Abstract: PN sequence generators used in the scrambling and descrambling circuits at remote locations are periodically preset to the same value in order to maintain synchronism, with the preset value being also periodically changed. The preset value can be transmitted to the scrambling and descrambling circuits over a privacy channel once per frame and stored in storage registers associated with each of the scrambling and descrambling circuits. The stored starting state values can be loaded into the PN sequence generators as often is desired to maintain proper synchronization, with the stored values themselves being changed at a rate in accordance with the desired degree of security.

Abstract: A time division multiple access communication system in which the repetitive frame is divided into fixed portions preallocated to separate stations and an overflow portion. Each station retains control of its own preallocated portion. Whenever one of the stations needs space that is not available in its preallocated portion, it requests a reference station for part of the overflow portion, which is relinquished as soon as the requirement stops.

Abstract: Impulse metering at local telephone switching offices in a DAMA DOMSAT communication system involves the storage of billing rate information in the control computer equipment at a master station. This billing information is maintained in the form of a look-up table containing all billing rates to apply to toll calls. Since the control computer knows the identity of the calling and called offices, it can select the proper billing rate for the call. Respective relatively remotely located interface stations, to which local exchanges are connected for coupling a subscriber with the satellite link, contain signalling converter circuits which, in addition to interpreting the dialed telephone number and formatting digital signals containing the dialed information, forward digital signals to a DAMA system controller where the signals are formatted and combined with other signals being transmitted to the master station.