Stepped FM Waveform

Signal generator with step frequency modulation.

stepped fm waveform

Description

The Stepped FM Waveform unit generates a step frequency modulated pulse signal with a specified pulse width, pulse repetition frequency (PRF) and number of frequency steps. The modulation frequency increases in constant steps over the pulse duration. The signal at the unit output is an integer number of pulses or a sequence of samples.

Ports

Input

FreqOffset - frequency offset
scalar

Frequency offset specified as a scalar.

*Example: 2e3

Dependencies

To use this port, set the Source of Frequency Offset parameters to Input port.

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

Output

Y - pulse signal
`complex vector

A signal at the block output specified as a complex vector.

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

PRF - pulse repetition frequency
positive scalar

Pulse repetition rate specified as a positive scalar value.

Dependencies

To use this port, set the Output signal format parameter to Pulses and 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 filter
vector | matrix

Coefficients of the matched filter given 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) - sampling rate
1e6 (by default) | positive scalar

The sampling frequency of the signal as a positive scalar. The unit of measurement is Hz.

The ratio of Sample rate (Hz) to the Pulse repetition frequency must be an integer.

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

Usage in program code
Block parameters	`SampleRate`
Values	`positive scalar`
By default	`1e6`

Method to specify pulse duration - pulse duration as time or fill factor (duty cycle)
Pulse width (By default) | Duty cycle

Method to specify pulse duration as Pulse width or Duty cycle:

Pulse width - the pulse width is set using the Pulse width (s) parameters.
Duty cycle - the pulse width is calculated from the Pulse repetition frequency (Hz) and Duty Cycle parameters.

Usage in program code
Block Parameters	`DurationSpecification`
Values	`string`
By default	`Pulse width`

Pulse width (s) - pulse width
50e-6 s (by default) | positive scalar

Pulse width , specified as a positive scalar value.

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

This constraint ensures that the pulse width is less than the pulse repetition period.

*Example: 300e-6

Dependencies

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

Usage in program code
Block parameters	`PulseWidth`
Values	`string`
By default	`50e-6`

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

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 parameters to Duty cycle.

Usage in program code
Block parameters	`DutyCycle`
Values	`positive scalar`
* By default*	`0.5`

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

Pulse repetition frequency (PRF) specified as a scalar or string vector. The pulse repetition interval (PRI) is the inverse of the pulse repetition frequency (PRF).

The Pulse repetition frequency (Hz) must meet the following constraints:

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

This constraint ensures that the pulse width is less than the pulse repetition period. For a phase encoded signal, the pulse width is equal to the product of the duration of one chip by the number of chips.

The ratio of Sample rate (Hz) to Pulse repetition frequency (Hz) should be

to *Pulse repetition frequency (Hz)* must be an integer:

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

Usage in program code
Block parameters	`PRF`
Values	`positive scalar`
By default	`1e4`

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

The linear frequency step size specified as a positive scalar value.

*Example: 2e4

Number of frequency steps - number of frequency steps in a pulse
5 (by default) | positive integer

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

*Example: 8

Source of Frequency Offset - frequency offset setting
Property (By default) | Input port

Frequency offset set as Property or Input port:

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

Usage in program code
Block parameters	`FrequencyOffsetSource`
Values	`Property` \| `Input port`
By default	`Property`

*Frequency Offset (Hz) - frequency offset
0 (By default) | scalar

Frequency offset set as a scalar.

*Example: 2e3

Dependencies

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

Usage in program code
Block parameters	`FrequencyOffset`
Values	`scalar`
By default	`0`

Output signal format - output signal format
Pulses (By default) | Samples

Output signal format as Pulses or Samples:

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

Usage in program code
Block parameters	`OutputFormat` `Pulses` `Samples`
Values	`Pulses` \| `Samples`
By default	`Pulses`

Number of samples in output - number of samples of the output signal
100 (By default) | positive number

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

*Example: 1000

Dependencies

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

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

Usage in program code
Block parameters	`NumSamples`
Values	`positive number`
By default	`100`

Number of pulses in output - number of pulses of the output signal
1 (By 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 parameters to Pulses.

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

Usage in program code
Block parameters	`NumPulses`
Values	`positive number`
By default	`1`

Enable PRF Output - enable PRF output
off (by default) | on

Select the checkbox to enable the PRF output port.

Dependencies

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

Usage in program code
Block parameters	`PRFOutputPort`
Values	`disabled` \| `enabled`
* By default*	`off`

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

Tick the checkbox to enable the Coeff output port.

Usage in program code
Block parameters	`CoefficientsOutputPort`
Values	`off` \| `on`
By default	`off`