Examples¶

Worked examples across every doppler subsystem — each one a runnable script under src/doppler/examples/, grouped below by DSP domain. Most pages render a figure; run make gallery to regenerate every image, or run a single script directly (each page lists its command under Reproduce / Run it).

C programs calling the library directly live on the C examples page; the end-to-end ZMQ pipeline is on the Streaming page.

Sources & Waveforms¶

• Waveform Generator — tone / PN / QPSK / BPSK from one declarative Synth.
• Symbols: bring your own constellation — pi/4-QPSK and 16-QAM from an arbitrary complex stream.
• Waveform Scenes — sum, add, headroom; a SoI under a CW interferer over one noise floor.
• Waveform I/O — one capture written to raw / CSV / BLUE / SigMF and read back.
• Waveform JSON Round-Trip — --record a scene to JSON and replay it byte-identically.
• Waveform Write — the shortest path from a Composer to a file and back.
• WCDMA Carriers — four RRC channels measured with PSD and AccTrace.
• AWGN — complex Box-Muller noise, amplitude histogram, and flat PSD.
• LO — complex phasor generator with FM control and phase continuity.
• NCO — raw uint32 phase accumulator with overflow carry and fixed-point scaling.

Filters & Resampling¶

• CIC Decimation — wideband IQ → CIC → narrowband slice; ~90 dB alias rejection.
• RateConverter — automatic CIC / halfband / polyphase cascade for any rate ratio.
• Farrow Interpolator — fractional-delay resampling.
• HBDecimQ15 — fixed-point Q15 halfband 2:1 decimator for interleaved IQ int16.

Down-Conversion (DDC)¶

• Functional DDCR — real passband in, complex baseband out, caller-owned buffer, thread-per-shard scaling.

Detection & Acquisition¶

• Correlation — coherent integration, 2-D template matching, streaming CFAR.
• Detection Curves — Pd vs SNR and dwell from closed-form Marcum Q.
• Monte Carlo — 30,000-trial validation of the Marcum Q curves.
• 2-D Acquisition — GPS/CDMA Doppler × code-phase search with Bonferroni-corrected CFAR.
• DSSS Acquisition & Despreading — burst acquisition into a streaming despreader.
• DSSS Acquisition: Pd/Pfa — detection characterisation curves.
• Streaming Async Despreader — Dll(segments) PN-epoch despreader.

Synchronization Loops¶

• Carrier Loop Stress — Costas loop pull-in under noise.
• Costas Loop (theory) — loop-filter design and steady-state behaviour.
• Code Loop Tracking — delay-locked loop code tracking.
• DLL Code Loop (theory) — discriminator and loop-filter derivation.
• Symbol Timing Recovery — timing-error-detector-driven resampling.
• Timing Loop (theory) — the timing loop's transfer function.
• M-PSK Carrier Loop (theory) — decision-directed carrier recovery.
• NDA Carrier Loop (theory) — non-data-aided carrier recovery.
• Tracking Channel — a combined carrier + code tracking channel.

Constellations & Receivers¶

• M-PSK Constellation — M-PSK mapping and constellation rendering.
• M-PSK Receiver — integrated carrier + timing + bit recovery.

Measurement¶

• Measurement Suite — SNR / SINAD / THD / SFDR / ENOB from ToneMeasure.
• Measurement Suite: IMD & NPR — two-tone IMD/IM3, TOI, and notched-noise NPR.

Quantization & Fixed-Point¶

• ADC Quantisation — staircase resolution and noise floor across 3–8 bits.
• Q15 vs UQ15 — bipolar vs offset-binary encodings of the same Q15 step.
• cvt Quantization — the three cvt formats overlaid at identical noise floor.

Gain Control¶

• AGC — closed-loop power controller with decimated and per-sample loop updates.

Fundamentals¶

• FFT — per-instance 1-D and 2-D FFT with plan reuse.
• Ring Buffers — double-mapped lock-free ring buffers for producer/consumer pipelines.
• C examples — minimal C99 programs calling the library directly.
• Streaming — ZMQ-based signal streaming end-to-end.