WiFi
From IPTrains
In a Nutshell
The DVRAC is a very small standalone single board computer with a built in web server that can output streaming video via TCP/IP from attached web cams. The DVRAC connects to the outside world via a WiFi dongle. There is a power supply with a floating battery that charges off track power with a low drop high efficiency regulator that provides power for all of the above. It is quite nifty ;-) If you are not familiar with WiFi (especially WiFI used outdoors) then keep reading.
The big picture
WiFi is a term used to describe IEEEs 802.11a/b/g/n protocols, normally when these protocols are used as a Wireless Local Area Network (WLAN). WLANs and the equipment used to support them have become common place in the past few years and equipment costs have dropped dramatically. IPTrains takes advantage of the low cost and high reliability of WLANs (remember, we have an error detecting/error correcting protocol 'under the hood' in a WLAN) to provide reliable transport from engines and other rolling stock back to a segment of your home network. Once configured WLANs 'just work' there is little or no management required once the network is set up.
We use WiFi for a number of things but our most basic use of WLANs is to provide a path for the transport of digital streaming video from unit in the the cab of an engine (referred to as an access point client) to an access point (AP) and on to your computer. The same connection also provides a back channel that is used to control and monitor the video server and camera(s).
A good outdoor AP can cover an area many hundreds of square feet and host multiple clients, located in engines, cabooses, or in track side structures. In a nutshell, a WiFi based WLAN can tie your layout to your computer, with only one cable required, the one from the AP to your house network. The rest is, err, wireless.
Learn more about our access points at Selecting an outdoor AP
Under the Hood
In a bit more detail, here is what an IPTrains trainvision equipped unit looks like under the hood. The heart of the unit is the Single Board Computer (SBC) that is connected via USB to all the on board video peripherals. A basic setup includes one camera and one WiFi dongle. With an external USB hub it is possible to add more peripherals including a second USB camera and a memory stick. The SBC runs a web server that you connect to across the WiFi link with any standard browser that supports Java or ActiveX to view video from the engine and manage the cameras and other peripherals. We also supply a standalone program (PC only) that permits multiple windows, full screen viewing, recording and much more.
Trainvision uses 802.11b/g as a communications method, standard WiFi. While it is possible to use Trainvision with any standard access point we take advantage of certain specialized features of the protocol not found in all consumer grade access points in order to deliver smooth high frame rate streaming video. We do this by utilizing Ubquiti access points which have unusually high receiver sensitivity, tunable output power and certain other features that make the a very good match for our product. Learn more about our access points at Selecting an outdoor AP.
The power for the on board computer, radio and camera(s) is provided by a custom battery backed up power supply that is engineered to provide the high degree of voltage stability required to reliably run the computer and radio, learn more at On board video power
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