Difference between revisions of "Radio Transmitter"

Revision as of 18:26, 6 August 2010

In radio electronics and broadcasting, a transmitter usually has a power supply, an oscillator, a modulator, and amplifiers for audio frequency (AF) and radio frequency (RF). The modulator is the device which piggybacks (or modulates) the signal information onto the carrier frequency, which is then broadcast. Sometimes a device (for example, a cell phone) contains both a transmitter and a radio receiver, with the combined unit referred to as a transceiver. In amateur radio, a transmitter can be a separate piece of electronic gear or a subset of a transceiver, and often referred to using an abbreviated form; "XMTR".

FM Broadcast Radio

Consumer Personal FM Transmitter

This is for the guy wanting to listen to his iPod through his car stereo, which has not audio input jacks. He plugs his personal FM transmitter into his iPod, and tunes his car FM radio to a select channel which allows him to listen to the music from his iPod. This works for "her" as well as "him."

These transmitters should operate between 88 to 108 MHz.

Low end short range

High end short range

• Pro FM Stereo Radio Station FM100B
• Whole House FM Transmitter 2.0

Pirate Radio

The funny thing is that, at its core, radio is an incredibly simple technology. With just a couple of electronic components that cost at most a d­ollar or two, you can build simple radio transmitters and receivers.

The FCC limits the broadcast power of an unlicensed individual's radio. The official regulation that handles non-licensed FM Transmitters (among other things) is FCC Part 15 and based on that regulation, the official rule is 250 micro volts measured at 3 meters (actually written as 250 µV/meter @ 3 meters). However when testing FM Transmitters they convert it to be measured as 47.95 dBµV/m, but it is usually rounded off to just 48 dBµV/m. The FCC put out a Public Notice that says the approximate distance you can transmit without needing a license is around a 200 feet.