Ultrasonic Emitters and Transducers:

Using Arduino Sensors
1

I bought one of these:

http://www.maplin.co.uk/ultrasonic-transmitter-40khz-16mm-open-591658

and one of these:

http://www.maplin.co.uk/ultrasonic-receiver-40khz-16mm-open-591659

and I am basically getting an analog reading from the receiver and turning the transmitter on and off using a delay.

I have 2 arduinos, the transmitter arduino has one side of the ultrasonic transmitter connected to pin 12 and the other to ground.

The receiver arduino has one side connected to analog pin 1 and the other to ground.

The result I get from the serial bus is a seemingly random oscillation of numbers from 1000 down to about 40. It will start at a bit over 900 and work its way down to about 40 then go back up.

I have a feeling there are several things I am doing wrong so any help is appreciated!

-Jack

2

There are two amplifiers missing, PA on transmitter side and LNA on receiver.
You can't interface such peripheral devices directly to arduino

3

You need to drive the transmitter with a 40kHz signal, it doesn't have a built in oscillator.
Similarly, the receiver has no amplifier, so unless you know how to build these, you're better off buying ready made units, like the ones from Devantech.