Viterbi decoder

• US 7,062,000 B1
• Filed: 03/14/2000
• Issued: 06/13/2006
• Est. Priority Date: 01/29/1999
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kishino, Masahiko
• Primary Examiner(s): Ghebretinsae, Temesghen
• Application Number:
  US10/070,802
• Time in Patent Office: 2,282 Days
• Field of Search: 375/341, 375/262, 714/795, 714/796, 714/794
• US Class Current: 375/341
• CPC Class Codes: H03M 13/4107 implementing add, compare, select [ACS] operations
• CPC Class Codes: H03M 13/6577 Representation or format of variables, register sizes or word-lengths and quantization
• CPC Class Codes: H03M 13/6591 Truncation, saturation and clamping

Abstract

In a Viterbi decoder a bit range converter (11) is provided for converting a bit range of the branch metric values calculated by a branch metric calculator (1) to meet the number of calculation bits used in an ACS portion (2). The bit range converter (11) is provided between branch metric calculator (1) and ACS portion (2). The decoder reads the received data and calculates the branch metrics, optimizes the branch metrics, changes the path metric, and stores it into the path memory until the frame is completed. When one frame has been completed the decoded result is output by backtracing.

Claims

1. A Viterbi decoder comprising:

a branch metric calculating portion for calculating a branch metric value based on a received sequence;

a bit range converting portion for converting a bit range of the branch metric value calculated by the branch metric calculating portion by truncating a least significant bit of the branch metric value calculated by the branch metric calculating portion;

a path metric calculating portion for calculating a path metric value based on the branch metric value whose bit range has been converted by the bit range converting portion; and

a decoding portion for decoding received codes based on the path metric value calculated by the path metric calculating portion.

2. A method of Viterbi decoding comprising the steps of:

calculating a branch metric value based on a received sequence;

calculating a path metric value based on the branch metric values; and

decoding a received codes based on the path metric value,

the method further comprising;

converting a bit range of the branch metric value by truncating a least significant bit of the branch metric value;

calculating the path metric value based on the branch metric value whose bit range has been converted.