| Nowadays, the development momentum of China’s road transport is very rapid,which has been a great help for the rise of China’s economic. But the increasinglycomplex problem of road traffic management has come, too. All kinds of illegal,unlawful actions happen everywhere. Speeding is the greatest harm. Currently, themonitor of speed depends on Radar velocimeter in our country. However, theinstability of the systems have occurred which reduces the justice and authority of thedepartments greatly. The only way to solve this problem is to use a verification deviceto test them before they are used or after the measurement cycle. Now there are avariety of Radar velocimeter verification devices in the domestic market, but theyneed to be used under the laboratory conditions, which makes it hard to be tested forthe Radar velocimeter installed on the road permanently.Based on extensive analysis and argumentation, we developed a new verificationdevice for Radar velocimeter. It can avoid the trouble of censorship and increase theeffectiveness of the test results. The design idea is that we use the device and a Radarvelocimeter to capture the speed of the vehicle used for test, and compare the data inorder to verificate the Radar velocimeter.The device consists of a speed capture device and PC data analysis software.Desired speed signal is provided by a vehicle speed sensor. The speed capture deviceconsists of the pre-conditioning circuit, microcontroller, display section and a wirelesstransceiver module. By the use of the pre-conditioning circuit which consist of abidirectional diode limiter, a two order active low-pass filter circuit and a schmitttrigger, we can change the sine wave signal which gets from the magnetic wheelspeed sensor into a square wave signal with the same frequency which can be used bythe microcontroller. The signal from the Hall-type speed sensor does not need to. The LED digital display part, showing the speed accurate to one decimal place, facilitatesthe driver for speed control. The wireless transceiver module is used for data transferbetween the microcontroller and PC. To ensure the synchronization of data transfer,we choose the PC software as the master node, the radar velocimeter and the speedcapture device as the slave nodes. During the test, the request for data sent by themaster node to the slave nodes every1ms, PC gets data when the slave nodes receivethe request, then analyses data, saves files and gives the test report. |
