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P/N 11934-S23
Section 9
Cirrus Design
Supplements
SR20
GPS Navigator
The GARMIN GNC 420 GPS navigator is the secondary system (GPS
2), is IFR certified, and is coupled to the airplane’s CDI. The GARMIN
GNC 420 GPS navigator is capable of providing IFR enroute, terminal,
and approach navigation with position accuracies better than 15
meters. The system utilizes the Global Positioning System (GPS)
satellite network to derive the airplane’s position (latitude, longitude,
and altitude) and the altitude digitizer to enhance the altitude
calculation. The GPS 2 antenna is located under the glareshield along
the airplane centerline. All GPS navigator controls and functions are
accessible through the GNC 420 front control panel located in the
center console. The panel includes function keys, power switches,
MSG and Nav status annunciators, color LCD display, two concentric
selector knobs on each panel, and a Jeppesen NavData card slot in
each panel. The GNC 420 navigator is powered by 28 VDC through
the 5-amp GPS2 and 7.5-amp COM 2 circuit breakers on the Avionics
Non-Essential Bus.
The Jeppesen Navigation Database provides access to data on
Airports, Approaches, Standard Instrument Departures (SIDs),
Standard Terminal Arrivals (STARs), VORs, NDBs, Intersections,
Minimum Safe Altitudes, Controlled Airspace Advisories and
Frequencies. North American and International databases are
available. Database information is provided on a card that can be
inserted into the card slot on the GPS unit. Subscription information is
provided in a subscription packet provided with each system.
Communication (COM) Transceiver
The GNC 420 includes a digitally-tuned integrated VHF
communications (COM) transceiver. The transceiver and integrated
controls are mounted in the GARMIN GNC 420 unit. The transceiver
receives all narrow- and wide-band VHF communication
transmissions transmitted within a frequency range of 118.000 MHz to
136.975 MHz in 25.0 kHz steps (720 channels). For European
operations, the COM can be operator configured for 8.33 kHz channel
spacing (2280 channels). The tuning controls are located at the left
side of the GNC 420 front panel. Frequency tuning is accomplished by
rotating the large and small concentric knobs to select a standby
frequency and then transferring the frequency to the active window.
Revision 1: 05-25-05
Summary of Contents for SR20
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