User's Manual

SYSTEM DESCRIPTION AND INSTALLATION MANUAL
TCAS 3000 Traffic Alert and Collision Avoidance System
34−43−23
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Page 4−9
15 Dec 2005
Table 4−1. TCAS 3000 Computer Unit Loading/Gradient Specifications (cont)
Connector Pin
Designation
Functional Description
RMP−12B Radio Altimeter Type Select Program Input No. 4 (NO)
The TCAS 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.
ARINC 552, Collins BCA, and metric type radio altimeters can be selected. In addition
radio altimeter inputs can be selected which include AHV−6, NR−AS−10A, LPIA, and
APN−232 CARA. 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)
Each of the military radio altimeter types provide two outputs that are connected to the
TCAS computer unit input pins. The two altimeter outputs are the Analog Data Output
and Analog Data Reliability Signal. The Data Reliability Signal is connected to RMP−2K
for source No. 1 and RBP−3C for source No. 2, except for altimeter type LPIA. For radio
altimeter type LPIA, the Analog Data Output must be connected to RMP−2H (HI) and
RMP−2J (LO), the Analog Data Reliability Signal must be connected to RBP−3A (HI) and
RBP−3B (LO), and the inputs RMP−2K and RMP−3C are set high (greater than 18.5 V).
The metric radio altimeters are defined as follows:
Metric
Altimeter Definition
No. 1 Metric unit− 1000 meter range, 25 mV/M scaling
No. 2 Metric unit− 1000 meter range, 20 mV/M scaling
No. 3 Metric unit− 1500 meter range, 20 mV/M scaling
No. 4 Metric unit− 750 meter range, 50 mV/M scaling