Inventors:
Randall L. Grunwell - Suwanee GA
Assignee:
Matsushita Communication Industrial Corp. of America - Peachtree City GA
International Classification:
H04M 1100
Abstract:
A car radiotelephone system having one or more wireless handsets communicating voice and control information via an ultrasonic link with a stationary unit connected functionally to a base station. The base unit (1) is connected by two cables, an audio-out cable (a) connected to the radio frequency receiver (2) and an audio-in cable (b) connected to the radio frequency transmitter (3), to a stationary transmitting/receiving unit (4). The stationary transmitting/receiving unit consists of two summing amplifiers, transmitting summing amplifier (5) and receiving summing amplifier (6), and any number of ultrasonic transmitters and receivers. Likewise, any number of handsets can be used. The handsets (15) comprise an ultrasonic receiver (19), an ultrasonic transmitter (20), transmitter and receiver circuitry (27), a keypad (28), display circuitry (29), microphone (30), earpiece/speaker (31), and a rechargeable battery and ringer. Each ultrasonic transmitter in the stationary unit and the handsets operate at a different frequency or other independent non-interfering methods so as to permit full duplex transmission.