ppm

[salman]

Sir thanx for responding earlier, as i am a student i will be requiring ur help at times.this time if you can plz tell me the exact magnetic field strength and corrosponding frequency in my area that will certainly help me constructing the amplifier and filter stages i am in karachi pakistan ,i hope you know the location it is in asia ,just with the borders of india and china.
Moreover i want to go by hardware filtering if you can suggest some good circuits for amplification and filtering i will be thankful.