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How a Game Camera Works

December 2, 2012
Bill Waugaman , Ohio Valley Outdoors

There are two common types of motion sensors, infrared (IR) and passive infrared (PIR). IR sensors use a transmitter and IR receiver. PIR sensors do not rely on a transmitter; they are activated by the infrared energy radiated by an object in field of view. Since PIR sensors do not require a continual power source for a transmitter, they are more suitable for game cameras that normally use dry cell batteries for power.

--- How PIR Game Cameras Work

When first turned on, a game camera measures the IR energy in the viewing area. This energy passes through a fresnel lens on the game camera that serves two purposes. First, it concentrates the energy passing through it. Second, it focuses the IR energy on a pyroelectric sensor after passing through an infrared filter. The amount of IR energy hitting the pyroelectric sensor divides the area into hot and cold zones. The pyroelectric sensor is made from materials that generate an electric charge proportional to the amount of thermal energy striking it. The electric charge is boosted with an amplifier circuit and passed on to a comparator. Now, a baseline is set for the game camera to use for sensing movement.

Article Photos

PIR Diagram (How it Works)

As a deer moves into the viewing area, the thermal heat (IR energy) from the deer causes different spots on the pyroelectric sensor to get hot resulting in variations of the electric charge sent to the amplifier. The comparator monitors for variations in the electrical signal coming from the amplifier. These variations in the electrical signal are compared to the baseline signal established previously. When the comparator identifies variations in the electrical charge, it's output circuit signals the game camera to activate and take a picture.

While this is the basic principle behind most PIR sensors, a variety of mechanical and technological enhancements can improve the performance and reduce false activations. With game cameras, the various enhancements can have a dramatic effect (or lack thereof) on performance.

Unlike PIR motion sensors used inside a building where the background IR energy is relatively constant, game camera manufacturers have to enhance performance due to a wide variety of factors. Game cameras have to function with temperature variations, weather extremes, sunshine, shadows, daytime, nighttime use, single and multiple animals.

If you decide to purchase a game camera, be sure to do some reading and research to make an informed purchase. Once a camera is purchased, follow the manufacturers instructions on how to set it up to maximize the performance.

--- Infrared (IR) Equipped Game Cameras

Some game cameras are equipped with a bright flash for nighttime use (like the flash on a camera). When the PIR sensor activates, the flash goes off and a picture is taken. Game cameras can also be equipped with an Infrared (IR) flash. In these game cameras, the PIR sensor activates a bank of LEDs emitting an infrared (IR) flash that is not visible to the eye but can be picked up by the camera. Game cameras using a regular flash produce color images at night; cameras using an IR flash produce black/white images with a reddish tint. Each type of flash has its obvious advantages and disadvantages. When considering a game camera, decide on the how, when and were it will be used. Will the type of flash fit your needs?



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