Intersymbol interference is a signal distortion in telecommunication. One or more symbols can interfere with other symbols causing noise or a less reliable signal. The main causes of intersymbol interference are multipath propagation or non-linear frequency in channels. This has the effect of a blur or mixture of symbols, which can reduce signal clarity. If intersymbol interference occurs within a system, the receiver output becomes erroneous at the decision device. This is an unfavorable result that should be reduced to the most minimal amount possible. Error rates from intersymbol interference Read More

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 18.8 GHz, as well as between 19.7 and 20.2 GHz. Downlink is often used in astronomy, radio science, and telecommunications.   How Downlink Works When a ground-based transmitter transmits data to a satellite in Earth’s Read More

DVB-RCS stands for Digital Video Broadcast – Return Channel Satellite. DVB-RCS is part of the DVB standards for satellite communication, DVB-S and DVB-S2. The purpose of DVB-RCS is to provide a return channel to enable Internet and other data services over satellite. ViaSat’s LinkStar system is one of the VSAT satellite broadband implementations which support DVB-RCS. The DVB standards are maintained by the DVB Project, which is an industry-led consortium of over 260 broadcasters, manufacturers, network operators, software developers, regulatory bodies and others in over 35 countries. DVB-RCS is officially Read More

GPS stands for Global Positioning System.  It refers to a system of satellites that constantly transmit a signal, and a GPS terminal that picks up those signals and calculates its position on Earth by measuring the distance between itself and two or more GPS satellites (by measuring the time it takes to receive the signals). How to Use GPS GPS operates using trilateration. Trilateration is the process of determining the position of an unknown point by measuring the lengths of the sides of an imaginary triangle between the unknown point Read More

GPS – A Short Introduction GPS, which stands for Global Positioning System, is a satellite navigation system that can ascertain the latitude and longitude of a GPS receiver device on the Earth.  The GPS consists of more than two dozen global positioning satellites orbiting the earth. Each satellite transmits radio signals, which can help determine the location, speed and direction of travel of users equipped with GPS receivers. To ensure that the whole world is covered by the constellation of the GPS satellites, they are so arranged that four satellites Read More

L band is a fequency range between 390MHz and 1.55GHz which is used for satellite communications and for terrestrial communications between satellite equipment. The high frequencies utilized by C band, Ku band, and Ka band would suffer from high signal loss when transported over a copper coax cable such as an Intra-Facility Link. An LNB is used to convert these higher frequency bands to L band, which can be transmitted over the IFL and processed by the IDU. Some satellites transmit on L band, such as GPS satellites.  

The symbol rate is the rate of state changes on a communications circuit. If a circuit can carry two tones per second, the circuit has a symbol rate of two. Circuits then use different modulation techniques to carry multiple bits per symbol. If the circuit is limited to two different tones, the first tone can represent a 0 and the second tone can represent a 1. In this circuit, the symbol rate is the same as the bit rate. If the circuit can carry four different tones, then the tones Read More

Before you ask what an LNB tester is, you should know what an LNB is. An LNB is the receiving end of a satellite dish. LNB stands for low noise blocker; it is a device that essentially does what it says. It blocks low noise (frequencies) in order to receive higher frequencies in which satellite transmissions use. Today, the majority of satellite dishes are sold for commercial use to receive digital television signals or for communication technology such as broadband Internet. Low noise blockers also amplify the high end frequencies Read More

A BUC (Block Upconverter) is a device that converts radio signals from a lower frequency to a higher frequency. BUCs are used in satellite uplink transmissions in order to transfer data from a ground based unit to a satellite in orbit that will then be redirected to another ground based unit in separate location. Likewise, BUCs are used in long distance communication between two or more ground based radio towers. BUCs are often found in communication broadcast systems for television and Internet access, weather systems, and government agencies. How a Read More

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 of available bandwidth by increasing the overall block size of the outgoing data, but also enables the receiver to correct for more errors without receiving any additional transmitted data. This dynamic makes FEC ideal when Read More