Basic Operation > Understanding Radar

Before transmission begins, the message “Spinning Up” is shown while the radar antenna reaches nominal rotation speed. After the message disappears, the radar begins painting an image.

Understanding the Radar Display

The Radar Page shows a status bar along the top, user-configurable digital navigation data down the right side, a Heading Line, and Range Rings. Soft keys that allow quick access to radar functions and setting changes appear along the bottom of the page.

Heading Line

Range

Rings

Soft

keys

Zoom scale

Ring separation

 

Using Range Rings

Use the Range Rings to quickly determine the distance to a target. The lower-right corner of the screen contains two scales. The scale value represents the distance from the center of the radar display to the outermost complete ring. The top scale represents this value. The bottom scale represents the ring separation or the distance between the Range Rings. Use the RANGE keys to zoom in or out. The tick marks on the Range Rings are arranged with major tick marks at 30 degree increments and minor tick marks every five degrees. The tick marks can help in quickly determining the azimuth to a target.

3/4 nm

1/2 nm

1/4 nm

Heading Line

The Heading Line is shown from your current position along the path of your current heading.

GMR 21/41 Owner’s Manual