Obtaining a satellite image

In order to decode the signals received from satellites, there is the special software called WXtoimg, which receives an audio signal taken from the satellite using the SDR# software as its input. The first time a user launches WXtoimg, it is necessary to set up the location. Go to “Options → Ground Station Location”, enter the city name and your coordinates.

Then proceed to “Options → Recording Options” and configure the sound source.

Select “CABLE Output” in the soundcard selection section.

Further you need to update the satellite coordinates. Go to “File → Update Keplers”.

When the update procedure is done, a confirmation will appear in the lower left corner.

Each time you start WXtoimg, you will need to check that the signal source is set up correctly.

Select the virtual CABLE Output.

Start recording.

Turn on the “Auto Record” function to receive signals.

Beginning from this moment, whenever any NOAA satellite appears to be higher than 10 degrees above the horizon, the software will automatically begin recording of the transmitted image.

Make sure the signal strength, provided in the lower right corner, is green, if not - turn up the audio volume in the SDR# software.

If the signal strength is good, then the resulting image will begin to appear in rows below. The visible range is indicated on the left and the infrared one - on the right.

Wait for the end of the transmission, and stop recording.

Begin automatic processing of received images.

The resulting image will be processed automatically and frames of corresponding states will be overlaid on it. Pay attention to interference which degrades the image.

This is an image provided in the Normal mode.

Considering the obtained image, a number of images will be automatically generated with various filters applied. A user can check these images in the “Saved Images” menu.

A user can also switch types of image processing in the “Enhancements” menu.

Contrast enhancement for channel A (visible range).

Contrast enhancement for channel B (infrared).

IR image with map overlay. The water volume is colored blue and the land volume is colored green. High clouds are colored white and low clouds are colored gray. Darker colors indicate warmer areas.

Multispectral analysis. An image is provided both in visible and infrared channels and this structure determines which areas are most likely to be clouds, land, or sea. The result is represented in a bright image in false colors.

An image with indication of blue water and colors is more suitable for land description.

The software creates a false color image based on temperature, using the HVC color model.

 

Sea surface temperature. The software creates a false color image based on the sea surface temperature. No attempts are made to distinguish cloud or land from sea. The sea surface temperature may be incorrect due to presence of thin or small clouds in pixels being evaluated or due to presence of noise in the signal.

The image provided in false colors, shows cloud and surface temperature values. The purple color indicates low temperatures and the red color indicates high temperatures.

  It is possible to change the projection type.

Normal projection.

Equal-velocity cylindrical projection

Projection of Eckert IV