ヘッドルーム - DTX CableAnalyzer

Headroom is a term often used within the data cabling industry to describe the performance of a cabling system. The figure is expressed in dB (decibels). It represents the margin between the chosen test standard and the measurement made. To further explain this, lets look at an example from the DTX CableAnalyzer: 

So how did we get to this 5.0 dB? To find out, lets press the ENTER button: 

Did you notice that 'i' next to the Length measurement? This indicates the measurement is recorded as information only, since length is not required for compliance to this chosen cabling standard.