Voice Encoder Using a DSP Chip
Brian Rockwood and Jason D. Brooks
Advisor: Dr. T. L. Stewart
The purpose of this project is to encode a voice signal to be transmitted
from a source to a receiver using digital technology. By reversing the
frequencies in a voice pattern, the original voice signal can be scrambled.
This reversal of frequencies is accomplished by mixing the voice signal
with a cosine wave having a frequency equal to the sum of the highest and
lowest frequencies of the voice signal. The output of the mixer is then
sent to a low pass filter where the encoded message is extracted. The encoded
voice is then passed along to a receiver where it undergoes the exact same
process to decode the information, thus recovering the original voice signal.
We achieved this encoding by performing the aforementioned steps on a digital
signal processing chip (Texas Instrument's TMS320C26). Digital signal processing
chips are becoming more popular in all forms of electronics today. Technology
like this will be useful specifically to help prevent outside parties from
overhearing cellular and cordless phone transmissions.
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