Satellite Elevation Control
Download GPSSatellite2.ocx Visual Studio Control

This shows the control's "naked state" as it is placed upon a form by the programmer. Note that throughout all of these sample images, the GPS Satellite Control is shown on a form: the minimize, restore, and close boxes, and the status bar on the bottom of the examples, are not part of the actual control.

This control shows the elevations of the GPS satellites within view, with the horizon at the bottom and zenith (90 degrees) at the top. The higher the satellite is in this image, the higher it is in the sky.

  • Click
  • DblClick
  • GPSSatError

When incorrect data is passed to the control, the error event will be triggered: your program should trap those errors and handle them.


  • AddBird
  • BirdCls
  • RemoveBird
  • ResetDefaults
The control's Methods allow your program to add satellites to the control and remove them. The AddBird Method adds a satellite one at a time; RemoveBird removes a satellite. To add satellites using a $GPGSV NMEA sentence, one may use the GPGSV Method; BirdCls removes all satellites from the control.

As the programmer, it is up to you to keep track of when to add and remove satellites from the control. You may do this manually by looking at NMEA/GPS data and noticing when a new satellite is detected and when an existing satellite is lost over the horizon; however, there is a Property that allows you to tell the control to remove satellites from the control when the satellite's signal strength drops below a specific decibel threshold (BirdExpireThreshold). Using the GPGSV Method to add satellites instead of AddBird, and using the BirdExpireThreshold Property, the control will add and remove satellites automatically for you.


  • BackColor
  • BirdExpireThreshold
  • BorderStyle
  • ErrorDescription
  • ErrorNumber
  • FontColor
  • LineColor
  • Night
  • SatStyle
  • ShowNoTracking
  • Twilight
These Properties allow you, as the programmer, to change how the control looks and behaves. You could expose some or all of these Properties to the end user (and be sure to give the user a "restore to defaults" option), to allow the user to set her own preferences.

One feature you may wish to provide to your end users is a "da " and a "night" option: at night a person on a boat does not like to look at glaring, bright computer screens--- setting the BackColor Property to black, and the FontColor Property and LineColor Property to white will darken the control, and thus make it easier to look at when on the night watch. You may do this by specifying your own colors, or using the built-in Night Property or Twilight Property. Changing one of these Properties turns off the other.

All controls in The NMEA Sage control suite include the same color scheme for the Night and Twilight Properties to give the suite an integreated look.


When the control is passed an invalid value for some of its Properties, the GPSSatError Event will be triggered. The following are the error codes returned by the Properties ErrorNumber and ErrorDescription.

0 - No current error.
1 - Satellite number value was out of bounds.
2 - Satellite elevation value was out of bounds.
3 - Satellite azimuth value was out of bounds.
4 - Satellite signal strength value was out of bounds.
5 - Satellite was not on the display.
6 - NMEA sentence must begin with $GPGSV
7 - Sentence $GPGSV appears malformed.
NMEA Sage Home Page

The Banded Compass Control
The Compass Control
The North Biased Compass Control
The Goto Control
Course and Speed (Ground)
The Position Control
Engine RPM Control
The Rudder Control
The GPS Satellite Health Control
The GPS Satellite Elevation Control
Set and Drift control
The NMEA Talker Control
Depth and Water Temperature Control
The Wind Control
The Cross Track Alarm Control
The Pilot Control
Waypoint Plotter Control
Radar Control
Goto Simple Control