qsp-filter¶

Signal conditioning and filtering tools for quaternionic and structured data streams.

What it is¶

qsp-filter provides filtering and signal conditioning tools designed for quaternionic and structured signals. It covers filter design, application, and preprocessing stages in a QSP-compatible workflow.

Why it exists¶

Filtering quaternion-valued signals requires careful handling of the non-commutativity of quaternion multiplication. Standard DSP filter libraries assume scalar or complex data. qsp-filter addresses this gap by providing filters that operate correctly on quaternionic types and structured signal containers.

Key responsibilities¶

FIR and IIR filter design for quaternionic signals
Filter application in time and frequency domains
Signal conditioning utilities (normalization, artifact suppression, resampling)
Compatibility with qsp-fft outputs for frequency-domain filtering

Typical users¶

Engineers preprocessing sensor data before orientation estimation
Communications engineers conditioning signals before modulation or demodulation
Signal processing pipelines requiring noise reduction or bandpass filtering on quaternionic data

Example use cases¶

Applying a low-pass filter to a quaternion-valued IMU data stream
Bandpass filtering a signal prior to spectral analysis with qsp-fft
Conditioning a received signal before passing it to qsp-modulation for demodulation

Relationship to other QSP packages¶

qsp-filter depends on qsp-core. It is commonly used after qsp-fft (for frequency-domain filtering) and before qsp-orientation or qsp-modulation (which operate on conditioned signals).

qsp-core → qsp-filter
qsp-fft  → qsp-filter (frequency-domain workflows)
qsp-filter → qsp-orientation (conditioned sensor data)
qsp-filter → qsp-modulation (conditioned communication signals)

Status¶

Core filtering functionality is the primary focus. Future expansion may include adaptive filter designs, quaternionic Wiener filters, and integration with real-time signal processing backends.