What is ISN?
The full English name of ISN is: Impedance Stabilization Network; Chinese name: Impedance Stabilization Network.
ISN is proposed by the CISPR22 and GB9254 standards and actually references the AAN parameter requirements of the CISPR16-1-2 standard.
The CISPR22 standard requires that common mode (asymmetric mode) current or voltage interference to an unshielded balanced pair of connected telecommunication ports should be evaluated with the telecommunication port connected to the ISN via a cable; therefore, the ISN should define the common mode termination impedance that is seen by the telecommunication port during the interference measurements.The ISN should allow for the proper functioning of the EUT, and for this purpose should be inserted into the signaling cable between the EUT and any auxiliary/associated Equipment (AE) or in the signaling cable between the EUT and any loads required to perform the EUT.
The ISN shall meet the requirements of Appendix E and Appendix F of CISPR 16-1-2.
What's AAN?
The full English name of AAN is: Asymmetric Artificial Network; Chinese name:不对称人工网络
AAN is a special form of coupling decoupling network, AAN is used to measure common mode voltages on unshielded balanced signal lines (e.g. telecom lines) and can be used to suppress differential mode signals.
The latest reference to the AAN is in the Form 8: Conducted Emission section of the CISPR32 standard, which explicitly directs that the AAN shall comply with the requirements of CISPR 16-1-2, Section 7. This is consistent with the ISN requirements.
Concept Summary:
As you can see from the above content, ISN is another name of AAN in CISPR22 and GB9254 standards, in fact, they both refer to the standard of CISPR16-1-2 and are referenced by other product standards. Therefore, we can think that ISN and AAN are the same test instrument.
Select the appropriate ISN and AAN based on the test criteria and technical parameters:
After distinguishing between the concepts of ISN and AAN, we can now shop for the right test instrument for our products by clicking on the parameter names in the first row of the table below, clicking on the first column of model numbers to see all the specific technical parameters of ISN and AAN, and contacting EUTTEST to get a quote.
| Model number | Compliance with test standards | LCL Longitudinal Conversion Loss | Measurable Cable Type | Number of measurable cables |
| ISN S1 | CISPR22 Figure D.9 CISPR32 figure G.9 | / | Shielded Cable | single article |
| ISN S8 | CISPR22 Figure D.11. CISPR32 figure G.11 | / | Shielded Cable | RJ45 or RJ11 connectors 2, 4, 8 lines |
| CAT5 8158 | CISPR22 Figure D.3. CISPR32 figure G.3 | LCL = 65 dB | CAT5 Cable | 8-wire up to 4 UTP pairs |
| CAT3 8158 | CISPR22 Figure D.3. CISPR32 figure G.3 | LCL = 55 dB | CAT3 Cable | 8-wire up to 4 UTP pairs |
| NTFM 8158 | CISPR22 Figure D.3. CISPR32 figure G.3 | LCL = 75 dB | CAT6 Cable | 8-wire up to 4 UTP pairs |
| NTFM 8131 A | CISPR15 CISPR32 | / | ordinary cable | 2 lines |
| NTFM 8131 discontinued | CISPR15 CISPR32 | / | ordinary cable | 2 lines |
