HIRS/4 interface with the Payload Module

The HIRS/4 interfaces with the following Payload Module (PLM) units :

• the NOAA Instrument Interface Unit (NIU) provides all command and control interfaces to the HIRS/4, i.e. configuration and mode switching (commands), command verification, housekeeping telemetry acquisition, and clock and time management. The NIU also acquires the measurement data from the instrument
• the Power Conversion Unit (PCU) provides the HIRS/4 with the regulated buses
• the Thermal Control Unit (TCU) provides heater power supply and acquires the corresponding thermistor outputs