Skip to content

README.md

Latest commit

 

History

History
54 lines (39 loc) · 2.15 KB

README.md

File metadata and controls

54 lines (39 loc) · 2.15 KB

DSP Algorithms

Lightweight, platform-agnostic C (C11) implementations of the localization and beamforming algorithms. Designed to run on low-power microcontrollers but fully testable on desktop with Bazel.

Localization (dsp/)

Localization is based on Generalized Cross-Correlation with Phase Transform (GCC-PHAT) [1].

  • gcc_phat.c/.h — Frequency-domain cross-correlation with partial phase normalization (exponent −0.3). Operates on a single microphone pair.
  • tdoa.c/.h — Extracts Time Difference of Arrival (TDOA) from GCC-PHAT peaks and converts delays to azimuth angles. Uses ARM CMSIS DSP for FFTs on embedded targets.
  • angle_estimation.c/.h — Aggregates TDOA measurements from all mic pairs into a single azimuth estimate (0–359°) using histogram accumulation and Kernel Density Estimation (KDE) with Gaussian or Pearson Type II kernels.

Unlike most localizers that use Steered Power Response (SPR), we use a lightweight statistical KDE approach that is well-suited to real-time embedded constraints.

Beamforming (beam/)

Two classical beamformer implementations are included. The SpeechCompass firmware uses localization only (not beamforming), but these are provided for completeness.

  • beam/das_beamformer.c/.h — Time-domain Delay-and-Sum beamformer; supports 2- and 4-microphone circular arrays; stateful ring buffer.
  • beam/fas_beamformer.c/.h — Frequency-domain Filter-and-Sum beamformer with complex steering weights for circular arrays.

Building and testing

Build rules are defined in defs.bzl using Bazel wrapper rules (c_binary, c_library, c_test) that enforce C11 and a consistent warning set.

# Run all tests
bazel test //...

# Run a specific test
bazel test //test:angle_estimation_test
bazel test //test:gcc_phat_test
bazel test //test:das_beamformer_test
bazel test //test:fas_beamformer_test

Tests use the CHECK() assertion macro from utility/logging.h.

References

[1] Knapp, C. H. and G.C. Carter, "The Generalized Correlation Method for Estimation of Time Delay." IEEE Transactions on Acoustics, Speech and Signal Processing, Vol. ASSP-24, No. 4, Aug 1976.