The US Department of Defense has released the MIL-STD-1553 military standard, which describes the features of a serial data bus. The MIL-STD-1553 standard defines the serial data bus’s technical, electrical, and functional features. The MIL-STD-1553 is suited for aircraft systems since it combines physical and protocol standards. MIL-STD-1553 design was initially for control of military aircraft. As a result, the protocols and connections of gadgets and systems provided dependable, redundant, and durable solutions.
Here are some important characteristics of the MIL-STD 1553
- Features of MIL-STD 1553 include;
- Several physical layers with redundant balancing lines
- An interface to the network
- Multiplexing with time division
- Command or response protocol that operates in half-duplex mode.
MIL-STD-1553 was originally developed for the United States Air Force, although it is now used by military and private aircraft.
- Data speed
MIL-STD-1553 employs a data rate of one megabit per second ( Mbps, which is sufficient for a wide range of applications. Other systems, on the other hand, need higher speeds.
- The standard for Physical Layers
Allows for a single wire with an impedance of 70-85 ohms on a bus running at 1MHz. The bi-phase signal is sent through the center pin of a circular connection—isolation transformers transport energy from the transmitters and receivers to the bus.
- Benefits of MIL-STD-1553 for Time-Triggered Networks
Differential signaling provides predetermined idle time to prevent collisions between consecutive transmitters, which is one of the numerous benefits of MIL-STD-1553 for time-triggered networks.
MIL-STD-1553 incorporates transformer isolation and optional transformer bus coupling, providing several benefits.
The MIL-STD-1553 is appropriate for use in severe environments. As a result, the serial data bus must be fault-tolerant, making MIL-STD 1553 perfect for commercial aviation systems.
- Benefits of transformer bus coupling in MIL-STD-1553 DC isolation
- Common mode
- Safety from lightning
- Series isolation resistors provide short circuit protection.
- For longer stub lengths, transformer bus coupling increases stub impedance.
MIL-high STD-1553’s transmit voltages provide reliable data rate and cable length performance.
- Specifications for MIL-STD-1553
- Overshoot
- Ringing
- Noise in the output
- Zero-crossing distortion in the transmitter
- The Voltage States of MIL-STD-1553
- MIL-STD-1553 defines three states for differential signaling:
- Condition of inactivity
- High level of activity
- Low-level activity
Voltage in an Idle State
Receivers can use the idle voltage to calculate the idle duration, signaling when it’s time to transmit to the next bus. Idle voltage protects the previous nodes from colliding.
Manchester bi-phase signal encoding is used in MIL-STD-1553.
- The Benefits of Differential Bus
A differential bus is used instead of a single-end bus provides common-mode performance and lightning immunity. As a result of the differential protection provided by MIL-STD-1553, a short circuit cannot bring the entire system down.
- Isolation of transformers has several benefits.
- It gives you a lot of power when it comes to DC isolation.
- The ability to withstand lightning
- Rejection is the most common manner
- It’s worth noting that common-mode rejection is critical for lowering noise on transmission lines.
- Specifications for MIL-STD-1553 Cables
- MIL-STD-1553 cable standards include the following:
- Twist and shield cable with a minimum of 75% shield
- At 1MHz, cable with a typical impedance of 70-85 ohms
- 5 dB/100ft at 1MHz cable with maximum attenuation
- 30pF/ft. maximum capacitance
- Applications of MIL-STD-1553
- Fighter planes are used to attack.
- Controlling the flight
- Computers for the mission
- Combatants’ weapon control
- Transport aircraft
In conclusion, the military standard MIL-STD-1553 specifies the electrical, functional, and mechanical properties of serial data buses used in avionics and aircraft. MIL-STD-1553 describes a physical layer that is suited for time-triggered networking systems. Idle voltages are important for preventing collisions between two successive transmitters, which improves communication and safety.
