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Simulate Signal Express VI

LabVIEW 2011 Help

Edition Date: June 2011

Part Number: 371361H-01

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Owning Palette: Input Express VIs

Requires: Base Package

Simulates a sine wave, square wave, triangle wave, sawtooth wave, or noise signal.

Examples

Dialog Box Options
Block Diagram Inputs
Block Diagram Outputs

Dialog Box Options

ParameterDescription
SignalContains the following options:
  • Signal type—Type of waveform to simulate. You can simulate a sine wave, square wave, sawtooth wave, triangle wave, or noise (DC).
  • Frequency (Hz)—Frequency in hertz of the waveform. The default is 10.1.
  • Phase (deg)—Initial phase in degrees of the waveform. The default is 0.
  • Amplitude—Amplitude of the waveform. The default is 1.
  • Offset—DC offset of the signal. The default is 0.
  • Duty cycle (%)—Percentage of time a square wave remains high versus low over one period. The default is 50.
  • Add noise—Adds noise to the simulated waveform.
  • Noise type—Specifies the type of noise to add to the waveform. This option is available only when you place a checkmark in the Add Noise checkbox. You can add the following noise types:
    • Uniform White Noise generates a signal that contains a uniformly distributed, pseudorandom pattern whose values are in the range [-a:a], where a is the absolute value of Amplitude.
    • Gaussian White Noise generates a signal that contains a Gaussian-distributed, pseudorandom pattern whose statistical profile is (µ,sigma) = (0,s), where s is the absolute value of the specified Standard deviation.
    • Periodic Random Noise generates a signal that contains periodic random noise (PRN).
    • Gamma Noise generates a signal that contains a pseudorandom pattern of values that are the waiting times to the Order number event of a unit mean Poisson process.
    • Poisson Noise generates a signal that contains a pseudorandom sequence of values that are the number of discrete events occurring in a given interval, specified by Mean, of a unit rate Poisson process.
    • Binomial Noise generates a signal that contains a binomially distributed, pseudorandom pattern whose values are the number of occurrences of an event, given the probability of that event occurring and the number of trials.
    • Bernoulli Noise generates a signal that contains a pseudorandom pattern of ones and zeros.
    • MLS Sequence generates a signal that contains a maximum length sequence of ones and zeros using a modulo-2 primitive polynomial of order Polynomial order.
    • Inverse F Noise generates a signal that contains a continuous noise waveform with a power spectral density that is inversely proportional to frequency over a specified frequency range.
  • Noise amplitude—Maximum absolute value the signal can have. The default is 0.6. This option is available only when you select Uniform White Noise or Inverse F Noise from the Noise type pull-down menu.
  • Standard deviation—Standard deviation of the noise you generate. The default is 0.6. This option is available only when you select Gaussian White Noise from the Noise type pull-down menu.
  • Spectral amplitude—Magnitude of the frequency domain components of the simulated signal. The default is 0.6. This option is available only when you select Periodic Random Noise from the Noise type pull-down menu.
  • Order—Specifies the event number of the unit mean Poisson process. The default is 0.6. This option is available only when you select Gamma Noise from the Noise type pull-down menu.
  • Mean—Specifies the interval of a unit rate Poisson process. The default is 0.6. This option is available only when you select Poisson Noise from the Noise type pull-down menu.
  • Trial probability—Probability that a given trial is TRUE. The default is 0.6. This option is available only when you select Binomial Noise from the Noise type pull-down menu.
  • One probability—Specifies the probability that a given element of the signal is TRUE. The default is 0.6. This option is available only when you select Bernoulli Noise from the Noise type pull-down menu.
  • Polynomial order—Specifies the order of the modulo-2 primitive polynomial to use to generate the signal. The default is 0.6. This option is available only when you select MLS Sequence from the Noise type pull-down menu.
  • Seed number—When greater than 0, causes reseeding of the noise sample generator. The default is –1. LabVIEW maintains the internal seed state independently for each instance of this reentrant VI. For a specific instance of this VI, if Seed number is less than or equal to 0, LabVIEW does not reseed the noise generator, and the noise generator resumes producing noise samples as a continuation of the previous noise sequence.
  • Exponent—Specifies the exponent of the inverse-f spectral shape you want. The default is 1. This option is available only when you select Inverse F Noise from the Noise type pull-down menu.
TimingContains the following options:
  • Samples per second (Hz)—Sampling rate in samples per second. The default is 1000.
  • Number of samples—Number of samples in the signal. The default is 100.
  • Automatic—Sets the Number of samples to be one-tenth of Samples per second (Hz).
  • Simulate acquisition timing—Simulates an acquisition rate comparable to an actual acquisition rate.
  • Run as fast as possible—Simulates the signal as quickly as the system allows.
  • Integer number of cycles—Sets the nearest frequency and Number of samples such that the waveform contains an integer number of cycles.
  • Actual number of samples—Indicates the actual number of samples in the waveform when you select Integer number of cycles.
  • Actual frequency—Indicates the actual frequency of the waveform when you select Integer number of cycles.
Time StampsContains the following options:
  • Relative to start of measurement—Displays the timestamp in terms of seconds starting from zero. For example, 100 in relative time equals 1 minute and 40 seconds.
  • Absolute (date and time)—Displays the timestamp in terms of time elapsed since 12:00 a.m., Friday, January 1, 1904, Universal Time [01-01-1904 00:00:00].
Reset SignalContains the following options:
  • Reset phase, seed, and time stamps—Resets the phase to the phase value and the time stamp to zero. Resets the seed number to –1.
  • Use continuous generation—Continuously simulates the signal. Does not reset the phase, time stamp, or seed number.
Signal NameContains the following options:
  • Use signal type name—Uses the default signal name.
  • Signal name—Displays the default signal name when you place a checkmark in the Use signal type name checkbox.
Result PreviewDisplays a preview of the signal to be simulated.

Block Diagram Inputs

ParameterDescription
Reset SignalSpecifies when to reset the signal. The value you wire to this input overrides the value you set in the configuration dialog box.
Duty Cycle (%)Specifies the percentage of time a square wave remains high versus low over one period. The default is 50. The value you wire to this input overrides the value you set in the configuration dialog box.
OffsetSpecifies the DC offset of the signal. The default is 0. The value you wire to this input overrides the value you set in the configuration dialog box.
FrequencySpecifies the frequency in hertz of the waveform. The default is 10.1. The value you wire to this input overrides the value you set in the configuration dialog box.
AmplitudeSpecifies the amplitude of the signal. The default is 1. The value you wire to this input overrides the value you set in the configuration dialog box.
PhaseSpecifies the initial phase in degrees of the signal. The default is 0. The value you wire to this input overrides the value you set in the configuration dialog box.
error inDescribes error conditions that occur before this node runs.
Noise amplitudeSpecifies the maximum absolute value the signal can have. The default is 0.6. The value you wire to this input overrides the value you set in the configuration dialog box.
Standard deviationSpecifies the standard deviation of the noise you generate. The default is 0.6. The value you wire to this input overrides the value you set in the configuration dialog box.
Spectral amplitudeSpecifies the magnitude of the frequency domain components of the simulated signal. The default is 0.6. The value you wire to this input overrides the value you set in the configuration dialog box.
OrderSpecifies the event number of the unit mean Poisson process. The default is 0.6. The value you wire to this input overrides the value you set in the configuration dialog box.
MeanSpecifies the interval of a unit rate Poisson process. The default is 0.6. The value you wire to this input overrides the value you set in the configuration dialog box.
Trial probabilitySpecifies the probability that a given trial is TRUE. The default is 0.6. The value you wire to this input overrides the value you set in the configuration dialog box.
One probabilitySpecifies the probability that a given element of the signal is TRUE. The default is 0.6. The value you wire to this input overrides the value you set in the configuration dialog box.
Polynomial OrderSpecifies the order of the modulo-2 primitive polynomial to use to generate the signal. The default is 0.6. The value you wire to this input overrides the value you set in the configuration dialog box.
Seed NumberReseeds the noise sample generator when this value is > 0. The default is –1. If seed is 0, the noise generator does not reseed and resumes producing noise samples as a continuation of the previous noise sequence. The value you wire to this input overrides the value you set in the configuration dialog box.
ExponentSpecifies the exponent of the inverse-f spectral shape you want. The default is 1. The value you wire to this input overrides the value you set in the configuration dialog box.
TrialsSpecifies the number of trials performed for each element of the simulated signal. The default is 1. The value you wire to this input overrides the value you set in the configuration dialog box.

Block Diagram Outputs

ParameterDescription
SignalReturns the output signal.
error outContains error information. This output provides standard error out functionality.

This Express VI operates similarly to the following VIs and functions:

Gaussian White Noise Waveform
Periodic Random Noise Waveform
Uniform White Noise Waveform
Basic Function Generator
Sawtooth Waveform
Sine Waveform
Square Waveform
Triangle Waveform

Examples

Refer to the following VIs for examples of using the Simulate Signal VI:

  • Express Filter VI: labview\examples\general\templates\Generate and Display
  • Basic Amplitude Measurements VI: labview\examples\express

 

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