Know the Bandwidth Limit of Your Satellite Communications Provider
Every customer of satellite broadband services should know how much is his allocated bandwidth, which determines how fast and reliable an Internet connection can be.
Calculating the Internet bandwidth is not a hard task. Just compute the total bandwidth of each amplifier (transponder). Most satellites operated by one carrier. Getting the bandwidth of more than one carrier is more challenging since not all carriers have the same features. Listed below are the key values that should be calculated to determine satellite communications speed, bandwidth and capacity.
The total carrier bandwidth is based on this formula: Symbol Rate (SR) = Data Rate (DR) / (modulation factor (m) x Viterbi FEC rate (CRv) x Reed Solomon FEC rate (CRrs)). DR is short for ‘data rate’, which is measured in terms of megabits per second (Mbp/s ). The DR of the carrier is usually shown in the parameter sheet. It pertains to the amount of data processed by the carrier. Information rate is another term for DR.
The modulation factor has something to do with the transmission scheme that reduces bandwidth during signal transmission. Several modulation schemes are available like 16QAM, BPSK, QPSK, 8PSK, and 8QAM. These are the modulation factors that are applicable to the above equation: 16QAM = 4, 8QAM = 3, QPSK = 2, 8PSK = 3 and BPSK = 1. The appropriate modulation scheme is indicated in the carrier’s parameter sheet.
Additional bits can be included in the data stream by changing the Viterbi Forward Error Correction (FEC) rate. There are several settings that can be used to correct errors, namely 3/4, 1/2, 2/3, 3/4 and 7/8. The amount of information bits is represented by the first number, while the sum of the first number and error correction bits is represented by the second number in each set. The FEC rate can also be found in the parameter sheet of the satellite communications provider.
As for Reed Solomon FEC rate, just interchange 188/204 "CRrs" . This rate has the same function as Viterbi FEC, but unlike the latter, it is a fixed value. Mode for Reed Solomon FEC rate can either be on or off. The parameter sheet also shows the Reed Solomon FEC rate.
Groundbreaking discoveries in the realm of satellite communications give rise to teleports that can support larger satellite bandwidth. Jitters and latency are becoming less a problem, and satellite-based communication is likely to further improve in the near future as satellite broadband becomes more cost-effective.
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I've been a part of various satellite research projects in Europe and Asia Pacific. I write about corporate deals, satellite communications contracts and the latest happenings in the ICT and broadband sectors.