Range of communication: where in advertising kilometers and how much you will get
Where does the number in advertising come from?
The declared range is measured under ideal conditions: open terrain, both antennas raised, no interference.
Sometimes it's a calculation, not a measurement, and then the number is closer to the limit of physics than to your backyard.
The real range in the city is usually less than the declared several times, and this is not a fraud, but the difference in conditions.
Comparing models on this figure is pointless: everyone has it in their own way.
Meaning only emerges when you measure yourself on your route.
Direct visibility and what breaks it
Communication in these ranges is almost in a straight line, so the main limiter is the curvature of the earth and the terrain.
From ground level, the horizon lies about five kilometers away, and everything further away is beyond the fold of the terrain.
The hill between correspondents cuts the connection more reliably than ten kilometers of open water.
Urban development works differently: the signal comes in reflexes, and the range drops, but does not stop abruptly.
Inside buildings, it is not the distance that decides, but the number of walls and overlaps between the interlocutors.
Power solves less than it seems
Doubling the power adds to the range of one percent, not doubles it.
The reason is that the signal weakens with distance much faster than it grows with watts.
Extra watts heat the device, plant the battery faster and interfere with neighboring users of the channel.
Handheld stations of five watts and four watts are indistinguishable in practice.
Therefore, the power is selected according to the rules and by battery, and the range is produced by other means.
Antenna and suspension height
A good antenna in a weak station works better than a bad antenna in a powerful one.
The regular short pin is convenient, but loses to the full-size by all indicators.
Raising the antenna a few meters pushes the horizon more noticeably than any power gain.
The antenna needs a counterweight: on a metal roof of a car, it works quite differently than on plastic.
The cable also eats the signal, and ten meters of cheap cable can nullify the gain from a good antenna.
How to measure the range in an hour
Take two stations, charged batteries and the usual route, which really drive or walk.
One stays in place, the second leaves and every few hundred meters comes into contact.
Points where the connection is lost are marked on the map, not remembered.
The check is repeated in the opposite direction: reception and transmission are not always symmetrical.
The resulting map is more useful than any characteristics from the description and lives for years.
If the range is short
The first way is to raise the antenna: the mast, the roof, the removal of lighting to the mast.
The second is to put a stationary station with an external antenna where the dispatcher is located.
The third is repeater: it receives on one frequency and immediately repeats on the other, covering both sides of the hill.
The repeater requires a separate pair of frequencies and resolution, so it is laid in advance.
If neither method works, it is more honest to switch to another kind of communication than to chase watts.
