Because light is at such a high frequency in the electromagnetic spectrum, it`s an even better medium for communications than radio waves. Lasers are perfect instruments for communications links because they emit a powerful, slender beam that`s least affected by interference and is nearly impossible to intercept. This section explains the basics o
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f laser light communications using both helium- neon and semiconductor lasers. You`ll discover the different ways light can be modulated and cajoled into carrying an analog signal from a microphone or FM radio. The following section details advanced projects in laser light communications. Higher frequencies in the radio spectrum provide greater bandwidth. The bandwidth is the space between the upper and lower frequencies that define an information channel. Bandwidth is small for low-frequency applications such as AM radio broadcasts, which span a range 540 kHz to 1600 kHz. That`s little more than 1 MHz of bandwidth, so if there are 20 stations on the dial, that`s only 50 kHz per deejay. Television broadcasts, including both VHF and UHF channels, span a range from 54 MHz to 890 MHz, with each channel taking up 6 MHz. Note that the 6 MHz bandwidth of the TV channel provides more than 100 times more room for information than the AM radio band. That way, television can pack more data into the transmission. Microwave links, which operate in the gigahertz (billions of cycles per second) region, are used by communications and telephone companies to beam thousands of phone calls in one transmission. Many calls are compacted into the single microwave channel because the bandwidth required for one phone conversation is small compared to the overall bandwidth provided by the microwave link. Visible light and near-infrared radiation...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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