Mode S Data Link Transponder

The ACSS XS-950 Mode S Data Link Transponder is a “full-featured” system implementing all currently defined Mode S functions – with built-in capability for future growth.

Current TCAS systems are used in conjunction with Mode S and ATCRBS Transponders to identify and track aircraft position, including altitude.  The XS-950 adds to this capability by allowing the operator to transmit and receive digital messages between aircraft and air traffic control.  This data link capability provides more efficient, positive, and confirmed communications than is possible with current voice systems.
Specifications

XS-950

Part number:

7517800-1000x (AC version)
7517800-5500x (DC version)

Size:

4MCU

Height:
Width:
Length:

7.6 in.
4.9 in.
15.2 in.

Weight:

11.5 lbs.

Transponder data link:

Level 4

Number of antenna parts:

2 (diversity)

Operating temperature:

-55 to +70°C

Operating altitude:

70,000 feet

Cooling:

Per ARINC 600 or ARINC 404

Power Input:

115VAC, 400Hz or +28VDC

Environment

DO-160C

COMM-D ELM capacity:

16 segments

COMM-D ELMs per second:

8

 

XS-950S/I

Part number:

7519350-2505x (AC version)
7519350-7005x (DC version)

Size:

4MCU

Height:
Width:
Length:

7.6 in.
4.9 in.
15.2 in.

Weight:

11.5 lbs.

Transponder data link:

Level 4

Number of antenna parts:

2(diversity)

Operating temperature:

-55 to +70°C

Operating altitude:

55,000 feet

Cooling:

Per ARINC 600 or ARINC 404

Power Input:

115VAC, 400Hz or +28VDC

Environment

DO-160D

COMM-D ELM capacity:

16 segments
COMM-D ELMs per second: 8
   
Gables G7300 TCAS/IFF Control Panel
Power Requirements
Primary +28VDC,2.0 A maximum current
Display & overlay lighting 5VAC,400Hz,2.3 A maximum

 

 
Dimensions
Height 5.20 in. (133.4 mm)
Width

5.75 in. (146.1 mm)

Length (incl.connector)

5.65 in. (143.7 mm)

Weight

2.5 lb (1.14kg)

 

Mounting

Dzus fasteners


The Leader in CNS/ATM Capability
Upgrading the XS-950 transponder with "Change 7" software now provides operators with Enhanced Surveillance functionality providing one of the critical components necessary for future free-flight operation. The addition of ADS-B squitter and DAPS functionality makes available an operators own aircraft state information such as latitude/longitude position, east-west velocity and track angle rate to both ground based and airborne interrogators.
XS-950 System Description
The ACSS XS-950 is used by the Air Traffic Control Radar Beacon System (ATCRBS) and Mode S (Mode Select) air traffic control systems.
For Our Military Customers
ACSS and TRW have joined forces to add Identification Friend or Foe (IFF) capability to the ACSS Mode S Data Link Transponder. Named the XS-950S/I, the ACSS/TRW transponder addresses the dual requirement for Mode S and IFF by merging commercial technology from the XS-950 and IFF technology developed for current Department of Defense (DOD) programs such as the F-22 and Comanche.


The XS-950/I meets DOD and NATO specifications for IFF Modes 1,2 and 4. It is designed to interface with existing IFF cryptographic equipment and will accommodate growth to the future IFF Mode 5 capabilities as they are defined. The ACSS/TRW design allows coordinated simultaneous Mode S and IFF operations. Equipped ID, Flight ID and ATCRBS 4096 fields are all keyboard-programmable via the Gables G7300 Mode S/IFF control panel.

Alternatively, the transponder and TCAS can be controlled with a Multifunction Control Display Unit (MCDU) over either an ARINC 429 or MIL-STD-1553 bus.

Future growth in the XS-950S/I will parallel changes in the commercial sector, thus affording the military future cost savings. Unique military growth paths such as utilizing its ADS-B squitter capability to perform formation flight/station keeping functions are also programmed.


Maximizing the use of commercial off-the-shelf (COTS) technology, ACSS and TRW have developed a dynamic system that will meet the unique needs of our military customers in the age of Free Flight.

XS950 Mode S Transponder Brochure (Download PDF document)

XS950SI Mode S Transponder Brochure (Download PDF document)

The XS-950 meets all requirements for a Mode S transponder as described in DO-181B. The unit conforms to ARINC Characteristic 718/718A with interfaces for current air transport applications, and includes dual altimeter inputs for Gilham (discrete 11 wire), synchro (ARINC 407), ARINC 429 and ARINC 575 interfaces.
The Traffic Alert and Collision Avoidance System (TCAS II) is fully supported, including "diversity" (top and bottom) antenna ports. Diversity provides for reliable RF communication links between both ground-based and airborne (TCAS) interrogators. The transponder incorporates a TCAS II systems conforming to ARINC 718A/735A characteristics.

ACSS’ XS-950 is an ICAO Annex 10 "Level 4" system. It is capable of transmitting and receiving 16-segment extended-length (112 bit) messages, which exceeds the minimum ICAO Level 4 requirement by a factor of four. The 16-segment Level 3/Level 4 message capability also meets the RF duty cycle requirement for the envisioned ICAO Level 5 transponder.
To provide maximum reliability while minimizing maintenance costs, ACSS has included full Built-In Test (BIT) and self-test capabilities. The BIT system separates aircraft installation and aircraft system failures external to the transponder, thus minimizing the time required to return removed units to service. The system has interfaces for all onboard aircraft maintenance computers on current major air transport production airplanes. Software in the transponder is certified to D0-178B, the FAA requirement for software development and certification. Software updates can be completed on-board the aircraft by means of an ARINC 615 portable data loader. The data loader port is located on the front connector.
Provisioned for Growth
Consistent with ACSS philosophy, the XS-950 design meets the needs of the future by including growth capacity to support CNS/ATM and the Aeronautical Telecommunications Network, with graceful growth to "Level 5" through added software.

ACSS has designed the XS-950 to accommodate the CNS/ATM and ATN data link functions currently being developed. These functions included an embedded Airborne Data Link Processor (ADLP) and the proposed ICAO Mode S data link Level 5.

The Mode S ADLP, which can be accommodated within the transponder, prepares it to work within the Aeronautical Telecommunications Network. The transponder will connect directly to an ARINC 758 Communications Management Unit (CMU) via an ARINC 429 data bus, and the internal ADLP supports data link capabilities. The transponder is hardware-provisioned for the ADLP and is planned to be upgraded through software changes.