From GpsWiki
Satellite Page
How do I get to the Satellite page?
If you have the Satellites page enabled (default from factory) in Page Order, either press the PAGE button or the QUIT button to scroll through your screens until you get to the Satellites page. If the Satellites page is disabled in Page Order, then press MENU button, use the UP/DOWN rocker pad to select Satellites, then press ENTER.
The Satellite Page
This page can be broken into three sections: Sky View, Signal Strength, and Battery.
Sky View
The top section of the Satellite page shows the location of all satellites above the horizon. The center of the circle is straight up over your head. In the above screenshot, Satellite 14 is positioned almost exactly overhead. The next circle out would be at approx 45° (half way between the horizon and straight up). In the above screenshot, Satellite 22 is at approx 45° to the East and a little to the North. The outer circle is the horizon. In the above screenshot, Satellites 3 and 6 are shown just above the horizon to the South and a little bit West.
There is also other information displayed at the four corners:
- Top Left: This value indicates the type of position fix. Additionally, a "W" will be displayed below the position fix if you are receiving WAAS corrections. Possible position fix types are:
- No Fix - Not enough satellites are being received to determine a position.
- 2-D - Only enough satellites are being received to determine your position, but not your GPS altitude.
- 3-D - Enough satellites are being received to determine your position and GPS altitude.
- GPS Off - The GPS module is turned off.
- Top Right: This displays the current time.
- Bottom Left: This value is the Estimated Position Error (EPE) in Feet. This value is only displayed if you have a 2-D or 3-D fix.
- Bottom Right: This value (if present) displays your elevation. The elevation is based on either the Barometric Sensor or the GPS elevation calculation.
NOTE: If the Barometric Altimeter is enabled, the PN-40 will calculate your altitude based on the Barometric Sensor even if the PN-40 is receiving a 2-D position fix.
Elevation
If the Barometric Altimeter is enabled (see [pn40:[Device Setup PAge#Compass & Altimeter Settings|Device Setup - Compass & Altimeter]] ), then the value displayed in the bottom right corner of the Sky View will be the Elevation: Altimeter, which is based on the Barometric Sensor. Additionally, if "Auto Calibrate Altimeter" is checked, the word "Calibrating" will be displayed each time the Altimeter elevation is adjusted. Typically, this will occur every 2 to 3 minutes.
If the Barometric Altimeter as been disabled, then the value displayed is the Elevation: GPS, which is a calculated value based on the Satellite signals being received.
The elevation value is blank if the Barometric Altimeter is disabled and you don't have a 3-D fix.
Signal Strength
This section of the display shows a list of satellites that are above the horizon. If more than 12 satellites are above the horizon, then only the first twelve will be displayed. Normal GPS satellites are numbered 1 to 32. The WAAS satellites are 135 or 138. When 12 satellites are shown, the WAAS satellite (either 135 or 138) will be displayed with a "W". This is done because of the lack of room to display the actual number. NOTE: Even thou only the first 12 satellites are displayed, all satellites being recieved will be used for position calculation.
Above each satellite number is a signal strength bar. The taller the bar, the stronger the signal is from the satellite. No bar means no signal is being received from that satellite. The color of the bar is used to indicate the status of the satellite signal:
- Red - Satellite signal is being received, but the signal from the satellite isn't being used to calculate your position.
- Yellow - Satellite signal is being received, but predictive ephemeris data is being used until new ephemeris data can be downloaded from the satellite. The satellite is used in the calculation of position, but until the new ephemeris data has been downloaded, the position calculation will be at a reduced accuracy.
- Green - Satellite has new ephemeris data and is being used in the calculation of your position.
- Blue - Same as Green, but has also received WAAS correction information and is using this information.
As a general rule, the more Green bars, the better your position accuracy will be. And the more Blue bars, an even greater accuracy.
Battery
This section of the page displays the battery level status. The level is displayed as a bar graph. When full, 4 green bars then down to 3 green bars. At two bars, they turn Yellow, and at one bar, it's red. When connected to a computer, the word "Battery" will change to "External" to left you know the unit is using USB power to run. Additionally, when using Li-Ion batteries and you're connected to a computer, the word "Charging" will appear to let you know the Li-Ion battery is being charged.
NOTE: Because of the difficulty to measure battery levels, the bar graph should only be used as a really rough gauge of remaining battery power.
NOTE: Once the battery level reaches a minimum level, you will receive a "Battery Low" message. If you don't change the batteries, the next message will say the batteries are "Critically" low and the unit will then automatically turn off.
