Getting in touch
A hunter got lost in the forest. He walks through the woods, calling for his comrades and shouting at the top of his lungs:
- Hellooooo!
A bear comes out to meet him and asks:
- Why are you shouting?
- Well, I got lost and thought maybe someone would hear me.
- Well, I heard you, do you feel better now?
Joking aside, there is always some truth in every joke. Reliable communication on a hunt, fishing trip, hiking expedition, or scientific fieldwork is just as important as having a compass and a map. This is especially crucial when you are in unfamiliar terrain. One recalls a case told by a gamekeeper. A hunter strayed from the main group during a drive hunt and got lost. He was well-equipped, so it seemed there was nothing to worry about. However, the scale of his map did not allow him to orient himself, and his compass turned out to be useless since he had not taken any landmarks from the beginning, apparently relying on chance. It was a cloudy winter day, the snow had melted during a thaw, and without snow, there were no tracks. His only hope was luck and the radio station provided by the organizer. However, he had wandered so far off that it took over an hour before the radio speaker finally hissed. Only then was the gamekeeper, who knew the area well, able to guide the lost hunter back to the group. The hunt, of course, was ruined, but at least the man was safe. Another example is equally telling. This time no one got lost, but the hunt was spoiled by “poor” radios that unexpectedly picked up voices from distant countries and police communications. But the radios were not at fault — the hunters had simply chosen the wrong band. And in the first case as well, if the radios had been more powerful, perhaps a whole day would not have been wasted searching for the missing client. Thus, the purpose of this article is to help hunters, fishermen, tourists, and extreme sports enthusiasts make an objective choice of radio communication equipment, which is as important as choosing the right ammunition, fishing lures, or climbing ropes.
Among the vast variety of radios on today’s market, everyone must select the one that best suits their specific tasks.
But before describing the types of radios, let us provide a brief introduction to the theory of radio wave propagation, which will help the uninitiated reader understand why some radios work farther than others, even when they have approximately the same technical characteristics.
At present, in Russia, the State Commission on Radio Frequencies (SCRF) has allocated the following main frequency bands for land and mobile radio communications:
27 MHz — Citizens Band (CB)
136–174 MHz — VHF band (Very High Frequency)
400–470 MHz — UHF band (Ultra High Frequency)
To determine which band is most suitable for communication in forests, on water, or in the mountains, let us examine the theory of radio wave propagation in these bands.
27 MHz band. Corresponds to a wavelength of 11 m. Radio waves in this band are strongly absorbed by the soil, and communication depends on solar activity. They can overcome obstacles such as small hills, slopes, and buildings up to 10–15 m high. As a rule, short-range communication in this band is carried out by ground waves (propagating along the earth’s surface). When propagating by skywave (reflected from the ionosphere), communication is possible over many thousands of kilometers. In practice, this means the airwaves are filled with signals from radios thousands of kilometers away, but you may not hear your neighbor just a kilometer away. There have been cases where someone said “one” and heard an echo of their own voice coming from the speaker. The radio wave circled the globe due to multiple reflections from the ionosphere and returned to its starting point!
136–174 MHz band. Corresponds to a wavelength of 2 m. In this band, radio waves propagate via direct and reflected waves. Since the earth’s surface is spherical rather than flat, the communication range is several tens of kilometers. If the antennas of the radios are located at heights of several tens of meters above ground, communication can be established up to 100 km away. Terrain and obstacles significantly affect radio wave propagation in this band. For example, a deciduous forest introduces attenuation of about 6 dB per 100 m. At different reception points, the signal level may vary from strong and clear reception to complete loss of communication. This is due to the fact that surface and reflected waves arrive in phase or out of phase, thereby adding or canceling each other out, which ultimately affects the received signal strength. Atmospheric noise and time of day have little effect on propagation in the VHF band, so communication is stable at any time. In buildings and reinforced concrete structures, VHF band radio waves propagate poorly.
400–470 MHz band. Corresponds to a wavelength of 70 cm. With increasing frequency, the influence of weather conditions increases and the communication range decreases, as propagation conditions in this band approach those of light. UHF radio waves propagate well in cities due to reflections from buildings and reinforced concrete structures. In forests, however, radio waves in the 400 MHz band propagate worse than VHF. For example, a deciduous forest introduces attenuation of about 10 dB per 100 m. At the same time, radio waves in this band work well in mountains, especially in gorges and ravines. Short-range communication in this band is stable and independent of the time of day.
From the above properties of radio wave bands, it follows that for forested and rough terrain, 27 MHz and 136–174 MHz radios are preferable, while for cities and mountains, 400–470 MHz radios are more suitable.
Now let us consider the types of radios available on the Russian market. All radios can be divided into three main groups:
portable radios
mobile radios
base radios
Portable radios. A radio is an electronic device consisting of a transceiver, antenna, and power source (battery or battery case). Sometimes radios are also called transceivers, meaning that some circuits are shared for both reception and transmission to save space and reduce cost. By their consumer qualities, radios are divided into several types.
Professional radios generally comply with the international military standard MIL STD 810 C, D, E. This means the chassis is a solid cast case, while the upper and lower panels are made of impact-resistant plastic. All rubber seals covering transmission and control buttons fit tightly to the radio body, preventing water and dust ingress. In short, these are radios resistant to splashes, dirt, dust, vibration, heat, and frost. If present, the LCD display is positioned to avoid damage during falls. Professional radios have a minimum number of keys and controls — usually a channel selector, volume control, and 2–3 programmable buttons. Today, almost all professional radios are computer-programmable, using special interface cables and software provided by manufacturers. The auxiliary keys can be programmed to switch power levels, backlight, scrambler on/off, and so on. Nearly all professional radios operate in simplex (reception and transmission on the same frequency) and semi-duplex (different frequencies for reception and transmission). The latter mode is used for repeater operation. Mid-range professional radios usually have 16–32 programmable channels. Their squelch is electronic, with thresholds programmable by computer. Many professional radios feature selective calling, which is useful when multiple groups operate on the same frequency. Each group has its own programmed analog sub-tone (CTCSS) or digital code (DCS), enabling intra-group communication without interference from other groups. Typically, professional radios are single-band, with versions for 136–174 MHz and 420–470 MHz. Within UHF, there are sub-bands such as 400–430 MHz and 450–490 MHz.
Amateur radios differ from professional ones by having continuously tunable frequency scales rather than fixed programmable channels. They usually have keypads for entering operating frequencies in the 136–174 MHz and 420–470 MHz ranges. Unlike professional models, they are fully programmable from the keypad without external software. They also have memory channels — far more than professional models. Professional radios usually display only the channel number on the LCD or selector, while amateur radios show the operating frequency as well. They also offer far more functions, such as adjusting tuning step, sub-tone frequency, transmit power, offset between reception and transmission, and more. Amateur radios include advanced menu systems, while only the most-used functions are assigned to the keypad. They are highly versatile and often include an S-meter to measure signal strength.
There are also dual-band amateur radios operating at 136–174 MHz and 420–470 MHz. They are highly versatile, usable in forests, cities, or mountains. Some models include built-in scanners with wide frequency coverage (500 kHz to 1000 MHz). Some even feature additional modules for measuring air temperature, atmospheric pressure, and altitude. Many amateur radios now have housings that comply with MIL STD 810 C, D, E.
The Japanese company VERTEX STANDARD has gone even further, producing waterproof VX-6R and VX-7R radios, which can be submerged to a depth of 1 meter for 30 minutes.
Car radios are generally installed in vehicles such as cars or snowmobiles. Unlike portable radios, they have an output power of 30–70 W and are powered by the vehicle’s onboard battery. Typically, these radios include external microphones with push-to-talk buttons. Mobile radios are also divided into professional and amateur models. Professional ones comply with MIL STD 810 C, D, E and are built on cast aluminum chassis enclosed in impact-resistant plastic. Functionally, mobile radios are similar to portable ones and are also programmed via computer. Amateur mobile radios are produced in both standard and rugged housings. They have tunable frequency scales and allow frequency entry via the keypad on the external microphone. Both professional and amateur mobile radios are produced in 136–174 MHz and 420–470 MHz bands. Professional UHF radios may be produced for specific sub-bands such as 400–430 MHz or 450–490 MHz. Professional mobile radios are single-band, while amateur ones may be dual-band or even duplex, with built-in cross-band repeaters. These have many functions accessible via keypad or front panel buttons. Unlike professional models, they are not designed for continuous duty and typically have a 50% duty cycle. Professional radios, by design, support 24/7 operation with 100% duty cycle. Mobile radios connect to external vehicle antennas with various mounts, tuned to the operating frequency.
Base radios are usually the same mobile units but connected to a base antenna via a coaxial cable with a wave impedance of 50 Ohms. Power is supplied from an external stabilized power source at 13.8 V and up to 15 A.
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