Garmin GNS 400W Series Maintenance Manual page 80

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Standard Glideslope Deflection
Standard glideslope deflection must be 52% (78 μA) of center to full scale deflection, when a
standard Glideslope deviation test signal is applied at an RF level of –56 dBm.
Course Deviation Output Characteristic Test
The deviation output must be capable of driving up to three 1000 ohm meter loads with 150 ± 15
millivolts for full scale deflection. The drive circuit must provide for more than full scale
deflection with a maximum course deviation output voltage of 300 ± 30 millivolts.
Course Deviation Centering Accuracy
When centered the deflection output must be 0 ± 7.8 millivolts.
Course Deviation Deflection Accuracy
With a standard deflection 'FLY DOWN' condition (90 Hz dominant), the output must be -78 ±
7.8 millivolts. With a standard deflection 'FLY UP' condition (150 Hz dominant), the output
must be +78 ± 7.8 millivolts.
Course Deviation Flag
When valid information is present (flag out of view) the course deviation flag output must be 375
± 80 millivolts. When invalid information is present (flag in view) the course deviation flag
output must be 0 ± 25 millivolts.
Glideslope Superflag Output
When the course deviation is valid (flag out of view) the G/S superflag output must sink at least
10 ma down to 1 volt. When the course deviation is invalid (flag in view) the G/S superflag
output must sink less than 10 µa.
Receiver Sensitivity
The receiver sensitivity measured through G/S SERIAL_OUT must be greater than -92 dBm.
Measure at G/S (LOC) frequencies of 329.15 mHz (108.95 mHz), 332.00 mHz (109.30 mHz),
and 335.00 mHz (110.30 mHz). The receiver sensitivity is defined as the minimum RF input
level of a standard glideslope deflection test signal which results in a maximum deviation .0546
ddm, 60% of standard deflection.
Sensitivity Variation
The receiver sensitivity variation must not be greater than 3dB when the input frequency is varied
from 329.15 to 335 mHz.
Centering Accuracy
The centering accuracy measured through G/S SERIAL_OUT must be 0 ± .0091 ddm when using
the standard glideslope centering test signal.
Page 4-54 GNS 400W Series Maintenance Manual
Rev. A 190-00356-05