Abstract: Modulation frequency setting device sets the modulation frequency on the basis of the vehicle speed data from a vehicle speed detector and the detected range data, causing a low frequency oscillator to generate a low frequency signal of the set frequency. A transmitter transmits an electromagnetic wave (e.g., infrared light) which have been modulated with the low frequency signal. A phase comparator detects the phase difference between the low frequency signal and a detector output, and a range operating device produces range data. Relative speed operating unit finds the relative speed based on the range data. In case of a high vehicle speed, the modulation frequency is set low to extend the detection range. If an object in a short distance is detected, the modulation frequency is set high to limit the detection range to a short range, thereby enhancing the range resolution.

Abstract: A field effect transistor for actual use and a pseudo field effect transistor are formed on a semiconductor substrate. The pseudo field effect transistor includes a source electrode, a drain electrode and a gate electrode, each being similar in shape to the field effect transistor for actual use except that it is formed without an active layer. Since the pseudo field effect transistor does not include any active layer, it becomes possible to measure only the transistor's parasitic components which are inherent to the shape of devices, such as electrodes, lead-out electrodes (pads) and lead-out conductor patterns. By comparing the characteristics (e.g., S parameter) of both the actual and pseudo field effect transistors, the characteristics of the intrinsic transistor region can be analyzed.

Abstract: A plurality of radar devices are provided on and along the periphery of a vehicle for monitoring in different directions. While sequentially switching the radar device to be used for the monitoring operation in response to a transmission-enable signal, a processing device detects, for each direction, presence of and distance to an obstacle or object on the basis of a phase difference (time difference) between signals transmitted and received via the corresponding radar device. Thus, the processing device causes an image display device to show the detected conditions around the vehicle and also causes a sound synthesizer to output a sound message to call the vehicle operator's attention.