Stepped FM Waveform

A signal generator with stepwise frequency modulation.

blockType: SteppedFMWaveform

Path in the library:

/Phased Array Systems/Waveforms/Stepped FM Waveform

Description

Block Stepped FM Waveform Generates a stepwise frequency modulated pulse signal with a preset pulse duration, pulse repetition rate (PRF), and number of frequency steps. The modulation frequency increases in constant increments over the duration of the pulse. 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 port, 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

Pulse repetition rate, set as a positive scalar value.

Dependencies

To use this port, set the Output signal format parameter to Pulses, and then check the box 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.

Ratio Sample rate (Hz) 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 — pulse duration as time or fill factor (duty cycle)
Pulse width (default) | Duty cycle

A method to set the pulse duration as Pulse width or 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	`DurationSpecification`
Values	`string`
By default	`Pulse width`

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

Pulse duration , specified as a positive scalar quantity.

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 (PRF), set as a scalar or string vector. The pulse repetition period (PRI) is the inverse of the pulse repetition rate (PRF).

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 restriction is equivalent to requiring that the number of samples in the pulse repetition period be an integer.

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

Frequency step (Hz) — the size of the linear step in the frequency of
2e4 Hz (default) | positive scalar

The size of the linear frequency step, set as a positive scalar value.

Example: 2e4

Number of frequency steps — the number of frequency steps in the pass pulse:q[ ] 5 (default) | positive integer

The number of frequency steps specified as a positive integer. If the number of frequency steps is 1, then the stepwise frequency-modulated signal is reduced to a rectangular one.

Example: 8

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	`FrequencyOffsetSource`
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	`FrequencyOffset`
Values	`scalar`
By default	`0`

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

Output signal format in the form of Pulses or `Samples':

If you set this parameter to Pulses, then the output of the block consists of several pulses. The number of pulses is the value of the parameter Number of pulses in output.
If you set this parameter to Samples, then the output of the block consists of several samples. The number of samples is the value of the Number of samples in output parameter.

Programmatic use
Block parameter	`OutputFormat`
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.

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	`PRFOutputPort`
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	`CoefficientsOutputPort`
Values	`off` \| `on`
By default	`off`