# Feng Yun-2 Geostationary Meteorological Satellite

## Feng Yun means Wind & Cloud

### Last update : 4 January 2005

- CMA new Homepage
- The China Meteorological Administration (CMA) WWW site.
- The CMA National Satellite Meteorological Centre (NSMC) site.
- FY-2 SV data format (detailed).

### Here is some basic information on FY-2 satellites.

    The FY2 series of satellites will be operationally similar to GMS with
    high resolution stretched VISSR (SV) data (5km IR, 5km WV &  1.25km VIS),
    low resolution analog Wefax (discontinued), DCP capability, digital S-band
    fax service (CCITT G3) for domestic distribution of charts and imagery (discontinued)
    and LRIT.

    FY-2A was launched on 10 June 1997 and has been decommissioned and re-orbited.
    FY-2B was launched on 25 June 2000 and has been decommissioned and re-located to 123.5° East.
    FY-2C was launched on 19 October 2004 and is operational at 105° East.

    FY-2 VISSR characteristics
    ----------------------------------------------------------------------
                    Visible         Infrared        Water Vapor
    ----------------------------------------------------------------------

    Wavelength      0.5-1.05        10.5-12.5       6.2-7.5
    (micro metre)

    Resolution      1.25 Km         5 Km            5 Km
    at SSP

    FOV             35              140             140
    (micro metre)

    Scan lines      2500 x 4        2500            2500
    per spin

    Detector        Si photodiode   HgCdTe          HgCdTe

    Noise           S/N = 6.5 @     NEDT=0.5-0.65K  NEDT=1K
    Performance     Albedo=2.5%     (300K)          (360K)
                    S/N >= 45 @
                    Albedo=95%

    Quantisation    6 bits          8 bits          8 bits

    Scan step angle 140 microR (N to S scanning)
    per spin

    Frame time      30 minutes, 25 scan, 2.5 retrace, 2.5 re-calibration

    FY-2 downlink characteristics
    --------------------------------------------------------------------
    Channel         Freq            Mod             Power           BW
    S.VISSR         1687.5 MHz      BPSK NRZ-M      +57 dBm         2 MHz
    LRIT		1691.0 MHz	BPSK		+57 dBm
    LR-FAX          1691.0 MHz      AM/FM           +57 dBm         260 KHz
    S-FAX           1699.5 MHz      AM/FM           +46 dBm         26 KHz

    Notes:
    LRIT on FY2-C
    S-FAX was on FY-2A only
    LR-WEFAX ceased on FY-2B in February, 2001

    S-VISSR (SV) signal characteristics (FY-2A, B and C)
    ---------------------------------------------------------------------
    Modulation      PCM/BPSK, NRZ-M
    Bit Rate        660 Kbps, fixed
    EIRP            +57 +/-1 dBm
    Polarisation    Linear, vertical
    Bandwidth       approx 2 MHz
    Data volume     329,872 bits per line including SYNC code
    Data coding     Byte complimenting and PN scrambling

    LR-FAX (WEFAX) signal characteristics (FY-2A and B only)
    -----------------------------------------------------------------------
    Frequency       1691.00 MHz
    EIRP            +57.5 dBm
    Polarisation    Linear, vertical
    Modulation      AM/FM
    Bandwidth       260 KHz
    (Sub-carrier)
    Bandwidth       1.68 KHz
    (Baseband)

    S-FAX signal characteristics (FY-2A only)
    -----------------------------------------------------------------------
    Frequency       1699.50 MHz
    EIRP            +46 dBm
    Polarisation    Linear, vertical
    Modulation      PM-AM/FM
    RF deviation -  +/-9 KHz
    RF bandwidth    26 KHz
    Subcarrier      PM-AM
       Frequency    1.7-1.8 KHz
       Bandwidth    300-3400 Hz
       Modulation   G3 FAX
       Coding       CCITT T.4
       Protocol     CCITT T.30
       Bit rate     300 bps, CCITT V.21
                    2400/4800 bps, CCITT V.27 ter
                    7200/9600 bps, CCITT V.29

    Scan density    3.85/7,7 lines/mm
    Horizontal      8 pixels/mm
    resolution

    Transmission    1-2 minutes for weather chart
    duration        3-10 for cloud image

    LRIT signal characterists (from FY-2C)
    -----------------------------------------------------------------------
    Frequency	1691.0 MHz
    EIRP            +57.5 dBm
    Polarisation    Linear, vertical
    Modulation      150 kilosymbols per seconds BPSK, unfiltered
    Data Format	CGMS LRIT and CCSDS compatibility TBC
                    Mission Specific Implementation TBA