The only problem I can see with your idea is that grain silos are often choked with grain dust (which, by the way, is HIGHLY explosive), which might very well introduce severe measurement errors. Also, I question whether the reflection from the grain would be of sufficient intensity to measure. The ultrasonic pulse would probably be stretched immensely during reflection too since the grain surface would likely be porous enough that reflection would occur from anywhere in the first inch or two of grain. Of course, all this might be irrelevant, so try it anyway. On Tue, 11 Nov 1997 01:57:06 -0400, Alberto Smulders wrote: >Hi Rick !!! > >Another very interested person here, looking for a cheap method to measure >contents in grain and oil storage bins - should be a kind of ultrasonic >rangefinder, maximum range around 10...12 meters, ruggedized for use in an >industrial environment, some serial communication means for rather long >distance (up to 1 km or so) if possible with unique address for >interrogation, and.... (hmmm... am I asking too much ????) > >Regards > >Albert Smulders >InSAD - Encarnacion, Paraguay >insad@itacom.com.py > Martin R. Green elimar@NOSPAMbigfoot.com To reply, remove the NOSPAM from the return address. Stamp out SPAM everywhere!!!