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A DSSS-CDMA signal

a. A DSSS-CDMA signal has a chip sequence that is 10,000 chips in length. The sequence repeats every millisecond. What is the chip rate?

b. What is the message signal rate of the signal in part (a) above?

c. The transmitter and receiver for the signal in part (a) above are both stationary so there is no Doppler shift in the received signal. The receiver knows the correct code to use when searching for the transmitted signal. What is the longest acquisition time in this case?

d. What is the shortest possible acquisition time?

e. Other transmitters create similar DSS-CDMA signals that appear as interference to the receiver. If the receiver requires a minimum of 10 dB CNR in the message signal to successfully lock to the DSSS-CDMA signal, what is the lowest CNR in the RF section of the receiver for which lock can be achieved successfully?

Solution Preview

There are 10 000 chips in 1 ms or 10^-3s so the chip rate R_c (the number of chips in one second) is given by

R_c = 10000/10^-3 = 10M chips/s (10^8 chips/s)

The chip sequence repeats and is applied to each message bit/symbol every 1ms so the message rate R_M is just given as the ...

Solution Summary

The solution discusses a DSSS-CDMA signal and determines the chip rate.