Fun with RADAR

Say 'radar' and most people think of FAA air traffic controllers following airplanes or NASA engineers tracking rockets. But RAdio Detection And Ranging can be used for a lot of purposes including some that are simply fun. Especially when you can put a whole radar system on a 5mm x 5mm chip, like ViaSat managed to do.

If you stand in a canyon and yell, you'll hear an echo when the sound of your voice bounces off the side of the canyon and back to you. Like timing a thunder clap to judge distance to lightning, if you time the echo of your yell and know the speed of sound (roughly a 1000 feet per second) you can estimate how far away the cliffs are (and how close a thunderstorm is).

With radar you essentially do the same thing except you use a radio signal instead of sound, and the signal propagates at almost the speed of light (about 11 inches per nanosecond). Send a radio pulse, listen carefully for an echo, and you can tell how far away something is by measuring how long it takes for the signal to go out and bounce back.

If you know the direction your antenna is pointing when you receive the signal you know where to look for the target. Compute the difference in position between two received signals and you can tell the direction your target is moving.  Measure the change in frequency of your radio signal, and you can determine the speed of the target with respect to your antenna (a target with zero speed may be traveling in a circle around you).

It doesn't take a van full of electronics and a huge rotating array to put radar to work. ViaSat has put the whole thing on a 5mm by 5mm chip. Add a power supply and an antenna and you're in business. It's not quite that easy of course, but that's essentially all you need.

ViaSat doesn't sell their chips retail, but a a similar radar sensor will set you back only about $10. You won't be able to track passing aircraft or bust speeding drivers, but you could create a back-up obstacle detector for your car or an intruder alarm that won't go off if a cat strolls by.

Or, just for fun, you could build a theremin—one of those weird sounding electronic musical instruments. They date back to the 1920s when people used an antenna and oscillator to produce spooky sounds. With a radar chip you could do the same to measure the motion of your hands.


ViaSat's chip is available for military and commercial applications that are a lot more serious, such as perimeter security, traffic management, and altimeters. In such applications the product has to survive challenging environmental conditions, take up up as little space as possible, use a tiny amount of power, and require no tweaking after it's installed—and do all that for a reasonable cost.

ViaSat's radar-on-a-chip is unique. It's the only self-contained frequency modulated continuous wave radar sensor on a single chip. What's more, it can be easily tailored to different applications using digital interface software to control frequency and bandwidth. Best of all, it works over a wide temperature range because it self-calibrates continuously.

With those capabilities, the chip can be used by the military to control vehicles in driverless convoys, provide UAV navigation in tight spaces, or watch for small boat intruders when ships are in port. Civilian applications include adaptive cruise control, already in some cars, so you don't have to brake and reset when traffic slows down.

Radar is just about business and war, it can be fun too.