Wideband UHF ISM-band transceiver supporting multichannel reception and DSSS modulation.

Wireless car keys, tire pressure sensors and wireless car diagnostic systems operate in the UHF ISM-bands using FSK/GFSK or ASK/OOK modulation with data rates between 0.5 and 200Kb/s. Recently, long-range car key applications have become popular, requiring the support of longer radio links within the boundaries of legislation and battery life. BPSK DSSS modulation allows increasing the transmitter power without violating legislation on maximum transmitted power density, but at the cost of having a non-constant RF signal envelope and a larger signal bandwidth. Unfortunately both these properties are not supported by classical narrow-band FSK/ASK transceivers.