is a civilian-use signal, to be broadcast on the same L1 frequency (1575.42 MHz) that contains the C/A signal used by all current GPS users. L1C broadcasting will start when GPS III Control Segment (OCX) Block 1 becomes operational, currently scheduled for 2022. The L1C signal will reach full operational status when being broadcast from at least 24 GPS Block III satellites, currently projected for the late 2020s. Implementation will provide C/A code to ensure backward compatibility. Assured of 1.5 dB increase in minimum C/A code power to mitigate any noise floor increase. Non-data signal component contains a pilot carrier to improve tracking. Enables greater civil interoperability with Galileo L1. It is defined in IS-GPS-800. Improvements Increased signal power at the Earth's surface: M-code: −158 dBW / −138 dBW. L1 and L2: −157 dBW for the C/A code signal and −160 dBW for the P(Y) code signal. L5 will be −154 dBW. Researchers from The Aerospace Corporation confirmed that the most efficient means to generate the high-power M-code signal would entail a departure from full-Earth coverage, characteristic of all the user downlink signals up until that point. Instead, a high-gain antenna would be used to produce a directional spot beam several hundred kilometers in diameter. Originally, this proposal was considered as a retrofit to the planned Block IIF satellites. Upon closer inspection, program managers realized that the addition of a large deployable antenna, combined with the changes that would be needed in the operational control segment, presented too great a challenge for the existing system design. NASA has requested that Block III satellites carry laser retro-reflectors. This allows tracking the orbits of the satellites independent of the radio signals, which allows satellite clock errors to be disentangled from ephemeris errors. This, a standard feature of GLONASS, will be included in the Galileo positioning system, and was included as an experiment on two older GPS satellites (satellites 35 and 36). The USAF is working with NASA to add a Distress Alerting Satellite System (DASS) payload to the second increment of GPS III satellites as part of the MEOSAR search and rescue system. Control segment The GPS Operational Control Segment (OCS), consisting of a worldwide network of satellite operations centers, ground antennas and monitoring stations, provides Command and Control (C2) capabilities for GPS Block II satellites. The latest update to the GPS OCS, Architectural Evolution Plan 7.5, was operationally accepted in 2019.