In conventional ultrasonic pulse-echo sensing,
accurate target bearing measurement is often
regarded as difficult due to the wide beam angle of ultrasonic transducers.
However, measurement of the accurate angle
is also very useful for many robot motions.
The proposed method exploits the frequency dependency on bearing angle
to the reflecting target.
It makes possible to measure the bearing angle by a single transducer.
The method employs a simple approach
using a zero crossing time interval of the reflected echo,
and consequently is a fast measurement technique.