Magnetic Sensor Design

Hi All,

I am working on the Design of a Magnetic Sensor, this sensor is a part of security system. This sensor should be able to detect human intrusion, can differentiate between human and vehicle.
I want to detect EMF Signature. What Kind of a method i Follow, I know there are some Hall-effect, of Magnetometer available can they serve me this purpose
I am thinking this to design by a coil who just sense Magnetic filed change I know that this signal is going to be too weak Tell me what king of analog and digital process i can apply on this.


Please Help!

Here's my S0.02 idea. You would probably need more than one type of sensor. I would try inductive and capacitive. Inductive is good for detecting metal. Capacitive can detect both metal and dielectric (it's used extensively in touch sensors and buttons).

I would also like to invite your question to a specialized group dedicated to sensors: http://tech.groups.yahoo.com/group/sensorforum. It's a fairly active group when it comes to responding to questions. You'll get more S0.02 ideas; which might add-up to something.
There's also a good number of allication notes in the "fles" section of the group.