are several caveats. Frequency 145.500 and two frequencies on the right and left are underlined, usually used by radio amateurs to conduct local communications with each other. Therefore, do not occupy these frequencies either. There remain 25 frequencies in the two-meter range, among which you will definitely be able to choose a free one. Be respectful and polite to everyone on air, and everyone will be polite to you.

This collection is prepared based on the author's experiences and frequently asked questions from the traveling public.

What radio stations can tourists use?
LPD And PMR radio stations do not require a permit; anyone can use them. Sold in electronics stores. Despite the “toy” appearance, the characteristics are at the modern level. The most popular companies producing these radios are ALAN/MIDLAND, MOTOROLA, ICOM.

Frequencies of license-free radio stations:
LPD: 433.075 - 434.775 MHz ( 69 channels),
PMR: 446.006 - 446.093MHz ( 8 channels).

Relative arrangement of frequencies on VHF:

CB (27MHz) radio stations also do not require registration! They are usually used by motorists because the choice of car radios of this type is very large. Portable 27 MHz stations with acceptable characteristics are produced only by the BERKUT design bureau. Car radios are produced by many companies and there is no point in listing them.

CB frequencies: 26.965 - 27.405 MHz (40 or 80 channels).
Detailed list of all CB frequency grids.

Relative arrangement of frequencies on HF:

Radio amateur(HAM) stations require not only permission, but also obtaining an amateur radio category and call sign. Amateur radio regulations do not allow talking about anything on the air. Negotiations are strictly regulated and limited mainly to experiments, competitions, and the completion of diplomas.

Amateur radio stations have similar characteristics to professional ones, but are more multifunctional and sophisticated. On the other hand, they do not shine with characteristics, they are often not strong, not economical and expensive. As a rule, they allow you to listen not only to amateur frequencies. Ranges: 144-146MHz, 430-440MHz, sometimes 1200MHz. The best amateur radio stations are produced by ICOM and YAESU.

If you are not a radio amateur, don’t bother with registering a call sign!

Professional radio stations require permission and registration! Usually issued to an organization. VHF range within 136-174 MHz or 400-470 MHz. They are distinguished by a robust body, splash resistance, many models are programmed from a PC, some do not have a display, etc. The most reliable radio stations are produced by ICOM, VERTEX, MOTOROLA, KENWOOD.

Which radio station to buy, LPD, PMR, CB, HAM (ham radio), professional?
If you are not a radio amateur with a call sign, then the best choice for you is LPD/PMR radios. LPDs have 69 channels and are compatible with amateur radio (HAM) radios in the 430-440 MHz range. PMRs have 8 channels and operate outside the amateur radio range (in some cases this is a plus), PMR stations are also more powerful, cheaper and are allowed in more countries around the world.

What is the real communication range of radio stations?
On LPD/PMR radio boxes the range is written in kilometers. Typically, the specified range can be obtained provided there is a clear line of sight and no obstacles. The practically measured communication range of any radio in the range 400-470 MHz, with a power of 0.5-2 W, with a sensitivity of 0.18 mKV and a half-shortened antenna, will be as follows:

What is LPD?
LPD - low power radio station (from the English Low power device). LPD radio stations operate in the ultra-short wave range - VHF (UHF), usually above 400 MHz, which allows you to achieve good quality and range of communication with low transmitter power (for more details, see Radio communication range). Devices with low radiated power, operating in a designated range, are designed to operate at a distance of up to 2-3 km, do not interfere with other radio equipment and minimize the harmful effects of radiation on the human body. The battery energy consumption of such devices is also lower. There are no disadvantages that are inherent in the CB range (atmospheric and industrial interference, unpredictability of propagation). Due to their characteristics and miniature design, LPD radios are gaining increasing popularity among non-professional users who do not need to achieve a communication range of more than 3 km.

What is the CTCSS code?
CTCSS - tone coding in a noise reduction system with a constant tone (Continuous Tone-Coded Squelch System. The tone coding function is necessary to divide correspondents (users) into groups working on the same radio channel. Only those correspondents who have the same CTCSS code (tone) can listen and transmit within “their” group. For those who are not configured for the required CTCSS code, these transmissions will be suppressed as unnecessary noise and nothing will be heard.
Tone squelch CTCSS (Continuous Tone-Coded Squelch System) is an access control method in radio communication systems based on the presence in the desired signal of audio tones of a certain frequency that lie outside the modulation frequency range (outside the audible range) at frequencies below 300 Hz.
During transmission, a subtone signal (below 300 Hz) of a certain frequency is sent (determined by the CTCSS code), which, upon reception, is instantly recognized by the CTCSS noise suppressor as “friend” or “foreign”. If the code is “own”, then the radio station turns on for reception and plays the message, if it is “foreign”, then it does not turn on and the correspondent does not hear anything.
The radio's receiver will only activate when the specified CTCSS tone it is programmed for appears.
CTCSS is a standard feature on most modern radio equipment. However, the number of stitched sub-tones in LPD radio stations is 38, in amateur radio stations 39.
In practice, this can be used like this (provided that the remaining radio channels are busy or unusable for some reason):
- if one group of people should do one type of work, the second another, etc., and they should not interfere with each other;
- some radios are configured to one CTCSS code, some to another, etc.;

- the boss can manage different groups by switching the code.
CTCSS is used to organize multiple independent and practically non-interfering groups of subscribers on the same frequency. Virtually no interference - because only one subscriber of any of the groups can transmit anything at any given time, and only subscribers of the group to which the transmitting subscriber belongs will receive his message.

Different manufacturers refer to CTCSS by different names. For example, Motorola designates CTCSS as PL (Private Line), GE`s / Ericsson as CG (Channel Guard), and Kenwood as QT (Quiet Talk).

As you know, in the Russian Federation there are several ranges that can be used by citizens for their own purposes. The most popular band, CB, is covered quite fully in the magazine, but the VHF bands were not particularly considered. The time has come to correct this shortcoming.

So, in Russia there are 3 bands that are available for use by citizens for their own personal purposes.

LPD band, 70cm, 433MHz with permitted power up to 0.01 W, it is allowed to use radio stations with built-in antennas.

PMR band, 70cm, 446MHz with permitted power up to 0.5 W, it is allowed to use radio stations with built-in antennas.

Terms of use

Everything is clear with CB, and the rules for using wearable and portable radio stations have been described more than once on the pages of the magazine. In short, transportable car CB radios with a power of up to 10 watts are not subject to registration. In this case, the antenna used must have a gain of less than 1.73dBi. Stations used permanently, with stationary antennas (bases), are subject to registration in the prescribed manner. Deviation from the above is, strictly speaking, illegal. But what about LPD and PMR?

If your portable radios operating in the LPD and PMR bands do not have the ability to operate at powers above those established by law, then you have nothing to worry about. You can use these ranges as ordinary citizens, and no one will say a word to you. Exceeding the established power limits transfers the station from the civilian category to the amateur category, and if you do not have the appropriate amateur radio category, at least the fourth, then the use of such a station becomes illegal and any authorized person can confiscate the radio station from you and impose a fine for radio hooliganism.

The organization Roskomnadzor monitors the observance of order on air. Her responsibilities include identifying radio stations that do not comply with the permitted power standards established by law. In practice, if you use walkie-talkies, albeit with increased power, not systematically, and do not interfere with anyone, then most likely no one will be interested in you and will not take the station away from you. In any case, when using the airwaves, respect other users, especially if they are using frequencies legally. This applies to all civilian bands.

In general, when choosing a range for communication, you should remember that:

1. There is always scattering of radio waves - the power of a wave from an unidirectional source weakens in proportion to the square of the distance (simply due to the fact that the energy is distributed over the area of ​​a sphere, the radius of which is equal to the distance to the source). That is, at some distance the antenna will not be able to catch more energy than is contained in the surrounding electromagnetic noise).
2. An obstacle to the propagation of radio waves is any object whose geometric size is more than half the wavelength. The opposite is also possible, when a shorter wave will pass through, for example, the reinforcement of a reinforced concrete building or a steel mesh with less loss than a wave whose length is significantly greater than the distance between the reinforcement or mesh cells.
3. There is attenuation of radio waves - the energy of the waves weakens in the propagation medium. For this, there are many tables and coefficients for different weather, different climates and other factors affecting attenuation in the atmosphere.
4. The Earth, to a first approximation, has the shape of a sphere (geoid) - waves propagate almost linearly. Therefore, effective propagation occurs mainly within direct radio visibility (due to refraction, it is slightly greater than optical visibility). The direct radio visibility distance depends on the height of the antennas and is calculated approximately as follows: R = 4.12* √ (h1² + h2²), where h1 and h2 are the heights of the transmitting and receiving antennas.
5. Ionospheric reflection and birefringence, re-reflection from the surface of the Earth and the ionosphere, curvature in the atmosphere, have little effect on VHF waves and are usually not taken into account. On the CB bands, long-distance transmissions, reflections of signals from the ionosphere and propagation over distances of more than a thousand kilometers are possible.
6. The higher the frequency, and accordingly the shorter the wavelength, the shorter the antenna used at this frequency. Each antenna has a gain (due to the ability to radiate and receive a large proportion of energy in the desired direction).
7. The higher the frequency, the less airborne noise is present on the range. On the CB band the airwaves are very dirty, heavily clogged with industrial interference and long-distance transmissions. On VHF, due to the lack of transmissions in the sense in which they are present on CB, the air is much cleaner, which has a positive effect on the range and quality of communication. However, in cities, LPD and PMR can also be heavily polluted by industrial noise.

LPD/PMR CB frequencies

LPD, 69 channels 433.075 - 434.775 MHz, step between channels 25 kHz.

PMR, 8 channels 446.00625 - 446.09375 MHz, step between channels 6.25 kHz.

CBS, 40 channels 26.965 - 27.405 MHz, step between channels 10 kHz

Radio communication range LPD/PMR and CB

On LPD/PMR radio boxes the range is written in kilometers. I can only say that usually this figure in real conditions can be divided by 2, 4, or even 8. The indicated range can be obtained under the condition of direct visibility and the absence of obstacles. The practically measured communication range of any radio in the range 400-470 MHz, with a power of 0.5-2 W, with a sensitivity of 0.18 mKV and a half-shortened antenna, will be as follows:

— in the city 0.3-0.6 km
— in the forest 0.4-1 km
— in the village 1-3 km
— in the field 2-5 km
— in the mountains 5-25 km (in direct visibility conditions)

Portable CB radio stations at 27 MHz: 1-10 km. (depending on interference, antenna and terrain)
These distances can differ by a factor of two, it all depends on the terrain and interference. If instead of a standard shortened antenna, you use a 1/4λ antenna, then the range will increase by 1.5-2 times. When using a directional antenna, the range will increase by 3-7 times. And if you increase the power by 2 times, then, all other things being equal, the range will increase by another 15-20 percent.

As for portable CB and VHF radio stations, this is a separate issue, since they have much greater power and, for example, LPD and PMR radio stations are moving from the civilian category to the amateur category. Since LPD/PMR stations are not available for cars, you can use a trick and adapt an ordinary portable device to work from the car. To do this, buy a car antenna for the 420 - 450 MHz range, install a connector (adapter) in the station and connect it to the antenna, this will increase the communication range by 2 - 3 times.

What to buy, LPD, PMR, CB?

If you are not a radio amateur with a call sign and the appropriate category, then the best choice for you is CB, LPD/PMR radio stations. LPDs are compatible with amateur radio stations in the 430-440 MHz range. PMRs operate outside the amateur radio range (in some cases this is a plus), and PMR stations are more powerful, cheaper and are allowed in more countries around the world.

Differences in the radio range of LPD and PMR radios

There are three indicators on which the communication range depends:

1. transmitter power
2. receiver sensitivity
3. antenna gain.

If LPD and PMR stations have these parameters approximately the same, the range will be the same. There will be no difference between them. The difference appears when changing any of the three parameters listed above. For example, PMR stations with a power of 500 mW will provide greater range than LPD stations with a power of 10 mW.

Call signs when using CB LPD or PMR

Since all three bands are civilian, users of such radio stations can come up with their own call signs or not use them at all. You can use your name as a call sign. For example: Masha, Vasya, Petya, digital call signs, etc. If there are many people in your group with the same names, use a name with a number (Vasya1, Vasya2, etc.) or nicknames.

Improvements for CB LPD/PMR radio station

Are they required? For cheap models, yes, they are desirable. Often you come across radio stations that are poorly tuned, which reduces communication range and intelligibility.

Tone and digital noise suppressor, or what are CTCSS and DCS

They are used mainly in professional communications, but they were also inherited by radio stations of civilian bands. These are special signals (subtones) that are transmitted along with the signal generated by the station. On radio stations working with each other, the code must be the same. This way, interference and other signals on the frequency are filtered out and do not interfere with the conversation. The conversations themselves are not encrypted.

CTCSS (Tone-Coded Squelch System) tone-coded squelch system (38-50 codes)

DCS (Digital-Coded Squelch) digital squelch code (83-104 codes)

Both encodings are designed to filter out interference from other radio stations or household noise. CTCSS is an analog system and therefore when a radio station with a neighboring tone appears next to you, you will also hear it. For example, you are using channel 4 with tone 22, if a radio station appears nearby on channel 4 with tone 21 or 23, you will hear it. There are no such overlays in DCS.

It must be said that such codes and subtones occur not only in VHF radio communications, which include LPD and PMR, but also on CB, where protection against long-distance transmissions is currently quite important. However, there is very little equipment capable of supporting such an anti-interference system.