Pulse Code Modulation (PCM) was pioneered by the British engineer Alec Reeves in 1937. The first transmission of a message using PCM was the SIGSALY voice encryption equipment used in high-level Allied communications during World War II starting in 1943. The original primary application for PCM was to convert analog signals into digital format by …
A photoresistor is a light-dependent resistor which slowly loses its resistance when exposed to high levels of ultraviolet light. As a result, photoresistors convert light energy into electrical energy. Photoresistors are used in a wide variety of devices to detect the presence of light, control a device, or activate a system. They are usually dependent …
An ultrasonic sensor is a device that works in much the same way as RADAR and SONAR. In fact, ultrasonic sensors mimic bats and other animals’ natural ability to use ultrasonic frequencies for navigation. Ultrasonic sensors broadcast a powerful, ultrasonic frequency, then detect the ultrasonic sound waves as they bounce off of objects and return …
More properly known as the Bayonet Neill-Concelman connector, the BNC connector is one of several radio frequency connectors on the market today. The name of the connector is derived from a combination of two things: 1) the connecting technology employed; and 2) the names of the two inventors of the device. Paul Neill of Bell …
Television antennas are generally installed on top of buildings, which makes the entire structure susceptible to lightning strikes. In order to protect the building that the TV antenna is attached to, the antenna has to be grounded properly. Another danger of mounting a television antenna that is not grounded properly is the excessive static electricity …
Round Trip Time, or RTT, also known as “round-trip delay time” is the time it takes for a signal to be sent from a transmitter to a receiver plus the time it takes to verify that the signal has been received; therefore, Round Trip Time is the time it takes for a signal to be …
An EMF meter detects and measures an electromagnetic field. There are many types of EMF meters and they have many uses, including ghost hunting. Most EMF meters are “AC EMF meters” and can only detect the rate of change in an oscillating magnetic field. However, commercial grade EMF meters that can detect specific electromagnetic frequency …
Business band stands for a series of frequencies in the UHF and VHF two-way radio bands, which are exclusively reserved for businesses to communicate within limited ranges. Of course, not just anyone can use this bandwidth. Anyone that wants to use the business band must first receive a license from the Federal Communications Commission, also …
A Zener diode transfers current forward and backward, while traditional diodes are only capable of transferring current forward. Many different electronic systems use Zener diodes to control their circuit’s voltage levels. While there are several ways of doing this, Zener diodes provide efficient voltage regulation without damaging the diode itself. How Zener Diodes Work For …
Downlink is a term in telecommunications that is used to refer to a data transmission in which data flows from an orbital satellite receiver to a ground-based transmitter. Downlink transmissions rely on the C Band between 3.7 and 4.2 GHz, the Ku Band between 11.7 and 12.7 GHz, and the Ka Band between 18.3 and …