One of the most important criteria for an outdoor camera is the ability to work over extremes of environmental conditions. In the United States, the commonly accepted operational outdoor temperature range for traffic or security applications is about -35° C (-31° F) to +75° C (+167° F). The Sidewinder series of cameras (and all of the other cameras manufactured by WTI) are designed to work over this extreme temperature range.
The Sidewinder camera incorporates several special features that allow it to operate at extremely low temperatures. Multiple temperature sensors distributed throughout the camera ensure that power is efficiently directed to the areas that require it, keeping all camera components operating within the optimum temperature range.
The camera tube section of the Sidewinder incorporates a solid-state temperature sensor to monitor the internal temperature of the tube and control the operation of a 10 Watt resistive heater that keeps the temperature of the video sensor and zoom lens optical assembly in the optimum range for best performance.
The camera tube faceplate assembly incorporates another solid-state temperature sensor that monitors the outside environmental temperature and controls the amount of power applied through a 3.5 Watt pulse width modulated power amplifier to the Indium-Tin Oxide (ITO) electrical coating on the inside of the window glass. This keeps the window glass from accumulating frost, or from becoming fogged up in high humidity conditions. By applying the power directly to the ITO coating on the window glass, a significant reduction can be made to the amount of power required to keep the glass clear of any ice or fog. This window glass temperature control is a feature found in all of the cameras manufactured by WTI.
A third temperature sensor within the main body of the Sidewinder monitors the temperature of the motor assemblies and electronics. In order to maintain the high pointing accuracy specification of the Sidewinder, the motor drive assemblies must be kept from changing temperature too much. When the temperature within the housing drops too low, the idling current in the precision stepper motors is increased, to gently warm the motor assemblies back up to optimum operating temperature and to help regulate the temperature of the drive electronics.
The combined operation of the multiple temperature sensors and multiple heating mechanisms allows the Sidewinder camera to come up to operating temperature in approximately 7 minutes after being shut off in -35° C temperatures for several hours.
Operation at the +75° C end of the temperature range is just as important as the low temperature performance. While the highest air temperature ever recorded on Earth was less than +60° C (+136° F in Libya on September 13th, 1922), all cameras manufactured by WTI are tested to the more demanding +75° C temperature standard required for traffic control cabinet products. Several features of the cameras contribute to reliable operation at elevated temperatures. All of the cameras are powder coated gloss white to reflect energy from the sun and help keep the cameras cool. All of the electronic and mechanical components are selected to be compatible with the extreme temperature range demands of the cameras. All of the electronic and mechanical components are designed to be energy efficient to keep self-heating to a minimum.
It takes careful monitoring and control of the environment inside the camera to allow the best possible performance of the camera, no matter how extreme the outside conditions may be.
~Dale Roche, Director of Engineering
~~**~~**~~
WTI (Wireless Technology, Inc.)
Video Surveillance Products Dedicated to the Broadcast, Global Security and Transportation Markets!
http://www.gotowti.com/ ● http://www.wirelesstech.com/
~~**~~**~~
Posts
No comments:
Post a Comment