Nonlinear FM (Pulse)

Menu Path: MeasSetup > Pulse Properties > Analysis Tab > Nonlinear FM Panel

The Analysis tab's Nonlinear FM Frequency Modulation panel lets you configure nonlinear FM pulses. Linear FM must be selected as a Pulse Modulation Type because nonlinear and linear FM pulses are both initially detected as linear FM pulses.

The Nonlinear FM panel allows you to set the following parameters:

• Nonlinear FM Analysis -- Enables or disables Nonlinear FM modulation support. When enabled, a pulse that is detected as Linear FM is assumed to be Nonlinear FM, where the frequency of the modulated pulse is recalculated with polynomial curve fitting.

  Default: Disabled

• Max Polynomial Degree -- Specifies the maximum order of the polynomial coefficients for the curve fitting.

  Default: 5

  Range: 1-10

• Time Scaling Region For Polynomial -- Specifies the range of time (region) to be normalized to +/-1. Polynomial coefficients are estimated based on the selected time scaling region.

  Top Region - Normalized by pulse top region time.

  Analysis Region - Normalized by pulse analysis region time.

  Pulse Width - Normalized by pulse width.

  User-defined (sec) - Normalized by time specified by the User-defined Pulse Region for Polynomial parameter.

  Default: Top Region

  Choices: Top Region, Analysis Region, Pulse Width, User-defined (sec)

• User-defined Pulse Region for Polynomial -- Sets the user-specified normalization time in seconds. This property is only used when Time Scaling Region For Polynomial is set to User-defined (sec).

  Default: 10 µs

• Pulse Region Diagram -- Toggles the display of a generalized pulse diagram that shows top region, analysis region, pulse width and detection threshold.

   

  

   

• Freq(t) Reference Trace Calculation: Specifies the reference generation method.

  • Auto Extracted Coefficients: (default) The reference of frequency/phase analysis is auto generated by estimated curve fitting of the measured frequency response.

  • User-defined Coefficients: The reference of frequency/phase analysis is generated by user specified polynomial coefficient values.

• User-defined Coefficients:

  • Copy Measured Pulse: Copies the auto extracted coefficient values of a particular pulse from the pulse table. When Copy Measured Pulse is clicked, Freq(t) Reference Trace Calculation is coerced to User-defined Coefficients.

  • Auto Extracted Pulse Number: Specifies the pulse to be copied using Copy Measured Pulse.

    Default: 1

  • Import from CSV: Import from CSV allows you to import coefficient values from the first column of a .csv file. This setting is enabled when Freq(t) Reference Trace Calculation is set to User-defined Coefficients.

• Coefficients Table -- Displays the configured polynomial coefficients. The number of coefficients is Max Polynomial Degree + 1. The coefficient values are either automatically extracted or user defined, depending on the Freq(t) Reference Trace Calculation selection.

See Also

Pulse Table