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Input Signal Creator



Input-Signal-Creator comprises a suite of MATLAB programs for the creation and support of periodic input signals with desirable properties for dynamic system identification. The main program provides users with a very wide range of choices for specifying the required signal through the signal power spectrum, the number of signal levels and the signal period. A subsidiary program also provides users with a tool for specifying appropriate sets of input signal periods for the identification of multi-input systems.

All the input signals created have the following properties in common:

  • A period between 3 and 27384 inclusive.
  • A spectrum with uniform power in all usable harmonics not specified to be zero.
  • A specified number of levels, which can be 2, 3, 5 or 7, symmetrical about 0.
  • A performance index for perturbation signals (PIPS) within the range 67% to 100%.
Three classes of input signal may be specified:
  • A Class 0 signal, with no harmonics specified as zero power.
  • A Class 1 signal, with all harmonic multiples of 2 specified as zero power.
  • A Class 2 signal, with all harmonic multiples of 2 and 3 specified as zero power.
An input signal is created in three stages:
  • The user specifies the signal class from a menu.
  • The user specifies the number of signal levels from a menu.
  • The user specifies the preferred signal period. If this period is not available then the closest available periods are displayed and the stage is repeated.
When an available signal period has been specified the program returns all signals that meet the specification. The phase of each signal has the least linear drift correlation (LDC). For each signal the power spectrum, autocorrelation function, PIPS and LDC are also returned.

Sets of signal periods for multi-input system identification are also obtained in three stages:

  • The user specifies the signal class from a menu.
  • The user specifies the number of signal levels from a menu.
  • The user specifies the number of system inputs from a menu.
The program then returns all sets of periods that meet the specification.

To install the programs, download Input-Signal-Creator.zip and extract the program to a MATLAB directory of choice.

To run the programs, make the current MATLAB directory the chosen MATLAB directory and enter either create_signal or multi_input_tool in the MATLAB command window.