L1/L2CS GPS Receiver Implementation with Fast Acquisition Scheme

The L2 Civil Signal (L2CS) will be transmitted by modernized IIR(IIR-M), IIF and all subsequent GPS satellites. It contains two codes of different length; CM code contains 10,230chips, repeats every 20milliseconds and is modulated with message data, and CL code contains 767,250chps, repeats every 1.5second Z-count and has no data modulation. And the message data is encoded for Forward Error Correction (FEC). Although it has a good cross-correlation performance by the long code length, but the acquisition time should be long. Because the acquisition time is directly proportional to the code length and/or code period. Therefore it takes about 100 hours for L2C signal acquisition in case of 20ms integration. So, there should be a fast signal acquisition scheme. There are many methods to reduce the acquisition time, but most of them require the modification of the correlator. The L1 aiding method does not require any modifications and it can acquire the L2C signal as fast as the L1 signal. Finally, the L1 aiding method would be confirmed by experimental results in this paper and the acquisition and tracking of L1 and L2C signal also would be shown.