Response Aggregation and Rendering

Description

This process takes all the individual simulated signal responses (e.g., echoes from different targets, the direct path signal from transmitter to receiver) that are calculated to arrive within a specific output time window and combines them. The combination is achieved by summing the complex voltage values of each response at corresponding time samples within the window. This applies the principle of superposition to the simulated received signals before final output generation.

Assumptions

• Linear Superposition: Assumes that the receiver system being modeled behaves linearly, meaning that signals arriving simultaneously simply add together according to the principle of superposition, without distorting each other.
• Correct Time Alignment: Assumes that the calculated propagation delays for each individual Response are accurately translated into the correct starting sample index (e.g., start_sample, roffset) within the output time window before summation occurs.
• Accurate Individual Responses: Assumes that the individual Response waveforms generated before this aggregation step (likely via resp->renderBinary(), using InterpPoint data) accurately represent the complex signal voltage over time for that specific interaction path (e.g., Tx -> Target -> Rx).

Limitations

• No Non-Linear Effects: The model uses simple linear summation based on superposition. It does not account for potential non-linear effects that can occur in real receiver hardware, such as receiver saturation (limiting output power when very strong signals are present) or intermodulation distortion caused by multiple strong signals arriving simultaneously.

Related Components

• Output Generation Effects (Category Page)
• Response objects (representing individual signal returns/paths)
• InterpPoint data (sampled channel state used to render individual responses)
• Thermal Noise Addition (AWGN) (Typically added after or before this stage)
• Phase Noise Simulation (Typically added after or before this stage)
• ADC Quantization Simulation (Typically applied after this stage)
• The HDF5 export process (where this aggregation commonly occurs within renderWindow)

Validation Status

• Needs Verification: The correctness of the summation and time alignment process under various conditions requires specific validation.
• Key Areas for Validation:
  • Verification of correct time alignment (sample indexing) when summing multiple responses with different, potentially fractional, delays relative to the window start.
  • Accuracy of the complex floating-point summation, especially concerning potential precision issues with a very large number of overlapping weak and strong signals.
  • Correct handling of responses that only partially overlap the defined time window (start or end).
• Priority: High (Fundamental to the correctness of the final combined output signal)