Cordless telephone system

• US 4,661,970 A
• Filed: 05/28/1986
• Issued: 04/28/1987
• Est. Priority Date: 05/30/1985
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Akaiwa, Yoshihiko
• Primary Examiner(s): Lev, Robert G.
• Application Number:
  US06/868,140
• Time in Patent Office: 335 Days
• Field of Search: 179/2 E, 179/2 EA, 179/2 EB, 179/2 EC
• US Class Current: 455/462
• CPC Class Codes: H04M 1/72505 Radio link set-up procedures

Abstract

A cordless telephone system includes a plurality of radiophones, each having a first transmitter and a first receiver of different transmission and reception frequencies; and a radio station, wired to a telephone line. The radio station comprises a second receiver and a second transmitter, each having the same reception and transmission frequencies as those of the radiophones; switching means for connecting an input terminal of the second transmitter and an output terminal of the second receiver to the telephone line, or for connecting the input terminal of the second transmitter and the output terminal of the second receiver; and control means for receiving a control signal from the second receiver and supplying a control signal to the switching means. Half duplex communication can be performed between the radiophones.

Claims

1. A cordless telephone system including a plurality of radiophones, each having a first transmitter and a first receiver of different transmission and reception frequencies;

and a radio station, wired to a telephone line,

said radio station comprising;

a second receiver and a second transmitter, having reception and transmission frequencies which are respectively same as the transmission and reception frequencies of said radiophones;

switching means for connecting an input terminal of said second transmitter and an output terminal of said second receiver to said telephone line, or for connecting said input terminal of said second transmitter and said output terminal of said second receiver in accordance with a switching control signal; and

control means for receiving a control signal from said radiophones through said second receiver and supplying the switching control signal to said switching means, wherein half duplex communication can be performed between said radiophones.

2. A system according to claim 1, wherein said switching means of said radio station normally operates to connect said input terminal of said second transmitter and said output terminal of said second receiver to said telephone line;

said switching means switches to connect said input terminal of said second transmitter to said output terminal of said second receiver when a ringing signal supplied to said first transmitter is transmitted to said radio station in order to allow communication of said radiophone to another radiophone and a switching signal is supplied to said switching means through said second receiver and said control means; and

said switching means restores a normal connection in response to a control signal from said control means when said second receiver receives an end signal.

3. A system according to claim 1, wherein said radiophones transmit an audio signal by a press-to-talk signal.