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Understanding the Connection Technology:
Connecting to other campus locations is not as simple as it may seem. We may feel when in the ITV
classroom that there is a one piece wire connecting us to other sites, however this is simply not the
case. Understanding how connections are made to other sites will also help us to understand some types
of failures and why they may occur. Understanding how connections are made will also help us to be more
tolerant during the initial connection and more appreciative of system which is working correctly.
the Basics:
Audio and video must be converted to a digital format for transmission; this is done with a computer
called a codec. That word simply means CO for COder and DEC for DECoder. Each site much has such a
device, or it is directed to a central location where the coding or decoding process occurs. Here at
Minnesota State, our codecs are located at South Central Technical College; this is where the
headquarters for the COMET service region is located. (There are six major service regions in the State
of Minnesota) Once converted to the digital format; the signal travels through fiber optic transmission lines to various locations with stops along the way. The path is not a direct point to point path.
Example:
If we choose to have a class in Hibbing, we cannot go directly to Hibbing via a special one piece
direct line to that area. The normal signal path would be more like this:
- MSU would send its signal to COMET at SCTC. They in turn would direct the signal to the Hickory
Tech Telephone Company. At that location the signal would arrive at a digital router. The router is an
electronic mixer/switching device which allows the signal to be routed to different locations, one
location selected would be back to MSU, so we can monitor our signal, and another signal of the same
source would go back to SCTC for their monitoring of our program. From the router, which is controlled
by COMET by computers at SCTC, the next location for travel is selected. If the signal was not going to
Hibbing, we would probably select sending it to Owatonna, the next router location. From there, the
signal could be sent to Rochester where there is another router for points further to the East, North,
and South.
Since we have selected sending the signal to Hibbing, we would direct the signal to St Paul, and
utilize one of two major video distribution centers located in the metro area, one is Onvoy, and one is
Interteck. These providers then would send the signal off to points within the metro area or well
outside of our region. The signal most likely would have one or two more routers to go through before
reaching its final destination of Hibbing. The example just given would be actually done in reverse for
the signal coming back from Hibbing. This is done simultaneously. The above gives a simple description
of a complex system. Remember our example only shows one site we connected with. Imagine what
complexity would result if we contacted four sites at the same time. Each time additional sites are
connected, we multiply or chances for technical difficulties. Although problems are not the norm,
multiple site connection will add to the connection complexity and therefore increase the odds of
technical difficulties. We always recommend a maximum of three sites for a worry free learning
experience. A new era of electronic video communication is fast approaching; soon we will be using the
Internet for Interactive television systems. Just a few years ago this was considered an impossibility,
today it is a reality. Modern day communication... all made possible by the ever changing world of
electronics.
