Energy efficient remote control protocol with improved reliability

• US 5,958,081 A
• Filed: 10/11/1995
• Issued: 09/28/1999
• Est. Priority Date: 10/11/1995
• Status: Expired due to Fees

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Ford Motor Company
• Inventors: Desai, Tejas B., Lemense, Thomas J.
• Primary Examiner(s): Chung, Phung M.
• Application Number:
  US08/541,092
• Time in Patent Office: 1,448 Days
• Field of Search: 371/57.1, 371/53, 371/37.7, 371/49.1, 371/20.1, 371/48, 371/37.01, 371/61, 395/142, 395/185.05, 395/550, 370/13, 359/142, 359/145, 714/811, 714/752, 714/758, 714/814, 714/799
• US Class Current: 714/811
• CPC Class Codes: G08C 19/24 using time shift of pulses
• CPC Class Codes: H04B 14/026 using pulse time characteristics modulation, e.g. width, position, interval
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00

Abstract

An energy efficient remote control protocol uses a start bit which has a variable length which corresponds to the parity of the transmitted symbol, a guard time which is fixed at a predetermined length, and a data transmission time which corresponds to the data to be transmitted. The data to be transmitted is transmitted as a logic low, thus improving the energy efficiency of the system. During the transmission of a code, only one stop bit is used at the end of the transmission. The guard time and parity check are used to verify proper transmission.

Claims

1. A remote control system comprising:

a transmitter for generating a transmission of a code, said code having a plurality of bits, said transmitter grouping said bits into a plurality of groups, each of said groups having a parity and a numeric value, said transmission having a plurality of segments corresponding to each of said groups, each of said segments having a start bit corresponding to said parity of said group and a data length corresponding to said numeric value of said group, said data length being determined by a length of time between successive start bits;

a memory;

a receiver connected to said memory for receiving said transmission and converting said transmission into a received code based on said data length of each of said segments and comparing said code to a stored code in said memory and enabling a function if said received code matches said stored code.

2. A remote control system as recited in claim 1 wherein said receiver separates said transmission into segments, each segment having a start bit and said data length, said receiver converting said data length into a numeric value having a parity, said start bit having a corresponding parity associated therewith, said receiver comparing said parity corresponding to said start bit to said parity of said numeric value, and if said parity of said numeric value is not equal to the parity indicated by said start bit, providing an indication of corrupt data.

3. A remote control system as recited in claim 1 wherein each of said segments has a guard time included in said length of time between successive start bits, said receiver comparing said guard time and said length of time between successive start bits, and if said length of time between successive start bits is less than said guard time, providing an indication of corrupt data.

4. A remote control system as recited in claim 1 wherein each of said segments has a first logic level start bit corresponding to said parity of said group and a second logic level data length corresponding to said numeric value of said group.

5. A remote control system as recited in claim 1 wherein said first logic level is a high logic level.

6. A remote control system as recited in claim 1 wherein said second logic level is a low logic level.

7. A remote control system as recited in claim 1 wherein said transmitter generates a single stop bit after said transmission.

8. A remote control system comprising:

a transmitter having;

a code register for storing a code having a plurality of bits, said code register grouping said plurality of bits into a plurality of groups each having a respective numeric value;

a parity encoder connected to said code register for determining the parity of each group;

a modulator connected to said parity encoder for converting said groups into a plurality of segments each segment having a start bit and a data length, said start bit corresponding to said parity of said group and said data length of said group having a length corresponding to said numeric value; and

an emitter connected to said modulator for generating a transmission encoding first and second logic levels defining said data length as a time period between successive start bits for successive segments; and

a receiver having;

a detector for receiving said transmission;

a demodulator connected to said detector for separating said transmission into segments, each of said segments having a start bit and a data length;

a timing controller connected to said demodulator for measuring time between successive start bits to determine said data lengths;

said demodulator converting said data lengths into a received code;

a code register for storing a stored code;

a code comparator connected to said demodulator and said code register for comparing said stored code and said received code; and

an output driver for enabling a function if said stored code is equal to said received code.

9. A remote control system as recited in claim 8 wherein said modulator generates a guard time within each of said segments, said comparator comparing said guard time and said data length, and if said data length is less than said guard time, providing an indication of corrupt data.

10. A remote control system as recited in claim 9 wherein said guard time has a second logic level.

11. A remote control system as recited in claim 9 wherein said start bit having a first logic level.

12. A remote control system as recited in claim 9 wherein said data length having a second logic level.

13. A remote control system as recited in claim 9 further comprising an error detector connected to said demodulator comparing said parity corresponding to said start bit to said parity of said received code, said error detector generating an error signal if said parity corresponding to said start bit is not equal to said parity of said received code.

14. A method for operating a remote control device having a transmitter and a receiver, said receiver having a memory, said transmitter generating a transmission of a code, comprising the steps of:

generating a code, said code having a plurality of bits;

grouping said bits into a plurality of groups;

determining a parity and a numeric value for each of said groups;

transmitting a code having a plurality of segments each corresponding to a respective one of said groups, each of said segments having a start bit corresponding to said parity of said respective group and a data length corresponding to said respective numeric value, said data length being determined by a length of time between successive start bits of successive segments;

receiving said transmission;

converting said transmission into a received code based on said received data length of each of said segments;

comparing said code to a stored code in said memory of said receiver; and

enabling said remote control device if said received code matches said stored code.

15. A remote control system as recited in claim 14 further comprising the steps of:

converting said data length into a numeric value having a parity;

comparing said parity corresponding to said received start bit to said parity of said numeric value; and

if said parity of said numeric value is not equal to the parity indicated by said start bit, providing an indication of corrupt data.

16. A remote control system as recited in claim 14 wherein each of said segments has a predetermined guard time, said method further comprising the steps of:

comparing said received data length to said predetermined guard time; and

if said received data length is less than said predetermined guard time, providing an indication of corrupt data.