Serial code format optimized for remote control applications over noisy communications channel

• US 5,572,555 A
• Filed: 06/15/1994
• Issued: 11/05/1996
• Est. Priority Date: 06/15/1994
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Soenen, Eric G., Davis, Gregory B.
• Primary Examiner(s): Bocure, Tesfaldet
• Application Number:
  US08/259,820
• Time in Patent Office: 874 Days
• Field of Search: 375/368, 375/364, 375/237, 375/340, 375/236, 375/259, 375/295, 375/316, 340/825.14, 340/825.65, 340/825.67
• US Class Current: 375/364
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 2209/06 Involving synchronization or resynchronization between transmitter and receiver; reordering of codes
• CPC Class Codes: G07C 9/00182 operated with unidirectional data transmission between data carrier and locks
• CPC Class Codes: H04L 1/246 two-level transmission codes, e.g. binary
• CPC Class Codes: H04L 25/069 by detecting edges or zero crossings
• CPC Class Codes: H04L 25/4908 using mBnB codes
• CPC Class Codes: H04L 7/044 using a single bit, e.g. start stop bit

Abstract

A transmitted data stream in a remote control system is a serial data stream having a synchronization sequence and a data sequence. The data sequence is encoded into a symbol comprised of a series of data bits wherein a 110 may represent a logic 1 and a 011 may represent a logic 0. A self adaptive filter adjusts its gain and offset to determine the duration of one bit. Providing a serial code format wherein the synchronization sequence has a smiller duty cycle as the duty cycle of a symbol aids the self adaptive filter to set its threshold switching level accurately and quickly, thus aiding the receiver to decode the transmitted data stream.

Claims

1. A method of decoding a data transmission in a remote control access system of a serial data stream comprising the steps of:

transmitting the serial data stream having a synchronization sequence and a data sequence, the synchronization sequence comprised of a plurality of high pulses and low pulses of about equal time length, the data sequence comprised of a plurality of high data pulses of time length L1 and low data pulses of time length L0, encoded into data symbols by three data pulses having a total time length L where L=L1+L0; and

decoding the serial data stream by;

recognizing said synchronization sequence when eight pair of consecutive high/low pulses are received for which 3/8 L≦

L1≦

5/8 L;

assigning a unit value UL to the time length of one high/low synchronization pulse of said synchronization sequence; and

recognizing a data symbol of said data sequence according to 11/8 UL≦

L≦

13/8 UL.

2. The method of claim 1 further comprising the step of:

recognizing a data symbol of said data sequence having a logical "1" according to 7/8 UL≦

L1≦

9/8 UL; and

recognizing a data symbol of said data sequence having a logical "0" according to 3/8 UL≦

L0≦

5/8 UL.

3. The method of claim 1 further comprising the step of:

recognizing a data symbol of said data sequence having a logical "1" according to 3/8 UL≦

L1-L0≦

5/8 UL;

recognizing a data symbol of said data sequence having a logical "0" according to 3/8 UL≦

L0-L1≦

5/8 UL.