Minggu, 18 Oktober 2009

PEMANCAR FM STEREO


SPECIFICATION
Freq Range : 50KHz steps from 70.00 to 140.00MHz
Freq Generation : Cystal ref. Phase Locked Loop
Freq Stability : +/- 1 KHz max typ +/- 500Hz
Lock Time : 3 sec
Spurious Emission- : Better than -45dB rel to carrier
RF Power Output : 900mW min
RF Output Connector: SO239
Power Supply : 13.8 DC regulated
Audio Input Sensitivity : 0.775 V rms for +/- 75 KHz dev
Signal To Noise Ratio : 75dBu
Audio Freq Respone : Flat from 20Hz to 76KHz
Pre-Emphasis : None or 50uS or 75uS
Audio Distortion : Better than 0.2 % THD
Audio Input Connector : Phono socket



Radio is a technology that is used for signal transmission and modulation by electromagnetic radiation (electromagnetic waves). These waves propagate across and through the air and can also travel through space vacuum, because these waves do not require the carrier medium (such as air molecules). Radio waves are a form of electromagnetic radiation, and is formed when electrically charged objects is modulated (increased frequency) at frequencies in the radio frequency (RF) in an electromagnetic spectrum. These radio waves at a frequency range of 10 hertz (Hz) to several gigahertz (GHz), and electromagnetic radiation move by electric and magnetic oscillations. Other electromagnetic waves, which have frequencies above the radio waves include gamma rays, X-rays, infrared, ultraviolet, and visible light. When the radio waves transmitted through the cable, the oscillation of electric and magnetic fields are expressed in the form of alternating current and voltage in the wire. This can then be converted into another audio signal or that carry information. Although the word 'radio' is used for things related to the sound wave receiver, but the wave transmission is used as the basis of the waves on television, radio, radar, and mobile phones in general.
In the early use of radio as a broadcast media to use low-frequency band (Low Band) is about 500 Khz is now often referred to as the Medium Wave (MW) in the so-called amplitude modulation Modulation (AM). Band (band) frequencies is still used by the broadcast media today. Besides being used in the frequency band below 1 MHz, frequencies above 1 MHz is also used as the broadcast media. The band is more known as Short Wave (SW) because using the short wave. Range can reach thousands of kilometers, because the nature of the waves at frequencies reflected from ionosphere layer. MW band was on, the gap coverage will only reach hundreds of kilometers.

The next technological developments lead to the use of frequencies above 50 MHz for various purposes, including for broadcasting. Allocations are set internationally for the use of broadcast media is 87 MHz - 108 MHz. At the modulation frequency used is Frequency Modulation (FM). One of the benefits of using the FM modulator is clean because his voice bandwidth (the bandwidth) is used at least 100 Khz. With a wide bandwidth, then the sound becomes clearer. In contrast to the modulation AM, the sound is not as good as FM modulation. FM is often used in VHF radio frequencies for broadcasting and conversation music high (see FM broadcasting). The sound of a normal TV (analog) is also broadcast using FM. One form of narrow lines used for voice communications in a commercial setting and amatur radio. Type of FM used to broadcast in held "extensive FM" (wide-FM), or W-FM. For two pages of the radio, "FM narrow" (narrow-FM, N-FM) narrow track width is used to track. Moreover, the narrow FM is used to deliver signals into space.
stereo, is the reproduction of sound, using more than one independent audio channels, through a loudspeaker configuration arrangement symmetrical, by causing an impression of a soft voice and naturally from various directions as if the natural hearing. Stereo sound has monoponik opponent, where the sound is in the form of a channel, usually located in the middle of the sound field. In the transmission line that does not match but the waves came flowing waves also bounce. Waves coming at him from the source to the load (from the transmitter to the antenna) while the waves reflected from the opposite direction (from the antenna to the transmitter). To measure the power of these waves is needed Power Meter. Usually on the Power Meter has two scales, one for power and another came to power bounce, bounce-scale for power is smaller than the scale of the power comes. Meter SWR (Standing Wave Ratio Meter - meter tall wave ratio) is used to measure the ratio of the wave coming and reflected waves. In other words SWR meter is used to measure how match a source with the load. Working principle is based Power Meter SWR Meter.

Wireless FM Transmitter is a device to transmit sound (audio output) of the device, such as MP3 players, VCD, computer etc to be heard through FM radio waves, so the sound can be captured in FM radio and a song can be heard with the car speakers. Songs from the computer can be heard on FM radio. Frequency can be selected (there are 4-channel option). Easy to use way.
Power Source can use 2 AAA battere fruit or through the cigarette lighter in the car. (all are included in the package).

radio inventor
Basic theory of electromagnetic wave propagation was first described in 1873 by James Clerk Maxwell in his paper at the Royal Society about the dynamics of electromagnetic field theory (the English language: A dynamical theory of the electromagnetic field), based on the results of research work between 1861 and 1865. In 1878 David E. Hughes was the first person to send and receive radio waves when he found that the induction balance caused disruption to phone product. He demonstrated his discovery to the Royal Society in 1880 but only say it was just an induction. Was Heinrich Rudolf Hertz who, between 1886 and 1888, the first time to prove Maxwell's theory through experiment, demonstrating that radio radiation had all the wave properties (now called Hertzian waves), and found that the electromagnetic equations can be formulated into the equation of partial derivatives is called the wave equation. Many of the early use of the maritime radio, for sending telegraphic messages using Morse code between ships and land. One of the early users included the Japanese Navy spy on the Russian fleet at Tsushima in 1901 War. One of the most memorable use is at the time of the sinking of the RMS Titanic in 1912, including communications

radio inventor
Basic theory of electromagnetic wave propagation was first described in 1873 by James Clerk Maxwell in his paper at the Royal Society about the dynamics of electromagnetic field theory (the English language: A dynamical theory of the electromagnetic field), based on the results of research work between 1861 and 1865. In 1878 David E. Hughes was the first person to send and receive radio waves when he found that the induction balance caused disruption to phone product. He demonstrated his discovery to the Royal Society in 1880 but only say it was just an induction. Was Heinrich Rudolf Hertz who, between 1886 and 1888, the first time to prove Maxwell's theory through experiment, demonstrating that radio radiation had all the wave properties (now called Hertzian waves), and found that the electromagnetic equations can be formulated into the equation of partial derivatives is called the wave equation. Many of the early use of the maritime radio, for sending telegraphic messages using Morse code between ships and land. One of the early users included the Japanese Navy spy on the Russian fleet at Tsushima in 1901 War. One of the most memorable use is at the time of the sinking of the RMS Titanic in 1912, including communications

between operators in a sinking ship and nearby ships, and communication to ground stations that saved register. Radio used to channel commands and communications between the Army and Navy on both sides in World War II; Germany using radio communications for diplomatic messages as underwater cable cut by the British. United States convey Main Fourteen President Woodrow Wilson to Germany via radio during the war. Press start can be made in the 1920s, with the popularity of radio, especially in Europe and the United States. In addition to broadcasting, broadcast point-to-point, including the phone and re-broadcast radio program, became popular in the 1920s and 1930s. The use of radio in the prewar years was the development of detecting and determining the location of aircraft and ships with the use of radar]. Today, the radio many forms, including wireless networks, mobile communications in all types, as well as radio broadcasting.

There are several things you can do to regulate the use of frequencies, among others by doing a restriction against:
  1. Transmit power. A transmitter can be limited radiance power. Transmit power is referred to the ERP (Effective Radiated Power). A transmitter with a transmit power at the frequency of X Y, then theoretically would be acceptable in one place at a distance Z A kilometer from reception at the receiver (receiver) B; to be received is for C dB. With the above principles, then these variables will be included in a formula so obtained an exact figure to be a transmitter in order to limit its scope in accordance with the agreed terms (the law). For example, a transmitter with 100 watts ERP with a height of 30 Meters for example, it will get the distance emit about 6 Km. When power is added, then the coverage will go further.
  2. Frequency band width allowed. In AM modulation modulation bandwidth of 20 Khz. While the FM wide modulation frequency required to achieve because there are 400 Khz Stereo FM modulator that require greater bandwidth than FM mono. Frequencies between 87 MHz to 108 MHz is technically divided per 100 Khz (from 108,000 to 87,100 Khz Khz). Each state a fixed rule for the use of these channels vary, Mexico applies the bandwidth to 87 Khz FM Stereo, whereas in the U.S. can up to 200 Khz. Rules in Indonesia is not clear of its provisions. At this time stereo FM transmitter spends most bandwidth of 350 Khz.
  3. The distance between points on the use of the same frequency. Characteristics of waves at frequencies above 50 MHz is a line of waves that sigth or visibility is limited by the eye. Theoretically these waves are not as far-reaching power of the waves in the frequency band MW or SW radiance power is strengthened though continued. An FM transmitter with the power of a 10 Kwatt urban areas with a flat contour, will not be able to reach the more than 70 Km. If the transmit power is limited, then the transmitter range will be defined with certainty that at some location, frequencies used do not interfere with each other. To have a place with a transmitter at a particular frequency does not interfere with each other on the same frequency, then there is the minimum distance required. Minimum distance can be determined by adjusting the transmit power.
  4. The use of frequency at a location. When a transmitter radiating at a specific location with a frequency f or the channel A, for example 87 MHz, then at least there should be a difference of about 600 Khz from the initial frequency. For example, if 87,100 Khz frequency given to a transmitter, then to other transmitters at the same location should be given the frequency: 87700 Khz (87.100 Khz + 600 Khz). Because the principle used is the third adjacent channel.
  5. Antenna height. As mentioned earlier, the characteristic waves at a frequency between 87 MHz - 108 MHz is the line of sight. Wave Line of site (LOS) is highly dependent on the curved Earth. To be able to reach longer distances, then the antenna should be as high as possible from the surface of the earth. To limit the transmit power can be a way of implementing a strong rules for transmitting antenna heights. For a transmitter with an antenna height of 30 meters with a 100 Watt transmit power (ERP), it will get the distance emit about 6 Km.

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