Data
In our experiment, seven
different signals were encoded and added together in the channel, the maximum
number possible for an 8 bit Walsh code.
Each was recovered perfectly from the summed encoded signals. See the Matlab
code for actual implementation.
Click on the wave files
below to listen to the signals used in the experiment. For improved listening, these are six second
signals, though only one second signals were used in the actual
experiment. Since signals were
perfectly recovered before addition of noise, “Decoded” and “Original” signals
are the same and are only listed once.
Original and Decoded |
Noisy(Channel SNR of 10dB) |
Measurements were made of
the recovered signal SNR using Gaussian white noise added to simulate negative
effects of a channel. Because of the
length of signals used(one second), low noise levels frequently led to perfect
recovery; the maximum resolvable SNR in our experiment was approximately 58
dB. This value was exceeded for channel
SNR’s above 12-13 dB.
In this experiment, three
different signals were added together in the channel and recovered. 21 bit Gold Codes were used, and 8 code bits
were used to encode each data bit. See
the Matlab code for actual implementation.
Click on the links below to
play the wave files of the signals before and after our simulated
transmission. All signals used in this
portion had a six second duration.
“Decoded” contains the
signals individually decoded from the sum of the three signals, while “Noisy”
contains the signals individually decoded from the sum of the three signals and
enough noise to make the channel SNR approximately 10dB.
Original |
Decoded |
Noisy(Channel SNR of 10dB) |
Measurements were made of
the recovered signal SNR using Gaussian white noise added to simulate negative
effects of a channel.
©2001 Kyle Bryson, Alison
Chen, and Allen Wan