Nonlinear FM Waveform

A signal generator with nonlinear frequency modulation.

blockType: NonlinearFMWaveform

Path in the library:

/Phased Array Systems/Waveforms/Nonlinear FM Waveform

Description

Block Nonlinear FM Waveform Generates a pulse signal with nonlinear frequency modulation with a preset pulse duration, pulse repetition rate (PRF), and frequency deviation. The output signal of the unit is an integer number of pulses or a sequence of samples.

Ports

Entrance

FreqOffset — frequency offset
scalar

The frequency offset specified as a scalar.

Example: 2e3

Dependencies

To use this parameter, set the Source of Frequency Offset parameter to `Input port'.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64, Bool

Output

Y — pulse signal
complex vector

The output signal of the block, specified as a complex vector.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64, Bool

PRF — pulse repetition rate
positive scalar

The pulse repetition rate, set as a positive scalar.

Dependencies

To use this port, set the Output signal format parameter to Pulses. Then select the checkbox for the Enable PRF output parameter.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64, Bool

Coeff — coefficients of the matched pass filter:q[ ] vector | the matrix

Coefficients of the matched filter, specified as a vector or matrix.

Dependencies

To use this port, select the Enable Matched Filter Coefficients Output checkbox.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64, Bool

Parameters

Sample rate (Hz) — pass sampling rate:q[ ] 1e6 (default) | positive scalar

The sampling frequency of the signal in the form of a positive scalar. The units of measurement are Hz.

The ratio of the sampling frequency to the pulse repetition frequency must be an integer.

This restriction is equivalent to requiring that the pulse repetition period (PRI) be an integer multiple of the sampling step. :

Programmatic use
Block parameter	`SampleRate`
Values	`positive scalar`
By default	`1e6`

Method to specify pulse duration — way to set the pulse duration
Pulse width (default) | Duty cycle

A way to set the pulse duration in the form of Pulse width or Duty cycle (there are two possible options in time or fill factor, i.e. duty cycle):

Pulse width — the pulse duration is set using the Pulse width(s) parameter.
`Duty cycle' — pulse duration is calculated from the parameter values Pulse repetition frequency (Hz) and Duty Cycle.

Programmatic use
Block parameter	`PulseDuratiion`
Values	`string`
By default	`Pulse width`

Pulse width (s) — pulse duration
50e−6 s (default) | positive scalar

The pulse duration, set as a positive scalar value.

Product Pulse width (s) and Pulse repetition frequency (Hz) must be less than or equal to one:

This limitation ensures that the pulse duration is shorter than the pulse repetition period.

Example: 300e−6

Dependencies

To use this parameter, set the Method to specify pulse duration parameter to Pulse width.

Programmatic use
Block parameter	`PulseWidth`
Values	`string`
By default	`50e−6`

Duty cycle — fill factor (duty cycle)
0.5 (default) | scalar in the range [0,1]

The fill factor, set as a scalar in the range [0,1].

Example: 0.7

Dependencies

To use this parameter, set the Method to specify pulse duration parameter to Duty cycle.

Programmatic use
Block parameter	`DutyCycle`
Values	`positive scalar`
By default	`0.5`

Pulse repetition frequency (Hz) — pulse repetition frequency
1e4 Hz (default) | positive scalar

Pulse repetition rate , specified as a scalar or string vector. Pulse repetition period is the inverse of the pulse repetition rate .

The value of Pulse repetition frequency (Hz) must satisfy the following constraints:

Product Pulse width (s) and Pulse repetition frequency (Hz) must be less than or equal to one:

This limitation ensures that the pulse duration is shorter than the pulse repetition period. For a phase-coded signal, the pulse duration is equal to the product of the duration of one chip and the number of chips.

Ratio Sample rate (Hz) k Pulse repetition frequency (Hz) should

be an integer. This condition expresses the requirement that the number of samples in one pulse repetition interval be an integer.

Programmatic use
Block parameter	`PRF`
Values	`positive scalar`
By default	`1e4`

Frequency modulation — type of nonlinear frequency modulation
Polynomial (default) | Hyperbolic | Hybrid Linear-Tangent | Stepped Price

A type of nonlinear frequency modulation.

'Polynomial' — the frequency of the signal at the output of the block is generated by a polynomial function. The coefficients of the polynomial are set by the parameter Coefficients of a Polynomial FM. The resulting frequency function is normalized so that each pulse occupies the frequency band specified in the Sweep bandwidth (Hz) parameter. Parameter Sweep interval is inactive if the Frequency modulation parameter is set to Polynomial.
Hyperbolic — the block generates a signal with hyperbolic frequency modulation. Use the Start frequency of a hyperbolic FM parameter to set the initial frequency of the hyperbolic sweep. Parameter Sweep interval is inactive in this case.
Hybrid Linear-Tangent — the block generates a hybrid waveform combining linear frequency modulation and partial modulation according to the tangential law. The balance between linear frequency modulation and partial modulation according to the tangential law is set by the parameter Balance between linear FM and tan-FM, and part of the curve , used for the tangential law of modulation, is set by the Tangent curve portion parameter.
Stepped Price — the block generates a stepwise version of the nonlinear frequency modulation of the Price. Parameter Sweep interval is inactive if the Frequency modulation parameter is set to Stepped Price. In this case, the frequency deviation is determined by the bandwidth coefficients specified in the Bandwidth factors parameter and the number of steps specified in the Number of frequency steps parameter.

Coefficients of a polynomial FM — coefficients of the polynomial function
[1 0 0] (default) | real vector of length (N+1)

Coefficients of the polynomial frequency change function, given as a real vector of length (N+1).

The vector represents the coefficients of an nth degree polynomial. The first entry in the vector is the coefficient of the highest degree N of the polynomial. The last entry is the coefficient of the zero term of the polynomial.

Example: [0.5,1,1,0.5]

Dependencies

To use this parameter, set the Frequency modulation parameter to Polynomial.

Sweep bandwidth (Hz) — pass frequency deviation:q[ ] 1e5 Hz (default) | positive scalar

Frequency deviation of a signal with nonlinear frequency modulation, specified as a positive scalar.

Example: 1e3

Sweep direction — the direction of deviation of the FM frequency band
Up (default) | Down

The direction of frequency deviation of a signal with nonlinear frequency modulation:

Up — increase in frequency.
`Down' — decrease in frequency.

Sweep interval — frequency deviation interval
Positive (default) | Symmetric

Frequency deviation interval, set as Positive or Symmetrical:

Positive — the frequency of the signal will vary in the range from 0 to B, where B is the value of the Sweep bandwidth parameter.
Symmetrical — the frequency of the signal will vary between −B/2 and B/2.

Envelope function — setting the envelope of the frequency modulated signal
Rectangular (default) | Gaussian

The envelope of a frequency-modulated signal, specified as Rectangular or `Gaussian'.

Source of Frequency Offset — setting the frequency offset
Property (default) | Input port

Frequency offset specified as Property or Input port:

If the value Property is set, the offset is determined by the value of the Frequency Offset parameter.
If the value Input port is set, the offset is determined by the port value FreqOffset.

Programmatic use
Block parameter	`FreqOffsetSource`
Values	`Property` \| `Input port`
By default	`Property`

Frequency Offset (Hz) — pass frequency offset:q[ ] 0 (default) | Scalar

The frequency offset specified as a scalar.

Example: 2e3

Dependencies

To use this parameter, set the Source of Frequency Offset parameter to Property.

Programmatic use
Block parameter	`FreqOffset`
Values	`scalar`
By default	`0`

Output signal format — pass output signal format:q[ ] Pulses (default) | Samples

The output format specified as Pulses or `Samples':

Samples is the output signal of the block, which has the form of a sequence of samples, the number of which is determined by the parameter Number of samples in output.
`Pulses' is the output signal of the block, which has the form of several pulses, the number of which is determined by the parameter Number of pulses in output.

Programmatic use
Block parameter	`OutSigForm`
Values	`Pulses` \| `Samples`
By default	`Pulses`

Number of samples in output — number of samples of the pass output signal:q[ ] 100 (default) | positive number

The number of samples of the output signal, set as a positive integer.

Example: 1000

Dependencies

To use this parameter, set the Output signal format parameter to Samples.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64

Programmatic use
Block parameter	`NumSamples`
Values	`positive number`
By default	`100`

Number of pulses in output — number of pulses of the pass output signal:q[ ] 1 (default) | positive number

The number of pulses of the output signal, set as a positive integer.

Example: 2

Dependencies

To use this parameter, set the Output signal format parameter to Pulses.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64

Programmatic use
Block parameter	`NumPulses`
Values	`positive number`
By default	`1`

Enable PRF Output — enable PRF pass output:q[ ] disabled (by default) | enabled

Select the checkbox to enable the PRF output port.

Dependencies

To use this parameter, set the Output signal format parameter to Pulses.

Programmatic use
Block parameter	`PRFOutport`
Values	`off` \| `on`
By default	`off`

Enable Matched Filter Coefficients Output — enable output of matched filter coefficients
disabled (by default) | enabled

Select the checkbox to enable the Coeff output port.

Programmatic use
Block parameter	`CoeffOutport`
Values	`off` \| `on`
By default	`off`