Specifications

3
The most constraining aspect of the design was finding a power source capable of supporting a
running time of one week that was both low cost and mobile. While a solar power solution was
considered feasible and could allow the system to run more than one week, that approach suffers
a number of limitations. First, the complexity and price of the system would be unacceptably
increased. The lack of light at night and during certain weather conditions would necessitate both
an onboard battery and charging system. Continuous video recording could not be guaranteed.
Furthermore, interaction with the system will already be periodically required in order to collect
the digital video for analysis. Therefore, the system was designed to run completely on batteries.
Given the power consumption ratings of the processing hardware and the one-week desired
running time, four high-capacity deep-cycle marine batteries are necessary.
A weatherproof case was selected to house the motherboard, hard drive, and power converter.
This case allows for mounting of the swappable drive bay to support easy removal and insertion
of hard drives. The batteries are housed in individual weather-proof polypropylene cases. The
camera is already ruggidized and is affixed atop a four-foot pole extending out from the base.
Figure 2.1 shows a photograph of the computer components and camera and two cut-away
computer-aided design (CAD) diagrams of the complete system.
Figure 2.1. Video recording system prototype
2.3 Prototype Components and Cost
The prototype design presented in the previous section is the lowest cost solution that meets all
of the other design constraints. The overall cost was minimized by using consumer-grade off-
the-shelf parts repurposed for the task of video recording. The parts for this system can be
acquired for an approximate total of $1,100 when purchasing the components individually.
However, it is expected that the cost could be reduced if bulk purchases were made. The
construction time is on the order of 10–15 hours, but because the design is simple and assembly
is straightforward, the associated labor costs are expected to be minimal. The remainder of this
section provides a list of the necessary components and their prices.
Motherboard—VIA EPIA CN10000EG Fanless Mini-ITX Mainboard, $185.00
This motherboard is well suited to this application because it does not consume much power
or produce much heat. Any heat generated by the system is dissipated through a heat sink in