User Guide

PAMS
Technical Documentation
NHD–4
System Overview
Page 3–30
Original 11/97
Walsh codes have the desirable characteristic of being “orthogonal” to each other.
What the heck does that mean(this is a rhetorical question)? ORTHOGONAL
Walsh Codes: when simultaneously transmitted they produce minimal interference
to other users. Look at the rows across in code set 4, any two rows have an equal
number of matches and mismatches. When correlation occurs between codes
(they match up) they will yield a cross correlation coefficient of 1. When the codes
do not match (correlate) the cross correlation coefficient is 0. Another way of
stating this is to say that when receiving the desired code a correlation receiver will
yield data and ignore all the unwanted codes.
Figure 30 overleaf should help sort out how Walsh orthogonal codes can keep
different CDMA users separated even though they are on the same frequency.