System level radiated emissions compliance using mathematical modelling
|Publication Date:||1 February 2004|
This Recommendation provides a procedure for demonstrating the compliance of the radiated RF emissions from telecommunication systems.
Telecommunication operators typically construct their systems from many items of equipment that are each engineered to individually meet EMC requirements, including radiated emissions. This means that a system will typically contain a number of emissions sources (i.e., separate equipment items) at a number of common frequencies. This is true if the system contains many items of the same equipment or many items of different equipment.
For such a system, the superposition of these multiple emissions has the potential to produce a system emission level that is greater than the system emission limit. This is of fundamental concern for telecommunication operators seeking to demonstrate the compliance of the radiated emissions of their systems.
This Recommendation introduces a statistical approach to systems radiated emission compliance. By applying a statistical approach to the treatment of basic variables that are not known by the operator, a method is presented that allows the system emission level to be described statistically in terms of a probability and cumulative probability distributions.
These distributions allow the compliance of the system emission level with respect to a limit to be expressed as a statistical confidence level (rather than as a simple "Pass" or "Fail" statement). It is proposed that the 80% confidence level be used for compliance to align with the approach taken for series production equipment within CISPR 22.
The method presented may also be used by other organizations that either build or operate other systems that are formed from the integration of many items of digital electronic equipment that each individually comply with their own radiated emissions limit.
This Recommendation does not define radiated emissions limits or methods of measurement for telecommunication systems.