NOAA-18 is a weather forecasting satellite run by NOAA. It was launched on 20 May 2005, and is currently operational, in a sun-synchronous orbit, 854km above the Earth, orbiting every 102 minutes. It hosts the AMSU-A, MHS, AVHRR and High Resolution Infrared Radiation Sounder (HIRS) instruments. It is the first NOAA POES satellite to use MHS in place of AMSU-B.

APT transmission frequency is 137.10 MHz