Patent ID: 6278722
Filing Date: 2001-08-21
Classification: H04B,H04L

Abstract:
A cordless telephone comprising:a base unit connectable to a telephone line, the base unit including a first transmitter and a first receiver;a handset unit for communicating with the base unit over any one of a plurality of communication channels in a frequency hopping system, the handset unit including a second transmitter and a second receiver for respectively transmitting to the first receiver and receiving from the first transmitter in the base unit;delta modulation circuitry for encoding audio signals in said base unit and said handset unit, said audio signals being encoded for transmission by said first and second transmitters for reception respectively by said second and first receivers; andintermediate frequency circuitry in said base unit and handset unit for modulating a reference frequency signal used for communicating over one of said plurality of communication channels, said intermediate frequency circuitry employing a first intermediate frequency signal for modulating said reference frequency signal for transmission by said first transmitter and a second intermediate frequency signal for modulating said reference frequency signal for transmission by said second transmitter, said reference frequency signal operating at substantially the same frequency in both the handset unit and the base unit, said first intermediate frequency signal and said second intermediate frequency signal are different frequencies for simultaneous transmission and receptions; wherein both said base unit and handset unit include frequency diversity circuits for transmitting both an upper and a lower sideband signal on each one the plurality of communication channels during a frequency hopping sequence for said handset and base units, said sideband signals being indicative of encoded audio signals being transmitted by both said handset and base units.