An ultrasonic positioning system is introduced in this report. With the help of this system, blind persons can receive an early warning of the location of an obstacle. The system has three ultrasonic sensors and an ultrasonic emitter, each sensor being located at a different apex of an equilateral triangle and the emitter positioned at the center. Three different-sized equilateral triangles are discussed regarding analysis of the deviations in positioning measurement. An area of ±15°, one to two meters in front of the sensors, is used as the testing area for the three different systems. Simulation results and conclusions are also given.