A number of stations world-wide transmit weather charts on a regular schedule. During the transmission of an image a characteristic and easily recognizable audio signal is heard. A specific frequency deviation may also be seen on a tuning indicator.

Most transmitters work with a wide shift (±400 Hz) and a few with narrow shift (±150 Hz).

By selecting the Auto function, the software waits for the IOC identifier and synchronization sequence. These signals are only transmitted once at the beginning of an image implying that capturing of the signal will only take place at the start of the next image.

By selecting WEATHER-FAX the application starts immediately. The drum speed and the IOC may be entered manually using the Drum speed and IOC items available from the Demodulator menu. The selected values are displayed in the decoder status bar. In the short-wave band, weather charts are transmitted almost exclusively with speeds of 60, 90 or 120 rpm. In the case of 60 rpm the drum rotates once per second, for 90 rpm at one and a half time and for 120 rpm at a speed of twice a second. The index of co-operation (IOC) is readily recognizable from the screen display when images are spread out too wide. An IOC of 576 is mostly used on short-wave.

The decoder allows a continuous and smooth alignment of the image as it is being received from Options/Fine Speed. By using the Phase item in the Options menu the image can be shifted into the correct position. Flip Left-Right and Flip Top-Down will reverse the image or turn it upside down.

To enhance the interpretation of gray-scale images, a false color option is available. Right-click on the image to open the zoom menu and from the bottom part selects a color scheme. A checkmark is placed to the left of the selection.