Installation Manual

Lynx NGT-9000
Installation Manual
0040-17001-01 (Revision W) Installation Checkout Page 3-52
3.11.3 Electromagnetic Interference (E.M.I.) Check
Check the following applicable aircraft systems, as well as any other system or device that is not listed,
for interference. Initial tests are to be conducted with the aircraft operating on external ground power.
Disregard any system or device that does not apply.
NOTE
The Electromagnetic Interference Check is required only for initial system
installations and not required if the unit is removed or replaced.
1. Communications
a. Cockpit Intercom
Using the cockpit intercom, verify interference free communications between the crew while
monitoring the effects of the unit.
b. VHF Communications
Set VHF communications radios to multiple frequencies and monitor effects of unit while
transmitting and receiving. At a minimum, the frequencies listed below should be tested, in
addition to locally available frequencies:
Check the GPS signal status of each satellite being received does not drop while transmitting
each frequency for a period of 35 seconds. Degradation of individual received satellite signals
below a point where navigation is no longer possible is not acceptable and will require that
additional isolation measures be taken.
For installations on rotorcraft, ensure that the rotor blades do not interfere with the received GPS
signals. This problem has been experienced in some rotorcraft and varies with the rotation rate.
Test the following frequencies for 25 kHz COM channel spacing:
121.150 MHz 121.200 MHz 121.250 MHz 131.225 MHz 131.275 MHz 131.325 MHz
121.175 MHz 121.225 MHz 131.200 MHz 131.250 MHz 131.300 MHz 131.350 MHz
In addition, test the following frequencies for VHF radios with 8.33 kHz channel spacing:
121.185 MHz 121.190 MHz 130.285 MHz 131.290 MHz
c. SATCOM Communications
If aircraft is equipped with a SATCOM system, operate the SATCOM equipment while
monitoring the GPS Satellite Status Page. Verify GPS position remains valid.