Tech sheet FEN-YUN 2 series

The Fen-Yun 2 series are geostationary satellites. The first of the series, FY-2A, was experimental. FY-2B and 2C are active and transmit images with a maximum resolution of about 1.25 km. Information on water vapor and clouds is sent at a resolution of 5km.

The series was designed to observe three spectral bands: Visible, Infrared, and water vapor. The satellite measures about 2 meters by 1.6 meters diameter, and is stabilized by rotating around its axis at 100 times per second. It uses the rotation to establish the actual line scan movement.

First image of FENG-YUN 2B

First image received by Feng-Yun 2B

Tech datasheet of the FEN-YUN 2 series

Descripción	Value	Value	Unidad
Satélite	FY-2A	FY-2B
Launzamiento	1987/06/10	2000/06/25
Nombre antes lanzamiento	n/a	n/a
Nombre actual	FEN-YUN 2A	FEN-YUN 2B
NASA ID	24834	26382
Altura aproximada	35800	35800	km
Inclinación órbita			degrees
Período orbital			minutes
Frecuencias	1687.5	1687.5	MHz

Data format

Channel No.	Wavelength (micrometer)	Primary use	Resolution
1	0.55-1.05	Visible	1.25 km
2	10.5-12.5	Infrarrojo	5 km
3	3.55-3.93	Vapor de agua	5 km

The transmission format:

- One image is acquired each 30 minutes. Each earth image corresponds to an aperture of about 20 by 20 degrees.

- The horizontal scan is realized by the satellite's own rotation (about 100 times per minute), and small steps of a mirror (2500 steps: 25 minutes)

- The raw - and distorted - image, is processed by the control station, and re-uploaded in S-VISSR format.

- An image consists of 2500 lines, of which 2291 are effectively covering the earth disk (the other lines are safety margins)

- The data is transmitted in 329.872 bit blocks. These blocks consist of:

- 20000 bits of PN code, starting with 010001001100001, and finishing with 15 bits = 1

- 2293 documentation bits

- 2 words (16 bits) of ID, and 2291 words of IR data, 2 words of CRC 256 fill/reserve bytes,

- 2 words (16 bits) of ID, and 2291 word of water vapor data, 2 words of CRC and 256 fill/reserve bytes,

- 2 word (16 bits) of ID, and 2291 reserved word, 2 words of CRC and 256 fill/reserve bytes,

- 2 words (12 bits) of ID, and 9164 word of visible image data, 2 words of CRC and 256 fill/reserve bytes

ID	Value 1	Value 2
PN	010001001100001
IR	00010001	00010001
Water vapor	00100010	00100010
Reserved	01000100	01000100
Visible 1	011011	011011
Visible 2	101101	101101
Visible 3	110110	110110
Visible 4	111111	111111