Range meter

[Electronman]

Hi.

Does any body know if this device is working just like those common ultrasonic range meters which the circuit is available on internet?:
**broken link removed**

Those circuits are working not more than 4 to 5 meters, so how does this ready device is working at more than 15m?
What is the story of the laser in the link too? Is it there just as a pointer or...?

 

[RadioRon]

This looks like a laser rangefinder to me, despite the name they give it.

 

[Electronman]

What about few models on the below link?:

e-Shop. Sensors, transducers, DAQ systems and measuring instruments

 

[Electronman]

No idea?

No one knows anything?

 

[duffy]

We are still converting meters. How many barleycorns is it to the inch?

Wait - I got it. 4 or 5 meters? Naw, my old Polaroid rangefinder could go 10 meters (about 35') and that was twenty years ago. You need a better transducer than those cheapie 40khz remote-control jobs. If it runs on less than 100 volts it ain't gonna do it.

 

[duffy]

Here - this shows the business end of one of those:
https://www.sensorsportal.com/HTML/E-SHOP/PRODUCTS_PHOTOS_3/3338_Dimension_Meter.jpg

See that gold foil? That's the Polaroid transducer. Runs at 300V, much wider bandwidth. You send on multiple frequencies, you ramp up a VCA ahead of the filters - lots of ways to improve on the basic hobby ultrasonic rangefinder.

 

[Electronman]

I did not get your explanation at all

 

[duffy]

1. Better transducer. Runs on a higher voltage, higher acoustic output, capable of more than one frequency. (it's also focussed by an integral waveplate assembly)

2. They use a Voltage Controlled Amp ahead of the ultrasonic filter. It is triggered by the microcontroller at the minimum echo pule reception time. The control voltage ramps up exponentially, so the amplification ramps up exponentially. This exponential increase exactly follows the exponential DECREASE in the level of the recieved echo so they cancel out. This reduces the dynamic range requirements of the ultrasonic filters.

3. They use multiple frequencies. Some materials will absorb certain ultrasonic frequencies, but reflect others. Using several frequencies improves your chances of catching a faint echo from a distant reflection.