I am interested in somehow tracking the "compass" direction of a moving object from a reference-station -- in other words, something similar to submarine sonar systems (although I'm unsure how those determine the angle/direction of the target).
Note that I only need the direction/2D-angular-position of the object, and don't care about its actual distance/spatial-position. So, I wish to know, e.g., the object is at South 45° East from the reference-station.
- Maximum size of circuitry at moving object: 10 cm X 10 cm
- Maximum size of circuitry at reference station: 15 cm X 15 cm
- The angular measurement needed is a relative one (i.e., as measured from the reference-station), not an absolute one.
- An accuracy of +/- 10 degrees is more than good enough.
- Measurement/tracking rate can be once per second, but faster wouldn't hurt!
- While this tracking is being done, the moving object might be between 3 meters (min) to 100 meters (max) aerial distance away from the reference-station.
- Assume that cost is not critical and that both the object and the reference-station can be electronically equipped (i.e., with sensors/receivers/transmitters/etc.)
- The object and the reference-station will be located in an outdoor/urban environment.
What technique could I use to get started on achieving this kind of direction measurement/tracking?
I've considered using standard wireless signal transmission, but with this, I've only been able to measure RSSI (signal strength), and not the actual angle/directionality! I'm guessing I need some sort of directional transmission sent from the object, whether ultrasonic or RF, and correspondingly a 360-degree sensor array on the reference-station to determine direction.