3. APPROACH 3.1. Hardware The hardware for this project includes two major parts: a sensor module and the recording device. The sensor module will capture data from EMF, temperature, and motion sensors, and forward this data to the recording device. The recording device will input the sensor data, video from a camera, and audio from a microphone and store the information on an internal disk. 3.1.1. Sensor Module Included in the sensing module are the sensors and the microcontroller that will input the measurements and forward the numbers to the recorder. The design of this module included the selection of the sensors and microcontroller. The general layout is shown in Figure 1. Figure 1. Diagram of Sensing Module 3.1.1.1. Microcontroller The PIC16F877, manufactured by Microchip, will be used in this project. The requirements of this project are relatively low, both in terms of processing capabilities and I/O pins. Approximately 10 pins will be needed by the sensors, and the serial connection will consume an additional couple of pins. The processing will be limited to reading data from the ports and relaying the information to the serial port; consequently, it would not have been justifiable to use a microprocessor or even a more powerful microcontroller for such an undemanding application. The development tools for the PIC16F87x chips are already present at the Mississippi State University ECE facilities and the shift to a similar controller manufactured by a different company could not be justified with the increase in overhead. 3.1.1.2. Temperature Sensor The first temperature sensors considered for this project were analog sensors such as thermocouples, thermistors, and resistance temperature detectors (RTDs). The advantages of these sensors were oftenbalanced by the unnecessary complexities of use and the inapplicability of certain capabilities. Thermocouples, though probably the simplest device, are most often used for measurements where a wide temperature range is required; however, this device is only expected to be used around ambient conditions. The RTD is more accurate than necessary, as are thermistors. All of these device are also associated with the cost of converting the signal to digital, which would consume pins on the PIC that could be allocated for other uses. Consequently, digital thermometers were considered. The 1-wire products from Dallas Semiconductor, such as the DS1820, were an obvious choice. Not only do these exceed the expected sensitivity, with capabilities of measuring temperatures between -10°C and +55°C with an accuracy of 0.5°C, but controlling 1-wire devices from Microchip PICs is an easy task with a base of working, well-established code available from Dallas Semiconductor. The ability to place multiple thermometers on a single bus allows for simple expansion of the device without complicated redesign of the circuitry. 3.1.1.3. Motion Sensor A passive infrared (PIR) motion detector was chosen over the two other options for movement sensing: ultrasonic and video detection. Ultrasonic motion detectors use the Doppler effect to determine whether movement has occurred; however, gusts of wind or loud noise may serve as false triggers while smaller movements may pass unnoticed. Though video motion detection would be a great addition to the software portion of this project, the reliance on ambient light is an unnecessary restriction. PIR motion sensors are inexpensive sensors that respond to the heat emitted by a human or other animal. Because paranormal events are not necessarily material phenomena but are associated with energetic emissions, use of the PIR sensors is more justifiable than the ultrasonic detectors. 3.1.1.4. EMF Sensor Currently marketed electromagnetic field (EMF) sensors vary widely in price and capabilities. Simple circuits that respond to EMF but offer no correlation to actual measurements may cost less than ten dollars, but more expensive units with integrated analog displays and several operating modes are priced at several hundred dollars. Because the operation of many of these devices is questionable, the Multidetektor II Profi, manufactured by Aaronia, was selected due to a favorable reputation and in spite of the price. 3.1.2. Recording Device The recording device needed to perform the following set of functions: 1. accept input from a digital camera via a Firewire connection 2. output using a 10/100 Base-T Ethernet connection 3. record one hour of data to an internal disk Research was directed into motherboards that contained the listed capabilities because the development time for integrating the individual components would have exceeded the allotted period for the project. The options included standard desktop processors (Intel, Athlon), DSP boards, and Mini-ITX boards. Though the former offered the widest range of products at the lowest prices with the highest proportion of devices exceeding the needed capabilities, the size of these motherboards was a deterrent. The DSP boards, though extremely powerful, are very expensive and require development tools beyond the abilities and pocketbooks of our team. The Mini-ITX motherboards are intended for small computers with low noise output but with reasonable performance. The VIA EPIA M-Series motherboards were picked because of the on-board Firewire inputs, network card, sound card, and video card. The ME6000, which will be used, can operate without a fan and uses at a clock speed of 600-MHz. The selected computer is shown in Figure 2 with the components that will be utilized in this project highlighted.Figure 2. Mini-ITX Computer Though the user will be expected to provide the camera for use with the PARDS, the necessary decision to limit compatibility was a hardware issue faced when designing the system. Two major types of digital video cameras exist: DV cameras and DCAM cameras. DV cameras are digital camcorders that compress the video onto small memory disks that cam be later transferred to a computer. DCAM cameras, more technically known as IEEE 1394 IIDC cameras, do not compress the video in the device and usually do not contain any ports for recording; however, these cameras connect to a computer via a Firewire link where software can download images and output compressed video. DV cameras are significantly more expensive than DCAM cameras, which include most Firewire web-cams. Free