# Just asking for a high speed sensor..

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#### yes_secreto

##### Newbie level 5
I'm in need of a sensor which could detect speeds at 60km/h...

I've tried an infrared TX and RX...the RX mounted underneath the car and the TX on the ground...but it only detects at a speed of 10km/hr-20km/hr...

Can you suggest a sensor that might Help me...tnx

#### bigdogguru

Have you considered utilizing a RPM/Tachometer sensing the revolutions of a rear wheel or a part of the drive train, e.g., drive shaft. The resulting RPM can then be used to calculate the velocity of the vehicle if traveling in a relatively linear fashion.

Another option, although more costly, is using a GPS module, which can provide fairly accurate velocity readings.

BigDog

yes_secreto

### yes_secreto

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#### yes_secreto

##### Newbie level 5
Have you considered utilizing a RPM/Tachometer sensing the revolutions of a rear wheel or a part of the drive train, e.g., drive shaft. The resulting RPM can then be used to calculate the velocity of the vehicle if traveling in a relatively linear fashion.

Another option, although more costly, is using a GPS module, which can provide fairly accurate velocity readings.

BigDog

Tnx for your suggestion sir...but I would like a sensor that would detect a fast vehicle...not using a high speed camera but something else...just like what i have mentioned an IR module but it when the vehicle reaches a speed of 60km/h the IR receiver module could not detect the IR trasmitter...

#### klystron

I assume that you use a cross correlation algorithm between two receivers that is separated by a known distance. The cross correlation peak delay gives the time estimate.The speed is the sensor separation distance / cross correlation time delay. Is your cross correlation algorithm fast enough?

yes_secreto

### yes_secreto

Points: 2

#### yes_secreto

##### Newbie level 5
Thanks for the advice sir...hmmmm...what sensor could possibly use from your suggestion sir??

#### karthickb3e

Are you try with, what frequency of operation(frequency of response) ......?

using of frequency of operation higher in sensor makes solution to your problem...

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yes_secreto

### yes_secreto

Points: 2

##### Full Member level 5
The IR receiver is fast enough to detect this speed. you are doing some thing wrong.
First you need to check how fast your IR TX and RX can work. attach you IR TX with a function Generator, set it to square wave and connect your IR receiver to Oscilloscope. Now crank up the frequency slowly, keep cranking up until your square wave shape on oscilloscope starts changing. That wold be the max frequency handling of your IR.

Now your car is traveling at 60Km/h = 16.66 m/sec. Suppose your wheel circumference is 1 meter.That mean 1 revolution of wheel is being done in 60 millisecond approx. You apply a white strip or line from center of the wheel to its end like drawing a radius for detection. the width of that strip is important. Suppose if you make that width of 1 cm then your IR receiver has the time (60 msec/100cm = 600 usec) to detect it. 1/600 usec = 1.6 KHZ. now check that was you sensor working at this frequency when you were checking on oscilloscope.if your IR cant handle this frequency then increase the width of the strip. I think you should approach the problem like this.

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### yes_secreto

Points: 2

#### yes_secreto

##### Newbie level 5
The IR receiver is fast enough to detect this speed. you are doing some thing wrong.
First you need to check how fast your IR TX and RX can work. attach you IR TX with a function Generator, set it to square wave and connect your IR receiver to Oscilloscope. Now crank up the frequency slowly, keep cranking up until your square wave shape on oscilloscope starts changing. That wold be the max frequency handling of your IR.

Now your car is traveling at 60Km/h = 16.66 m/sec. Suppose your wheel circumference is 1 meter.That mean 1 revolution of wheel is being done in 60 millisecond approx. You apply a white strip or line from center of the wheel to its end like drawing a radius for detection. the width of that strip is important. Suppose if you make that width of 1 cm then your IR receiver has the time (60 msec/100cm = 600 usec) to detect it. 1/600 usec = 1.6 KHZ. now check that was you sensor working at this frequency when you were checking on oscilloscope.if your IR cant handle this frequency then increase the width of the strip. I think you should approach the problem like this.

tnx sir...hope this works...i think my IR transmitter is modulated at 40Khz..I'm not really sure because this is a circuit module ordered at a local store..

Maybe my IR transmitter isn't to strong or its radiation angle isn't too large...I am really confused on how to troubleshoot this thing...

#### bigdogguru

...but I would like a sensor that would detect a fast vehicle...not using a high speed camera but something else...

Camera? Neither of my suggestions involved the use of a camera.

Apparently, there is a degree of miscommunication present in our discussions.

I've tried an infrared TX and RX...the RX mounted underneath the car and the TX on the ground...but it only detects at a speed of 10km/hr-20km/hr...

The above quote seems to suggest you are attempting to monitor the speed of a vehicle utilizing a sensor mounted on the said vehicle. Is this correct?

just like what i have mentioned an IR module but it when the vehicle reaches a speed of 60km/h the IR receiver module could not detect the IR trasmitter...

What microcontroller are you using in your design?

By implementing a tachometer utilizing a simple IR TX/RX pair coupled with a IR reflective marker on a portion of the vehicle's drive train, e.g., wheel, drive shaft, etc, the associated RPM of wheel or drive shaft can be easily obtained and used in the calculation of the vehicles speed.

Tachometer/RPM II.

DIY PIC Microcontroller Based Digital Tachometer Project

How to make a contact-less digital tachometer using IR-light reflection technique

The following thread provides and in depth discussion of implementing a RPM tachometer using IR sensors:

[SOLVED] some questions motor speed monitoring

The other method that was previously mentioned utilized a Global Positioning System (GPS) module, which would provide not only speed (velocity), but heading and current coordinates as well.

GPS uses orbital satellites and a GPS receiver module to obtain a constant update of various information, including velocity.

The modules range in price from $30 USD to several hundred per unit depending on the desired features. GPS to SD-Card Data Logger Hope the info helps in your endeavors, BigDog yes_secreto ### yes_secreto Points: 2 Helpful Answer Positive Rating #### yes_secreto ##### Newbie level 5 Camera? Neither of my suggestions involved the use of a camera. Apparently, there is a degree of miscommunication present in our discussions. In your original posting: The above quote seems to suggest you are attempting to monitor the speed of a vehicle utilizing a sensor mounted on the said vehicle. Is this correct? What microcontroller are you using in your design? By implementing a tachometer utilizing a simple IR TX/RX pair coupled with a IR reflective marker on a portion of the vehicle's drive train, e.g., wheel, drive shaft, etc, the associated RPM of wheel or drive shaft can be easily obtained and used in the calculation of the vehicles speed. Tachometer/RPM II. DIY PIC Microcontroller Based Digital Tachometer Project How to make a contact-less digital tachometer using IR-light reflection technique The following thread provides and in depth discussion of implementing a RPM tachometer using IR sensors: [SOLVED] some questions motor speed monitoring The other method that was previously mentioned utilized a Global Positioning System (GPS) module, which would provide not only speed (velocity), but heading and current coordinates as well. GPS uses orbital satellites and a GPS receiver module to obtain a constant update of various information, including velocity. The modules range in price from$30 USD to several hundred per unit depending on the desired features.

GPS to SD-Card Data Logger

Hope the info helps in your endeavors,

BigDog

tnx sir for your suggestion...I really like your suggestions...Sorry for making a bit fuzzy and confusing
statement of my problem...

actually sir.. the my main problem is on how to detect a fast moving car...but the sensor(receiver) should be on the fast moving vehicle and the transmitter might be mounted at the ground or on top or we could hang it somewhere near the pedestrian lane...

My project basically is detecting those beating through red light or red light violators...and we know that in order to beat a red light we must have a speed of at least 60kph...the speed of the vehicle is my problem....my sensor(the IR receiver underneath my car) could only be detected when the speed of the car is at 10kph to 20kph.....

I know that we detect red light violators through high speed camera...but we would like to pursue this project because we thought of this as a cheaper alternative for high speed cameras...

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