NOAA-17 is a weather forecasting satellite run by NOAA. It was launched on 24 June 2002, and is currently operational, in a sun-synchronous orbit

Sun-synchronous orbit

A Sun-synchronous orbit is a geocentric orbit which combines altitude and inclination in such a way that an object on that orbit ascends or descends over any given point of the Earth's surface at the same local mean solar time. The surface illumination angle will be nearly the same every time...

, 824 km above the Earth, orbiting every 101 minutes. It hosts the AMSU

Advanced Microwave Sounding Unit

The Advanced microwave sounding unit is a multi-channel microwave radiometer installed on meteorological satellites. The instrument examines several bands of microwave radiation from the atmosphere to perform atmospheric sounding of temperature and moisture levels.-Products:Level-1 radiance data...

, AVHRR and High Resolution Infrared Radiation Sounder (HRIS) instruments.

APT

Automatic Picture Transmission

The Automatic Picture Transmission system is an analog image transmission system developed for use on weather satellites. It was introduced in the 1960s and over four decades has provided image data to relatively low-cost user stations at locations in most countries of the world...

transmission frequency is 137.62 MHz