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well.
Frequency span and pulse width are in inverse ratio. The broader the frequency span is, the narrower the impulse response
pulse is; The shorter the step response rise time is, the higher the response Measure resolution is.
b)
Window width (parameter β)
Response resolution is also the function of time domain transformation window width. The smaller the β is, the narrower the impulse
response pulse is, and the shorter the step response rise time is , the higher the response Measure resolution is.
Selection of window width depends on response of the measured piece. If the response is signal with equal electrical level, minimum
window shall be applied to improve Measure resolution, and if not, maximum window shall be implemented to improve dynamic range
of Measure; see Section 3 "Window Filtering" in this chapter for detailed information about window setting.
When setting time domain Measure, in Time Domain Transform dialog box, the Analyzer will calculate width of response pulse
automatically according to current setting.
c)
Time domain transformation mode
In low-pass and band-pass transformation modes, resolutions of Measure responses are different. For the same frequency span and
Sweep spot number, low-pass mode has higher resolution and pulse width can reduce by half compared with band-pass mode; figure
below provides the resolution comparison in two modes.
See Section 8.6 "Band Pass and Low Pass Time Domain Modes" in this chapter for detailed information about time domain
transformation mode.
Techniques to optimize response resolution
In most conditions, the highest time resolution is obtained by selecting maximum frequency span; however, frequency setting
must meet operating frequency requirements of the DUT.
Resolution is affected by frequency span, window width and time domain mode, so optimal setting must be performed according
to response of the DUT.
8.2.2. Display Resolution
Display resolution of time domain refers to the capability to locate a signal response accurately in term of time. Good display
resolution can improve peak point of response and location accuracy of zero point and display resolution is affected by time span and
Sweep spot number:
Fig. 8-4 Effect of Transformation Modes on Resolution
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