NorthStar 957 Operator's Manual page 155

Chapter 11 - Setting up your 957
To change any of the options (fully described in the following
Changing the
pages), select it by pressing the CURSOR PAD to move the
settings
arrow at the left of the screen, then press the EDIT menu key.
The selected option begins to flash, waiting for you to change
it using the CURSOR PAD or the KEYPAD.
When you're using uncorrected GPS, you may see that your
Choosing a speed
Speed-Over-Ground readings, which are obtained from the
averaging
GPS satellites, are slightly erratic, varying by up to several
knots. The 957's GPS speed averaging function can help steady
these readings. This function lets you select the time over
which your speed is averaged, with choices between two and
ten seconds. Averaging can also be turned off for the quickest
possible reaction time. You can change the speed averaging
value at any time without affecting other navigation functions.
Shorter averaging times provide a faster display of speed but
with less accuracy. A longer averaging time is useful at lower
speeds when you require the highest accuracy, such as when
you want to trawl at a certain optimum speed. In this case,
you'll see a steadier, more accurate display that changes more
slowly.
957 Operator's Manual, Rev. B Page 147