Garmin Apollo CNX80 Installation Manual page 94

Post-Installation Configuration & Checkout
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.
a) Verify that at least five satellites are displayed in green boxes (with the corresponding satellite
vehicle number displayed in green on the left of the bar graph). Ensure that NO POSITION
FIX is not displayed.
b) Press the COM bezel key and tune the CNX80 Com to 121.125 MHz. Listen on the frequency
to ensure it is not in use, and then transmit for 30 seconds.
When the mic has been keyed for 35 seconds, a "WARNING Stuck Microphone" message
will pop-up and the com transmitter will stop transmitting. If required to transmit for an
additional 15 seconds, the PTT switch must be momentarily released and then re-keyed to
continue transmitting – the WARNING message does not have to be cleared to continue
transmitting.
c) While transmitting, observe the signal status of each satellite being received. If the satellite
signals are significantly degraded or some satellite signals are lost during the test, continue
transmitting for another 15 seconds. Verify that the GPS position remains valid (if position is
lost, NO POSITION FIX will be displayed in place of the position data). If position is lost,
additional isolation measures will have to be taken.
3-22
Figure 3-22 – GPS Status Page
NOTE
NOTE
560-0982-00 Rev D Apollo CNX80 Installation Manual