Modifying Slots in Test Vectors to Validate Decoders of a Train Network

Networks in trains are mobile communication systems which require, above all, safety and reliability. So, the electronic creation flow should ensure that the designed line controller (mainly coder and decoder) is secure. However, verifying the behavior and performance of such an electronic circuit is not a simple task. Most times, the receiver must accept a certain minimum distortion, so some imperfect frames should not be rejected. This article presents a tool, based on simulation, to make easier the verification flow. It produces the suitable test vectors in order to validate, specially, the decoder of the Multifunction Vehicle Bus devices. These proof inputs are VHDL signals forming specific frames: some of them can be perfect but others will include distortions introduced according to the designer´s wish. In this way, the circuit will be tested under not perfect but acceptable conditions (tolerable distortion). The user is able to shift some selected edges within the frame, introduce additional delays and change the logical level of some symbols.