What is VHF propagation?

The primary mode of propagation for VHF radio waves is through direct waves. These travel in a straight line, becoming weaker as distance increases. Transmitting and receiving antennas must be able to ‘see’ each other for communications to be effective, so antenna height is critical in determining range.

What is VHF used for?

VHF- Very High Frequency

Very high frequency is commonly used for FM radio broadcast, two-way land mobile radio systems, long-range data communication, and marine communications, just to name a few. VHF includes radio waves from 30 MHz to 300 MHz.

What affects VHF propagation?

Radio propagation at VHF is mainly controlled by physical objects, such as terrain and ground cover (clutter), and tropospheric factors, principally refraction. … Such propagation events may be significant in causing interference at VHF, particularly for systems requiring high reliability.

Is VHF the same as FM?

FM and VHF are not the same thing.. literally. However FM radio is generally broadcast on VHF, but then again so is DAB…

Are police radios UHF or VHF?

Police radios operate in a 700/800 MHz UHF band. This gives them a considerable amount of range which is pretty good in urban areas.

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How do you talk in VHF?

How do I operate it?

  1. Make sure you are on the correct channel.
  2. Adjust “Squelch” control as low as possible without hearing static or “white noise”.
  3. Push the button on the microphone to transmit (send).
  4. Speak in a normal voice.
  5. Take your finger OFF the button to hear the other person.

How far can VHF transmit?

A typical VHF station operates at about 100,000 watts and has a coverage radius range of about 60 miles. A UHF station with a 60-mile coverage radius requires transmitting at 3,000,000 watts.

Do I need a Licence for VHF radio?

Anyone who uses a Marine VHF Radio needs a licence. … If you need a radio, you may need both a radio licence and an operator’s licence. This depends on the type of radio you have and how you use it. Once installed in a vessel, a marine VHF radio requires a ship’s radio licence.

What VHF channel should I use?

Federal Communications Commission regulations require boaters having VHF radios to maintain a watch on either channel 9 or channel 16, whenever the radio is turned on and not communicating with another station. All non-emergency traffic should be communicated on another channel (not channels 9 or 16).

Is VHF affected by weather?

In line-of-sight communication airborne elements such as rain, fog and snow can all affect communication quality. Of these weather conditions, rain has the greatest effect on VHF data transmission.

What affects radio propagation?

As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. … Line-of-sight propagation means radio waves which travel in a straight line from the transmitting antenna to the receiving antenna.

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Do radio waves decay in space?

Some radiowaves, such as those of a short-wave frequency, bounce back off the ionosphere and are therefore poor candidates to be picked up in space. But waves like FM radio or television signals can pierce it and travel through the vacuum of space at the speed of light. … “As you go into space that power would dissipate.

Can VHF talk to UHF?

VHF and UHF Walkie Talkies can’t talk to each other. The terms UHF and VHF refer to the “wavelength”. … That said, if a VHF wave and a UHF wave are transmitted over an area without obstructions, then the VHF wave would travel around twice as far. Since the VHF frequency waves are bigger, then the antenna must be bigger.

How far will a 25 Watt VHF radio transmit?

For example, a 25-watt marine radio will roughly have a maximum range of 60 nautical miles (111 km) between antennas mounted on tall ships, but that same radio will only have a range of 5 nautical miles (9 km) between antennas mounted on small boats at sea level.

How many VHF channels are there?

The most important channels on your VHF radio are 13, 16, 19, 22, and 70. Channel 13 is used by commercial shipping to communicate their actions and confirm passage. Channel 16 (156.8 MHz) VHF-FM is designated by the FCC (Federal Communications Commission) as the national distress, safety and calling frequency.

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