prowave-400fs080 : omnidirectional or not ?

I can't quite see your problem  - it's omnidirectional horizontally but not vertically - the data sheet is quite clear. The shortform description on Farnell's web page is just a condensed summary of the data on the data sheet. (Actually many of the Farnell shortform descriptions contain errors so you should never rely on  them but they are very useful for finding likely parts.)

MK

I have one more doubt.Does prowave-400fs080 has the internal circuitry required for transmission? The question  might sound weird. I came across this circuit http://www.electronicsforu.com/electronicsforu/circuitarchives/view_article.asp?sno=582&ar.. In here is the explanation on ultrasonic transmitter and receiver .My doubt is that whether the module has the internal circuit as given in the link or prowave-400fs080 is just the transducer labelled tx in the diagram.

The part Farnell sell is just the transducer. The circuit in the article you refer to is not suitable for anyhting other than experimentation. Look more widely on the web to find circuit idea to use with the Prowave sensor.

If this is a first project you would find more conventional (and not omnidirectional) sensor easier to work with.

MK

What is the maximum distance at which the transducer at receiver can pickup the signal ?

That depends on the quality and complexity of your electronics and signal processing.

It's not  a very sensitive sensor so the range won't be as good as directional sensors, so a few metres at the very most.

You should do some research on the web, find the specs for commercial or published systems and see if you can find out how they are done.

MK

That depends on the quality and complexity of your electronics and signal processing.

It's not  a very sensitive sensor so the range won't be as good as directional sensors, so a few metres at the very most.

You should do some research on the web, find the specs for commercial or published systems and see if you can find out how they are done.

MK

I have got the datasheet(     http://www.datasheetlib.com/datasheet/1154043/400fs080_pro-wave-electronics.html      ) of the transducer and it says that the maximum drive voltage is 150 vp-p for burst and the resonant frequency is 40khz. To produce such a signal ,I thought of using an opamp(741) multivibrator to produce the 40 khz square wave(Vpp - 24v) and connecting  it to a primary of step up transformer(24v -120v).Will this work and what would be the current needed to drive the transducer.I cannot find the minimum  or maximum current rating in the datasheet .How will the drive voltage and current  affect the transmission .

You can't easily work out the impedance of the sensor at 40kHz - you will need to measure it.

A 741 is not  a suitable device for this purpose (a 741 is not a suitable device for ANY purpose except replacement in an existing board - it is an ancient design and there are much better parts available for any application.).  Downalod a data sheet from somewhere and check out the 741's slew rate and bandwidth - then read this paper:

http://www.ti.com/lit/an/snoa852/snoa852.pdf

to understand why the 741 wont' t do.

Then Google for ultrasonic trsansducers and look for drive ciruits  - you'll find that your suggestion is not the normal way to do it.

The transducer you are using is not the same as the typical ceramic piezo electric parts and you will need to either get  a recommended drive ciruit from Prowave or devise your own.

It is not necessary to drive at the maxim possible voltage - if you drive it less you will get less output and a smaller echo - does this matter to you ?

MK