GPS Frequencies.

GPS first began operations with two signals, L1 and L2. L1 operates at a frequency of 1575.42 MHz, whereas L2 operates at a frequency of 1227.60 MHz. These GPS signals include two ranging codes: P (Y) or Precision code and C/A (Carrier Acquisition) code. The first code is only for civilian usage, while the second is only for military use. These ranges codes are used to calculate the distance to the satellite as well as to uniquely identify the navigation message.

Although the GPS system has nearly reached its full operational capabilities, modernization and implementation of a new GPS system have recently begun due to increased demand for better service and technological improvements. The insertion of L5 GPS signals is part of the US Department of Defense’s modernization activities.

Now there are three civilian GPS frequencies: L1 at 1575.42 MHz, L2 at 1227.60 MHz, and L5 at 1176.45 MHz. Each frequency has unique properties that make it better suited for certain types of applications. For example, L1 frequency is used to track GPS satellite location, L2 frequency is used to track the health of the GPS satellites and the L5 frequency is used to improve accuracy for civilian use such as aircraft precision approach guidance.