2 Planes, 1 Blip: Range Resolution Explained (It's Bandwidth, Not the Pulse)

Two aircraft are flying just 100 meters apart, and the radar shows only one echo. Why? This video explains range resolution from the ground up: the smallest gap at which a radar can tell two targets apart. We follow one pulse out to two targets and back. You'll see why the echoes merge, where the famous "divided by two" comes from, and why the real limit is bandwidth, not pulse width. Then we cover pulse compression, the trick that gives a long pulse's energy with a short pulse's sharpness. We also cover: range sidelobes and windowing; range bins and straddle loss; the difference between resolution and accuracy; how much bandwidth real radars use, from 150 m surveillance down to 3.75 cm car radar. Key formulas: Pulse length in space = c × τ (1 µs → 300 m) Range resolution ΔR = c τ / 2 (1 µs → 150 m) Range resolution ΔR = c / 2B (B = bandwidth; B ≈ 1/τ for a simple pulse) Compression ratio = τ × B (100 µs × 10 MHz = 1000) Range bin = c / 2fs (fs = 10 MHz → 15 m) Chapters 0:00 Two planes, one blip 0:44 A pulse has a length 1:14 Two targets, one echo (why c τ / 2) 2:36 Shorter pulses, sharper eyes 3:34 The real secret: bandwidth 4:27 Pulse compression 5:47 The catch: range sidelobes and windowing 7:01 Range bins, straddle loss and accuracy 7:49 The resolution cell: range, angle, Doppler 8:43 Bandwidth in the real world 9:58 Your turn: design a car radar 10:50 Recap and comment challenge 💬 Comment challenge: a radar sends a 50 µs chirp, sweeping 5 MHz. What's its range resolution, and its compression ratio? 📚 References: M. I. Skolnik, Introduction to Radar Systems (3rd ed.); M. A. Richards, J. A. Scheer and W. A. Holm, Principles of Modern Radar: Basic Principles; IEEE Std 686 (Standard Radar Definitions). ▶ Previous: Peak Power, Average Power and Duty Cycle ▶ Next: PRF and Range Ambiguity, when a radar sees a target at the wrong distance Chirp Theory: radar, explained by an engineer. New videos every few days. #radar #rangeresolution #pulsecompression #signalprocessing #radarengineering