Spacecrafts in this series are launched every 2 or 3 years so that there are always at least two operational satellites, sometimes as many as four. The NOAA launch schedule is known till 2007. The satellites are in sun-synchronous orbits, i.e. a satellite passes any territory approximately in the same local time every day, but passes of different satellites are distributed in time as uniformly as possible. The orbit altitude is about 800 km and the orbits pass near the Earth poles. Taking into account the swath width, this guarantees at least 4 good images a day of any surface patch from each satellite.
HRPT format includes all scientific and calibration data.
The format is digital, the data are transmitted by means of BPSK modulation of the carrier frequency in 1.7 GHz radio wave band. The data rate is equal to 665.4 Kbps. To receive HRPT you can use our ScanEX stations . To receive APT Liana stations are intended. DSB is a digital format used to download data from the low-rate sensors in 137 MHz band.