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How to obtain vehicle speed using LMS Test.lab and Correvit S-350 sensor



I'm using LMS Test.Lab. I have correvit S-350 optical sensor for speed measurement. It has a default output setting as 340 pulses/m. Can anyone help me in figuring out the formula i need to enter in the trigger level (derived) in tracking setup ? 

Basically I'm not aware how to convert the output of correvit sensor to the vehicle speed. 

Thanks in advance Smiley Happy


Re: How to obtain vehicle speed using LMS Test.lab and Correvit S-350 sensor

[ Edited ]

Hello - 

To convert a pulse-train of speed properly, the best method is to plug the signal into a Tacho input of a SCADAS, i.e. T1 or T2 on your frontend, or maybe the PDT module on older hardware.  Then in Test.Lab, use the Tracking Setup tab to configure the conversion of your 'ppm' signal into speed.  That can be done with a button that makes a derived tachometer for you, which uses the 'SPEED_CALIBRATION' function:

SpeedCalibration.jpgThis method requires you to have a known velocity and unit, and a corresponding 'rpm' - i.e. pulses per second at that speed.  In your case, figuring a speed of 1 m/s, i.e. 340 pulses/sec, leads to values of 3.6 km/h and 340 rpm.  When you enter those values and hit 'OK', a new Derived Tacho channel is created for you automatically; this can be viewed by hitting the 'Derived' button, where you will see this function (I've also opened the Edit dialog for clarity):DerivedTacho.jpgThis derived tacho can then be used for tracking or displaying results in your processed data.  Note that you'll also have to set the crossing level for the pulse-counting, just like any tacho - i.e. if your signal is 0-2 volts DC, either directly enter or move the cursor in the display to tell the system to look for the cross-level around 1.0 volts.  Hopefully this feedback is clear enough for you to continue with your testing, good luck!




Re: How to obtain vehicle speed using LMS Test.lab and Correvit S-350 sensor

I did as u have mentioned Jason but couldn't get a proper result. The speed shown was way below the actual speed with which the vehicle was moving.

I used a CORREVIT S-350 sensor 

It's a non contact optical sensor mounted in front of the vehicle (Hall effect sensor) 

Defaut output setting :- 340 pulses/m ( I'm not sure if m is meter or minute think ). I'm totally new to the field. 

I entered the value in speed calibration and pressed ok. Actually there was a start and stop button too, Should I calibrate using that and then go for the reading? 

I got the same formula (in the derived... tab) as shown by u in the the screenshot u pasted.

Kindly help me out in identifying the place where i made a mistake.

Thank You Jason