Abstract: A compandor converts a linear code signal consisting of a polarity bit and a plurality of absolute value bits. The polarity bit represents the polarity of each sample value of an original analog signal. The absolute value bits represent the absolute value of the sample. The compandor converts the linear code into a nonlinear code including the polarity bit, a plurality of segment bits representing the segments in a characteristic curve to which the original analog signal belongs, and mantissa bits which indicate the position of the sample value in that segment.

Abstract: In a digital time division multiplexed telephone transmission system, a plurality of telephone signals are cyclically sampled and quantized so that each sampled value may be encoded into a binary codeword of a preset number of bits and that a series of codewords equal in number to the telephone signals may constitute a frame and a series of a predetermined number frames may in turn constitute a superframe. At the transmission end, an input circuit (202) receives the time division multiplexed telephone signals, and a code converter (204) coupled to the input circuit and responsive to a state-representing signal successively converts each of the binary codewords into a plurality of modified codewords. The modified codewords are variably assigned comparatively smaller and greater numbers of binary digits depending on the state-representing signal, the comparatively greater number being equal to or smaller than the preset number.

Abstract: A FDM/TDM transmultiplexer uses sampling rate multiplication to increase the sampling rate for time division multiplexed (TDM) to frequency division multiplexed (FDM) conversion and decrease the sampling rate for FDM to TDM conversion. The rate multiplication filters are realized digitally in order to exploit the computational advantage of Fast Fourier Transform (FFT) algorithm, and channel filtering is implemented by a single time-shared sixth-order elliptic digital recursive filter. A novel FFT processor and recursive filter are disclosed which may be used in the system.

Abstract: An asynchronous PCM common decoding apparatus decodes asynchronous PCM signals sent from a plurality of transmitter sources. The apparatus includes a plurality of receiver units each of which generate a digital signal to be decoded, a channel-number-designating signal, and a decode-requesting signal. One or more decoders are provided to decode the digital signals from the receiver units to analog signals. The decoders produce status signals indicating availabilities of the decoders for decoding the digital signals. A common control unit is responsive to both the decode-requesting signals and the status signals to successively allot a combination of a given receiver and a given decoder.

Abstract: A non-recursive digital filter is disclosed, composed of a cascaded plurality of basic sections, each of which is characterized by coefficient values of integer powers of two's. No hardware multipliers are required in the filter and the operating speed is several times faster than other filters which utilize multipliers.