�From:�	al_ward (al_ward)
�To:�		sowacs@aqua.ccwr.ac.za
�Date:�	Tuesday, July 2, 1996  5:09 pm
�Subject:�	Re[2]: Cracking clays and radio sensors! sowacs

          It is true that Delta-T Devices markets a probe, the 
          "ThetaProbe", that has all of the electronics on board.It 
          is essentially a frequency domain probe that depends onthe 
          frequency shift induced by energy storage in wet soilsin 
          response to a 100 MHz signal. We are probably allfamiliar 
          with the sensitivity of FD probes to soil texture. 
          Furthermore, this probe still requires a cable and a 
          datalogger. It is marketed in the US by a company called 
          DYNAMAX. This probe does not fall into the category of 
          "cheap" sensors. The price varies from US $770.00 for a1-10 
          probes, $670.00 each for 11-20 probes and $570.00 eachfor 
          21-40 probes.
          
         -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= 
          Anderson L. Ward, Ph.D
          Research Scientist
          Battelle Pacific NW National Laboratory
          P.O. Box 999, K9-33
          Richland, WA 99352
          Tel (509) 372-6046
          Fax (509) 372-6328
          Email: al_ward@pnl.gov 
         -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=


          


______________________________ Reply Separator_________________________________
Subject: Re: Cracking clays and radio sensors! sowacs
Author:  L_HUTLEY@BLIGH.NTU.EDU.AU at -SMTPlink
Date:    7/2/96 3:47 AM


Re: Cable-less TDR Devices
          
          
I THINK Delta-T Devices (UK) have a TDR system on the market withthe 
electronics, logger, memory etc. built into the sensor and thewhole 
lot is buried, except an RS232 interface that is used for down- 
loading with a PC.
          
          
          
          
Lindsay Hutley
CRC and the School of Biological Sciences 
Northern Territory University
Darwin 0909
          
Ph (08) 8946 7103
Fax (08) 8946 7107