![]() ![]() Connect the two leads from the earplug to either end of the diode.Lay it out on the ground, or hang it in a tree, but make sure the bare end does not touch the ground. Take another piece of wire, 10 to 20 feet (3 to 6 meters) long, and connect one end of it to the other end of the diode.Attach the diode to the other end of the ground wire. ![]() Strip the insulation off the end of a 10-foot (3-meter) piece of wire and wrap it around the stake/post five or 10 times to get a good solid connection. Drive the stake into the ground or find a convenient metal fence post.In FM, the detector turns the changes in frequency into sound, but the antenna, tuner and amplifier are largely the same. In an FM radio, the detector is different, but everything else is the same. What you hear coming out of the speakers is the DJ's voice! The amplifier is made of one or more transistors (more transistors means more amplification and therefore more power to the speakers). The radio next amplifies the clipped signal and sends it to the speakers (or a headphone).A diode allows current to flow through in one direction but not the other, so it clips off one side of the wave. In the case of an AM radio, the detector is made with an electronic component called a diode. This is done with a part of the radio called a detector or demodulator. Now the radio has to extract the DJ's voice out of that sine wave. The tuner causes the radio to receive just one sine wave frequency (in this case, 680,000 hertz).It is easy to create a resonator with a capacitor and an inductor. That is, tuners resonate at, and amplify, one particular frequency and ignore all the other frequencies in the air. Tuners work using a principle called resonance. In this case, the tuner is tuned to receive the 680,000-hertz signal. The job of a tuner is to separate one sine wave from the thousands of radio signals that the antenna receives. The antenna will receive thousands of sine waves. An AM antenna is simply a wire or a metal stick that increases the amount of metal the transmitter's waves can interact with. Unless you are sitting right beside the transmitter, your radio receiver needs an antenna to help it pick the transmitter's radio waves out of the air.Once you modulate a sine wave with information, you can transmit the information. over-the-air television has moved entirely over to digital transmission, and many terrestrial radio stations operate on digital antennas in addition to their analog signals. Audio data will sound scrambled, and videos will be highly pixelated. However, a digital signal that is too weak will quickly become unusable. This way, the transmitter will only send data to particular devices. ![]() In the case of things like wireless routers, digital modulation also allows the signal to be encrypted. Digital Modulationĭigital modulation encodes digital information onto an analog carrier signal and provides higher fidelity without any of the typical static. FM uses higher frequency signals than AM, which have higher fidelity but a decrease in range. In FM, the transmitter's sine wave frequency changes very slightly based on the information signal. The advantage to FM is that it is largely immune to static. Each different radio signal uses a different sine wave frequency, and that is how they are all separated.įM radio stations and hundreds of other wireless technologies use frequency modulation. It is amazing how many uses there are for radio waves today. If you had some way to see them, you would find that there are literally thousands of different radio waves (in the form of sine waves) around you right now - TV broadcasts, AM and FM radio broadcasts, police and fire radios, satellite TV transmissions, cell phone conversations, GPS signals and so on. We use continuous sine waves today is because there are so many different people and devices that want to use radio waves at the same time. ![]() The narrow frequency band also allows many transmitters to operate in an area without interfering with one another. A sine wave transmitter narrows this band down to more specific frequencies which can effectively reproduce complex information like audio streams, video and internet data. All they could reproduce were simple noises which could be used to communicate with Morse code. Very early radio transmitters emitted a large band of frequencies at once. All radios today, however, use continuous sine waves to transmit information. As seen in the previous section, it is incredibly easy to transmit with static. ![]()
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