A self-coupling laser distance sensor detects a distance signal via slight fluctuations in the semiconductor laser terminal voltage due to interference between the laser light and the returned light. The output signal of this sensor is composed of the distance signal, the white Gaussian noise, and a harmonic wave. Conventionally, real-time distance measurement using these signals is impossible. However, although the white Gaussian noise is a random signal, the distance signal is periodic under the condition that the semiconductor laser is driven by a triangular current. In addition, the second-harmonic-wave frequency is twice that of the distance signal frequency. Utilizing these features, we propose a new signal processing technique in which the white Gaussian noise is reduced and the distance signal is corrected on the basis of the second harmonic wave. Hence, real-time distance measurement using a self-coupling distance sensor without a photodiode becomes possible. This processing system is constructed using a system-on-chip device. It is found that one measurement is completed within 2 ms, which is one period of modulated signal, and distances of 10 to 40 cm can be measured with an average error of approximately 2%.