Martino Ferrari
105 lines
3.4 KiB
Markdown
105 lines
3.4 KiB
Markdown
# SineArrayGAM
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`SineArrayGAM` is a helper GAM bundled with the UDPStreamer library. It fills a `float32`
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output array with a continuous sinusoidal waveform, maintaining phase continuity across
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RT cycles. It is intended for testing and demonstrating the UDPStreamer's packed-burst
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signal capability.
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> **Library:** The class is compiled into `UDPStreamer.so` alongside the UDPStreamer
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> DataSource. A `SineArrayGAM.so → UDPStreamer.so` symlink is required for MARTe2's
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> auto-loader (created automatically by `Test/MARTeApp/run.sh`).
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---
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## Configuration
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```
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+Ch1GAM = {
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Class = SineArrayGAM
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Frequency = 1000.0 // Signal frequency [Hz] (default: 1.0)
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Amplitude = 1.0 // Peak amplitude (default: 1.0)
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Offset = 0.0 // DC offset (default: 0.0)
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Phase = 0.0 // Initial phase [radians] (default: 0.0)
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SamplingRate = 1000000.0 // Sample rate [Hz] (default: 1000000.0)
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// Must match the SamplingRate declared in the
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// UDPStreamer signal config.
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OutputSignals = {
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Ch1 = {
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DataSource = DDB
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Type = float32
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NumberOfDimensions = 1
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NumberOfElements = 1000 // N samples per RT cycle
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}
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}
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}
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```
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### Parameters
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| Parameter | Type | Default | Description |
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|-----------|------|---------|-------------|
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| `Frequency` | float64 | 1.0 | Signal frequency in Hz |
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| `Amplitude` | float64 | 1.0 | Peak amplitude (half peak-to-peak) |
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| `Offset` | float64 | 0.0 | DC offset added to every sample |
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| `Phase` | float64 | 0.0 | Phase shift in radians |
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| `SamplingRate` | float64 | 1 000 000.0 | Sample rate in Hz; must be > 0 |
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### Output signal
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Exactly **one** output signal of type **`float32`** is required. The signal must have
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`NumberOfDimensions = 1` and `NumberOfElements = N` where N ≥ 1.
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---
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## Waveform formula
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Each `Execute()` call fills elements `[0 .. N-1]` using:
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```
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v[k] = Amplitude × sin(2π × Frequency × (offset_total + k) / SamplingRate + Phase) + Offset
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```
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where `offset_total` is a cumulative sample counter that increments by `N` after each call.
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This guarantees a gapless, phase-continuous waveform across RT cycles.
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---
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## Bandwidth and fragmentation
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For a 1 MSps burst at 10 kHz RT rate with 1000 samples per cycle:
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```
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N = SamplingRate / RT_rate = 1 000 000 / 1000 = 1000 samples per cycle
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Wire bytes = 1000 × 4 (float32) = 4000 B per channel per cycle
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At 10 kHz: 4000 × 10 000 = 40 MB/s raw (UDP, before quantization)
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```
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Using `QuantizedType = uint16` halves the wire bandwidth to 20 MB/s.
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With `MaxPayloadSize = 1400` the 4 000-byte payload spans 3 UDP datagrams
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(`ceil(4008 / 1383) = 3`).
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---
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## Example: two-channel quadrature pair
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```
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+Ch1GAM = {
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Class = SineArrayGAM
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Frequency = 1000.0; Amplitude = 1.0; Phase = 0.0; SamplingRate = 10000000.0
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OutputSignals = {
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Ch1 = { DataSource = DDB; Type = float32; NumberOfDimensions = 1; NumberOfElements = 1000 }
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}
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}
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+Ch2GAM = {
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Class = SineArrayGAM
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Frequency = 1000.0; Amplitude = 1.0; Phase = 1.5708; SamplingRate = 10000000.0
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OutputSignals = {
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Ch2 = { DataSource = DDB; Type = float32; NumberOfDimensions = 1; NumberOfElements = 1000 }
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}
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}
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```
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This produces two signals 90° out of phase, useful for verifying IQ-style signal chains.
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