Cross-correlation performance comparison of L1 & L2C GPS codes for weak signal acquisition

The GPS constellation now contains six fully-operational Block IIR-M satellites. Each of these modernized satellites transmits the second GPS civil signal L2C. One of the key objectives of the L2C signal is to offer high cross-correlation protection, allowing weak signal acquisition in the presence of strong GPS signals in environments such as inside buildings and in urban canyons. The L2C signal achieves this by using longer spreading codes. The L2C signal is composed of CM and CL codes multiplexed together on a chip-by-chip basis. The CM code is 20 milliseconds long while the CL code has a length of 1.5 seconds [1]. The worst-case cross-correlation performance of CM and CL codes is about 2