L2 is the second civilian GPS signal designed for commercial needs. Its name refers to the radio frequency (1227 MHz, or L2) the signal uses and the fact that it is for civilian use. There are also two military signals on the L2 frequency. When used in conjunction with the L1 C/A in a dual frequency receiver, the L2 enables ionospheric correction, a technique that improves accuracy. Civilians with dual-frequency GPS receivers enjoy the same (or better) accuracy as the military. For professional users of existing dual-band operation, the L2 offers faster signal acquisition, higher reliability, and greater operating range. L2 broadcasts at higher effective power than traditional L1 C/A signals, making it easier to receive under trees or even indoors
Half of the GPS constellations now transmit the new civil signal L2. In a few weeks, when the IIF-10 is set to be active and available to users, that number will peak in most constellations. By the end of the year or early 2016, look for 18 available satellites transmitting L2. This could be considered a nominal initial operational capability (IOC), although the Air Force is unlikely to declare it as such. We can expect to have full operational capability (FOC) within five years. Many high-precision GPS receivers currently have L2 signal processing capabilities. It is also the most widely used signal band for civilian GPS trackers.
L2 GPS jammer has better signal transmission rate and is generally used by more professional personnel or institutions. So you have to use a targeted L2 GPS jammer.
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