IFF TRANSPONDER M424 - SELEX Elsag

IFF transponder m424
IFF TRANSPONDER M424
DESCRIPTION
M424 IFF TRANSPONDER
The M424 Transponder set is a member of a family of
new generation airborne IFF transponders developed
to satisfy the broad spectrum of IFF requirements
established for modern aircraft systems.
The M424 is equally suitable for helicopter
applications as well as in fixed-wing aircraft.
Its applications cover also naval installations. The M424
system is capable to operate MkXA, Mode S up to level
3 and in addition, as an option adapted for the specific
application: Secure Mode (crypto).
Secure Mode operation can be achieved through the use
of an external Crypto or, as an alternative, an internal
crypto module. For Mode C, the transponder operates
with an external pressure/altitude digital converter.
The M424 is designed to be controlled mainly by the
following interfaces:
• Serial, dual redundant 1553 Bus.
• Dedicated interface with the M 910 Control Unit.
As an alternative, the control is also possible via an
ARINC 429 interface (for example by means of the
CNI-MU/FMS).
When the control is by the 1553 Bus, only the
Transponder unit is needed, but a Backup Control Panel
(M911) can be provided for emergency control of
essential functions, in case of failure of the data Bus.
The Control Unit (M910) is necessary when a data Bus
is not available for control.
TYPES OF M424 EQUIPMENT
The M424 transponder set comprises equipment suitable
for different applications and installation requirements.
The M424 Transponder unit is intended for avionics bay
installation and is controlled or by a 1553 data Bus or
remotely by a Control Unit located in the cockpit panel;
it is also suitable for naval applications.
The main features are summarized in the following table, in
which according to the configuration, the type of equipment,
its function, control and installation are specified:

System Type Function Intended Control Control Unit
Configuration installation means required
1- Data Bus M424 Transponder Avionics bay MIL-STD-1553B No
data Bus
M911 Optional Cockpit Front panel N.A.
Back up control Unit
for emergency
operation
2- Control Unit M424 Transponder Avionics bay Control Unit M910
OPERATION
M910 Control Unit Cockpit Front panel N.A.
The M424 IFF Transponder receives coded RF signals
from interrogators, decodes these signals and generates
coded RF replies. The M424 operates, iaw Stanag 4193,
in Modes MkXA and Mode S, i.e.:
• Modes 1, 2, 3/A and C (Stanag 4193 MkXA, Part I
and II)
• Mode S up to Level 3 (Stanag 4193 Part IV and ICAO
Annex 10)
and in addition, as an option adapted for the specific
application:
Secure Mode (crypto)
Secure Mode operation can be achieved through the use
of an external Crypto or, as an alternative, an internal
crypto module.
CONTROL
The flexibility of the Transponder allows a wide range of
operations and alternative solutions.
M910 CONTROL PANEL
• Provides full control of transponder operation
• Friendly display and keyboard design for system
initialization in pre-flight
• Conventional controls for recurrent in-flight operations
• Display of equipment status
• APX 100 compatible size
• Display
- NVG compatible lighting scheme i.a.w.
MIL-L-85762A, Type 1A
- Compatible with centralized background dimming
- Ambient Light Sensor
BACKUP EMERGENCY OPERATION
In the DataBus configuration, by means of the BCP.
DIVERSITY
The Transponder must be connected to a dual omnidirectional
antenna system to provide a full coverage above and
below the aircraft plane; in this case the Transponder
M424 performs the diversity operation in accordance
with STANAG 4193.
ALTIMETER
The M424 provides wide flexibility for the Altimeter
interface, since, in addition to the MIL1553, it
incorporates a discrete (Gillham) interface and an
additional serial A429 interface.
TIME OF DAY
The Transponder provides wide flexibility for the Time
of Day (ToD) interface, needed for certain applications,
since, in addition to the MIL 1553, it incorporates a
serial PTTI (GPS) interface and a serial A429 interface.
NAV DATA
The Transponder supports multiple standards, as input
interfaces, i.e. 1553 Bus, NMEA and A429.
CRYPTO VARIABLES FILL CONNECTOR
The Transponder is provided with a standard Fill
connector for Secure Mode supporting two selectable
standards:
• DS 101
• DS 102
TCAS AND MODE S
The M424 incorporates two bi-directional A429
interfaces, one to support the on-board TCAS function
(iaw A735A) and another dedicated interface for the
exchange of Full Level 2 or Level 3 Mode S data (function
provided by an external ADLP function)
Mode S operation:
Level 2 basic surveillance, as defined in Stanag 4193
Part IV, para. 5.1.1
Full Level 2 and Level 3, in accordance with Stanag
4193 Part IV and ICAO Annex 10; it will need the
implementation of the specific interface with the
aircraft for the exchange of data and controls (via the
1553 DataBus or the A429 bi-directional interface).
DISCRETE CONTROLS AND INDICATIONS
The M424 provides the necessary discrete interfaces
with the platform for the IFF functions, controls and
indications that are needed. Additional discrete
interfaces are provided in the equipment to allow, for the
MIL 1553 Bus configuration, redundant controls by
means of the Backup Control Panel (BCP).
DESIGN AND CONSTRUCTION
The M424 is a fully solid state equipment;
it makes extensive use of large scale programmable
components and state of art technologies, in order to
reduce volume and weight maximising the reliability.
Its structure is modular and includes a powerful BITE
(Power-up, Continuous and Initiated BIT).

COOLING
The Transponder Unit, the BCP and the Control Unit do
not require forced air and do not include ventilators for
cooling.
SOFTWARE
The M424 is designed according to a flexible software
architecture.
The loading of updates can be accomplished via a
standard serial interface (part of the Support Port).
GROWTH POTENTIAL AND VARIANTS:
Options: Extended Squitter (for ADS-B operation), ACC
Growth: User defined Secure Mode.
POWER SUPPLY
The power supply accepts 28 V DC and provides DC
voltages to operate the transponder.
28 V DC is i.a.w. MIL-STD-704D;
maximum input power is 60 W.
MAIN FEATURES
28 VDC or 115 Vac (if provided for routing out),
switched out for an external Crypto.
M910 CONTROL UNIT
POWER SUPPLY
The power supply accepts 28 V DC and provides DC voltages
to operate the control Unit.
28 V DC is i.a.w. MIL-STD-704D; maximum input power is
30 W.
28 V DC Panel Light for front panel illumination.
5 V AC Panel Light also available for front panel
illumination.
M911 BACKUP CONTROL PANEL
Provides reversionary control of the transponder in case
of failure of the DataBus
POWER SUPPLY
5V DC Panel Light for front panel illumination.
5 V DC Lamp Power.
• M424, transponder system of new generation design, satisfies the broad spectrum of IFF requirements
established for modern aircraft systems
• STANAG 4193 MkXA transponder, including Mode S up to Level 3
• Secure Mode capability
• Crypto for Secure Mode operation can be an external unit or embedded crypto (internal module)
• Diversity operation for spherical coverage
• Alternative solutions of control interface (databus, control Unit)
• Interface flexibility accommodates different installation requirements
• Integration capability with TCAS II equipment provided via a dedicated interface
• 1800 hours specified MTBF at 40°C AUF, more than 2000 achieved
• Comprehensive Built-in test (PBIT, CBIT, IBIT)
• Loading capability of software updates
• Extended Squitter and ACC available

TECHNICAL SPECIFICATIONS
M 424 Transponder
Environmental conditions MIL-STD-810 E
Operating temperature -40°C to +71°C
Electromagnetic compatibility MIL-STD-461E
Rx frequency 1030 ±0.5 MHz
Sensitivity MkXA and Secure Mode: from –72 to –78 dBm
Mode S: from –73 to –79 dBm
Skirt bandwidth (selectivity) ±12 MHz at -40 dB
±25 MHz at -60 dB
Dynamic range from MTL to –22 dBm
Tx frequency 1090 MHz
Frequency stability ±0.1 MHz
Output power from 25 dBW to 29 dBW
1 dB max peak power variation between the pulses in the reply
Reliability MTBF > 1800 hours at 40°C AUF
Maintainability & Testability MTTR: < 10 min (LRU) and 40 min (SRU)
Dimensions 136 x 136.5 x 219.3 mm (W x H x D)
Weight 6.0 kg (6.5 kg when an embedded cryptomodule is included)
Input power 28 V DC, 60 W
M 910 Control Unit
Environmental conditions MIL-STD-810 E “Panel mounted in cockpit console”
Operating temperature -40°C to +71°C
Electromagnetic compatibility MIL-STD-461E
NVG MIL-L-85762A, Type 1, Class A
HMI Alphanumeric display and keyboard, menu driven operation
Reliability MTBF > 8000 hours at 40°C AIF
Maintainability & Testability SRU MTTR < 30 min
Dimensions 146 x 133.4 x 42.3 mm (W x H x D)
Weight 2.0 kg
Input power 28 V DC, 30 W
M 911 Backup Control Panel
Environmental conditions MIL-STD-810 E “Panel mounted in cockpit console”
Operating temperature -40°C to +71°C
Electromagnetic compatibility MIL-STD-461E
NVG MIL-L-85762A, Type 1, Class A
Reliability MTBF > 20000 hours at 40°C AIF
Maintainability & Testability SRU MTTR < 30 min
Dimensions 146 x 47 x 42.3 mm (W x H x D)
Weight 0,5 kg
Input power 5 VDC, (28 VDC available)
SELEX Elsag S.p.A.
Sales Department - Point of Contact: getinfo@selexelsag.com - www.selexelsag.com
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