The meteorological imager is composed of a sensor module that performs the actual meteorological observations, a power module that supplies stable power to the meteorological imager after proper modulation of the power the satellite receives, and a electronic module that is responsible for the control of the sensor module as well as the various electrical signals exchanged and the power connection between the meteorological imager and the satellite.

Configuration of the sensor module

- Scan mirror: Allows observations of user’s points of interest
- Aperture: Gathers the light that reaches the scan mirror
- Spectroscope: Sorts the incoming radiation through the telescope according to wavelengths
- Detector: Converts radiant energy into electrical energy
- Black body: Black body used to secure the performance of infrared radiant energy
- Cooling system: Responsible for maintaining the sensor temperature at a cryogenic level

Configuration of the sensor module of the meteorological imager
Meteorological imager specifications
Bus dimensions 2.4m × 2.4m × 2.6m
Mass at launch 2,500 kg
Operational life 7 years
Meteorological sensor 5-channel imager (1 visible, 4 infrared)
For each Channel specifications
Channel Center wavelength (㎛) Wavelength range (㎛) Spatial resolution (km)
Visible 0.675 0.55~0.8 1
Shortwave infrared 3.75 3.5~4.0 4
Water vapor 6.75 6.5~7.0 4
Infrared 1 10.8 10.3~11.3 4
Infrared 2 12.0 11.5~12.5 4

Observation principles of meteorological imager

The meteorological imager receives commands from the ground and then makes observations of the requested areas by moving the scan mirror in East/West and North/South directions. The radiant energy collected through the aperture first passes through the main and secondary apertures, is sorted according to wavelengths in the spectroscope, and is then sent to the detector: see the diagram below.

The radiant energy flow after passing the scan mirror

The radiant energy observed and entered into a telescope is distinguished by channel in the manner presented in the following picture and detected by each detector.

Radiant energy of the channel categor

Observation principals and materials of detector

- The meteorological imager’s detectors store the observed energy in the form of photon energy. The electric energy is then boosted and expressed in voltage and current according to the potential difference.
- In COMS, the visible channel detector uses the semiconductor material silicon (Si.), shortwave infrared channel detector indium antimonide (InSb), and the remaining channel detectors HgCdTe (MCT) that are commonly used in infrared detectors.
- The Infrared detector is sensitive to low temperatures so a cooler is required to remove the surrounding heat sources.

Transmission and reception of data

Transmission and reception of observed data

- The COMS transmits observed satellite data to Earth in the form of Windband data.
- The data transmitted to Earth, after having gone through location and radiation verification processes, is provided as image data and processed using the meteorological data processing system to produce output including Asian dust, fog, and sea surface temperature.
- The image data and output are reprocessed with other data such as numerical forecasting data and oceanographic observation data, and others to produce a data package complying with international standards for satellite information, LRIT/HRIT. The data package is retransmitted to the satellite to be distributed to users worldwide.

Satellite status information

- The satellite, in addition to the observed data, continuously transmits to Earth information regarding its operating status such as its attitude, orbit, temperature and others by telemetry so the ground station can respond effectively during emergencies and determine the quality of the observed data received.
- The status information for the COMS is made up of two parts: Windband telemetry provided by the meteorological payload and Analog telemetry provided by the satellite.