Abstract: A method is provided for identifying the frequency of a logic signal that may have a frequency equal to one of n discrete frequencies. The method includes the steps of sequentially transmitting trains of clock pulses of decreasing frequencies. Each clock frequency is a constant multiple of one of the discrete frequencies. The time duration of the first train of clock pulses corresponds to the measurement time duration of a logic signal at the first discrete frequency. The time duration of the i.sup.th train of pulses is such that the sum of the time durations of the first to the i.sup.th pulse trains corresponds to the measurement time duration of a logic signal at the i.sup.th discrete frequency.

Abstract: A succession of variable length data packets containing a header portion and data portion are received. Selected data from the data packet headers is stored in designated locations of a header memory. A data packet start address is provided with each stored header portion to designate a location in a data memory for commencing the storage of data contained in a corresponding data packet. The data from the received data packets is stored commencing in the data memory locations designated by the corresponding data packet start addresses. In an illustrated embodiment, the data packets are macroblocks from digitized television frames. A plurality of next data packet position indicators are provided in the data, for use in periodically verifying macroblock boundaries during the receipt of the television data and to provide a rapid recovery from a transmission error affecting the actual or identified length of a macroblock.

Abstract: A system and method for asynchronously transmitting data blocks, in parallel, across multiple fibers in a serial manner. Frame groups are provided as a mechanism to transmit associated data serially on each fiber and tie the data being transmitted together. The frame groups do not have sequence numbers, therefore, the receiver determines which frames are part of a frame group by the arrival times of the individual frames. The transceivers for each member of the parallel bus asynchronously achieve synchronism from either end of the fiber. Thus the need for a common clock is eliminated. The receivers on each side of the bus determine the relative skew for each conductor by performing skew measurements on a calibration message generated by the transmitters on the other side of the bus. When the skew on all conductors, viewed from both sides of the bus, has been determined, the skew values are exchanged across the bus, thus enabling the transmitters to set proper frame spacing.

Abstract: A transceiver module for coupling between cells in a distributed intelligence network and a twisted pair line. The module receives power from the line and provides power to its respective cell. At the end of transmitting a packet, the transceiver transmits a code violation, then an anti-code violation to dissipate energy in the line. This is followed by clamping the line for the dead time between packets. N transceivers may be connected (without a cell) to form a repeater. The transceiver module may be used in a network having free topology; that is, an ideal transmission line, with terminators is not needed.

Abstract: The RF meter reading system includes a transmitter having an encoder. Meter data is encoded and modulated using a bi-phase modulating scheme. In order to uniquely identify the start of a data transmission, a super start field, which is an "illegal" bi-phase signal is used. The super start field is selected such that it cannot be recognized if transmissions from more than one transmitter are being received by the receiver.

Abstract: An improved digital communications system is disclosed in which synchronization information is transmitted with the data. A start pulse, having a duration different than the other pulses in the transmitted digital data signal is used to mark the beginning of the frame of digital data. Preferably, a midpoint pulse is also transmitted with the start pulse to mark the midpoint of the frame to facilitate the generation of a local clock signal. Bit positions within the transmitted signal are sampled by sampling pulses which are generated by digital timers having time intervals keyed to the start and midpoint pulses.