User's Manual Part 2

T
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CAS / Part No. 9000000
SYSTEM DESCRIPTION AND INSTALLATION MANUAL
34-43-20
15 Feb 2003
Use or disclosure of information on this page is subject to the restrictions in the proprietary notice of this document.
4--81
The minimum External Sensor input accuracies accepted for Glideslope Deviation
are as follows:
• 0.00455 for ddm < 0.0455
• 10% for ddm < 0.175
• non--decreasing for ddm < 0.800
(a) Analog ILS Input
The glideslope deviation input signal is defined in ARINC 547 and ARINC 578--4.
This input accepts signals which have a common mode voltages of --5.0 V to
+5.0 V, a differential voltages between pins of --2.5 V to +2.5 V and an input
impedance relative to ground of greater than 1M Ohm on each pin.
NOTE: The common mode ranges allow for a ±2.5 V ground voltage differential.
NOTE: ARINC 547 ILS receivers have current mode outputs which drive 5
meter movements in parallel, each with 1k Ohm impedance. The ILS is
calibrated to output the correct current into 5 -- 1k Ohm loads in parallel.
Any additional impedance added to the circuit will cause an error in the
output. A 1M Ohm input impedance will induce a 0.02% error. Newer
ARINC 578 ILS receivers have voltage mode outputs which are immune
to load variations.
(15) Localizer Deviation (Digital/Analog)
The T
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CAS Localizer Deviation input parameter is updated using either Localizer
Deviation data OR MLS Azimuth Deviation from the following LRU data sources: ILS,
FMS, DFS and MLS.
The minimum External Sensor input accuracies accepted for Localizer Deviation are
as follows:
• 0.00465 for ddm < 0.0465
• 10% for ddm < 0.155
• 20% for ddm < 0.310
• non--decreasing for ddm < 0.400
(a) Analog ILS Input
See Glideslope Deviation Analog ILS Input
(16) Selected Decision Height
The T
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CAS Selected Decision Height input parameter is updated using one of the
following LRU data sour ces: EFIS, MCP or FMS.
If the Decision Height is not available from one of the above L RU sources, the
Decision Height will not be annunciated.