of the cable. jitter occurring at a frequency of less than 10Hz. Wander, like jitter, Conversely, a low level signal will discharge the line. If the number is a back and forth (cyclic) displacement of bits from their expected of highs and lows is matched, then the net energy level on the line positions. But, because wander occurs at such low frequencies, its will be zero. But if the number is not matched (which is normally cause within the network and effects on the network are very the case), the transmission line will have periods during which different from those of jitter. Wander is most often caused by energy is stored. This stored energy will result in a d.c. offset being instabilities in a master timing source, or by nocturnal cooling superimposed on the transmitted signal. The d.c. offset will interfere (cooling as the sun goes down). The end result is usually slips. with the decoding of the received pulse by reducing the difference between the high and low signal levels and the threshold level. For instance, if the threshold level is 1.3V and a low level signal is 0.8V, then a DC offset of greater than 0.5V will stop the decoding of a low Coding schemes level signal and affect the overall performance of the transmission system. Another aspect of digital transmission systems is the algorithm used To overcome this, transmission codes with three levels, positive for data transmission on the line. There are various ways in which high, zero, and negative low, have been developed. The highs and the data can be represented as signals on the line. One of the lows are used to represent the same logic level. The main difference important factors of a transmission system is the number of discrete between this system and the unipolar system is that the highs and levels a signal can have. For example, TTL has two levels to encode lows are alternated for the same logic level. For example, in the the binary data. One voltage level indicates a logic 1, and the other system of coding known as alternate mark inversion (AM