Abstract: A frequency comb multiple access (FCMA) communications system in which address and message data are transmitted on a common channel to different users. The data transmitted are in the form of signatures, each of which consists of combined specific frequencies selected from a range of discrete frequencies available in the bandwidth of the common channel. Each signature corresponds to an address and to a data message directed to the address. This system does not require handshaking nor channel assignment. A transmitter and a receiver for the system are also disclosed.

Abstract: A fault location arrangement for either electrical or optical digital transmission systems is provided by a distinct diagnostic signal at each of a series of regenerators which is used to modulate data signals. The modulated data signals are then recovered by demodulation and analyzed to determine the status of each regenerator. Diversion of signals by "loop-back" at each regenerator is also provided for.

Abstract: A fractionally spaced adaptive equalizer structure provides improved processing speed. Equalization is performed by time-spaced processing arrays, each array having a plurality of elements each performing one of the required complex component multiplication. Particular advantages are achieved in high data-rate low-cost modem design.