Since the standard is limited to specific bands, the high-pass and low-pass filters are provided to help blocking high out-of-band signals.
Interested? Ask our distributors
Why is filtering on the LISN provided
Is filtering needed?
Filtering of the LISN’s output is important is the DUT produces high interference outside the band of interrest. For signals below 150kHz, the standard does not provide a limit. If high net-harminic currents exist (multiples of 50Hz) these may saturate the input of the spectrum analyzer. When that happens, the spectrum analyzer will show erratic signals and will not measure the actual noise of interrest.
What filtering is provided
- 9kHz high-pass
- 110MHz low-pass
- Limiter protection
⇛
LISN, filtering