User's Manual Part 2

T
2
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--9
Table 4--1. TT--950/951/952 T
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CAS Computer Unit Interface Description (cont)
RMP--12B Radio Altimeter Type Select Program Input No. 4 (NO)
The T
2
CAS computer unit uses radio altitude to inhibit advisories and aural annunciation
when in close proximity to the ground. This analog input No. 1, as well as analog input
No. 2 can accept data as a dc voltage from several types of radio altimeters. Program
pin RMP--12B is used, along with program pins RMP--12H, --12J, and --12K, to identify the
type of analog radio altimeter installed.
For T
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CAS CU ARINC 552, Collins BCA, AHV--6, NR--AS--10A, LPIA, APN--232 CARA
and metric type radio altimeters can be selected. The program pin inputs use
ground/open logic levels. All unassigned program pin combinations are invalid and
should not be selected. Pin RMP--6K can be used to supply a ground.
Program Pin
RMP--12K RMP--12J RMP--12H RMP--12B Altimeter Type
Open Open Open Open ARINC 552/552A
Open Open Open Ground Collins BCA
Open Open Ground Open Metric Altimeter No. 1
Open Open Ground Ground Unassigned
Open Ground Open Open Metric Altimeter No. 2
Open Ground Open Ground Unassigned
Open Ground Ground Open Metric Altimeter No. 3
Open Ground Ground Ground Unassigned
Ground Open Open Open Metric Altimeter No. 4
Ground Open Open Ground Unassigned
Ground Open Ground Open Military AHV6 (Linear)
Ground Open Ground Ground Military AHV6 (Log)
Ground Ground Open Open Military NR--AS--10A (Alternate)
Ground Ground Open Ground Military APN--232 CARA
Ground Ground Ground Open Military LPIA
Ground Ground Ground Ground Military NR--AS--10A (Curve Fit)
The Radio Altitude sources listed are defined by the following:
ARINC
552/552A
-- 2 0 < H <
480 feet: Voltage = [ 0.02 x (H + 20) ] Vdc
480 < H < 2500 feet: Voltage = [ 10 x ( 1 + ln((H + 20)/500)) ] Vdc
Were H = Radio Altitude in feet.
Maximum Voltage output is 26.2 Vdc at any height above 2500 feet.
Collins
BCA
-- 2 0 < H < 500 feet: Voltage = [ 0.02 x (H + 20) ] Vdc
500 < H <
2500 feet: Voltage = [ 10.4 + 0.003 x (H -- 500) ] Vdc
Were H = Radio Altitude in feet.
Maximum Voltage output is 26.2 Vdc at any heightabove 2500 feet.
AHV 6
Linear
0.0 to 25.0 Vdc: H = 200V -- 20
Were H = Radio Altitude in feet and V = Voltage in Volts dc.