Determining the Electromagnetic Environment on Board Ships for Risk-based Approach EMC Analysis

Abstract

The increased implementation of new electronic systems in a small physical space has resulted in complex electromagnetic environments. A ship is an example of such a system with a complex electromagnetic environment. In order to prevent electromagnetic interference in such complex systems, one needs to understand the composition of the environment and the interaction between the different elements. This paper determines the electromagnetic environment onboard ships, with the intention of achieving electromagnetic compatibility using a risk-based approach.

Risk-based EMC Approach for the Ship's Semi-enclosed Reverberant Indoor Environment to evaluate EMI generated by Wireless Devices

“…The rule-based EMC approach is based on the assumption that if a piece of equipment meets the criteria of a standard, no interference will occur [16]. According to the rule-based EMC approach, any marine electrical device; including bridgemounted equipment, radio communication, and navigation equipment; must comply with either the IEC 60945 [17] or the IEC 60533 [18] standard.…”

“…Such a technique can lead to a cost-effective ship installation with a defined environment that can be developed by stating technical criteria and having the tests performed, verified, and validated. The four major steps [16] included in the risk-based EMC approach are: 1) EMC management plan 2) EMC control plan…”

A System’s Perspective on the Use of EMI Detection and Correction Methods in Safety Critical Systems

“…Together they have the ability to detect bit errors. The channel, for layer 3, consists of the (i) Hamming (7,4) encoder, (ii) the physical layer transmitter, (iii) the physical channel, (iv) the physical layer receiver and (v) the Hamming (7,4) decoder.…”

“…The Hamming coding method [20] is an error correction code that uses parity bits to determine if and possibly where a bit error has occurred. As shown in [15] a Hamming (7,4) (four data bits and three parity bits) has the ability to correct one bit error or detect two bit errors. However, it does not know whether a single error or two errors occurred.…”

“…Hence a possible correction can still end up as a wrong output. When more than 2 bit errors occur in the Hamming (7,4), two possible outputs can be expected. The output can either be a detection and failed correction or no detection and a false negative as a result.…”