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The bit error rate (BER) measures the number of errors in a transmission compared to the total number of bits transmitted. It is used to assess network performance and detect system integrity. BER can be improved by addressing factors causing bit errors, such as noise and variations in the radio propagation path. Simulations, such as pseudo-random binary sequences, are used to check for phase jitter in the system. All-Ones test is used to test span power.
During a specified time interval, the bit error rate (BER) is the number of times a transmission’s received bits were changed by interference, noise, bit synchronization errors, phase jitter, or distortion. The number of errors in that time interval is then compared to the total number of bits transmitted to get the error rate. As such, BER is a network performance ratio for digital transmissions over radio data links, Ethernet data networks, or fiber optics. For example, if a sent broadcast packet contains 10 bits of binary code and two of those bits are garbled during transmission, the BER would be 20 percent. In fiber optic telecommunications, this BER is calculated differently as calculations of user visible error rates are required; the measurements are erroneous seconds, found by measuring the one-second intervals during which any bit errors occur.
Because BER measurements can be performed on transmitters, receivers, and the communication networks connecting them, BER is a total system assessment tool for detecting system integrity in effective performance. Bit error rate analysis on systems is usually done using simulation models. The results of the simulations determine which forward error correction codes should be applied by a system administrator to improve the transmission performance of the raw channel.
Sometimes the bit error rate can be improved by using a stronger signal; however, this can cause multiple crosstalk errors as well as bit errors. If the bit errors have already been resolved with forward error correction coding and the BER is still too high, it is best to address the factors causing the bit errors. The main culprit is usually noise and variations in the radio propagation path. In fiber optic networks, the problems are usually in the components of the network itself, requiring thorough testing of the network. Noise can come from the optical receivers themselves when the photodiodes or amplifiers do not respond to very small changes and produce high noise levels.
To check the causes of the bit error rate, one of the simulators used is a pseudo-random binary sequence of numbers sent in pattern sequences to check for phase jitter in the system. A similar test is when a quasi-random signal source generates and sends every possible combination of a 20-bit word and repeats it every 1,048,575 bits. At the same time, the source generator would suppress consecutive zeros to less than 14 and cycle between high and low density changes to measure phase jitter. Another test, called All-Ones, sends packets of suns and repeats to consume maximum power to see if the DC current to the repeater is regulated correctly and to test span power. Many simulations can test all components of any drive system.
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