# Discrepancy between EMF measures

Why, using a EMF tester on a smartphone in airplane mode, do I get a very low measure ($$\< 1 mG\$$), whereas using some applications which exploit the phone magnetometer, I get a very high value, something as $$\35 \mu T\$$? I get also a significant difference when I switch airplane mode off.

• I'm guessing it's something to do with the cellular antennas being switched off in airplane mode. – AlfroJang80 May 27 '19 at 19:39
• Somehow I doubt that these applications are any accurate. – Eugene Sh. May 27 '19 at 19:40
• Can you please provide context as to what this "EMF tester" instrument is, preferably with a link to a datasheet? Electromagnetic compatibility is a complicated field (pardon the pun). – Peter May 27 '19 at 19:40
• @Bento - the EMF tester almost certainly only measures AC fields. The magnetometer only DC fields of which the Earth's magnetic field is the most significant. – Kevin White May 27 '19 at 20:12
• @Bento What sort of radiation? You have a device which is (presumably) giving you output in Gauss. Is it an AC gaussmeter? If so, over what frequency range does it measure? – Peter May 27 '19 at 20:27