Hi Richard, I'm sure you are not the only one with doubts on this new standard for Telecom port measurements.
I beleive that this standard is already under scrutiny and revisions are underway to clarify some of the issues, especially for current measurement methods. About your question, I think you only need to comply with either the Current limits or the Voltage limits of table 3 or 4 of EN55022:1998. If you closely look at the bullet points under section C.1.2 : Bullet 4 says "Voltage measurement is also possible.... ". I don't see any reason why you need to comply with both Voltage and Current limits. You mention about using ISN for your Voltage measurements. ISNs are used to measure the asymmetrical (common mode) emissions of unshielded symmetrical (balanced) Telecom ports of the Equipmentg Under Test. In your case (shielded ports) you may have to use a high impedence Voltage probe (not defined in this standard, but similar to the one used in EN55014 but not the same). This is my opinion and lets wait and see for the experts in this forum for their comments. Praveen Rao -----Original Message----- From: Richard Lee [mailto:[email protected]] Sent: Tuesday, 24 April 2001 3:31 AM To: [email protected] Subject: ISN or Current probe method on telecommunication ports? Dear Colleague, Does anybody have done any conducted emission test on telecommunication ports per EN55022 1998 standard requirement? Currently, we have performed a conducted emission test of our product on the shielded telecom port by using ISN and current probe methods, and the results of both tests are totally different. With ISN method, the EUT failed the conducted emission on shielded telecom port by 20 dB. With current probe method, our product passed the conducted test with good margin. We don't know what is the theory behind the ISN and Current probe methods? Can anybody explain to us or advise what we need to do to pass the conducted emission test? Can the test lab accept the current probe method test data or we have to meet both limits of voltage and current requirements that listed in table 4 of CISPR. 22 1997 standard? Our product used all shielded cables on telecom ports. Per Clause 9.5.3.3 & 9.5.3.4 of CISPR. 22 1997, both methods are allowed for telecom port testing. Any suggestions or feedback will be very appreciated. Thanks in advance! Richard Lee Compliance Engineer ------------------------------------------------------------------ Terawave Communications, Inc. 30680 Huntwood, Ave. Hayward, CA 94544 Tel: 510-401-6590 Fax: 510-401-6628 www.terawave.com
