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What Is A Transmitter And Its Type ?

Date:2020/10/10 17:09:27 Hits:






Many people don’t know what an FM transmitter is, how it works, and what type of function it does. Next, I will give you a thorough understanding of the following four points.


                                                                                                                                               --FMUSER




Key Content:



  1. What is FM transmitter?
  2. What is FM transmitter (personal device)?
  3. Regulation Of Fm Transmitters
  4. Types of FM transmitte





What is FM transmitter?

In electronics and telecommunications a transmitter or radio transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the antenna radiates radio waves.

Transmitters are necessary component parts of all electronic devices that communicate by radio, such as radio and television broadcasting stations, cell phones, walkie-talkies, wireless computer networks, Bluetooth enabled devices, garage door openers, two-way radios in aircraft, ships, spacecraft, radar sets and navigational beacons. The term transmitter is usually limited to equipment that generates radio waves for communication purposes; or radiolocation, such as radar and navigational transmitters. Generators of radio waves for heating or industrial purposes, such as microwave ovens or diathermy equipment, are not usually called transmitters, even though they often have similar circuits.

The term is popularly used more specifically to refer to a broadcast transmitter, a transmitter used in broadcasting, as in FM radio transmitter or television transmitter. This usage typically includes both the transmitter proper, the antenna, and often the building it is housed in.


A transmitter can be a separate piece of electronic equipment, or an electrical circuit within another electronic device. A transmitter and a receiver combined in one unit is called a transceiver. The term transmitter is often abbreviated "XMTR" or "TX" in technical documents. The purpose of most transmitters is radio communication of information over a distance. The information is provided to the transmitter in the form of an electronic signal, such as an audio (sound) signal from a microphone, a video (TV) signal from a video camera, or in wireless networking devices, a digital signal from a computer. The transmitter combines the information signal to be carried with the radio frequency signal which generates the radio waves, which is called the carrier signal. This process is called modulation. The information can be added to the carrier in several different ways, in different types of transmitters. In an amplitude modulation (AM) transmitter, the information is added to the radio signal by varying its amplitude. In a frequency modulation (FM) transmitter, it is added by varying the radio signal's frequency slightly. Many other types of modulation are also used.


The radio signal from the transmitter is applied to the antenna, which radiates the energy as radio waves. The antenna may be enclosed inside the case or attached to the outside of the transmitter, as in portable devices such as cell phones, walkie-talkies, and garage door openers. In more powerful transmitters, the antenna may be located on top of a building or on a separate tower, and connected to the transmitter by a feed line, that is a transmission line.


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What is FM transmitter (personal device)?

A personal FM transmitter is a low-power FM radio transmitter that broadcasts a signal from a portable audio device (such as an MP3 player) to a standard FM radio. Most of these transmitters plug into the device's headphone jack and then broadcast the signal over an FM broadcast band frequency, so that it can be picked up by any nearby radio. This allows portable audio devices to make use of the louder or better sound quality of a home audio system or car stereo without requiring a wired connection. They are often used in cars but may also be in fixed locations such as broadcasting from a computer sound card throughout a building.


Being low-powered, most transmitters typically have a short range of 100–300 feet (30–100 metres), depending on the quality of the receiver, obstructions and elevation. Typically they broadcast on any FM frequency from 87.5 to 108.0 MHz in most of the world, 76.0 - 95.0 MHz for Japan, 65.0 - 74.2 MHz for Russia, and 88.1 to 107.9 MHz in the US and Canada.


Personal FM transmitters are commonly used as a workaround for playing portable audio devices on car radios that don't have an Auxiliary "AUX" input jack or Bluetooth audio connectivity. They are also used to broadcast a stationary audio source, like a computer or a television, around a home. They can also be used for low-power broadcasting and pirate radio but only to a very limited audience in near proximity. They can also be used as a "talking sign" in real estate sales or similar


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Regulation Of Fm Transmitters

Two radio transmitters in the same area that attempt to transmit on the same frequency will interfere with each other, causing garbled reception, so neither transmission may be received clearly. Interference with radio transmissions can not only have a large economic cost, it can be life-threatening (for example, in the case of interference with emergency communications or air traffic control).

For this reason, in most countries, use of transmitters is strictly controlled by law. Transmitters must be licensed by governments, under a variety of license classes depending on use such as broadcast, marine radio, Airband, Amateur and are restricted to certain frequencies and power levels. A body called the International Telecommunications Union (ITU) allocates the frequency bands in the radio spectrum to various classes of users. In some classes, each transmitter is given a unique call sign consisting of a string of letters and numbers which must be used as an identifier in transmissions. The operator of the transmitter usually must hold a government license, such as a general radiotelephone operator license, which is obtained by passing a test demonstrating adequate technical and legal knowledge of safe radio operation.

Exceptions to the above regulations allow the unlicensed use of low-power short-range transmitters in consumer products such as cell phones, cordless telephones, wireless microphones, walkie-talkies, Wi-Fi and Bluetooth devices, garage door openers, and baby monitors. In the US, these fall under Part 15 of the Federal Communications Commission (FCC) regulations. Although they can be operated without a license, these devices still generally must be type-approved before sale.


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Types of FM transmitte

    --LPFM And High power fm transmitter


A normal FM station transmits at thousands of watts. This level of power means that the station needs lots of expensive transmitting equipment, as well as a fairly substantial antenna. It might cost in the range of a million dollars to get a basic FM station on the air at this level of power, and it can cover an entire urban area.
That level of investment has several side effects. First, only a business entity or an extremely wealthy individual can afford to create an FM station, and the station must, of necessity, be driven by business logic in order to cover the high operating costs. This limits creativity and makes it difficult for small organizations or individuals to get air time.

The LPFM station is designed to let individuals and small organizations own and operate radio stations for a wide variety of not-for-profit reasons. An LPFM station is a 10-watt or 100-watt transmitter. This level of power gives the station a range of approximately 3.5 miles (5.6 km). A transmitter this size and its antenna might cost $2,000 to $5,000. In a city, the range of an LPFM transmitter can encompass lots of people, and it can completely cover an entire neighborhood or community area. The owner/operators of low-power FM radio stations could include, among others:

● Religious groups
● Local neighborhoods
● Amusement parks
● PTA-sponsored school stations for parents picking up or dropping off children
● Ethnic organizations wanting to create foreign language programming
● Race track pit and parking areas, as an extension to a public address system
● Universities too new or previously unable to get a full-power license
● Movie-theater schedule information
● Interstate highway rest stops
● High schools

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