MIL-STD-1760
Encyclopedia
MIL-STD-1760 Aircraft/Store Electrical Interconnection System defines a standardized electrical interface between a military aircraft
and its carriage stores. Carriage stores range from weapons, such as GBU-31 JDAM, to pods, such as AN/AAQ-14 LANTIRN, to external fuel tanks. Prior to adoption and widespread use of MIL-STD-1760, new store types were added to aircraft using dissimilar, proprietary interfaces. This greatly complicated the aircraft equipment used to control and monitor the store while it was attached to the aircraft: the stores management system, or SMS.
MIL-STD-1760 defines the electrical characteristics of the signals at the interface, as well as the connector and pin assignments
of all of the signals used in the interface. The connectors are designed for quick and reliable release of the store from the aircraft. Weapon stores are typically released only when the aircraft is attacking a target, under command of signals generated by the SMS. All types of stores may be released during jettison, which is a non-offensive release that can be used, for example, to lighten the weight of the aircraft during an emergency.
Note that the standard describes three groups: A) the signal lines (consisting of the high & low bandwidth, MIL-STD-1553 communications, and fiber optic signals); B) the discrete lines (consisting of the MIL-STD-1553 discretes and other discrete signals); and C) the power lines (which are the same as those described here).
In common practice, an aircraft will support most of the MIL-STD-1760 signals, whereas the store needs to accommodate only those signals it needs to perform its mission. As a result, stores typically use only a partial subset of the MIL-STD-1760 signals. MIL-STD-1760 was intended to support both current needs as well as to provide growth capability as the technology matures. MIL-STD-1760 defines a Class I aircraft interface, which has four high bandwidth and two fiber optic interfaces, and a Class II interface, which has only two high bandwidth and no fiber optic interfaces.
power connections provide the store with access to 28 VDC, three-phase wye
400 Hz, 115/200 VAC and 270 VDC aircraft power; it is usual to route only one of the last two supplies, however, if both are made available, then they are never made active simultaneously. The MIL-STD-1760 interface provides power through the primary interface (2 off 28 VDC and either one or both 115/200V VAC and 270 VDC), where it is routed to the store along with all of the other signal types. The standard also allows for an optional auxiliary power interface (1 off 28 VDC and either 115/200 VAC or 270 VDC) for stores with more demanding power requirements. The auxiliary power interface includes its own interlock discrete signals so that the aircraft can determine whether the store's auxiliary power connector is attached to the aircraft.
is a military standard for the Digital time division command/response multiplex data bus that has been used since the 1970s for data communications between avionics
devices on American military aircraft. It is a dual-redundant
differential serial interface that operates at a rate of one megabaud
. The MIL-STD-1553 interface includes four signal lines, five lines used to assign one of 31 communications addresses to the store (one address is reserved), and address parity
and return lines, for a total of 11 lines.
(GPS). The low bandwidth signals are intended for carrying audio and other low frequency signals.
. Activation of the Release Consent discrete signal is used to ensure that the store will only accept such a command when it is authorized to do so.
s and starting its MIL-STD-1553 communications interface. The weapon will read its address from the settings on its MIL-STD-1760 interface and will start to listen for MIL-STD-1553 commands to that address from the SMS. These commands will commence with requests for the weapon to report its status, and will continue with commands that ready the weapon for its mission, such as navigation initialization and target coordinates. The weapon's GPS receiver will be able to lock onto the signals from GPS satellites and resolve its position much more quickly after it separates from the aircraft if it is initialized with the current position and time. The aircraft may use the MIL-STD-1553 interface to send current position and time to the weapon, and a high bandwidth signal to route the GPS satellite signal from a topside aircraft antenna to the weapon.
Just prior to release, the aircraft activates the Release Consent discrete and sends the weapon an arming command using the MIL-STD-1553 interface. The SMS will verify that the weapon release conditions have all been fulfilled, and it will activate the signals (not part of the MIL-STD-1760 interface) that cause the weapon to be released. In the case of a bomb, this is typically done by energizing an electro-explosive device that simultaneously opens the hooks that hold the bomb on the aircraft during carriage, and also operate a plunger that pushes the bomb away from the aircraft (at high speeds there is a tendency for the weapon to remain in close proximity to the aircraft after the bomb hooks open). The MIL-STD-1760 connector will release as the bomb falls away from the aircraft, and the SMS will detect that the bomb has separated by the open circuit between the Interlock and Interlock Return discrete signals.
Military aircraft
A military aircraft is any fixed-wing or rotary-wing aircraft that is operated by a legal or insurrectionary armed service of any type. Military aircraft can be either combat or non-combat:...
and its carriage stores. Carriage stores range from weapons, such as GBU-31 JDAM, to pods, such as AN/AAQ-14 LANTIRN, to external fuel tanks. Prior to adoption and widespread use of MIL-STD-1760, new store types were added to aircraft using dissimilar, proprietary interfaces. This greatly complicated the aircraft equipment used to control and monitor the store while it was attached to the aircraft: the stores management system, or SMS.
MIL-STD-1760 defines the electrical characteristics of the signals at the interface, as well as the connector and pin assignments
Pinout
In electronics, a pinout is a cross-reference between the contacts, or pins, of an electrical connector or electronic component, and their functions.- Purpose :...
of all of the signals used in the interface. The connectors are designed for quick and reliable release of the store from the aircraft. Weapon stores are typically released only when the aircraft is attacking a target, under command of signals generated by the SMS. All types of stores may be released during jettison, which is a non-offensive release that can be used, for example, to lighten the weight of the aircraft during an emergency.
Signal description
There are five main groups of MIL-STD-1760 signals:- MIL-STD-704MIL-STD-704MIL-STD-704 Aircraft Electrical Power Characteristics defines a standardized power interface between a military aircraft and its equipment and carriage stores....
power connections; - MIL-STD-1553MIL-STD-1553MIL-STD-1553 is a military standard published by the United States Department of Defense that defines the mechanical, electrical, and functional characteristics of a serial data bus. It was originally designed for use with military avionics, but has also become commonly used in spacecraft on-board...
data communications interface; - high and low bandwidth analog signals;
- discrete signals; and
- fiber optics.
Note that the standard describes three groups: A) the signal lines (consisting of the high & low bandwidth, MIL-STD-1553 communications, and fiber optic signals); B) the discrete lines (consisting of the MIL-STD-1553 discretes and other discrete signals); and C) the power lines (which are the same as those described here).
In common practice, an aircraft will support most of the MIL-STD-1760 signals, whereas the store needs to accommodate only those signals it needs to perform its mission. As a result, stores typically use only a partial subset of the MIL-STD-1760 signals. MIL-STD-1760 was intended to support both current needs as well as to provide growth capability as the technology matures. MIL-STD-1760 defines a Class I aircraft interface, which has four high bandwidth and two fiber optic interfaces, and a Class II interface, which has only two high bandwidth and no fiber optic interfaces.
Power connections
The MIL-STD-704MIL-STD-704
MIL-STD-704 Aircraft Electrical Power Characteristics defines a standardized power interface between a military aircraft and its equipment and carriage stores....
power connections provide the store with access to 28 VDC, three-phase wye
Three-phase electric power
Three-phase electric power is a common method of alternating-current electric power generation, transmission, and distribution. It is a type of polyphase system and is the most common method used by grids worldwide to transfer power. It is also used to power large motors and other heavy loads...
400 Hz, 115/200 VAC and 270 VDC aircraft power; it is usual to route only one of the last two supplies, however, if both are made available, then they are never made active simultaneously. The MIL-STD-1760 interface provides power through the primary interface (2 off 28 VDC and either one or both 115/200V VAC and 270 VDC), where it is routed to the store along with all of the other signal types. The standard also allows for an optional auxiliary power interface (1 off 28 VDC and either 115/200 VAC or 270 VDC) for stores with more demanding power requirements. The auxiliary power interface includes its own interlock discrete signals so that the aircraft can determine whether the store's auxiliary power connector is attached to the aircraft.
Data communication
MIL-STD-1553MIL-STD-1553
MIL-STD-1553 is a military standard published by the United States Department of Defense that defines the mechanical, electrical, and functional characteristics of a serial data bus. It was originally designed for use with military avionics, but has also become commonly used in spacecraft on-board...
is a military standard for the Digital time division command/response multiplex data bus that has been used since the 1970s for data communications between avionics
Avionics
Avionics are electronic systems used on aircraft, artificial satellites and spacecraft.Avionic systems include communications, navigation, the display and management of multiple systems and the hundreds of systems that are fitted to aircraft to meet individual roles...
devices on American military aircraft. It is a dual-redundant
Redundancy (engineering)
In engineering, redundancy is the duplication of critical components or functions of a system with the intention of increasing reliability of the system, usually in the case of a backup or fail-safe....
differential serial interface that operates at a rate of one megabaud
Baud
In telecommunications and electronics, baud is synonymous to symbols per second or pulses per second. It is the unit of symbol rate, also known as baud rate or modulation rate; the number of distinct symbol changes made to the transmission medium per second in a digitally modulated signal or a...
. The MIL-STD-1553 interface includes four signal lines, five lines used to assign one of 31 communications addresses to the store (one address is reserved), and address parity
Parity bit
A parity bit is a bit that is added to ensure that the number of bits with the value one in a set of bits is even or odd. Parity bits are used as the simplest form of error detecting code....
and return lines, for a total of 11 lines.
Analog signals
The high and low bandwidth signals are for routing analog signals between the aircraft and the store. Note that either the aircraft or the store can be the source of the signal. The high bandwidth signals are intended for carrying video and other high frequency signals, such as those transmitted by the Global Positioning SystemGlobal Positioning System
The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...
(GPS). The low bandwidth signals are intended for carrying audio and other low frequency signals.
Discrete signals
There are two sets of discrete signals. The Interlock discrete is used by the aircraft to determine whether the store is attached to the aircraft. This interface uses two signals, the Interlock, and the Interlock Return. These signals are simply connected together within the store, and when the store is released from the aircraft this connection is broken on the aircraft side. The aircraft determines the presence of the store by measuring the continuity between the two signals. Certain stores, typically weapons, may be commanded into modes that can be hazardous if not managed properly, such as the arming of a warheadWarhead
The term warhead refers to the explosive material and detonator that is delivered by a missile, rocket, or torpedo.- Etymology :During the early development of naval torpedoes, they could be equipped with an inert payload that was intended for use during training, test firing and exercises. This...
. Activation of the Release Consent discrete signal is used to ensure that the store will only accept such a command when it is authorized to do so.
Fiber optic interface
The fiber optic interface is intended for much higher digital communications speeds than can be supported by MIL-STD-1553, such as Fiber Channel, which can operate at gigabaud rates.Interface usage
The MIL-STD-1760 interface is used as follows with a notional weapon that uses GPS for terminal guidance. Prior to activating any of the store's interface signals, the aircraft will examine the interlock discretes to ensure that the store is attached to the aircraft, thereby preventing the ground crew from being subjected to an electrical shock hazard while servicing the aircraft. The interface will be energized to supply the weapon with electrical power when the air crew determines that hostilities are imminent. The weapon electronics will initialize itself, including running a battery of self testBuilt-in self-test
A built-in self-test or built-in test is a mechanism that permits a machine to test itself. Engineers design BISTs to meet requirements such as:*high reliability*lower repair cycle timesor constraints such as:...
s and starting its MIL-STD-1553 communications interface. The weapon will read its address from the settings on its MIL-STD-1760 interface and will start to listen for MIL-STD-1553 commands to that address from the SMS. These commands will commence with requests for the weapon to report its status, and will continue with commands that ready the weapon for its mission, such as navigation initialization and target coordinates. The weapon's GPS receiver will be able to lock onto the signals from GPS satellites and resolve its position much more quickly after it separates from the aircraft if it is initialized with the current position and time. The aircraft may use the MIL-STD-1553 interface to send current position and time to the weapon, and a high bandwidth signal to route the GPS satellite signal from a topside aircraft antenna to the weapon.
Just prior to release, the aircraft activates the Release Consent discrete and sends the weapon an arming command using the MIL-STD-1553 interface. The SMS will verify that the weapon release conditions have all been fulfilled, and it will activate the signals (not part of the MIL-STD-1760 interface) that cause the weapon to be released. In the case of a bomb, this is typically done by energizing an electro-explosive device that simultaneously opens the hooks that hold the bomb on the aircraft during carriage, and also operate a plunger that pushes the bomb away from the aircraft (at high speeds there is a tendency for the weapon to remain in close proximity to the aircraft after the bomb hooks open). The MIL-STD-1760 connector will release as the bomb falls away from the aircraft, and the SMS will detect that the bomb has separated by the open circuit between the Interlock and Interlock Return discrete signals.
External links
- MIL-STD-1553B MilesTek Online (No Registration Required)
- MIL-STD-1760 Standard - currently issue E 10-2007
- MIL-STD-1760 Standards
- MIL-STD-1553 Designer's Guide from Data Device Corporation (DDC)(No registration required)
- MIL-STD-1553 Tutorial (Video - 4 Parts) - Excalibur Systems Inc. (No Registration Required)
- MIL-STD-1760 References - Excalibur Systems Inc.(registration required)
- MIL-STD-1553 Tutorial (Condor Engineering)
- DODSSP U.S. Department of Defense Single Stock Point for Military Specifications, Standards and Related Publications
- MIL-STD-1553/1760 Products by Alta Data Technologies
- C-MAC MicroTechnology 1760 remote terminal