We propose a spread spectrum (SS) wireless modem suitable for hand-held terminals. The SS wireless modem simultaneously fulfills the requirements of the hand-held terminals such as compact size, low power consumption, and high speed acquisition. In order to fulfill these requirements, a novel de-spreading method is introduced. In this method, a spreading code is demodulated from a received SS signal. On the basis of the demodulated spreading code, the received SS signal is acquired and de-spread with a digital correlator. The introduction of the de-spreading method makes it possible to realize the high speed acquisition and the low power consumption. Since the de-spreading method can be embodied in an ASIC ( Application Specific Integrated Circuit ) by digital signal processings, the compact size is also realized.

Furthermore, we have developed the proposed SS wireless modem experimentally and evaluated its performance. The compact size of the developed modem including the antenna is also achieved through the integration of a post loaded T-shape antenna with low profile and a radio-frequency circuit board. The evaluation result shows that the developed modem is capable of capturing in the received SS signal sufficiently fast to realize the high speed acquisition. The capability of the acquisition in severe communication environment is also shown. �@
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