The probes only penetrate the ground by a handful of inches, but the electrical signal itself can penetrate lots of meters. Reference soil samples can also be accessible for obtain by quite a few highly regarded reference typical companies, NIST, or other sources on-line. SIMEX Bangladesh may be very Qualified! https://bouncehouse65433.anchor-blog.com/10920517/considerations-to-know-about-soil-resistivity-testing-solutions-bangladesh