Data

 

Forward Link

 

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)

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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.


SNR Data for 8 bit Walsh Codes

 

Reverse Link

 

 

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)

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Codes Used

 

Measurements were made of the recovered signal SNR using Gaussian white noise added to simulate negative effects of a channel.

 

SNR Data for 21 bit Gold Codes

 

©2001 Kyle Bryson, Alison Chen, and Allen Wan