Option 238 is the time gating option for Field Fox analyzers.

With time gating, you can measure the spectrum of a periodic signal during a specified time interval. Pulsed-RF signals are an example of a periodic signal that can be measured with time gating. For example, you can measure the pulse during the on period, not the transition or the off period. Or you can exclude interfering signals such as a periodic transient. Time gating allows you to view spectral components that would otherwise be hidden. FieldFox’s time gating method is a Gated FFT.

• Gate method: Gated FFT
• Span range: Any span
• RBW range: 1 Hz to 300 kHz (derived from gate width)
• Gate delay range: -150 ms to 10 s
• Gate width (length) range: 6 μs to 1.8 s
• Gate sources: External, RF burst, Video