Signal Generator Client

The signal generator can be used to generate various signals including:

• Sine wave
• Square wave
• Triangle wave
• Random walk

Below is a screen-shot of the generated data displayed in Grafana.

Configuration

The signal generated can be configured with the following parameters:

Most of the parameters are self-explanatory. With a Random Walk, you typically need to enter a negative number for the minimum. Increment as shown above. This causes the negative number generated to be negative roughly half the time.

The rounding can also be used to generate binary signals. Imagine a signal generator with these settings:

• Max. value = 1
• Min. value = 0
• Initial value = 0
• Round to = 1
• Min. increment = -7
• Max. increment = 3
• Sample Rate = 20 milliseconds

Due to min/max/round to options, this is a binary value, either 0 or 1, biased toward 0 (due to min/max increment options). This could be useful for simulating binary switches or something like it. Effectively, this will hold the value for at least 20m and picks a random number between -7 and 3. Due to rounding, if value is currently 0, there’s a 25% chance it becomes 1. If 1, there’s a 65% chance it becomes 0. This means that the value will be 0 roughly 91.25% (= 75% + (1 - 75%) * 65%) of the time.

Schema

signalType is sine, square, triangle, or random walk. frequency applies to the three waveforms and minIncrement, maxIncrement, and roundTo apply to a random walk. sampleRate is in Hz and batchPeriod is in milliseconds.

A generator writes to itself unless it is told otherwise. A node configured to write elsewhere carries a destination mapping, whose keys are nodeID, parent, highRate, pointType, and pointKey. nodeID there is a key rather than a point type, so it is written as the ID of the node it names rather than as a description, which is worth knowing when moving a generator between instances.

Below is an export of several types of signal generator nodes:

nodes:
  - signalGenerator:
      batchPeriod: 1000
      description: Variable pulse width
      frequency: 1
      initialValue: "0"
      maxIncrement: 3
      maxValue: 1
      minIncrement: -7
      minValue: "0"
      roundTo: 1
      sampleRate: 5
      signalType: random walk
      units: Amps
      value: 1
  - signalGenerator:
      batchPeriod: 1000
      description: Triangle
      frequency: 1
      initialValue: "0"
      maxIncrement: 0.5
      maxValue: 10
      minIncrement: 0.1
      minValue: "0"
      sampleRate: 100
      signalType: triangle
      value: 6.465714272450723e-12
  - signalGenerator:
      batchPeriod: 1000
      description: Square
      frequency: 1
      initialValue: "0"
      maxValue: 10
      minValue: "0"
      sampleRate: 100
      signalType: square
      value: 10
  - signalGenerator:
      batchPeriod: 1000
      description: Sine
      frequency: 1
      initialValue: "0"
      maxValue: 10
      minValue: "0"
      sampleRate: 100
      signalType: sine
      value: 4.999999999989843
  - signalGenerator:
      batchPeriod: 1000
      description: Random Walk
      frequency: 1
      initialValue: "0"
      maxIncrement: 0.5
      maxValue: 10
      minIncrement: -0.5
      minValue: "0"
      roundTo: 0.1
      sampleRate: 10
      signalType: random walk
      units: Amps
      value: 9.1