# Pattern Generator (Chirp) (G Dataflow)

Generates a signal containing a chirp pattern.

## amplitude

Amplitude of the pattern.

Default: 1

## f1

Beginning frequency of the pattern in normalized units of cycles/sample.

Default: 0

## f2

Ending frequency of the pattern in normalized units of cycles/sample.

Default: 0.5

## error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

## dt

Sampling interval.

Default: 0.1

## samples

Number of samples in the pattern.

samples must be greater than 0. Otherwise, this node returns an error.

Default: 128

## t0

Timestamp of the output signal. If this input is unwired, this node uses the current time as the timestamp of the output signal.

This input is available only if you configure this node to return a waveform.

## chirp pattern

Output chirp pattern. The output pattern contains frequency ramping from f1 * fs to f2 * fs, where fs is the sampling rate.

This output can return a waveform or an array of double-precision, floating-point numbers.

## error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

## Algorithm for Generating the Chirp Pattern

If the sequence Y represents chirp pattern, this node obtains the elements of Y using the following equation:

${y}_{i}=A*\mathrm{sin}\left(\left(0.5*a*i+b\right)*i\right)$

$\text{for}\text{\hspace{0.17em}}i=0,\text{\hspace{0.17em}}1,\text{\hspace{0.17em}}2,\text{\hspace{0.17em}}...,\text{\hspace{0.17em}}n-1$

where

• A is the amplitude
• $a=2\pi \left(\text{f2}-\text{f1}\right)\text{\hspace{0.17em}}*\text{\hspace{0.17em}}\mathrm{dt}/n$
• $b=2\pi \text{f1}\text{\hspace{0.17em}}*\text{\hspace{0.17em}}\mathrm{dt}$
• f1 is the beginning frequency in normalized units of cycles/sample
• f2 is the ending frequency in normalized units of cycles/sample
• n is the number of samples

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application