lrl Detector circuit - removal (NEED)

[doral]

HI
any one have circuit of lrl detector -removal with Lowest percentage error??
because of our country have a lot of mineral soil and in this case lrl errors is more and have to build a device can be removal all of the bad signals or Metal surface and just detect the frequency that we give to device..
if any body have some circuit please help me.
i think the best lrl have generator with prob and a circuit that contact to L rod..
i wait for any response
sry if my grammar is not good.
best regards