Often times, you would like to measure the characteristics of a DUT by connecting to it with a cable. Unfortunately, the cable is not ideal and degrades the measurement of the DUT. Frequency Gated by Time (FGT) is a feature that allows the unwanted characteristics of the devices surrounding the DUT to be “gated” out of the measurement. FGT first transforms the frequency data into the time domain, “gates” out the unwanted time domain data, and then transforms the gated time domain data back into the frequency domain.

The screen capture in Figure: DUT at Far End of Cable Measurement – Frequency Gated by Time (FGT) shows the measurement of a DUT at the far end of a 30 cm cable.

 

Another feature that is related by FGT is called GATE NOTCH”. Instead of gating the desired portion of the time domain response, notch allows you to suppress an unwanted portion of the time domain response. To turn on GATE NOTCH, from main menu select MEASURE > TIME > GATE >GATE NOTCH.

For illustration purposes, the screen capture in Figure: DUT at Far End of Cable Measurement – Notch with Frequency Gated by Time places a “notch” on the DUT location, leaving just the cable in the time domain response.