Forward Error Correction (FEC) is a type of error correction that involves encoding a message in a redundant way, which allows the receiver to reconstruct lost bits without the need for retransmission. How Forward Error Correction Works FEC works by adding “check bits” to the outgoing data stream. Adding more check bits reduces the amount …
Linear amplifiers are electronic circuits that have an output that is proportional to the input of the device while providing additional power to the load. A linear amplifier is normally a variant of a radio-frequency (RF) power amplifier and is used frequently in amateur radio and in laboratory and commercial audio equipment with an output …
Generally, a transmission signal contains more than a single frequency. This is to say that there might be several different frequencies linked together or else superimposed on each other. This is just the way all telecommunication systems function. For example, with today's communication technology it is virtually impossible to send low frequencies without experiencing any …
dBm is the standard unit of measure for levels of power based on a one milliwatt (mW) reference signal. The dBm measurement is very similar to dB (decibel); however, dB is a relative measure of the power of an input signal while dBm is always an absolute value based on a single milliwatt. If there …
A frequency changer makes it possible to change electricity moving at one frequency to another frequency. However, in order to fully understand what a frequency changer does, it is helpful to understand the frequency of electricity. The Frequency of Electricity Electricity doesn't move at one specific speed. In fact, it can move at many speeds. …
A spot beam is a beam of radio signals that is directed towards a specific area on the Earth’s surface. Spot beams are the opposite of broad beams, which are beams that are directed towards a large area of the Earth’s surface. While broad beams are used for general telecommunication and surveillance, spot beams are …
Portable radios are limited in the power at which they can transmit, usually somewhere between .5 watts and 5 watts. A very rough rule of thumb is that one watt equals one mile of range over flat and open terrain. Buildings and mountains will, of course, greatly modify effective range. When two radios communicate directly …
In order to understand how sunspots effect radio reception, you need to understand that the light waves and radio waves that the sun emits are both categorized as electromagnetic (EM) radiation. While light waves are visible to the human eye, they are still electromagnetic waves that oscillate. There are many electro magnetic waves, some oscillate …
A high-frequency alternator is an electrical device used for radio communications. It yields high-frequency, periodically alternating current that can go as high as 100,000 Hz for the purpose of producing stable radio waves. The History of High-Frequency Alternators By the first decade of the 20th century, wireless telegraphy was already in place and was no …
A Capacitor Bank is a group of several capacitors of the same rating that are connected in series or parallel with each other to store electrical energy . The resulting bank is then used to counteract or correct a power factor lag or phase shift in an alternating current (AC) power supply. They can also be …