Abstract: A differential pulse-code modulation coder obtains an improved signal-to-noise ratio, with only a small increase in bit rate, by repetitive coding. In one aspect, the coder divides the input signal into frames, codes each frame repeatedly using different prediction coefficients or different quantizing step functions, and selects the coefficient or step function that produces the least quantization error. In another aspect, the coder repeats the coding of individual samples located in the outermost steps of the quantizing step function.

Abstract: The synchronizing apparatus includes a block for detecting a code from an input signal, a block for detecting from the code the variable points of the code at several times as high as the symbol rate, a block for calculating a histogram of the detected variables of the code to time, and a block for deciding that the phase number at which the calculated histogram takes the maximum value is a symbol synchronization point. This synchronizing apparatus detects the zero-cross points of an intermediate frequency band signal at N times as high as the symbol rate. It also calculates a histogram of detected time (0 to N−1). The time (0 to N−1) at which the histogram is the maximum within a predetermined detected time is selected as a symbol clock, and thereby symbol synchronization is established.

Abstract: The invention relates to a method for monitoring the earth's surface with a moving aircraft using a radar sensor with a synthetic aperture. In order to produce high resolution radar images, the flight parameters of the aircraft are also required. According to the inventive method, key parameters, such as speed and acceleration, are detected in the sight line of the radar sensor from the radio signals received. One of the advantages of the invention is that an inertial navigation system (INS) is no longer required for this purpose.

Abstract: A Viterbi decoding method for decoding a received signal, doing an ACS process and a trace back process a first number of times, and doing the ACS process a second number of times and the trace back process the first number of times until the trace back process is complete for all of the bits to be decoded if the tracing back has not already been finished for all bits, the Viterbi decoding method further including: after the trace back processing has finished for all of the bits to be decoded, deciding a fame error based on the result of calculating a Hamming distance between the received signal and re-encoded decoded signal, and possibly changing the first number and/or the second number depending on value stored in a counter which signifies the condition of the frame error for the past several times.

Abstract: In a multi-value modulation system such as M bits/1 symbol, a pattern matching apparatus is arranged by a coincident bit number detecting circuit for detecting a coincident bit number between a reception symbol and the known pattern owned by a receiver within 1 symbol; a delay circuit for delaying a detection result; and an adder. Then, a coincident bit number between the received 1 symbol (M bits) and 1 symbol (M bits) of the known pattern is detected. This detected bit number is added to each other, so that when a length of a UW pattern is N bits, the total number of adders can be reduced to N/M.

Abstract: An interface circuit permits a customer who receives two-phase service from an electrical utility company to use power from an on-site source instead of or in addition to the utility company's power. Several embodiments are disclosed, in some of which the interface circuit automatically disconnects the utility company's power lines if the utility's power is lost and connects the on-site power source. The interface circuit may be installed in whole or in part in a meter collar which fits between an electric meter and the meter socket box that the meter would otherwise plug into.

Abstract: A transmission device performs encoding by a speech encoding portion including a speech encoder and error correction encoder, and transmits a continuous signal without any further processing. A reception device receives the continuous signal and performs channel decoding and speech decoding as one unit by a speech decoding portion including a soft-decision error correction decoder and a soft-decision speech decoder. Thus, a transmission and reception system performs an accurate signal reproduction without removing the signal including a normal bit error rate by correcting the error by the speech decoder.

Abstract: To realize an ATM cell switch capable of reducing the transmission rate of cells to be transmitted, a output buffer-type ATM cell switch includes input units buffer unit, and output units, wherein the buffer units reduce the transmission rate of the cells. Furthermore, the ATM switch compares the destinations of the cells with destination set signals that are provided to address filter units in the buffer units, and controls the transfer of cells to the buffer memories in the buffer units, thereby efficiently reducing the transmission rate of cells.

Abstract: There is provided a switch 140 between an address line 121 and external output terminals A0.about.An, controlled by outputs of a counter circuit 117 and a test mode control circuit 119. The switch 140 transfers a variation of an address signal to external output terminals A0.about.An, without connecting the address line 121 with the external address terminals A0.about.An, directly.

Abstract: An adaptive maximum likelihood sequence estimator includes a channel estimator and a Viterbi algorithm processor for estimating the maximum likelihood transmission symbol sequences. The algorithm processor includes a branch metric computer in which common components are found from regularity in computations of coded alphabets of the transmission symbols and are used for all branch metric computation to reduce the total amount of the operations. Such effective computations are implemented by either of hardware and software in accordance with the constitution of the system of the adaptive maximum likelihood sequence estimator.

Abstract: An impact printer having a print head, the print head having a movable armature, a printing wire fixed to the armature, and sensor for detecting movement of the armature. The position of the armature is monitored based on an output of the sensor. A home sensor detects whether the print head is at a home position. A paper end sensor detect whether a printing medium is between the platen and the print head. A gap motor means adjusts a gap between the printing wire and the platen. A gap controller is responsive to detection signals output by said home sensor and said paper end sensor, for controlling the print head to swing the armature so as to cause the tip of said printing wire to strike the platen, determining a time of impact of the tip with the platen based on the monitored position of the armature, performing a comparison of the time of impact with a predetermined impact time, and outputting a drive signal to the gap motor for adjusting the gap according to a result of the comparison.

Abstract: A code-division multiple-access spread-spectrum communication system uses pairs of spreading codes with rates of N/2 chips per data symbol to provide a capacity equivalent to that obtained in a conventional system with N chips per symbol. In the transmitter, identical input data are spread in parallel by both spreading codes, then used to modulate two orthogonal carrier signals, and the resulting radio-frequency signals are combined for transmission from an antenna. In the receiver, the received signal is demodulated by parallel multiplication with the two carrier signals, the resulting baseband signals are correlated with the two spreading codes, and the results are added.