The Design Of The Instrument Verification System Based On The Photoelectric Sensor Radar Velocimetry

The calibrator of traffic Doppler speed radar is insufficient; the project is relative lack of research in China at present. The speed that traffic Doppler radar got is commonly inaccurate, this greatly reduced traffic radar as a basis for administrative law enforcement with impartiality and authority. For the sake of carrying out the Measurement Law and solving the needs of radar speed detector traceability, proposed the design of calibration of radar measuring speedometers. The purpose of this paper is to design precise vehicle speed detector and the corresponding signal processing circuits and software. Compared with the speed data that got by speed radar on the same vehicle at the same time, calibrating the radar speed detector can be achieved.After comparison and demonstration, this paper selected combed photo-electric sensor with the advantages of high precision, fast response and non-contact. While getting the vehicle speed, as the sensor manufacturing process and the process of traffic ups and other reasons, the ground photo signal amplitude acquisitioned by comb photoelectric sensor changes a lot, and random change, signal contains a considerable amount of DC, noise and harmonic components, then photoelectric-sensor output signal from dozens of Hz to tens of kHz. It is bound to affect the measurement accuracy if use common band-pass filter, therefore, tracking filter was used in this paper, the pass-band of the tracking narrow-band pass filter changes as the signal changes in fundamental frequency, accordingly achieve accurate tracking filter. Signal processing circuit was designed based on an analysis of the CD4046 phase-locked loop. Phase-locked loop circuit can't track when vehicle speed is low, a pre-bias circuit designed can achieved low-speed phase-locked tracking. Finally, deal with the signal that through the tracking filter into a standard TTL level pulse then input computer data acquisition system for data processing. Experiments demonstrated that the circuit can meet the design requirements.As the single-chip storage and data-processing capacity is limited, on the needs of comparing with the velocity data that radar got on the same vehicle, software that run in Personal-Computer for this equipment was designed. Use PC powerful data-processing capabilities to store and manage data, single-chip only responsible for underlying data acquisition and transmission. PC software rendering speed curves, so that changes in vehicle speed is more intuitive. At the same time, with the design of the database, user can store data, query, second analysis and calculate, printing operation, a great convenience to users.