Abstract: A method for determining the initial values of the coefficients of a transversal equalizer for a synchronous data transmission system, wherein a training sequence is transmitted to allow the equalizer coefficients to be adjusted to optimum initial values. According to the method, a sequence (v.sub.i) of L elements v.sub.i, having a periodic autocorrelation function, only the first coefficient of which is not zero, is derived from a periodic binary pseudo-random sequence (u.sub.i) of L binary elements u.sub.i having a periodic autocorrelation function, the first coefficient of which is equal to L and each of the other coefficients are equal to -1. Then, the sequence (v.sub.i) is transmitted through the transmission channel and the initial values of the equalizer coefficients are derived from the received sequence.

Abstract: A digital data communication network in which bidirectional communications are established between a central station and plurality of remote terminal devices under control of the central station and in which groups of serially connected terminals are connected in parallel to a simplex link for receiving data signals from the central station and in which one group of serially connections stations is selectively connected to a second simplex link for transmitting, in a predetermined sequence, data signals to the central station.

Abstract: An ink jet copier is provided with a document scanner which scans a document to be copied one line at a time producing non-coded binary data. The binary data is inserted in storage in a predetermined arrangement. Stored data is removed from selected predetermined locations in accordance with an algorithm and applied to a plurality of ink jet nozzles arranged in multiple linear arrays about the circumference of a rotating paper drum. The data signals selectively applied to the ink jet printers control the deposition of ink on the paper supported on the rotating drum to cause the reproduction of the original scanned image on a predetermined interlaced basis.

Abstract: A frequency shift keyed (FSK) modulator capable of substantially simultaneously modulating a plurality of binary encoded data signals at different baud rates and modulation frequencies for substantially simultaneous transmission over a plurality of communication lines and in which the modulated signals are of narrow bandwidth thus requiring the same simple RC filter for all lines regardless of the baud rates or signalling frequencies used.

Abstract: A multi-line multi-mode modulator uses compatible digital modulation techniques for multifrequency (MF), frequency shift keyed (FSK) and differential phase shift keyed (DPSK) modulation to achieve a multi-line multi-mode modulator which is capable of handling a plurality of lines requiring a dynamic mix of the three modulation techniques. The compatible modulation techniques utilize bandwidth reduction schemes which enable the use of simple RC filters on each output line for the sole purpose of removing the quantizing noise introduced by the digital modulation technique.

Abstract: A digital automatic gain control circuit in which the input signal is multiplied by a gain control parameter whose value is generated in a feedback loop such that the resultant product has specified constant metric.

Abstract: A wand suitable for scanning the universal product code (UPC) symbol uses a light emitting diode for illuminating the symbol and a silicon photodetector for receiving the reflected energy. A single optical fiber is coupled to the diode and to a portion of a second single fiber for conducting narrow bandwidth visible light centered about 6,500 A to the terminus of the wand. The reflected light energy from the symbol when it is scanned by the wand is transmitted to the silicon photodetector via the said second single fiber which is also coupled to a third single fiber which conducts the reflected light energy to the silicon detector.

Abstract: A digital data communication network in which half-duplex communications are established between a central station and a plurality of remote terminal devices under control of the central station and in which said remote terminal devices are grouped and each group is serially connected and receives data signals in parallel over a simplex link from the central station and in which one group of serially connected stations is selectively connected to a second simplex link for transmitting, in a predetermined sequence, data signals to the central station.

Abstract: A multi-line multi-mode modulator uses compatible digital modulation techniques for multifrequency (MF), frequency shift keyed (FSK) and differential phase shift keyed (DPSK) modulation to achieve a multi-line multi-mode modulator which is capable of handling a plurality of lines requiring a dynamic mix of the three modulation techniques. The compatible modulation techniques utilize bandwidth reduction schemes which enable the use of simple RC filters on each output line for the sole purpose of removing the quantizing noise introduced by the digital modulation technique.

Abstract: In a system including several devices connected by means of a common data bus the adverse effects of reflections due to two or more devices simultaneously seeking access to the bus are minimized by confining such reflections to parts of the bus remote from the devices. This is achieved by preventing the amplitude of a signal at a receiving station on the bus from exceeding a predetermined level; and integrated circuit serving as a near ideal diode clamped to a reference voltage performs this function.