Garmin GNS 480 Installation Manaul page 112

Post-Installation Configuration & Checkout
3.3.2.1.2 GPS Operation and Position
Check the GPS operation as follows:
1. Turn on the GNS 480 and allow the unit to acquire a position. All other avionics should be turned
off for this part of the test.
2. Check the position using the GPS Status page, which is shown in Figure 3-31. This page is accessed by
pressing the FN key twice, causing the SYS smart key to be displayed. The SYS smart key is then
pressed, followed by the GPS smart key, if necessary. The lat/long displayed on this page should agree
with a known reference position.
3. Check the GPS signal reception using the GPS Status page. Typical signal levels are between 60%
and 80% of full scale (viewed using the bar graph), although values above and below this range are
normal.
4. Turn on other avionics one at a time and check the GPS signal reception to make sure it is not
affected.
5. Check for VHF COM transmitter interference.
The interference check must be completed on all IFR installations.
3-32
Figure 3-31. GPS Status Page
NOTE
560-0982-01 Rev L GNS 480 (CNX80) Installation Manual