The DSP-4x00 CableAnalyzer has been independently verified to Level IIe and Level III accuracy in accordance with ANSI/TIA/EIA-568-B and IEC 61935-1. A requirement of these standards is for the test equipment vendor to state their accuracy against the given test limit for all parameters. The tables at the end of this article represent the typical accuracy of the DSP-4x00 CableAnalyzer as verified by Underwriters Laboratories.
In accordance with the standards, any margins falling within these values must be marked with an asterisk (*).
To better understand this, let's take an example:
Both tests report a NEXT margin of 1.6 dB, yet only one of them is marked with an asterisk (*).
If we look at the graph for Link 1 below, the closest point to the limit line falls within the accuracy band (two blue lines).
If we look at the graph for Link 2 below, the closest point to the limit line does not fall within the accuracy band (two blue lines) because the closest point is at the lower frequencies where the measurement accuracy is better.
You will notice that there are two columns for Return Loss below. The accuracy of the Permanent Link Return Loss measurement can be improved significantly by calibrating the Permanent Link Adapters with the DSP-PLCAL.
It is important to understand that the accuracy band changes with frequency.