Title:
PRIVACY TELEPHONE SET
Document Type and Number:
Japanese Patent JPH0522281
Kind Code:
A
Abstract:
PURPOSE: To surely prevent interception by the 3rd party by varying a conversion/decoding circuit in a programmable logic for each required time at any time.
CONSTITUTION: Plural kinds of conversion/decode circuits are revised by programmable logic circuits 14, 24 and the revision of the conversion/decode circuit with respect to the programmable logic circuits 14, 24 is instructed by a control circuit 15 based on a circuit data received from an opposite party, a circuit data designated from an external device or a circuit data reserved in the inside at any time.
Inventors:
HANE TOSHINAO
Application Number:
JP19833691A
Publication Date:
January 29, 1993
Filing Date:
July 15, 1991
Export Citation:
Assignee:
MITSUBISHI ELECTRIC CORP
International Classes:
H04L9/14; H04L9/18; (IPC1-7): H04L9/00; H04L9/10; H04L9/12
Domestic Patent References:
| JP89007375Y | ||||
| JPH03500117A | 1991-01-10 | |||
| JPS63278438A | 1988-11-16 |
Foreign References:
| US4914697A | 1990-04-03 | |||
| US4484025A | 1984-11-20 |
Attorney, Agent or Firm:
Hiroaki Tazawa (2 outside)