Gps Usage; Versatility - Suunto M9i User Manual

Mobile accessory for boaters

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spot, as some errors will be averaged out. Under all-in-view satellite conditions a

global average horizontal positioning error is 7.8 meters (95% confidence level).

However, depending on the satellite constellation and the distortion the GPS signal

experiences when traveling through the ionosphere, the instantaneous accuracy can

vary from a couple of meters to over ten meters. The vertical position estimate is

roughly two times more inaccurate than the horizontal.

2.4.4. GPS Usage

When you turn on the GPS, the receiver starts searching for radio signals from the

satellites and as soon as one is found, data starts flowing from the satellite to the

receiver. The data includes a list of the satellite positions and the GPS time. The GPS

time is highly accurate because each satellite has an atomic clock on board.

The data flows quite slowly and usually a little less than a minute is needed for the

calculation of the first position estimate. To minimize the duration, you should maintain

an unobstructed view of the sky right after turning on the GPS. You need the satellite

positions and the GPS time before you can perform the actual position calculation and

before the GPS becomes functional. After the first position fix has been established, it

still takes additional 10 minutes before all relevant data has been received from the

satellites. The position estimate accuracy improves during this time as more satellites

can be used for position calculation.

The downloaded data is valid roughly for the next four hours during which the receiver

starts more quickly, typically in less than 10 seconds if it was turned off in between.

You should turn off the GPS when you do not need it. This is because satellite tracking

consumes large amounts of power. Suunto M9i uses the lowest power consuming

GPS technology available but you should still turn off the GPS when you do not need it.

The GPS system is run by the United States Department of Defense and has been fully

operational since 1995. At least 24 operational satellites circle the globe every 12

hours in 6 orbital planes with 4 satellites per plane to provide a true global coverage.

A worldwide ground control network monitors the health and status of the satellites.

The system works 24 hours a day regardless of the weather. It can provide service to

an unlimited number of users and it is free of charge.

NOTE: The very first time you initiate the GPS, it will take longer than usual for the

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