Realization phase hardware

The Chebyshev filter offers higher attenuation and a steeper roll-off near the cutoff frequency than the Butterworth filter. There is a tradeoff to achieve the higher attenuation. The cost of utilizing a Chebyshev filter is higher values of Q, which leads to difficulties in hardware realization, and nonlinear phase characteristics, which can result in difficulties in predicting circuit performance. 

Bose s derivation resulted in hardware that compared directly at the instruction level to Hunt s LSI realization (Bose 1994). Beneath the instruction level granularity, the two devices were significantly different. A important difference lies in the memory implementations used. The FM specification models memory as a simple, functional object, subject to atomic read and write operations. In Hunt s implementations, memory transactions involve an explicit, four-phase handshake. 

The required SIL designates the methods and measures that have to be executed during the overall safety lifecycle phases. The SIL is a probabilistic quantitative concept. If certain techniques and measures are applied one expects on average that a certain reliability of the safety functions is realized. Besides statistic and systematic hardware errors this concept also takes systematic software failures into account. 

Generally, it is only possible to conduct a functional analysis as a top down approach since the function of a certain hardware element needs to be known first before the cause of failure can be derived. On the other hand, for the failure observation of sheer technical (realized) elements, such as components or structural elements, the failure of elements and also random hardware failures can be inferred from the characteristics of the elements. The failure effects can then be referred to as inductive analysis. However, as a result only the inductive analysis truly addresses the effects of random hardware failure. By a deductive approach only requirements for random hardware-failure could be elaborated so that required failure rates and related diagnostics could be specified. By adequate verifications and tests the fulfillment of given metric requirements could be shown. This will widely indicate a mix of inductive and deductive analysis, whereas the lower level is designed inductively and in the upper level the technical malfiinctional behaviour is described functionally, so that the consistency (see Figs. 4.35 and 4.36 analysis phase) could be assured. 

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