Range finding

[wizard]

Hi,

Yesterday I decided to make an ultrasonic range finder using a PIC chip.

I have 5 pairs of those 16mm open air ultrasonic sensors (5 T and 5 R). Because those sensors are on the shelf, so I thought of using 5T sensors all in parallel for more distance to be measured. I will make a powerful driver for them so there is no problem to drive them.
I wanted to know your idea of doing so? Do you think it will work ok?
If you think of any problem using this way please let me know it.

Thanks

 

[wizard]

I guess(not sure) that when we go ahead to get more distance, we will face problems with accuracy? Maybe that's the main reason of not doing what I decided to do(because I was not able to find any similar approach on the net)!?

 

[blueroomelectronics]

What sort of range are you hoping for?

 

[wizard]

Hmm, I want to get the longest range I can!
BY now Want to know the influence of several T sensors rather than just one?

 

[ericgibbs]

Hmm, I want to get the longest range I can!
BY now Want to know the influence of several T sensors rather than just one?

The maximum range will depend greatly on the reflecting surfaces of the 'distances' you want to measure.

If the multi transducers are phased correctly the range will be increased.

The arrangement of the transducers will also determine the shape of the transmitted beam

You should decide what maximum range would be acceptable for 'reliable' operation.

Exactly what are you trying to do.?

 

[wizard]

The maximum range will depend greatly on the reflecting surfaces of the 'distances' you want to measure.

If the multi transducers are phased correctly the range will be increased.

The arrangement of the transducers will also determine the shape of the transmitted beam

You should decide what maximum range would be acceptable for 'reliable' operation.

Exactly what are you trying to do.?

Thanks,

Well, I think I told what want to do!
I wanted to make this:
http://www.interq.or.jp/japan/se-inoue/e_pic6_61.htm
While I was looking at the page and thought of my spare sensors, I thought why not to use several of them to get more range. When I could'nt find any info of the reason, then I started this thread.

I want to use those sensors all in parallel and side by side. Can you let me know your idea of how to make them 'in phase'? I think those sensors would be in phase when used side by side.

If I had more sensors I preferred a hexagon shape to reduce the gap between sensors.

I like 20 meters of distance and more

 

[ericgibbs]

Can you let me know your idea of how to make them 'in phase'?

In phase means all the sound pressure waves from all the sensors in phase and in sync for the duration of the pulse.
It important to have the outputs of the sensors so that the dont cancel each other.

I cannot see a simple way to guarantee the phase and frequency lock of using multiple transmitters.

 

[wizard]

In phase means all the sound pressure waves from all the sensors in phase and in sync for the duration of the pulse.
It important to have the outputs of the sensors so that the dont cancel each other.

I cannot see a simple way to guarantee the phase and frequency lock of using multiple transmitters.

I know what it means but thought maybe putting them on a side by side position is the best solution to reduce the out of phase problem...

 

[ericgibbs]

I know what it means but thought maybe putting them on a side by side position is the best solution to reduce the out of phase problem...

How would putting 5 ultrasonic transducers side by side reduce the phasing problem.?

 

[audioguru]

Transducers side-by-side makes the sound beam narrow horizontally.

The original project has a round-trip range of only 3.6m so the actual range is only 1.8m. The transmitting circuit needs to be more powerful to drive more transducers.
Two transmitter transducers will increase the range to 3.6m.
Four transmitter transducers will increase the range to 7.2m.
Adding more receiving transducers will not make it more sensitive but it will make the receiving angle narrow.

 

[Boncuk]

Why not use a high power tweeter as transmitter? It should be able to work at 38 to 40KHz.

The transmission angle could be narrowed using a pipe. This eliminates the phase problem which will occur since the transducers don't have the same reaction time.

For distances greater than 20m (~65ft) you should compensate for air density (meaning humidity and temperature as well as local air pressure).