Gaussian Monopulse — Control Systems/Waveform Functions
Control_Systems/Waveform_Functions/Gaussian_Monopulse · 1 input / 1 output port(s) at insert · exports to Python, MATLAB, Java, Rust, C, C++, VHDL, Verilog, SystemVerilog, PLC Structured Text
Description#
The block's own DESCRIPTION_HTML, rendered verbatim — the same text the config dialog's info panel and the library navigator show. Fix a wrong sentence in the block's .cpp (R-D9), never here.
Gaussian Monopulse
Control Systems / Waveform Functions
The unity-amplitude Gaussian monopulse of centre frequency fc, evaluated entry by entry. With u = (π·fc)·x,
y = 2√e · u · exp(−2u²)
It is the first derivative of a Gaussian, scaled so its peak is exactly +1 and its trough exactly −1, and it carries no DC because the two lobes cancel – which is why it is the standard excitation for ultra-wideband radar and ground-penetrating sounding.
The peak and trough sit at x = ±1/(2π·fc), so the interval between them is 1/(π·fc). That is the number to weigh against the range the argument actually covers: a centre frequency far above it leaves the output flat at zero – correctly, and uselessly.
Ports
- Input – the argument x of the relation above, of any size [m,n], applied entry by entry. It is a time, in the unit the centre frequency is the reciprocal of.
- Output – the result y, of the SAME size [m,n], in [−1, +1]. The block never reshapes a signal.
Parameters
- Center Frequency (Hz) – the centre frequency fc, a
non-negative scalar. It sets the whole width of the pulse through
u = (π·fc)·x; a non-scalar or negative value is reported and
stops the run. Default 1, which places the peak and trough about 0.16 apart
– MATLAB's
gmonopulsdefaults to 1000 instead, so set 1000 to reproduce a script exactly. Zero is accepted and gives a flat zero output. - Sampling Time (s) – zero or less inherits the solver's rate; a positive value runs the block at that period.
Code export
All ten targets: Python, MATLAB, Java, Rust, C, C++, VHDL, Verilog, SystemVerilog and PLC Structured Text.
The centre frequency is structural: the angular scale π·fc and the amplitude 2√e are folded once at export time and written into the body as decimal literals, so the generated core carries no tunable parameter. Re-export after changing the frequency.
The three HDL targets are simulation-only. There is no fixed-point
exponential in the Q16.16 datapath to call, and the squared argument inside it
spans a range sixteen fractional bits cannot hold, so the generated cores convert
at the port boundary and evaluate in real arithmetic – correct
in simulation, but not offered as synthesizable.
Simulink bridge
None. The Simulink standard library has no monopulse block: MathWorks
offers it as the Signal Processing Toolbox function gmonopuls, which
is not a block and has no library path a diagram could name. A model carrying
this block is reported rather than silently dropped when it crosses, and neither
"Center Frequency (Hz)" nor "Sampling Time (s)" has a counterpart to be written
to.
Notes
- Algebraic, with no state: the output depends only on the current input.
- Not linear, so the block deliberately carries no state space and model reduction reports it as unmergeable.
- Odd about the origin: y(−x) = −y(x), and y(0) = 0.
- The scale is grouped as (π·fc)·x rather than π·x·fc. The same three factors multiplied in a different order round differently, and every generated core folds them the same way so the ten exports agree to the last bit.
Code facts#
| Fact | Value |
|---|---|
| registered type | Control_Systems/Waveform_Functions/Gaussian_Monopulse |
| family | Control_Systems/Waveform_Functions |
| solver environment class | ICoreBlock_0_Control_Systems_1_Waveform_Functions_2_Gaussian_Monopulse |
| source | src/ICoreBlocks/ICoreBlockLibrary/Blocks/Control_Systems/Waveform_Functions/Gaussian_Monopulse/ICoreBlock_0_Control_Systems_1_Waveform_Functions_2_Gaussian_Monopulse.cpp |
| header | src/ICoreBlocks/ICoreBlockLibrary/Blocks/Control_Systems/Waveform_Functions/Gaussian_Monopulse/ICoreBlock_0_Control_Systems_1_Waveform_Functions_2_Gaussian_Monopulse.h |
| default size on canvas | 70 × 70 px |
| ports at insert | 1 in, 1 out |
| code generators implemented | Python, MATLAB, Java, Rust, C, C++, VHDL, Verilog, SystemVerilog, PLC Structured Text |
Ports#
| # | Direction | Signal type | Description label |
|---|---|---|---|
| 1 | in | ICoreDouble | — |
| 2 | out | ICoreDouble | — |
Ports the constructor creates. A block whose port list changes with its configuration adds or removes ports at load time; the count above is the one a freshly inserted block has.
Configuration variables#
| Config variable | Default | Simulink parameter |
|---|---|---|
Center Frequency (Hz) | 1 | — |
Every block also carries Sampling Time (s) from ICoreBlockSolverEnvironment: zero or less inherits the solver's rate, a positive value runs the block at that period.
Simulink bridge#
| support | Support::None |
| Simulink path | — |
| port-count rule | PortsParam::None |
SampleTime parameter | yes |
Caveat (shown to the user): the Gaussian monopulse is a Signal Processing Toolbox FUNCTION (gmonopuls), not a Simulink library block, so there is no path a diagram could name; the block is reported rather than dropped when a model crosses
Catalog contract: src/ICoreBlocks/ICoreCoder/ICoreCommandSystem/SimulinkBridge/ICoreSimulinkBlockCatalog.h
Description vs code#
The lists agree. check_block_descriptions.py finds no disagreement between the description's Ports, Parameters, Code export and Simulink bridge lists and the code's.
The verdict above is
tools/docs/check_block_descriptions.py(P7.1), which compares LISTS. It cannot read a sentence: "stateless" on a block with a state, an initial-value semantic the recursion does not implement, a "not synthesizable" caveat the HDL banner contradicts. That is the agent audit (P7.3) on BLOCK_DESCRIPTION_AUDIT.md, and this tool's green is not a substitute for one.
File banner (developer view)#
The top comment of the block's .cpp — the maths, the realization and the export strategy, addressed to whoever changes it. It must not contradict the description above (P7.5).
Gaussian Monopulse -- y = 2*sqrt(e) * u * exp(-2*u^2), with u = (pi*fc)*x The first derivative of a Gaussian, scaled to a peak of exactly +1. Algebraic and stateless. No state space -- see the header for why.
Two constants are folded once, here, and embedded in every generated core as decimal literals: the angular scale pi*fc and the amplitude 2*sqrt(e). Grouping the scale as (pi*fc)*x rather than pi*x*fc is what makes the ten backends agree to the last bit -- the same three factors multiplied in a different order round differently, and the comparison this block is measured by has no tolerance for a difference it cannot explain.
The three hardware-description targets evaluate in floating point and are offered as simulation-only: the Q16.16 datapath carries no exponential, and the squared argument inside it spans a range no sixteen fractional bits can hold.
Sample results#
| t | in ICoreDouble-Out-0 | out ICoreDouble-Out-0 |
|---|---|---|
| 0 | -2 | -1.061e-33 |
| 0.4 | 0.5 | 0.03725 |
| 0.8 | -2 | -1.061e-33 |
| 1.2 | 0.5 | 0.03725 |
| 1.6 | -2 | -1.061e-33 |
| 2 | 0.5 | 0.03725 |
| 2.4 | -2 | -1.061e-33 |
| 2.8 | 0.5 | 0.03725 |
| 3.2 | -2 | -1.061e-33 |
| 3.6 | 0.5 | 0.03725 |
| 4 | -2 | -1.061e-33 |
| 4.4 | 0.5 | 0.03725 |
| 4.8 | -2 | -1.061e-33 |
| 5.2 | 0.5 | 0.03725 |
Every 4th of 60 samples, from the table stimulus.
The same rig also ran:
| Stimulus | What it is | Output range |
|---|---|---|
impulse | Impulse: one sample of 1 at k = 5, 0 elsewhere (Repeating Sequence Stair) | 0 … 2.771e-8 |
ramp | Ramp: slope 1 from t = 0 | 0 … 0.9407 |
sine | Sine Wave: amplitude 1, 2 rad/s, no phase, no bias | -0.9912 … 0.9867 |
step | Step: 0 -> 1 at t = 1 s | 0 … 2.771e-8 |
Plotted: table — Repeating Sequence Stair: [-2 -1 -0.5 0 0.5 1 2 3], one entry per sample
Category static · sample time 0.1 · 60 steps · commit 87d3936094fa2ff37688c80c5846c4dd08d6a27d · produced by docsSample --out <folder> --blocks Sinc Rectangular_Pulse Triangular_Pulse Gaussian_Monopulse Gaussian_RF_Pulse Dirichlet_Function --steps 60 · data docs/generated/samples/Control_Systems__Waveform_Functions__Gaussian_Monopulse.json · the SVG is generated from those numbers by tools/docs/plot_svg.py, so it is a run and not a drawing (R-D10).