The Fengyun-2 series of satellites are geostationary satellites that deliver images of earth once per hour. The delivery consists of S-VISSR data: 1 VIS, 3 IR and 1 Watervapour images. They are delivered on the L-band frequency 1687.5 MHz. If you are within the footprint of the satellite, it is possible to receive with at least a 1.2m dish and Nooelec Saw filter. As there are both VIS and IR channels, it is possible to create false colour images by using CLUT (colour look up table).
Below are the following images and their resolutions delivered by the satellite.
| Channel | Type | Resolution |
|---|---|---|
| FY-2x_1 | IR | 2291 x 2501 |
| FY-2x_2 | IR | 2291 x 2501 |
| FY-2x_3 | WV | 2291 x 2501 |
| FY-2x_4 | IR | 2291 x 2501 |
| FY-2x_5 | VIS | 9160 x 10004 |
To use the CLUT requires the following:
| Name | For | Author | Source |
|---|---|---|---|
| Decoder | Decodes the S-VISSR data | @aang254 | https://github.com/altillimity/S-VISSR-Ingestor |
| GeoSatSignal | Applies the CLUT from a file | David Taylor | https://www.satsignal.eu/software/geosatsignal.htm |
You can use a 1.2m or larger dish. The feed skew needs to be set accordingly depending on location. For example in Japan, I need to set the feed skew to 45 degrees. I use a patch antenna (shown) as it gives good dish illumination.
You need to rotate the feed to set the correct skew.
I use Nooelec Sawbird and SPF5189Z LNA for extra gain (if you need it). I don't think the bias tee output on the Airspy can output enough current to power both LNAs, so you would need to use external +5V supply. I use 4 x NiMH batteries.
The signal in SDRSharp is a 1 MHz wide signal and you need to get at least 10 dB SNR for an 100% error free image:
Use the decoder to get the images by visiting the link above (instructions to use are on the site).
Open the IR image in your image editor eg. GIMP and invert the image colour so the clouds appear white. In addition the IR image needs to match the pixel size for the visible. In your image editor, upscale the IR to 9160 x 10004 and save as IR.bmp. Open the visible FY-2x_5 image and re-save to VIS.bmp file as GeoSatSignal needs both of the files to be .bmp
Download the Geosatsignal software from the above link.
Download the CLUT above (.bmp) and copy it in GeoSatSignal folder below:
"Tools\SatSignal\GeoSatSignal"
To use the CLUT you need to activate it in "Vis Ch." Set the "Brightness" and "Crispen" to "None". Also set the output file as ".TGA".
In GeoSatSignal, to apply the CLUT correctly requires correct adjustment. Goto "Options" and "Common setup". Under "WEFAX thermal calibration", use the below values:
| Setting | Gain | Offset |
|---|---|---|
| Cloud cyan top | 150 | 0 |
| Cloud white top | 70 | 50 |
Drag and drop one of the files into the corresponding box (e.g. visible for VIS) Then save as 1:1 size.
Since the EWS-G1 has an IR channel, in theory the above file can be used here. Although you need to play with the settings to get the best results. Since I cannot receive this satellite, I cannot verify this.
Thanks to @aang254 for his decoder for FY-2x satellites and David Taylor for GeoSatSignal program.