AdvancedTopic 97 of 101Signals, Control & Comms
Radar basics
Radio waves reflect from targets to measure range and speed.
In depth
Radar measures range from echo delay R=cτ/2, radial speed from Doppler shift f_d=2v/λ, and angle from antenna beam. Radar equation relates received power to R⁻⁴. Types: pulsed, FMCW, phased array, synthetic aperture. Uses: air traffic control, weather, automotive, defence.
Key points
- Range resolution c/2B
- Ambiguities
- Clutter and CFAR detection
ExampleAn automotive FMCW radar at 77 GHz measures distance and speed of vehicles ahead.
Radar uses reflected radio waves to measure range, speed and direction, so it is used in aviation, weather and traffic systems.
What is Radar basics?
Radio waves reflect from targets to measure range and speed.
Why is it important to understand radar basics?
Radar uses reflected radio waves to measure range, speed and direction, so it is used in aviation, weather and traffic systems.
How does radar measure range?
It times the round trip of a pulse, so the range is the speed of light times the time delay, divided by two.
How does radar measure speed?
The Doppler shift of the reflected wave gives the radial speed of the target relative to the radar.
How is Radar basics used in practice?
Typical applications include detecting aircraft and measuring their speed at an airport, monitoring rainfall with a weather radar and measuring vehicle speed with a traffic radar gun.
What should I learn before Radar basics?
Study "Optical fibre communication" first (topic 96 of 101 in Signals, Control & Comms). It covers the groundwork this topic builds on.
What are the key points of Radar basics?
Range resolution c/2B. Ambiguities. Clutter and CFAR detection.
Can you give an example of Radar basics?
An automotive FMCW radar at 77 GHz measures distance and speed of vehicles ahead.
What comes after Radar basics?
The next topic is "Software-defined radio", which builds directly on this one.
How difficult is Radar basics?
It is classed as Advanced in Signals, Control & Comms (topic 97 of 101). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Signals, Control & Comms.