Ultrasonic transmitter capsule as receiver capsule?

[cozturk]

ultrasonic capsule

**broken link removed**
Ultrasonic Range Meter systems uses 2 transducer. Unit transmits a wave about 40kHz and waits echo... Transmitter and receiver capsules looks like same case (2-3nF).

Can I use Transmitter capsule as receiver capsule while listening echo?
with changing gain adjustment neded at preamp.

What are different trasnmitter and receiver capsule? Probably reeiver can not transmit.

But trasnmitter receives echo signal?

Added after 29 minutes:

OK. I'm answering my question.:
1 transtucer example:
http://www.ele.uva.es/~jesus/sonar/sonar.html

 

[kender]

ultrasonic range meter + principle + explanation

Can I use Transmitter capsule as receiver capsule while listening echo?

Yes, you can. Although, there's a phenomenon, called "ringdown". See, after you transmit the pulse, you transducer doesn't immediately stop oscillating. Oscillation takes some time to decay. This phenomenon makes it difficult to measure distances shorter than a certain length - there's a lower limit. Sonars with separate receiver and transmitter don't have this inherent problem, if receiver and tramsmitter are close to each other.

Here are sample ringdown waveforms: http://www.prolifictec.com/filehost/Ringdown_waveforms_rev01.pdf

 

[cozturk]

Ok. Transducer doesn't immediately stop .

If mcu waits about a few 10uS can I detect echo from Transducer ?

The mcu how much time should wait before detecting echo?

PS. The project doesnt need to measure short ranges. Only 1m+ ranges neded.
I don't have scope to see doesn't immediately stop problem.

 

[kender]

Usually, an ultrasonic transducer is a piece of piezoelectric ceramic attached to a piece of damping material. The damping material (sometimes it's rubber) absorbs the energy and reduces the ringdown time.

If mcu waits about a few 10uS can I detect echo from Transducer ?
The mcu how much time should wait before detecting echo?

It depends: on the design of the transducer and, on how much power you apply to it, when you send the pulse, and (to less extent) on the sensitivity of your receiver. You can get some of the information from the manufacturer. You should also do some experimentation to determine the required delay. You can do it without the scope: point the transducer in the sky (away from any the obstacles), set the delay to zer0 - you should get false detection, increase the delay until you stop getting false detections.

PS. The project doesnt need to measure short ranges. Only 1m+ ranges neded.

Round trip time for 1m distance is 6ms. I think, your transducers should be fine for 1m+. But don't take my word for it - check with the manufacturer and community.

 

[binu G]

is it possible to have a lowest measuring height of 10 cm using a ultasonic capsule ?

binu g

 

[PaulHolland]

Sound is traveling through the air at about 340m/s so 1 meter in about 3 ms and 10cm in about 300us !. This number of 340m/s is depending on air presure, hight above sealevel, dry or high mousture levels.

You can also maybe use IR or magnetic detection if your distance is no more than 20cm and reflective in the case of IR or metal in the case of magnetic.

regards,

Paul.

PS: Ringing can be prevented (dampened) by focusing the sound wave by a plastic tube !.

 

[binu G]

i want to measure the level of water in the tank.
can this capsule help me ?

 

[PaulHolland]

Hi, Waterlevel detection should be done different. One perfect way of doing this is the detuned oscillator coil detection principle.

It works as follows:

You make an oscillator LC based for 100KHz or so. You use a plastic pipe for the coil (L) part of the oscillator and wind some 100 windings of thin wire arround the pipe close to each other. This part is going to detect water level. The pipe is placed in the watertank and if the water increases it will partly have the coil underwater alternating its frequency a little bit. You can detect this frequency shift with a microcontroller or a simple LF radio receiver tuned at 100KHz if the frequency is high its full and if the frequency is low its empty (low).

Very cheap to make ony needs one transistor and some resistors and capacitors.

regards,

Paul.

 

[kender]

water level sensor

You make an oscillator LC based for 100KHz or so. You use a plastic pipe for the coil (L) part of the oscillator and wind some 100 windings of thin wire arround the pipe close to each other. This part is going to detect water level. The pipe is placed in the watertank and if the water increases it will partly have the coil underwater alternating its frequency a little bit.

Did I get it right: the liquid acts as a moving core in the winding, and the winding of the inductance changes? That way, the winding can be electrically insulated forom the liquid?

 

[PaulHolland]

Did I get it right: the liquid acts as a moving core in the winding, and the winding of the inductance changes? That way, the winding can be electrically insulated forom the liquid?

No, The inductances changes by the liquid but there are NO moving parts only the liquid is moving as like a core in a coil. The windings can be electrically isulated by using special wire or build all in a plastic coating. The longer the coil the lower the frequency and the higher resolution you will get since the coil can be 1 meter long !!!.

Paul.