Introduction to FengYun cHRPT

Thursday, 12 August 1999, we ( Roberto Ferrari and Enrico Falconelli ) have received our first image of FengYun 1C satellite. The receiver was tuned on the frequency 1700.4 MHz and the signal was very weak.
The hardware was our Noaa95 card, the same we used for Noaa HRPT, but with some components changed to reach the new bit rate (1.3308 Mbps), twice the bit rate of HRPT NOAA now. The modulation of cHRPT data is PSK and bit format is split phase.
The software Noaa95 was rewritten again to receive and decode correctly the 10 channels of the new satellite. Also we've find that some channels are not perfetcly alligned: the new software FengYun99 allow you, once a channel is selected (as commonly you must do to change the color palette), to shift it horizontally (press F9 or F10 key).
The orbit altitude of FengYun 1-C is 870 km, each spectral band image is 2048 pixell width. Resolution is the same as HRPT, each pixel ratio is square 1,1 km x 1,1 km on the ground.

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Once you have received an image, our FengYun99 software allow you to add different channels and re-build an RGB color image as you like.

WARNING !!!

Some channels are shifted horizontally. When you build an RGB color image you need to allign them. To do this, use the TAB key to select and F9 or F10 to adjust fine each color channel.

### FengYun 99 software output File Notation ###

FENGnnn_.RAW = 10 bit file multiplexed (the 8 MSbit as received)

After SPLIT function: nnn (image number) will be the same

*file name*	*description*
FENGnnnA.RAW	1st FengYun Channel
FENGnnnB.RAW	2nd FengYun Channel
FENGnnnC.RAW	3rd FengYun Channel
FENGnnnD.RAW	4th FengYun Channel
FENGnnnE.RAW	5th FengYun Channel
FENGnnnF.RAW	6th FengYun Channel
FENGnnnG.RAW	7th FengYun Channel
FENGnnnH.RAW	8th FengYun Channel
FENGnnnI.RAW	9th FengYun Channel
FENGnnnL.RAW	10th FengYun Channel

By pressing CTRL+J a JPG file will be created and named FENGnnn.JPG

By pressing CTRL+P after split function (while the 8 channels are displayed)
a PCX image wiil be created and named FENGnnn.PCX

" MVISR " spectral bands

*channel*	*wavelength [nm]*	*Primary use*
1	580 - 680	Daytime cloud, ice and snow vegetation
2	840 - 890	Daytime cloud, vegetation, water
3	3550 - 3930	Heat source, night cloud
4	10300 - 11300	SST, day/night cloud
5	11500 - 12500	SST, day/night cloud
6	1580 - 1640	Soil humidity, ice/snow distinguishing
7	430 - 480	Ocean color
8	480 - 530	Ocean color
9	530 - 580	Ocean color
10	900 - 965	Water vapor

10 Feng Yun Channel

wavelength of base color

*color*	*wavelength [nm]*
R	620 - 680
G	500 - 520
B	440 - 470