pulsecompression

Pulse compression is a signal processing technique used in radar, sonar, and some medical imaging systems to improve range resolution without reducing transmit energy. A long-duration pulse is modulated with a known code or waveform and transmitted. The received echo is then compressed in time by a matched filter or correlator, recovering a short, high-peak pulse. The energy remains, but the pulse is effectively shortened in the receiver. Range resolution is set by the pulse bandwidth rather than its duration, approximately ΔR ≈ c/(2B), where B is the effective bandwidth.

Common implementations include linear frequency modulated (chirp) pulses and phase-coded sequences such as Barker codes or Golay pairs. In a chirp system, frequency sweeps across B during the pulse; after correlation, the return is compressed to a peak whose width is about 1/B. Phase codes are designed to yield sharp autocorrelation peaks and low sidelobes, improving target detection and reducing range sidelobe interference. Matched filtering or pulse compression decoding is essential to achieve SNR gain.

Applications span radar, sonar, and ultrasonic imaging, where high resolution is needed without requiring extremely high peak transmitter power. Advantages include improved detectability and resolution with energy efficiency; limitations include processing bandwidth requirements, potential sidelobe artifacts, and sensitivity to Doppler shifts and clutter. Pulse compression continues to be refined with advanced codes and adaptive processing to balance resolution, SNR, and operational constraints.