step

System object: dsp.TransitionMetrics
Package: dsp

Transition metrics of bilevel waveform

Syntax

PULSE = step(H,X)
[PULSE,CYCLE] = step(H,X)
[PULSE,TRANSITION] = step(H,X)
[PULSE,PRESHOOT] = step(H,X)
[PULSE,POSTSHOOT] = step(H,X)
[PULSE,SETTLING] = step(H,X)
[...] = step(H,X,T)

Description

PULSE = step(H,X) returns a structure array, PULSE, whose fields contain real-valued column vectors. The number of rows of each field corresponds to the number of complete pulses found in the real-valued column vector input, X. Each pulse starts with a transition of the polarity specified by the Polarity property and ends with a transition of the opposite polarity.

PULSE fields:

  • PositiveCross — Instants where the positive-going transitions cross the mid-reference level of each pulse

  • NegativeCross — Instants where the negative-going transitions cross the mid-reference level of each pulse

  • Width — Absolute difference between PositiveCross and NegativeCross of each pulse

  • RiseTime — Duration between the linearly-interpolated instants when the positive-going (rising) transition of each pulse crosses the lower- and upper-reference levels

  • FallTime — Duration between the linearly-interpolated instants when the negative-going (falling) transition of each pulse crosses the upper- and lower-reference levels

[PULSE,CYCLE] = step(H,X) returns a structure array, CYCLE, whose fields contain real-valued column vectors when you set the CycleOutputPort property to true. The number of rows of each field corresponds to the number of complete pulse periods found in the real-valued column vector input, X. You need at least three consecutive alternating polarity transitions that start and end with the same polarity as the value of the Polarity property if you want to compute cycle metrics. If the last transition found the input, X, does not match the polarity of the Polarity property, the pulse separation, period, frequency, and duty cycle are not reported for the last pulse. If the RunningMetrics property is set to true when this occurs, all pulse, cycle, transition, preshoot, postshoot, and settling metrics associated with the last pulse are deferred until a subsequent call to step detects the next transition.

CYCLE fields:

  • Period — Duration between the first transition of the current pulse and the first transition of the next pulse

  • Frequency — Reciprocal of the period

  • Separation — Durations between the mid-reference level crossings of the second transition of each pulse and the first transition of the next pulse

  • Width — Durations between the mid-reference level crossings of the first and second transitions of each pulse. This is equivalent to the width parameter of the PULSE structure.

  • DutyCycle — Ratio of the width to the period for each pulse

[PULSE,TRANSITION] = step(H,X) returns a structure array, TRANSITION, when you set the TransitionOutputPort property to true. The fields of TRANSITION contain real-valued matrices with two columns which correspond to the metrics of the first and second transitions. The number of rows corresponds to the number of pulses found in the input waveform.

TRANSITION fields:

  • Duration — Amount of time between the interpolated instants where the transition crosses the lower- and upper-reference levels

  • SlewRate — Ratio of absolute difference between the upper- and lower-reference levels to the transition duration

  • MiddleCross — Linearly-interpolated instant where the transition first crosses the mid-reference level

  • LowerCross — Linearly-interpolated instant where the signal crosses the lower-reference level

  • UpperCross — Linearly-interpolated instant where the signal crosses the upper-reference level

[PULSE,PRESHOOT] = step(H,X) returns a structure array, PRESHOOT, when you set the PreshootOutputPort property to true. The fields of PRESHOOT contain real-valued 2-column matrices whose row length corresponds to the number of transitions found in the input waveform. The field names are identical to those of the POSTSHOOT structure.

[PULSE,POSTSHOOT] = step(H,X) returns a structure array, POSTSHOOT, when you set the PostshootOutputPort property to true. The fields of POSTSHOOT contain real-valued 2-column matrices whose row length corresponds to the number of transitions found in the input waveform.

PRESHOOT and POSTSHOOT fields:

  • Overshoot — Overshoot of the region of interest expressed as a percentage of the waveform amplitude

  • Undershoot — Undershoot of the region of interest expressed as a percentage of the waveform amplitude

  • OvershootLevel — Level of the overshoot

  • UndershootLevel — Level of the undershoot

  • OvershootInstant — Instant that corresponds to the overshoot

  • UndershootInstant — Instant that corresponds to the undershoot

[PULSE,SETTLING] = step(H,X) returns a structure, SETTLING, when you set the SettlingOutputPort property to true. The fields of SETTLING correspond to the settling metrics for each transition. Each field is a column vector whose elements correspond to the individual settling durations, levels, and instants.

SETTLING fields:

  • Duration — Amount of time from when the signal crosses the mid-reference level to the time where the signal enters and remains within the specified PercentStateLevelTolerance of the waveform amplitude over the specified settling seek duration

  • Instant — Instant in time where the signal enters and remains within the specified tolerance

  • Level — Level of the waveform where it enters and remains within the specified tolerance

The above operations can be used simultaneously, provided the System object™ properties are set appropriately. One example of providing all possible inputs and returning all possible outputs is :

[PULSE,CYCLE,TRANSITION,PRESHOOT,POSTSHOOT,SETTLING] = step(H,X) which returns the PULSE, CYCLE, TRANSITION, PRESHOOT, POSTSHOOT, and SETTLING structure arrays when the CycleOutputPort, PreshootOutputPort, PostshootPort, and SettlingOutputPort properties are true. You may enable or disable any combination of output ports. However, the output arguments are defined in the order shown here.

[...] = step(H,X,T) performs the above metrics with respect to a sampled signal, whose sample values, X, and sample instants, T, are real-valued column vectors of the same length. The additional input T applies only when you set the TimeInputPort property to true.

Was this topic helpful?