Abstract: A spread spectrum communication apparatus employs a surface acoustic wave matched filter and surface acoustic wave delay lines which enables the demodulation in accordance with the QPSK scheme. A SS demodulator has a correlated signal acquisition circuit for demodulating a received SS signal to acquire a correlated signal, first and second delay circuits for delaying an output signal from the correlated signal acquisition circuit, and first and second adder circuits for adding the output signal of the correlated signal acquisition circuit and respective outputs of the first and second delay circuits. The first delay circuit delays the input signal by T+(.+-.n+5.times.a/8)/fc, while the second delay circuit delays the input signal by T+(.+-.m-5.times.a/8)/fc. Thereby, a spread spectrum communication apparatus which enables the demodulation in accordance with the QPSK scheme by a simple configuration using a surface acoustic wave matched filter and surface acoustic wave delay lines is provided.

Abstract: A spread spectrum communication apparatus includes at least one surface acoustic wave matched filter, a plurality of surface acoustic wave delay lines having different delay amounts, and integrating circuits for integrating an output signal of the surface acoustic wave matched filter and the respective output signals of the plurality of surface acoustic wave delay lines.

Abstract: Column packings for liquid chromatography comprising porous granules which have hydrophilic surfaces prepared by calcining a crystalline clay mineral having a fibrous structure. Median pore diameter of the porous ceramic granules is in the range of from 0.001 .mu.m to 0.01 .mu.m. The crystalline clay mineral can be sepiolite or attapulgite. The column packings for liquid chromatography have high mechanical strength, are presssure resistant and very stable to elutants having a high pH value and/or a high polarity so that the separating characteristics thereof are not changed even after long use.

Abstract: A magnetoresistive head for use in, for example, a magnetic recording/reproducing device such as a magnetic disc unit is provided. This magnetoresistive head includes a substrate, a magnetoresistive element film, first and second antiferromagnetic films, and a first and second lead layers mounted on the first and second antiferromagnetic films for supplying a sense current to the magnetoresistive element film. The magnetoresistive element film includes first and second stepped side portions each having a thickness smaller than that of a central portion of the magnetoresistive element film which defines a reproducing section. The first and second antiferromagnetic films are formed on the first and second stepped side portions of said magnetoresistive element film. With these arrangements, the Barkhausen noise is reduced greatly while maintaining a reproduced output voltage at a desired level.

Abstract: A magnetoresistive magnetic head comprising a magnetoresistive film, a pair of hard magnetic material films disposed on the magnetoresistive film, and a pair of leads disposed on the magnetoresistive film for feeding a sense current to the magnetoresistive film, wherein at least a part of each lead is formed between the pair of hard magnetic material films on the magnetoresistive film. According to this construction, generation of unstable magnetization at both ends of the track portion can be suppressed, so that a large reproduction output may be obtained.

Abstract: A method of generating oxygen for emergency use wherein oxygen is generated by adding a catalyst such as manganese dioxide etc. to an aqueous solution prepared by intermixing an addition compound of sodium carbonate and hydrogen peroxide with water and wherein the catalyst is formed into a continuous and integral shape so as to thereby make it possible to put the catalyst into and take it out of the aqueous solution so that generation of oxygen can be started and stopped easily.