MIL-STD-1553: Extending Capability and Applications
Category : MIL-STD-1553
The MIL-STD-1553’s superior performance and robustness makes it an unrivalled choice for military avionics. This deterministic multi-drop data bus is designed for data and command transfers at 1Mbps. The emergence of high speed derivatives such as Turbo-1553 and HyPer-1553 is making the data bus an attractive option for applications that demand higher data rates.
Introduction
For over three decades, the avionics industry has used the serial MIL-STD-1553 as the primary interface for data and command communications in military avionic systems. This serial data bus offers robust performance, superior EMI immunity, and a high level of interoperability. Apart from military avionics, this fault tolerant data bus is also used in satellite systems, military ground vehicles, and commercial aerospace systems.
High Speed derivatives of the MIL-STD-1553
Although the MIL-STD-1553 offers a robust physical layer, its 1Mbps data rate has been a limitation to applications that demand higher data rates. To address this challenge, high speed derivatives have emerged and they are expected to make the serial data bus attractive to more applications.
The Turbo-1553 supports data rates of up to 5 Mbps and it suitable for applications that require a speed that is slightly higher than that of the standard interface. This derivative offers an increased bandwidth without changing the coupling method, modulation techniques, and other architectural features of the 1553 interface. Another derivative, the HyPer-1553, is designed for applications that demand 50 to 100+ Mbps data rates. This derivative uses alternate modulation techniques and lines codes to allow concurrent low speed and high speed communications.
Turbo 1553
This derivative is designed to offer a data rate that is slightly higher than that of the 1553 standard. It uses the same architecture and it is, therefore, critical to consider the impact of the data rate extension on the bus length, length of stubs, location of stubs, and other key design variables of the 1553 interface. Before implementing this derivative, it is also important to understand how the higher frequency will impact phase distortion and attenuation. Both phase distortion and attenuation can affect the bit error rate of a network. Attenuation impacts the bit error rate by affecting the signal to noise ratio while phase distortion impacts it through inter-symbol interference.
High Performance 1553
The High Performance 1553, also known as HyPer-1553, allows a high data rate communication, usually up to 200 Mbps, over MIL-STD-1553 cabling. It combines the strengths of a multi-drop data bus with high data rates. Although the technology provides high speed communication by employing advanced filtering and signalling techniques, it does not interfere with the legacy 1 megabit-per-second rate. When implementing this variant, it is critical to consider the signal to noise ratio since it determines the capacity of the high performance system. The data rate of the HyPer-1553 system is also determined by the number and length of stubs.
One of the key benefits of the HyPer-1553 is its capability to extend the data rate of an existing 1553 network without interfering with its legacy 1Mbps communication. To achieve reliable concurrent operation, the High Performance 1553 employs frequency division multiplexing.