LFM chirp radar emitter

ChirpRadarEmitter is the retained radar surface: a deterministic, single-emitter, SciPy-backed linear frequency-modulated (LFM) pulse at complex baseband. Its sole supported class is lfm_chirp.

For bandwidth B, pulse duration tau, and time 0 <= t < tau, the up-chirp uses f(t) = -B/2 + (B/tau)t. The phase is its integral, and the emitted IQ is the corresponding unit-envelope complex signal. A down-chirp reverses the slope. Samples at and after the pulse boundary are exactly zero. f_offset_hz is metadata/provenance; it is not mixed into this baseband waveform.

The generator validates finite positive parameters and requires the declared bandwidth to remain below the Nyquist limit. Its deterministic output supports the 24-record chirp-radar Golden Path template at seed 1337.

Contract limits

The emitter models an isolated waveform only. It does not claim target returns, scattering, propagation, range-Doppler processing, pulse trains, coherent processing intervals, scan behavior, empirical radar-system fidelity, or RadarSimPy support. Those exclusions are limitations, not unimplemented promises in this release.

See the chirp validation report for the tested slope, bandwidth, gating, direction, metadata, and provenance contracts.