EN 55022 (equivalent to CISPR 22) : Limits methods for measurement of radio disturbance characteristics of information technology equipment.

Procedures are given for the measurements of the levels of spurious signals generated by the ITE (and Telecom Terminal Equipment TTE) and limits are specified for the frequency range 9kHz to 1GHz for both Class A and Class B equipment. The intention of this standard is to establish uniform requirements for the radio disturbance level of the equipment contained in the scope, to fix limits of disturbance methods of measurement and to standardise operating conditions and interpretation of results.

Information Technology Equipment is any equipment which has a primary function of either (or a combination of) entry, storage, display, retrieval transmission, processing, switching, or control of data and telecommunication messages and which may be equipped with one or more terminal ports typically operated for information transfer.

ITE is subdivided into two categories denoted Class A ITE and Class B ITE

Class A: Class A equipment is information technology equipment which satisfies the Class A interference limits but does not satisfy the Class B limits. In some countries, such equipment may be subject to restrictions on its sale and/or use.

Class B : Class B equipment is information technology equipment which satisfies the Class B interference limits. Such equipment should not be subject to restrictions on its use.

Tests required by the standard are :

• The measure of main terminal interference voltage from 150kHz to 30MHz measured using 50ohms//50microH CISPR artificial main network.
• Antenna terminal disturbance voltage over the range 30 to 1000MHz.