VHF radios operate at very high frequencies, particularly those between 150 and 170 megahertz (MHz). They are used in a variety of applications, including FM, airline and amateur radio broadcasting, but are perhaps most well known for their marine applications. All large watercraft, and a vast majority of smaller vessels, are equipped with marine VHF radios, which can be used for relaying weather information and coordinates, as well as for making (and receiving) distress calls.
Obstructions
One of the main benefits of using VHF radios is that their high-frequency waves are capable of traveling, with relative ease, through obstructions. According to dfa-inc.com, they are able to pass through buildings and trees, and can also adapt to the earth's terrain, by dipping into small depressions or arching over hills.
Range
According to codan.com.au, VHF radios cannot transmit/receive at a distance greater than 3,000 km, which is approximately 1,864 miles (most VHF radios have shorter ranges, but 3,000 km is the max). For this reason, VHF radios can only be used for local transmissions, such as within a specific coastal/ocean area for boats, or a specific broadcasting area for radio stations. However, according to dfa-inc.com, VHF radios can be used over long distances if there is a series of relay towers or repeaters present, which can help carry signals along.
Noise
Another problem with VHF radios is that they are very susceptible to interference or "noise," which in this application refers to radiant energy. This energy can interfere with and even block VHF signals. According to fcc.gov, the most common causes of VHF noise are industrial equipment, power lines and home appliances, such as microwaves, vacuum cleaners and dimmers.
Transmission Power
One of the upsides to using VHF radios is that they require very little amounts of energy when it comes to operating them. According to dfa-inc.com, the vast majority of VHF radios require only between 2 and 5 watts of power.
Low Baud Rate
Baud rate refers to the number of symbols, or amount of data, that can be transferred per second by a system. According to dfa-inc.com, because VHF radios operate on a narrow bandwidth, or range of frequencies, they have low baud rates. This means that they are slower at sending and receiving information in comparison to other systems, such as UHF, or ultra high frequency radios.
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