| 摘要 |
PURPOSE: A digital cordless telephone apparatus and a method therefor are provided to transmit/receive digital voice data and digital command data between a handset and a base unit. CONSTITUTION: A microprocessor based battery powered portable handset unit and a microprocessor based stationary base unit transmit/receive digital voice data and digital command data to/from one another over multiple RF channel frequencies in the 902-928MHz band. A user's voice is digitized, scrambled and modulated for transmission. Upon reception, the modulated digital voice data signal is demodulated, descrambled and decoded. A command data-voice data interface inserts command data packets into the stream of digital voice data prior to transmission, and locates and captures command data packets from the incoming stream of received digital data. A silence sequence replaces the captured command data packet such that no audible sound is heard by the user. A link check command signal is also periodically transmitted by the base unit and is acknowledged by the handset unit to evaluate the quality of the RF link toward triggering an automatic channel change or signaling an out-of-range condition. |
