MuRata PIR sensor to PIC16F873A help!

[kylee]

hi there,
am in need for some desperate help in this field with PIR sensors. have searched pir found some useful info but no luck
have purchased and rigged up a PIR sensor dual element from murata pdf at link below with fresnel lens. its just the bog standard sensor no amplification.
IRA-E700ST0 datasheet pdf datenblatt - Murata Manufacturing Co., Ltd. - Pyroelectric Infrared Sensors ::: ALLDATASHEET :::
i connected up to 5v supply from my 7805 and measured output using osc. am getting approx 1V output signal offset and the changes depending if sensor is passed from point a--b or b--a gives a voltage change +-15 mV. i need to connect this sensor to my PIC16f873a ADC pins an0 and an1 but the voltage change compared with the offset is negligible. i want to know how i can increase the voltage change so that i can compare the value with a Vref in the PIC when i use the ADC. if it is greater that ref voltage i know that someone has crossed from a-->b and if lower than vref i will know its b-->a thus being able to sense direction.
iam working on a lighting motion system model as a project to be used in corridoors
will be really grateful for all help on this matter best kaye

 

[crutschow]

The PIR output signal is very small and difficult to detect. But you would know that problem has already been solved for you if you had read the data sheet. You need to amplify the signal with an amp similar to that shown on pg. 8.