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發表於 16-10-2010 22:17:01
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FY1 C and D Polar Orbiting Spacecraft
FY-1C was launched at 0133Z 10 May 1999 on a CZ-4B vehicle from Taiyuan.
International Designator - 1999-025A
NORAD Catalog Number - 25730
CHRPT Transmission frequency - 1700.4 MHz (actual), 1700.5 MHz (published)
FY-1D was launched at 0150Z 15 May 2002 on a CZ-4B vehicle from Taiyuan.
International Designator - 2002-024B
NORAD Catalog Number - 27431
CHRPT Transmission frequency - 1700.4 MHz
Spacecraft Characteristics
Parameter
Item
Orbit altitude
870 Kilometers
Inclination
98.85°
Eccentricity
< 0.005
Orbtial period
102.301 minutes
Sensor
Multichannel Visible and IR Scan Radiometer (MVISR).
This instrument is a 10 channel sensor with 4 vis, 3 near IR, 1 short IR and 2 long IR.
The IFOV is 1.2 mrad with a nadir resolution of 1.1km
MVISR Characteristics
Channel
Wavelength
Primary use
1
0.58-0.68
Daytime cloud, ice and snow, vegetation
2
0.84-0.89
Daytime cloud, vegatation, WV calibration
3
3.55-3.95
Night cloud
4
10.3-11.3
SST, day/night cloud
5
11.5-12.5
SST, day/night cloud
6
1.58-1.64
Soil humidity, ice/snow separation
7
0.43-0.48
Ocean colour
8
0.48-0.53
Ocean colour
9
0.53-0.58
Ocean colour
10
0.90-0.985
Water vapor
FY1-C High Resolution Picture Transmission (CHRPT)
As the MVISR is now 10 channel instead of 5, the bit rate has been increased to 1.3308 Mbps, exactly twice the current HRPT bit rate.
The scan rate is 6 lines/sec with 2048 10 bit words per channel per line plus sync and auxiliary infromation (ie 22,180 10-bit words per line).
Transmission frequency - 1700.5 MHz (Prime) or 1704.5 MHz (back-up).
EIRP - +39.4 dBm
Polarization - Right Hand Circular
Modulation -PCM/BiPhase-Level/PSK
Modulation Index - +/-67.5 +/- 7.5 deg;
Bit Rate -1.3308 Mbps
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CHRPT Frame Format (from CGMS-XXV PRC WP-02)
CHRPT Frame Format
Function
Frame
Sync
ID
Time
Code
Telemetry
(Ramp)
Telemetry
(Temperature)
Black
Body
Space
Data
Spare
Earth
Data
Aux
Data
Number
of Words
6
2
4
10
10
60
100
1408
20480
100
CHRPT Parameters
Number of words in a frame - 222180
Number of channels - 10 with 2048 words per channel
Frame Rate - 6 frames/sec
Number of bits of word - 10 bits /word
Bit Rate - 1.3308 Mbps
Bit Format - Split-phase with a data "1" as high to low level and data "0" as low to high level at the data mid-bit
Detailed CHRPT Frame Format
Function
Number of words
Word
position
Bit number
12345678 90
Meaning
Frame Sync
6
1
2
3
4
5
6
1010000100
0101101111
1101011100
0110011101
1000001111
0010010101
First 60 bits are a 63 bit PN generator, started in the all ones state.
The generator polynominal is X^6 + X^5 + X^2 + X + 1
Identification
2
7
1-4 bit
Satellite ID - binary 1100
7
5-10 bit
Spare bits
8
Spare word
Time Code
4
9
1-9 bit
Binary day count
9
10 bit
binary 0
10
1-3 bit
binary 101
10
4-10 bit
Binary part of millisecind of day count
11-12
1-10 bit
Binary part of millisecind of day count
Telemetry (Ramp)
10
13-22
Ramp calibration of 10 channels of MVISR
Telemetry (Temp)
10
23
Temperature of the first stage of radiant cooler A
24
Temperature of the first stage of radiant cooler B
25
Temperature of the second stage of radiant cooler A
26
Temperature of the second stage of radiant cooler B
27
Temperature controlling voltage of the second stage of radiant cooler A
28
Temperature controlling voltage of the second stage of radiant cooler B
29-32
Temperature of sheath of radiometer, one word for each platinium resistance bulb
Reference Black Body
60
33-92
6 sampling words for every channel
Space Data
100
93-192
10 sampling words for every channel
Spare words
1408
193
194
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1599
1600
0000011101
0000001100
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1100001101
1101100101
Derived fron the inverted output of a 1023-bit PN sequence provided by a feedback shift register generating the polynominal : X^10 + X^5 + X^2 + X + 1. The generator is started in the all ones state at the beginning of word 7
Earth Data
20480
1601-22080
2048 words for every channel from channel 1 to Channel 10. Each frame contains the data obtained during on Earth scan of the MVISR sensor. The data from the 10 sensor channels of the MVISR are time multiplexed.
Auxiliary Sync
100
22081
22082
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22179
22180
1111100010
1111110011
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0111110000
1111001100
Derived fron the non-inverted output of a 1023-bit PN sequence provided by a feedback shift register generating the polynominal: X^10 + X^5 + X^2 + X + 1. The generator is started in the all ones state at the beginning of word 22081
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FY-1C Delayed Picture Transmission (CDPT)
. Playback of recorded data of 4 channels at 4 km resolution
. Only available over groundstations in China on 1708.5 MHZ (Prime) or 1695.5 MHz (backup)
. No other details available
Note - There will no APT transmission from FY1 C. |
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樓主: VR2GY
發表於 23-9-2010 00:56:52
