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Note also the Infrared obstacle sensor located on the wall to prevent the gate from closing while a vehicle or other obstacle is in the way. Driveway gate openers can be the rollback (sliding) type that retracks a gate along the fence or wall on wheels or bearing, or the swing type that draws the gate open or closed on hinges.
The simplest sensor consists of a light beam aimed across the opening: when the beam is broken by an obstacle, the operator prevents the door from closing. Infrared and radar safety sensors are also commonly used. Other sensors such as resistance-sensing motors can be used to reverse the closing action of the door after an obstacle is encountered.
User manuals and user guides for most non-trivial PC and browser software applications are book-like documents with contents similar to the above list. They may be distributed either in print or electronically. Some documents have a more fluid structure with many internal links. The Google Earth User Guide [4] is an example of
Wired and wireless remote control was developed in the latter half of the 19th century to meet the need to control unmanned vehicles (for the most part military torpedoes). [5] These included a wired version by German engineer Werner von Siemens in 1870, and radio controlled ones by British engineer Ernest Wilson and C. J. Evans (1897) [ 6 ...
The electric overhead garage door opener was invented by C.G. Johnson in 1926 in Hartford City, Indiana. [1] Electric Garage Door openers did not become popular until Era Meter Company of Chicago offered one after World War II where the overhead garage door could be opened via a key pad located on a post at the end of the driveway or a switch inside the garage.
It has a wired connection to the ISP, at least one jack port for the LAN (usually four jacks), and an antenna for wireless users. The wireless gateway could support wireless 802.11b and 802.11g with speed up to 56 Mbit/s, 802.11n with speed up to 300Mps and recently the 802.11ac with speed up to 1200 Mbit/s. [3]
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A wireless system can be moved to a new property easily. An important wireless connection for security is between the control panel and the monitoring station. Wireless monitoring of the alarm system protects against a burglar cutting cables or from failures of an internet provider. This setup is commonly referred to as fully wireless.