What is VHF MF HF?

Digital selective calling or DSC is a standard for transmitting predefined digital messages via the medium-frequency (MF), high-frequency (HF) and very-high-frequency (VHF) maritime radio systems. It is a core part of the Global Maritime Distress Safety System (GMDSS).

What is the range of VHF MF HF?

MF/HF Radiotelephone

Your VHF radio is intended mainly for short range communications, generally 5-10 miles, and at least 20 miles to a USCG station. To communicate at longer ranges, you will normally need a satellite telephone or an MF/HF marine radiotelephone.

What is HF and MF?

The MF band is also known as the hectometer band as the wavelengths range from ten to one hectometers (1000 to 100 m). Frequencies immediately below MF are denoted low frequency (LF), while the first band of higher frequencies is known as high frequency (HF).

What does HF VHF stand for?

Once you've got a grasp of how High Frequency (HF) and Very High Frequency/Ultra High Frequency (VHF/UHF) radio waves carry information from A to B, you can optimise your radio network for more dependable communications.

Which is better HF or VHF?

HF communications are best suited for long distance communication between ground operators and base stations. The field benefits of VHF over HF radio is in their relative immunity to space weather conditions or electrical interference.

Radio Fundamentals: An Introduction to HF | Codan Radio Communications

Which is better HF or VHF marine radio?

If you are venturing far off the coast then a HF Radio is a good investment as it offers a far superior range than a VHF radio and it also offers more security than a Satellite phone. You can only call one person on a Satellite phone where as you can reach many people in one call with a HF radio.

How far can MF transmit?

MF/HF Radio Waves

A reliable range of more than 150 nautical miles can be expected in most areas in the daytime, more in the nighttime. The high frequency range 4 – 30 MHz can provide communication for hundreds or even thousands of nautical miles. The long range is achieved by sky waves reflected from the ionosphere.

What HF frequency is best?

HF users have found that using a frequency that is the MUF times 0.85 gives the best chance for good results. This is called the frequency of optimum transmission (FOT). Usually the FOT is a good choice for HF communications, but not always.

Do ships still use HF radio?

When the distances involved get out beyond 30 NM's or so (depending on antenna heights,) the VHF marine radio is no longer adequate to provide either normal or emergency communications. In order to maintain this communications lifeline will now require the use of MF/HF radio or a satellite communications system.

How far offshore does a VHF radio work?

If you are planning an offshore voyage, you need to know VHF radios and cellular telephones are limited in range, usually no more than 15 to 25 miles from shore.

How do I choose a marine VHF antenna?

Marine VHF Antenna Height and Strength

A 3- to 4-foot antenna that's 3 dB is generally recommended for boats under 24 feet. Larger vessels can opt for 12- to 18-foot, 7 to 8 dB antennas. “As a general rule, antenna height should be less than half the length of the boat,” Catoe says.

Who uses HF frequencies?

These frequencies are used by amateur (ham) radio operators and many industries such as commercial airlines. They are also used by a number of government agencies such as the Federal Emergency Management Agency and the Department of Defense.

What frequencies does the military use?

The primary HFGCS voice frequencies are 4724.0 kHz, 8992.0 kHz, 11175.0 kHz, and 15016.0 kHz. In addition to the HFGCS, U.S. aircraft frequently use Military Auxiliary Radio System (MARS) HF stations (13927.0 kHz) and Canadian Forces HF stations (11232.0 kHz) to relay messages.

What is the best sound frequency for human?

Humans can detect sounds in a frequency range from about 20 Hz to 20 kHz. (Human infants can actually hear frequencies slightly higher than 20 kHz, but lose some high-frequency sensitivity as they mature; the upper limit in average adults is often closer to 15–17 kHz.)

How long does it take for MF trades to settle?

The two-day settlement date applies to most security transactions, including stocks, bonds, municipal securities, mutual funds traded through a brokerage firm, and limited partnerships that trade on an exchange. Government securities and stock options settle on the next business day following the trade.

How far can a 100 watt radio transmit?

If an ERP of 100 Watt is used, it is very likely that 20 kilometers of range will be reached because a 100 Watt ERP is able to propagate a strong signal as far as 20 kilometers.

Can I transfer MF units to another person?

The only time mutual fund units can be transferred to another person is if the unitholder passes away. This is frequently in the name of a joint holder or a legal nominee to whom a mutual fund unit is transferred.

What are the disadvantages of HF radio?

The primary drawback to HF use is that it is highly susceptible to changes in the ionosphere and therefore several frequencies must be available for use.

Why is HF radio less reliable at night?

Because HF uses the ionosphere, it is affected by the sun. The time of day affects the transmission and reception of HF radio waves. Typically, lower-level HF waves work best at night, while higher-level HF waves work best during the day.

What is the most powerful HF transmitter?

HAARP utilises is the world's most capable high-power, frequency agile HF transmitter for study of the ionosphere, with a power output of 3.6 Gigawatts.

Do I really need a marine radio?

Although not required in recreational boats under 65.5 feet long, a Very High Frequency (VHF) Marine Radio allows instant communication between your boat and other boats, marinas, bridges, and the United States Coast Guard (USCG).

Is a longer antenna better VHF?

Other factors you should consider include the length of the antenna: longer antennas perform better than shorter ones. Additionally, transmitter power directly impacts your signal: the more power, the farther your signal can reach. Consumer VHF equipment has a maximum transmitter power of 25 watts.

What radio does the USMC use?

AN/PRC-117G Falcon III MNMR (Multiband Networking Manpack Radio), also referred to as AN/PRC-117G-MP, covering the 30-2000 MHz frequency range, and provided with internal SAASM GPS (optionally an external commercial GPS can be connected).

Does the military use HF radio?

Markets. HF Radio is an important element of military communication, providing support in Denied Degraded Communications and Control Environments (D2C2E) and is the only practical alternative to SatCom for Beyond Line of Sight (BLOS) communications.