Uniform
- Updated2023-02-17
- 5 minute(s) read
Uniform
Generates a signal containing a uniform white noise wave.
You can use uniform white noise as a stimulus to measure the frequency response of amplifiers and electronic filters.
Inputs/Outputs
offset
DC offset of the signal.
Default value: 0
reset
A Boolean that controls the reseeding of the noise sample generator after the first call of the node.
| True | Accepts a new state or new seed value and begins producing noise samples based on the new state or new seed value. |
| False | Maintains the initial internal seed state and resumes producing noise samples as a continuation of the previous noise sequence. |
Default value: False
amplitude
Maximum absolute value the signal can have.
Default value: 1
state in
Initial internal seed state of the noise generator.
This input must be passed from the state out output of another call to this node.
This node uses state in as the initial internal seed state of the noise generator if reset is True or if this is the first call of the node. If state in is unwired or contains invalid values, this nodes uses seed as the initial internal seed state of the noise generator.
x seed
Internal x seed.
y seed
Internal y seed.
z seed
Internal z seed.
seed
Number that this node uses to initialize the noise generator.
This node initializes the noise generator using seed when this node meets both of the following conditions:
- This is the first call of this node or reset is True.
- state in is unwired or contains invalid values.
| seed is greater than 0 | Generates noise samples based on the seed value. |
| seed is less than or equal to 0 | For the first call, this node generates a random seed value and produces noise samples based on that seed value. For subsequent calls to the node, if seed remains less than or equal to 0, the node maintains the initial internal seed state and produces noise samples as a continuation of the initial noise sequence. |
Default value: -1
error in
Error conditions that occur before this node runs.
The node responds to this input according to standard error behavior.
Default value: No error
sample rate
Sample rate in samples per second.
This input is available only if you configure this node to return a waveform.
Default value: 1000
samples
Number of samples in the signal.
samples must be greater than 0. Otherwise, this node returns an error.
This input is available when you configure this node to return a waveform or an array of double-precision, floating-point numbers.
Default value: 1000
t0
Timestamp of the output signal.
This input is available only if you configure this node to return a waveform.
uniform white noise
Uniformly-distributed, pseudorandom pattern.
This output can return the following data types:
- Waveform
- Double-precision, floating-point number
- 1D array of double-precision, floating-point numbers
state out
Final internal seed state of the noise generator.
x seed
Internal x seed.
y seed
Internal y seed.
z seed
Internal z seed.
error out
Error information.
The node produces this output according to standard error behavior.
Algorithm for Generating the Uniform White Noise
This node generates the pseudorandom sequence using the Wichmann-Hill generator. The pseudorandom number generator implements a triple-seeded linear congruential algorithm. Given that the probability density function, f(x), of the uniformly distributed uniform white noise is
where a is the absolute value of amplitude.
The following equations define the expected mean value
and the expected standard deviation value of the pseudorandom sequence:The pseudorandom sequence produces approximately 6.95 * 1012 samples before the pattern repeats itself.