Abstract: To meet the challenge of future mobile communication and integrated communication and wireless location systems, a new spread spectrum communication system with eight phases space-time modulation technology is proposed to transmit azimuth and communication message. The spectrum, capacity and bit error rate of this system are similar to the spread-spectrum QPSK. The paper suggests a method of matrix to describe the principle of modulation. The key technical problems such as modulation, transmitting array antennae, demodulation, carry recover and direction-finding are solved, by taking into consideration the orthogonal metrics and the fact that a walsh sequence wⁿ is orthogonal to (-1) ^n-1 wⁿ.

Key words: modulation, spread spectrum system, direction finding, wireless location, mobile communication