To: Dr. Winfred Anakwa

From: Jennifer Dilliner & Melissa DePriest

Date: October 30, 2001

Subject: Complete System Level Block Diagram

Title: Hamming Code Error Detector/Decoder

Overall system

The overall system receives, from a source, a 7-bit vector input that consists of four bits of information and three bits of parity. The system also contains three 7-bit error-checking vectors. The system will output a signal indicating whether or not the signal input was correct as well as a 4-bit information vector decoded from the b vector if the input was correct. The various subsystems are described below. Diagram 1 describes the subsystems in tabular format. Diagram 2, a detailed block diagram, will help clarify the following descriptions.

B vector

The b vector is the 7-bit vector input from the source, which is stored in a 7-bit register. If the signal is correct, the vector will be decoded and output from the system as a 4-bit vector. If the signal is incorrect, the vector will be retransmitted by the source and restored in the 7-bit register.

H matrix

The H matrix is a three by seven matrix, which takes its input from three 7-bit error-checking vectors. The vectors are stored in three 7-bit registers. The data is then sent through three tri-state buffers that direct which signal to be output into the matrix multiplier circuitry using a controller.

Matrix Multiplier Circuit

The matrix multiplier circuit takes its input from the H matrix and the b vector to form the new 3-bit vector, S. The circuitry will perform the following function: H*b = S. The resulting S vector will be sent to the error-checking subsystem for analysis.

Error Checking Circuit

This circuit detects if an error is present in the b vector transmitted from the source. It receives the S vector and, through analysis of the bits, outputs a signal to indicate if an error is or is not present.

Decoder Circuitry

The decoder subsystem receives the 7-bit b vector as input and decodes the signal by removing the three parity bits and outputting a 4-bit information vector.

 Subsystem Inputs Outputs Source Signal indicating if error is detected 7-bit vector b vector Seven bits from source and signal indicating if error is detected Stored 7-bit vector H matrix Error-checking vectors Three 7-bit vectors Matrix Multiplier Circuitry Stored 7-bit signal from b vector and three 7-bit vectors from H matrix 3-bit S vector Error-Checking Circuit 3-bit S vector from matrix Signal indicating error or no error detected Decoder Circuitry Stored 7-bit b vector 4-bit decoded vector

Diagram 1: Subsystems with I/O Descriptions

Diagram 2: Complete Block Diagram