I ordered two HB100 Doppler radar modules from China. They arrived and I took them down to the lab for a quick test. First off, the boards look nice. Good solder masks and silkscreens. On the surface they look of good construction and materials. Quickly soldered some leads to the 5V, Gnd, and IF connections. To these I applied my power and connected the IF lead to my scope. Powering up the unit appeared to work. It is always a good thing not to see smoke. Now I waved my hand in front on the unit and and did not see any response on the scope. Now I read the documentation I was able to scrounge and found that the signal would be a sin wave in the micro/millivolt region with a DC offset.
So I adjusted the scope for AC coupling, cranked the sensitivity up and waved my hand again. Success, but only just when the object is a few inches away from the sensor. The document talked about a range of 20 meters! So I gave up, and went upstairs to pout. Goggling I did find a reference that might indicate the sensor is not good in tight confines (like my lab). Next step if to take the rig outside.
Although this is a Doppler sensor and only reports speed of an approaching object, I still hope to use it for AVC obstacle avoidance. My hope is pinned on the fact that the amplitude of the sin wave output is inversely proportional to object range. With an appropriate comparator, I might be able to sound an alarm for objects closer than some panic distance.