Abstract: A time-division multiplexing apparatus time-division multiplexes, in units of m bits, each bit of n-channel digital signals (n is a natural number more than 2), transmitted in a serial manner in synchronous to transmission clock pulses of a frequency of f0, by using m channels (m is a natural number smaller than n). Serial signals supplied to n channels are respectively converted into m-bit signals by shift register blocks provided for the n channels. The same bit outputs of the blocks are supplied, as an n-bit signal, to corresponding one of latch blocks, and are latched in synchronous to latch pulses of a frequency of 1/m of f0. The outputs of the latch blocks are input to n : 1 selector blocks. One of the bit signals of the selector blocks is selectively output in accordance with gate pulses.

Abstract: In a frame synchronization circuit, a serial data signal, which includes a frame synchronization code constituted by an M number of bits in one frame, is converted by a serial/parallel converting circuit to a parallel data signal of a 2M-1 number of bits. An M number of pattern detectors of a first synchronization detecting circuit detect the code pattern of the first block of the frame synchronization code from the parallel data signal. A selection signal generating circuit holds outputs of the pattern detectors, and outputs them as a selection signal designating the bit position allotted to the pattern detector which detects the synchronization code pattern. An output of the serial/parallel converting circuit is delayed by a time required for the above-mentioned processing, and supplied to a selector, which selectively outputs an M-bit data signal corresponding to the bit position designated by the selection signal.

Abstract: Ceramic powders selected from the group (a) consisting of ZrB.sub.2, HfB.sub.2, ZfC, ZrN and HfN and ceramic powders selected from the group (b) consisting of TiC, TiN and TiO.sub.2 are mixed, the mixture is sintered in a non-oxidizing atmosphere, a substitution reaction of chemical elements between the compound of the ceramic powders of the group (a) and the compound of the ceramic powders of the group (b) is caused in the sintering, and a ceramic composite substantially comprising compounds which do not belong to the groups (a) and (b) is produced by the substitution reaction. By this process, the affection of the particle size and the aggregation of raw powders to the sintering can be greatly reduced, the ranges of the applicable sintering conditions can be broadened, and dense ceramic composites having fine crystal grains and having excellent mechanical properties can be obtained.