Measurement principle

Infrared Fourier-transform spectrometer SICH-F is intended for spectral distribution power measuring of atmospheric and ionospheric emissions in range of 2 - 9 mkm and it's height distribution. Instrument work regimes: 1) Inside. 2) Calibration at inside standard sources 2 - 4 times per a rotation. 3) Calibration at "free space" 2 - 4 times per a rotation. 4) Infrared radiation measuring 10 - 40 min. per a rotation.

Experiment configuration and heritage

Spectrometer consists of the photodetector block and the block of signal processing and control.

Photodetector block is set onto external surface of station. Optical axis direction 1 is set at angle of 18° to satellite velocity vector and it is located in plane «velocity vector - Nadir».

- Optical axis scanning 1 - +5 –30 deg

- Optical axis direction 2 - Zenith +-50 deg

- There haven't to be satellite device details into space angle +20 deg

Diagnostic information and attach data will transfer by state telemetric channels.

Four digital channels:

Three analog channels:

Digital 5 channels:

Main characteristic of the SICH-F instrument

Sight field: 0.5 degree

Space resolution: 5 km (vertically)

Spectral resolution 2 cm

Time resolution 1 - 4 s

• Spectrometer consists of next blocks:

  • Photodetector block.

    • Dimensions 480x280x170 mm

    • Weight < 10 kg

    • Using power < 12 W

    • Block has two radiation enters

    Demands for device:

    • Block is set onto external surface of station;

    • Optical axis direction 1 is set angle of 18 vector and it is in plane: speed vector - Nadir.

    • Optical axis scanning 1 - +5

    • Optical axis direction 2 - Zenith +50

    • There haven't to be satellite device details into space angle +20

  • Block of signal processing and control

    • dimensions 270x260x160 mm

    • weight < 8 kg

    • using power < 18 W

    • Block is set inside of station.

    
    

• Total using power < 30 W

  Total weight < 18 kg

   

• Instrument work regimes:

  • Inside

  • Calibration at inside standard sources 2 - 4 times per a rotation.

  • Calibration at "free space" 2 - 4 times per a rotation.

  • Infrared radiation measuring 10 - 40 min. per a rotation.

  
  

• Instrument control commands.

  • For the instrument control (choice from four regimes, program controller control, scanning regime definition etc.) the corresponding channels have to have eight dry contacts "to switching".

  • Before this the instrument will use with service commands "LIGHT" and "SHADOW".

  • Instrument disfixing and it's transfer for duty-regime will be carried out during first connection of board net in 27 V and will not require separate commands.

  
  

• Data structure.

  Data to go out from instrument is separated for two types:

  scientific data and technical ones (diagnostic) that testifies about capacity for work of instrument at all and it's separate system condition.

  • Scientific data (1 block under 16K per one measuring).

    This data enters with each measuring and is necessary for discipherring and interpretation obtained results:

    • Spectrum or interferogram.

    • Object's sign.

    • Regime sign.

    • Scanner’s position.

    • Gain factor.

    • Sign of move smooth.

    • Interferogram "zero" position.

    • Tests pass sign.

    • Attenuated position.

  It should have consistent channel of RS232 type or like to it. Total volume of receive information is resulted in point 8 it's TCh.

  
  

  Diagnostic information and attach data will transfer by state telemetric channels.

  • Four channels :

    • Detector temperature.

    • Engine temperature.

    • Absolute black body temperature.

    • Beamsplitter temperature.

    
    

  • Three analog channels:

    • Reper mark frequency.

    • Black body current.

    • Signal roughly.

    
    

  • Digital 5 channels:

    • Calibration 1.

    • Calibration 2.

    • Calibration 3.

    • Calibration 4.

    
    

• Total volume of information transferring to Earth at receive rate of one spectrum is:

  For one cycle for one for of measuring rotation 24 hours

  Regime "L" 4 2400-4800 till 115000

  Regime "Sh" 8 4800-9600 till 230000

  
  

• Total regime of instrument work is separate periods in a rotation (it is mainly in zone of Earth shadow).
  The instrument will switch on automatically by signals of own detectors taking into account service commands "LIGHT" and "SHADOW".