SPREIZSPEKTRUM-KOMMUNIKATIONSSYSTEM IN MEHRFACHBAND- UND MEHRFACHMODETECHNIK

摘要

A technique for spread-spectrum communication (figs. 1, 3, 12 and 14) which uses more than one mode and more than one frequency band. Selectable modes include a narrowband mode (113) and spread-spectrum mode (111), or cellular mode and microcellular mode. Selectable frequency bands include both licensed and unlicensed frequency bands, particularly frequency bands including the 902-928 MHz, 1850-1990 MHz and 2.4-2.4835 GHz frequency bands. Spread-spectrum communication channels are 10 MHz or less in width. The frequency band onto which spread-spectrum signals are encoded may be changed upon a change in environment or other control trigger, such as establishment or de-establishment of a communication with a private access network. A multi-band transmitter (fig. 12) comprises a single frequency synthesiser and a frequency source (606) (e.g. a local oscillator), coupled to selectable band pass filter (619, 620). A multi-band receiver (fig 14.) capable of monitoring one or more frequency bands comprises bank of bandpass filters (714, 715) and a demodulator comprising a single frequency synthesiser and a frequency source (721).