NorthStar Navigation 800/628-4487, 978/897-6600 Section Five Checking out the system

SECTION FIVE: Checking out the system

Turning the 958 on and off

To turn on the 958, briefly press the PWR key. The 958 emits several short beeps as it displays the START-UPscreen, then performs a series of self-tests to check its critical components and functions. Next, a message is shown as a reminder against relying on the 958’s chart cartography as the only means of safe navigation.

To see DGPS status, on the GPS POSITION screen, press DGPS INFO to display the DGPS STATUS screen. Check for low noise levels and mid-range SNR readings.

To see information about signals from the satellites, press SAT INFO.

GPS satellite number

36

WAAS satellite number

Figure 14: Satellites on the GPS satellites screen

The satellite map on the GPS SATELLITES screen shows the current location of the satellites in the sky. The 958 displays GPS satellites as circles; WAAS satellites as hexagons. You can check the quality of their signals by looking at each satellite’s Signal-to-Noise Ratio (SNR). The higher the ratio, the better the quality.

Although the U.S. government identifies WAAS satellites by their pseudo random number (PRN)—a three-digit number ranging from 120 to 138—the 958 identifies them by two-digit numbers ranging from 33 to 51. For example, the satellite for the Atlantic Operating Region (AOR) is PRN 122, which the 958 displays as 35. See Table 5 below for the satellite identification numbers that may be displayed on the 958’s screen.

958 Installation Manual, Rev. A1 Page 21