Regions Tab (Pulse)

Menu Path: MeasSetup > Pulse Properties > Regions

The Regions tab lets you set thresholds, FM Frequency Modulation Filter bandwidth, and the pulse width for Frequency/Phase and Ripple calculations.

Thresholds

Rise Time -- You can specify the lower and upper threshold levels for the pulse amplitude Rise Time. These levels are used for the calculation of Pulse Table, Current Record Statistics and Cumulative Statistics reported Rise Time (s) and Rise Edge (s) performance metrics. Rise Time (Lower & Upper) threshold levels are specified as a percentage of the measured per-pulse signal amplitude deviation. The signal amplitude deviation is defined in the user specified Amplitude Domain of either Voltage (Volt) or Power (Watt) according to the following formula:

Measured 100% Top Level – 0% Base Level

The reported Base Level (dBm deciBels referenced to a milliWatt: dB relative to 1 milliwatt dissipated in the nominal input impedance of the analyzer) metric within the Pulse Table is used as the Rise Time 0% Base Level in the user specified Amplitude Domain.
- Lower -- Specifies Pulse Rise Time Lower Threshold in percent (%) of Pulse Top 100% Power level. Directly affects reported Rise Time analysis result metrics
  Default: 10%
- Upper -- Specifies Pulse Rise Time Threshold in percent (%) of Pulse Top 100% Power level. Directly affects reported Rise Time analysis result metrics
  Default 90%
Fall Time -- You can also specify the lower and upper threshold levels for the pulse amplitude Fall Time. These levels are used for the calculation of Pulse Table, Current Record Statistics and Cumulative Statistics reported Fall Time (s) and Rise Edge (s) performance metrics. Fall Time (Lower & Upper) threshold levels are specified as a percentage of the measured per-pulse signal amplitude deviation. The signal amplitude deviation is defined in the user specified Amplitude Domain of either Voltage (Volt) or Power (Watt) according to the following formula:

Measured 100% Top Level – 0% Base Level

The reported Base Level (dBm) metric within the Pulse Table is used as the Fall Time 0% Base Level.
- Lower -- Specifies Pulse Fall Time Lower Threshold in percent (%) of Pulse Top 100% Power level. Directly affects reported Fall Time analysis result metrics
  Default: 10%
- Upper -- Specifies Pulse Fall Time Upper Threshold in percent (%) of Pulse Top 100% Power level. Directly affects reported Fall Time analysis result metrics
  Default 90%
Pulse Width -- Specifies Pulse Width Threshold in percent (%) of Pulse Top 100% Power level. The calculated pulse width is from the time between the Pulse Width level (50% default) on the rising edge and the Pulse Width level on the falling edge. The value that you set directly affects reported Pulse Width Time analysis result metrics.
Default 50%
Amplitude Domain -- Specifies the Pulse Amplitude Units used during Pulse Rise/Fall Time threshold level calculations as either "Volt" or "Watt". Directly affects reported Rise Time, Fall Time, and Pulse Width Time analysis result metrics. Also affects reported units of Droop (%), Overshoot (%) and Ripple (%) result metrics. Droop (%), Overshoot (%) and Ripple (%) are reported in %Volt amplitude units when “Amplitude Unit” = “Volt”, otherwise they are reported in %Watt power units
Top/Base Level Calculation Method -- Determines how the Top Level and Base Level metrics are calculated for each detected pulse. Valid choices are “Mode”, “Median” or “Mean”. Measurements are based on IEEE Institute of Electrical and Electronics Engineers. A US-based membership organisation that includes engineers, scientists, and students in electronics and related fields. The IEEE developed the 802 series wired and wireless LAN standards. Visit the IEEE at http://www.ieee.org Std 181-2011, where a bi-modal histogram is generated for each individual detected pulse. The bi-modal histogram is then split into two sub-histograms representing pulse amplitude ON (Top) and Off (Base) regions. Top and Base Levels are derived as either the Mode, Median or Mean levels from each of the respective pulse amplitude sub-histograms.
Adjust Thresholds For Droop
- When checked (TRUE), the measurement compensates the Rise Time and Fall Time 100% Top Levels for Droop when applying Rise/Fall Thresholds. Note that the measurement uses the reported Droop Start (dBm) and Droop Stop (dBm) levels as the Rise Time and Fall Time 100% Top Levels, respectively
- When unchecked (FALSE), the measurement does not compensate the Rise Time and Fall Time 100% Top Levels for Droop when applying Rise/Fall Thresholds. Note that the measurement uses the reported Top Level (dBm) as the Rise Time and Fall Time 100% Top Levels

Analysis Regions

Droop Estimation Width -- Adjusts the pulse analysis width (from 0-100 %) to remove overshoot. Typically, the first and last 25% of the pulse are usually where the majority of overshoot occurs. A value of 50% will remove the first and last 25% of the pulse from the analysis region. As overshoot is removed, you will see droop levels move toward 0 dB in the Droop column of the Pulse Cumulative Statistics trace/result table.

Default: 100%
Ripple Analysis Width -- Specifies the range of measured pulse amplitude samples to be included within the ripple analysis results, as a centered percentage of each detected pulse's Top Part samples. This is useful when the detected pulse contains known amplitude modulation on/off transition and settling effects, which you want to exclude from the Pulse Table, Current Record Statistics, and Cumulative Statistics ripple metrics.

The Ripple Analysys Width is displayed as a dark green band that is centered on each pulse in the Amplitude Meas Time, Amplitude Ref Time, Amplitude Error Time and Acquisition Time traces.

Metrics affected include:
- Ripple (%)
- Ripple (dB)
Default: 50%
Frequency/Phase Analysis Width --Specifies the range of measured pulse frequency and phase samples to be included within the frequency and phase analysis results as a centered percentage of the each detected pulse's top part, chirp region, or BPSK Binary phase shift keying - A type of phase modulation using 2 distinct carrier phases to signal ones and zeros. chip state samples, as follows:
- CW/Linear FM/NLFM (% of pulse top): Specifies Continuous Wave, Linear FM, or Non-Linear FM waveforms analysis range as a centered percentage of the pulse Top part.
- Triangular FM (% of chirp region): Specified Triangular FM waveforms analysis range as a centered percentage of each symmetrical (or asymmetrical) LFM modulation chirp region.
- Barker Phase (% of chip): Specifies Barker Phase coded waveform analysis range as a centered percentage of each BPSK chip state.
This is useful when the detected pulse contains known amplitude modulation on/off transitions and other LFM chirp or BPSK phase transition modulation-settling effects, which you want to exclude from the Pulse Table, Current Record Statistics, and Cumulative Statistics frequency, phase, and best-fit FM metrics.

Trace results affected include:
- FM Reference
- FM Error
- Phase Reference
- Phase Error
Performance metric results affected include:
- Freq Error RMS (Hz)
- Freq Error Peak (Hz)
- Freq Error Peak Loc (s)
- Phase Error RMS (Hz)
- Phase Error Peak (Hz)
- Phase Error Peak Loc (s)
- Best-Fit FM Mean (Hz)
- Best-Fit FM Start (Hz)
- Best-Fit FM Stop (Hz)
- Best-Fit FM Pk-Pk Dev (Hz)
- Best-Fit FM Slope (Hz/us)
- Best-Fit FM INL (%)
- Best-Fit FM Start 2nd (Hz)
- Best-Fit FM Stop 2nd (Hz)
- Best-Fit FM Slope 2nd (Hz/us)
- Best-Fit FM INL 2nd (%)
- Best-Fit Apex Freq (Hz)
- Best-Fit Apex Time (%)
- Barker Code
- Chip Count
- Bits
- Chip Width (s)
- Chip Offset (s)
Default: 75%
Pulse-to-Pulse Analysis -- Specifies the desired pulse-to-pulse measurement sample time window location and length over which to perform the pulse frequency and phase mean measurements, plus associated pulse-to-pulse difference measurements of Freq Mean (Hz), Freq Pulse-Pulse Diff (Hz), Phase Mean (deg), Phase Pulse-Pulse Diff (deg) reported within Pulse Table, Current Record Statistics and Cumulative Statistics.

When Use Same Data as Frequency/Phase Analysis checkbox is enabled (default), the pulse-to-pulse measurement sample time window location and length is the same pulse sample range used to calculate the reported pulse frequency and phase error metrics, Freq Error RMS (Hz), Freq Error Peak (Hz), Freq Error Peak Loc (s), Phase Error RMS (Hz), Phase Error Peak (Hz), Phase Error Peak Loc (s), as determined by user specified Frequency/Phase Analysis Width (%) property.

When Use Same Data as Frequency/Phase Analysis checkbox is disabled, the measurement sample time window location and length for pulse frequency and phase mean measurements, plus associated pulse-to-pulse difference measurements of Freq Mean (Hz), Freq Pulse-Pulse Diff (Hz), Phase Mean (deg), Phase Pulse-Pulse Diff (deg) is determined by the user specified Pulse-to-Pulse Analysis property time settings for Reference Time, Offset (s) and Window Length (s), as follows:
- Reference Time
  - Rise
    - Offset specifies the center of the pulse-to-pulse measurement sample window relative to the detected pulse rising edge (pulse-on transition), determined by the Pulse Width (%) threshold level crossing on the pulse amplitude rising edge.
  - Center (default)
    - Offset specifies the center of pulse-to-pulse measurement sample window relative to detected pulse center, determined by the center of Pulse Width (%) threshold level crossings on the pulse amplitude rising and falling edges.
  - Fall
    - Offset specifies the center of pulse-to-pulse measurement sample window relative to detected pulse falling edge (pulse-off transition), determined by the Pulse Width (%) threshold level crossing on the pulse amplitude falling edge.
- Offset (s)
  - Specifies the time offset in seconds from the selected Reference Time (Rise / Center / Fall) detected location, to center of pulse-to-pulse measurement sample window.
  Default: 0s
- Window Length (s)
  - Specifies the pulse-to-pulse measurement sample window length in seconds. The center of the pulse-to-pulse measurement sample window length is determined by Offset (s) relative to the selected Reference Time (Rise / Center / Fall).
    
    Note that for very small or zero-valued Window Length (s) settings, a minimum of 1 measurement time sample point will be used for Pulse-to-Pulse Analysis results.
  Default: 0s
Performance metric results affected include:
- Freq Pulse-Pulse Diff (Hz)
- Phase Pulse-Pulse Diff (deg)

Spectrum Window -- Lets you specify among the following types of windows used for FFT analysis:

Uniform (Rectangular)
Hanning
Gaussian Top (for best dynamic fange)
Flat Top (for amplitude accuracy)
Blackman Harris
Kaiser-Bessel
Gaussian

Max Spectrum FFT Fast Fourier Transform: A mathematical operation performed on a time-domain signal to yield the individual spectral components that constitute the signal. See Spectrum. Length -- Lets you set the maximum FFT length for the current measurement. Smaller FFT lengths result in faster measurements. Larger lengths give more precise frequency values.