Digital cordless telephone apparatus

• US 5,297,203 A
• Filed: 01/06/1993
• Issued: 03/22/1994
• Est. Priority Date: 05/29/1991
• Status: Expired due to Term

• Current Assignee: Video Technology Engineering Limited
• Original Assignee: Video Technology Engineering Limited
• Inventors: Rose, Chris, Heung, Charley
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): Bost, Dwayne D.
• Application Number:
  US08/001,026
• Time in Patent Office: 440 Days
• Field of Search: 370/110.1, 370/111, 370/118, 379/61, 379/62, 379/63, 375/5, 375/104, 380/9, 380/23
• US Class Current: 380/270
• CPC Class Codes: H04M 1/724 User interfaces specially adapted for cordless or mobile telephones
• CPC Class Codes: H04M 1/72505 Radio link set-up procedures
• CPC Class Codes: H04M 1/72516 with means for out-of-range alerting
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A digital cordless telephone apparatus comprising a microprocessor based battery powered portable handset unit and a microprocessor based stationary base unit which each transmit and receive digital voice data and digital command data to and from one another over multiple RF channel frequencies in the 902-928 MHz band, is disclosed. The user'"'"'s voice is digitized, scrambled and modulated for transmission and 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 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.

Claims

1. An improved digital cordless telephone apparatus of the type having a microprocessor based battery powered portable handset unit and a microprocessor based stationary base unit which each transmit and receive distinct digital voice data and digital command data to and from one another over a radio frequency link, wherein the improvement includes a command data - voice data interface means or inserting said digital command data, int the form of a command data packet, into a stream of said digital voice data transmitted between said handset unit and said base unit and for locating and capturing said command data packet from a received digital voice data signal stream, and comprising:

security code register means associated with said portable handset unit for storing said security code generated by said base unit microprocessor;

firs microprocessor interface means associated with said portable handset unit for receiving from said base unit microprocessor said security code toward transferring said security code to said security code register means and for receiving a digital command code from said handset unit microprocessor for transmission to said base unit;

transmitter register means associated with said portable handset unit for receiving as an input said digital voice data to be transmitted to said base unit;

transmitter register controller means associated with said portable handset unit for controlling the transfer of said digital voice data to said transmitter register means, said transmitter register controller means further serving to transfer said security code from said security code register means to said transmitter register means, and to transfer said digital command code from said first microprocessor interface means to said transmitter register means, said security code and said digital command code together forming said command data packet, said transmitter register controller means further causing the flow of said digital voice data through said transmitter register means to be interrupted and said command data packet to be inserted into said stream of said digital voice data for transmission to said base unit;

receiver register means associated with said base unit for receiving as an input said stream of said digital voice data intermixed with said command data packets;

receiver register controller means associated with said base unit for controlling the transfer of said stream of digital voice data intermixed with said command data packets into said receiver register means, said receiver register controller means further serving to transfer said stream of digital voice data intermixed with said command data packets to a security code comparator means;

said security code comparator means serving to locate and identify said command data packets intermixed within said stream of digital voice data toward causing said receiver register means to transfer said command data packets to a second microprocessor interface means associated with said base unit toward connection to said base unit microprocessor, said receiver register controller means further serving to replace said command data packet with a quiet sequence data packet, said digital voice data nd said quiet sequence data packet being transferred to the output of said receiver register controller means for further operation by said base unit.

2. In a digital cordless telephone apparatus of the type having a microprocessor based battery powered portable handset unit and a microprocessor based stationary base unit which each transmit and receive distinct digital voice data and digital command data to and from one another over a radio frequency link, each of said handset and base units including a command data - voice data interface means which includes a security code register means, microprocessor interface means, transmitter register means, transmitter register controller means, receiver register means and receiver register controller means, a method for transmitting said digital command data intermixed with said digital voice data, and for receiving said intermixed digital data nd recovering said digital command data, said method comprising the steps of:

transferring said digital voice data to a command data interface means connected between a voice signal digitizer and voice signal transmitter and between a voice signal receiver and a voice signal decoder within each of said handset unit and said base unit,

transmitting said intermixed digital data by

transferring a security code stored in said security code register to said transmitter register means;

transferring said digital command data from said microprocessor interface means to said transmitter register means, thereby forming a command data packet composed of said security code and said digital command data;

inserting said command data packet into a steam of said digital voice data generated by said voice signal digitizer prior to transmission by said voice signal transmitter;

receiving said intermixed digital data nd recovering said digital command data by

transferring said intermixed digital data received by said voice signal receiver means to said receiver register means;

transferring said intermixed digital data from said receiver register means to said comparator means;

scanning said intermixed digital data transferred to said comparator means toward identifying a match between said security code stored in said security code register means and said intermixed digital data thereby locating said command data packets within said stream of said digital voice data,

transferring located command data packets to said microprocessor interface means toward execution of said digital command data,

resetting located command data packet in said receiver register means with a quiet sequence data packet,

transferring said digital voice data intermixed with said quiet sequence data packet to said voice signal decoder mean which in turn treats said quiet sequence data packet intermixed with said digital voice data as silence thereby precluding the generation by said voice signal decoder means of an undesirable audible sound which should otherwise be generated by said voice signal decoder means if said command data packet were decoded by said voice signal decoder means.

3. The invention according to claim 2 wherein said method further includes the steps of:

scrambling said intermixed digital data comprising said stream of said digital voice data signals and said inserted command data packet prior to transmission by said voice signal transmitter to thereby minimize the potential that unintended persons listening to the transmission frequency of said radio frequency link may monitor said conversation; and

unscrambling said intermixed digital data comprising said stream of said digital voice data signals and said inserted command data packet upon receipt by said voice signal receiver.

4. In a digital cordless telephone apparatus of the type having a microprocessor based battery powered portable handset unit and a microprocessor based stationary base unit which each transmit and receive distinct digital voice data and digital command data to and from one another over a radio frequency link, a method for transmitting said digital command data intermixed with said digital voice data, and for receiving said intermixed digital data and recovering said digital command data, said method comprising the steps of:

transferring said digital voice data to a command data-voice data interface mans connected between a voice signal digitizer an voice signal transmitter and between a voice signal receiver and voice signal decoder within each of said handset unit and said base unit;

transmitting said intermixed digital data by

inserting said digital command data in the form of a command data packet into a stream of said digital voice data generated by said voice signal digitizer prior to transmission by said voice signal transmitter;

receiving and recovering said digital command data by

locating said command data packets within said stream of said digital voice data received by said voice signal receiver,

transferring located digital command data packets to said microprocessor for execution of said digital command data,

replacing located command data packets with a quietly sequence data packet,

transferring said digital voice data intermixed with said quiet sequence data packet to said voice signal decoder which treats said quiet sequence data packet as silence thereby precluding the generation by said voice signal decoder of a sound which would otherwise be generated by said voice signal decoder if said command data packet were decoded.

5. An improved digital cordless telephone apparatus of the type having a microprocessor based battery powered portable handset unit and a microprocessor based stationary base unit which each transmit and receive distinct digital voice data and digital command data to and from one another over a radio frequency link, wherein the improvement includes a command data - voice data interface means for inserting said digital command data is not a stream of said digital voice data transmitted between said handset unit and said base unit and for locating sand capturing said command data packet from a received said stream of said digital voice data signal stream and comprising:

microprocessor interface means for receiving a digital command data code from said handset unit microprocessor for transmission to said base unit;

transmitter register means for receiving as an input said digital voice data of be transmitted to said base unit;

transmitter register controller means for controlling the transfer of said digital voice data to said transmitter register means, said transmitter register controller means further serving to transfer said digital command data code from said microprocessor interface means to said transmitter register means, said transmitter register controller means further causing the flow of said digital voice data through said transmitter register means to be interrupted and said digital command data code to be inserted into said stream of said digital voice data for transmission to said base unit;

receiver register means for receiving as an input said digital voice data intermixed with said digital command data code;

receiver register controller means or controlling the transfer of said intermixed digital data into said receiver register means, said receiver register controlled further serving to transfer said intermixed digital data signal to a comparator means, said comparator means serving to locate and identify said command data code within said intermixed digital data toward causing said receiver register means to transfer said digital command data code to said microprocessor interface means toward connection to said base unit microprocessor, said receiver register controller means further serving to replace said digital command data code with a quiet sequence data packet, said digital voice data nd said quiet sequence data packet being transferred to the output of said receiver register controller means for further operation by said base unit.

6. An improved digital cordless telephone apparatus of the type having a microprocessor based battery powered portable handset unit and a microprocessor based stationary base unit which each transmit and receive distinct digital voice data nd digital command data to and from one another over a radio frequency link, wherein the improvement includes a command data - voice data interface means for inserting said digital command data, in the form of a command data packet, into a stream of said digital voice data transmitted between said handset unit and said base unit and for locating and capturing said command data packet from a received digital voice data signal stream, and comprising:

security code register means associated with said base unit for storing said security code generated by said base unit microprocessor;

first microprocessor interface means associated with said base unit for receiving from said base unit microprocessor said security code toward transferring said security code to said security code register means, and for receiving a digital command code from said handset unit microprocessor for transmission to said base unit;

transmitter register means associated with said base unit for receiving as an input said digital voice data to be transmitted to said portable handset unit;

transmitter register controller means associated with said base unit for controlling the transfer of said digital voice data to said transmitter register means, said transmitter register controller means further serving to transfer said security code from said security code register means to said transmitter register means, and to transfer said digital command code from said first microprocessor interface means to said transmitter register means, said security code and said digital command code together forming said command data packet, said transmitter register controller means further causing the flow of said digital voice data through said transmitter register means to be interrupted and said command data packet to be inserted into said stream of id digital voice data for transmission to said base unit;

receiver register means associated with said portable handset unit for receiving as an input said stream of said digital voice data mixed with said command data packets;

receiver register controller means associated with said portable handset unit for controlling the transfer of said stream of digital voice data intermixed with said command data packets into said receiver register means, said receiver register controller means further serving to transfer said stream of digital voice data intermixed with said command data packets to a security code comparator means;

said security code comparator means serving to locate and identify said command data packets intermixed within said stream of digital voice data toward causing said receiver register means to transfer said command data packets to a second microprocessor interface means associated with said portable handset unit toward connection to said portable handset unit microprocessor; and

said receiver register controller means further serving to replace said command data packet with a quiet sequence data packet, said digital voice data and said quiet sequence data packet being transferred to the output of said receiver register controller means for further operation by said base unit.