At a previous employer we had this discussion with a vendor of ours. We contacted several compotent bodies (30+) in the United Kingdom and other countries in the European Communittee. We came up with a full 66% that would test products to CISPR 22 at ten meters. The other 33% would allow products to be tested at 3 meters. Of the 33% that allowed testing to occur at 3 meters almost all stated that if a product were to be audited by the authorities it would be tested at 10 meters.
Also if the measurement distance in CISPR 22 were to be three meters why would the FCC have change their rules to allow the acceptance of CISPR 22 data? The FCC's rules had already called out 3 meter testing the addition of a second method of testing to 3 meters would not have been worth their time. The only time that the three meter distance is used in testing to CISPR 22 is when there is a high ambient level at a given frequency. Then it is permissable to move in to 3 meter to distinguish between the ambient level and the EUT signal. Best regards, Murrell Waldron RHEINTEXAS, Inc. EMC Engineering and Testing Services P: (972) 509-2566 F: (972) 509-0073
