A method is disclosed for receiving transmitted signals in the presence of
CW interference in a communication system that determines the presence of
a code in a received signal by comparing with a detector threshold
calculations made in accordance with a sample of a received signal. Such
systems include but are not limited to those incorporating a Sequential
Probability Ratio Test. The method includes obtaining a first input power
value of the received signal at a first sample time and obtaining a second
input power value of the received signal at a second sample time. The
first and second power values are compared in order to provide an input
sample comparison and the forgoing steps are repeated in order to provide
a plurality of input sample comparisons. The detector threshold is
adjusted in accordance with the plurality of sample comparisons.
The CW signal can be strongly correlated with a short code used for the
acquisition purposes. Therefore in the CDMA systems if the received signal
contains a CW signal, then the strong correlation between the CW signal
and the short code used for acquisition may result in a false alarm. To
prevent this, the following algorithm is suggested to be used for the
cancellation of CW, if there is a CW signal present in the received CDMA
signal.
