Compression plays an important role in the ability to transmit digital television signals.
Consider High Definition Television (HDTV). If we wanted to transmit a HDTV signal without
any compression, we would need to transmit about 884 Mbits per second. In order to transmit
this much data, we would need a channel bandwidth of about 220 MHz. With data
compression, we need to transmit less than 20 Mbits per second, which, along with audio
information, can be accommodated in 6 MHz of transmission bandwidth. The amount of
bandwidth allocated to transmit analog television in the United States is 6 MHz.
As human activity has a greater and greater impact on our environment, there
is an ever-increasing need for more information about our environment, how it
functions, and what we are doing to it. Various space agencies from around the
world, including the European Space Agency (ESA), the National Aeronautics and
Space Agency (NASA), the Canadian Space Agency (CSA), and the Japanese Space
Agency (STA), are collaborating on a program to monitor global change that will
generate half a terabyte of data per day by the early part of the next century.
Compare this to the 130 terabytes of data currently stored at the EROS data
center in South Dakota, the largest archive for land mass data in the world.
As society becomes more complex, we need to be able to communicate ever more rapidly.
The 1980s saw tremendous growth in the use of the fax machine. This would not have been
possible without compression technologies that permit speedy transmission. Without
compression, it would take 24 hours to send one ISO-page document.
Compression is now very much a part of everyday life. For example, when we use
computers, we are probably using a variety of products that make use of compression.
Most modems now have compression capabilities that allow us to transmit data many
times faster than otherwise possible. File compression utilities that permit us
to store more on our disks are now commonplace, and if we downloaded an image from
a bulletin board, odds are the image was in a compressed format.