jncraton / nrz-decode

Computer networks lab assignment to decode NRZ data from a wav file

NRZ Decoder

This project provides the scaffold to build a basic non-return-to-zero decoder.

Task

The file decode.py provides a simple framework and several unit tests for a decoder. It can be invoked as (assuming that your system Python 3 interpretter is python3):

python3 decode.py message.wav

Invoked in this way, it will decode the data in message.wav and return it as a string.

The tests are implemented as doctests and can be run using:

python3 -m doctest decode.py

They can also be run by invoking make test assuming that GNU make or equivelent is in your path.

Protocol Description

The included message.wav file is a playable sound file that encodes a message using the following scheme (very similar to RS232). It is encoded using 16 bits per sample and a sample rate of 44.1k samples per second.

The message is first encoded using UTF-8 and then split into bytes. Prior to sending a byte, a single start bit (0) is transmitted followed by the 8 bits in the byte, beginning with the least significant bit. A stop bit (1) is sent at the end of each byte.

The transmission uses a baud rate of 300.