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--35
Table 4--4. XS--950 Data Link Transponder Interface Description
Connector Pin
Designation
Functional Description
P1A--1A THRU
P1A--1K, AND
P1A--2K
ENCODING ALTIMETER #2 INPUTS:
These Mode C pulse discrete inputs allow for altitude inputs from an encoding altimeter
that contains a discrete 11 wire interface. The standards for this interface are defined in
ARINC Characteristic 572, “Air Traffic Control Transponder”. The inputs use ground/open
logic levels.
NOTE: Two encoding altimeters are required if the transponder is used with TCAS.
P1A--2A, 2B ARINC 429 ADLP TO COMM A/B BUS INPUT: [P1A--2A (A), P1A--2B (B)]
Four high speed ARINC 429 busses (100k bits/second nominal) are provided for
interfacing to a Mode S Airborne Data Link Processor (ADLP). The COMM A/B input and
output busses are used for the transfer of standard length messages to and from the
ADLP. The COMM C/D input and output busses are used for the transfer of extended
length messages (ELM) to and from the ADLP. The standard for this interface is defined
in ARINC Characteristic 718, “Air Control Transponder (ATCRBS/Mode S)”.
P1A--2C, 2D ARINC 429 ADLP TO COMM C/D BUS INPUT: [P1A--2C (A), P1A--2D (B)]
See pins P1A--2A, 2B
P1A--2E, 2F ARINC 429 COMM C/D TO ADLP BUS OUTPUT: [P1A--2E (A), P1A--2F (B)]
See pins P1A--2A, 2B
P1A--3B XPDR FAIL DISCRETE OUTPUT #2:
This discrete output is set to annunciate an internal transponder failure or the Mode S
address is illegal (All 0’ s or 1’s). A ground logic threshold (<+3.0 Vdc) is output when the
transponder is operating normally, and an open logic threshold (resistance >100k Ohms
to unit ground) when a failure has occurred. The output is capable of sinking 200 mA of
current. Connect this pin to the Control Panel XPDR F AIL #2 input.
P1A--3C,
P1A--3D,
P1A--3E,
P1A--3F
CABLE DELAY PROGRAM INPUTS:
The Cable Delay Program Inputs are used to compensate for the difference in
propagation delays in the transponder due to antenna transmission line length differences
between the top and bottom antennas. The inputs use ground/open logic levels. The
Cable Delay Program Common (pin P1A--3F) can be used to supply a ground.
Program Pin Differential Transponder
P1A--3C P1A--3D P1A--3E Delay Adjustment
Open Open Open 0--50 nsec No Change
Open Open Ground 51--150 nsec Add Delay to Top Channel
Open Ground Open 151--250 nsec Add Delay to Top Channel
Open Ground Ground 251--350 nsec Add Delay to Top Channel
Ground Open Open 0--50 nsec No Change
Ground Open Ground 51--150 nsec Add Delay to Bottom Channel
Ground Ground Open 151--250 nsec Add Delay to Bottom Channel
Ground Ground Ground 251--350 nsec Add Delay to Bottom Channel
The differential delay column is the difference in the round trip cable delay between the
top and bottom antenna cables. The differential delay can be calculated as follows:
[Top length in feet -- Bottom length in feet] X [Characteristic Delay (nsec/foot)] X 2.