Triple modular redundancy

For other uses of "TMR", see TMR (disambiguation).
Triple Modular Redundancy. Three identical logic circuits (logic gates) are used to compute the specified Boolean function. The set of data at the input of the first circuit are identical to the input of the second and third gates.

In computing, triple modular redundancy, sometimes called triple-mode redundancy,[1] (TMR) is a fault-tolerant form of N-modular redundancy, in which three systems perform a process and that result is processed by a majority-voting system to produce a single output. If any one of the three systems fails, the other two systems can correct and mask the fault.

The TMR concept can be applied to many forms of redundancy, such as software redundancy in the form of N-version programming, and is commonly found in fault-tolerant computer systems.

Space satellite systems often use TMR,[2][3] although satellite RAM usually uses Hamming error correction.[4]

Some ECC memory uses triple modular redundancy hardware (rather than the more common Hamming code), because triple modular redundancy hardware is faster than Hamming error correction hardware.[5] Called repetition code, some communication systems use N-modular redundancy as a simple form of forward error correction. For example, 5-modular redundancy communication systems (such as FlexRay) use the majority of 5 samples – if any 2 of the 5 results are erroneous, the other 3 results can correct and mask the fault.

Modular redundancy is a basic concept, dating to antiquity, while the first use of TMR in a computer was the Czechoslovak computer SAPO, in the 1950s.

  1. ^ "David Ratter. "FPGAs on Mars"" (PDF). Retrieved May 30, 2020.
  2. ^ "Actel engineers use triple-module redundancy in new rad-hard FPGA". Military & Aerospace Electronics. Retrieved 2017-04-09.
  3. ^ ECSS-Q-HB-60-02A : Techniques for radiation effects mitigation in ASICs and FPGAs handbook
  4. ^ "Commercial Microelectronics Technologies for Applications in the Satellite Radiation Environment". radhome.gsfc.nasa.gov. Archived from the original on March 4, 2001. Retrieved May 30, 2020.
  5. ^ "Using StrongArm SA-1110 in the On-Board Computer of Nanosatellite". Tsinghua Space Center, Tsinghua University, Beijing. Archived from the original on 2011-10-02. Retrieved 2009-02-16.