Gate Form - Saluki S3601 Series User Manual

Start and stop: to define -6dB cut-off time of the gate.
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Center: to define center time of the gate.
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Span: it equals to terminal time minus start time.
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Gate Type:
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Band-pass: to filter response outside the gate.
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Band-stop: to filter response inside the gate.
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8.4.3. Gate Form

Similar to window wave filter, the gate also has corresponding wave filter form and Measure can be optimized by selecting
reasonable wave filter form:
Minimum gate: the wave filter has highest sidelobe level, with sharpest edge falling and maximum band-pass ripples.
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Maximum gate: the wave filter has lowest sidelobe level, with slowest edge falling and minimum pass band ripples.
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Passband ripples of the gate
8.4.3.1.
The gate is a pass band (or band-stop) wave filter on time domain and each form of wave filter has different filter property. Figure
below indicates band-pass ripples of four filters in different forms and the scale in the figure is 0.5dB/grid. It can be seen from the
figure that the minimum gate has the largest band-pass ripples.
Sidelobe level of the gate
8.4.3.2.
Four wave filters of different forms have different sidelobe levels, in actual Measure, there must be a balance between lower sidelobe
level and faster cut-off ratio.
The minimum gate is with highest sidelobe level and fasted cut-off speed, which is very applicable to filtering undesired
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interference near the response.
The maximum gate is with lowest sidelobe level, slowest cut-off speed, widest gate band-pass and maximum attenuation
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outside the gate band.
Fig.8-11 Band-Pass Ripples of Different Gate Wave Filters
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