Modern Digital Cable

With deregulation of the telecommunications industry in the 90’s, cable providers could use their hybrid fiber-optic coaxial networks that they constructed to deliver additional services.   The capabilities of the new topology opened the door to digital video services, multi-channel video, video on demand, two-way voice, internet access and high definition television (HDTV).

Digital information has some attractive properties, the biggest of which is that the information can be compressed.  By compressing the information you make it smaller, so you can transmit more information across the same physical wire.  So network broadcasters and cable providers began converting analog broadcasts into digital streams, compressing the stream using the MPEG-2 standard, then broadcasting that to their subscribers.

Space and transmission limitations are significant obstacles to delivering the superior picture of HDTV. Moving to a digital transmission scheme and using digital compression, now allowed cable TV providers to carry as many as 12 channels in the bandwidth occupied by one analog channel. With the use of compression, bandwidth thirsty HDTV could now be transmitted within the 6-MHz channel allocation. Digital cable allows for transmission of 480P SDTV, as well as 720P, 1080i and eventually 1080P HDTV. Currently 1080i is the highest resolution signal that is being delivered by digital cable.

How Cable Gets to Your House

The original setup first used by John Walson, used a ground based antenna placed in a high location to pickup a distant broadcast from another ground based antenna, and then distributed the signal through a coaxial network.  With all major broadcast networks using satellite to distribute their signal, the cable TV signal now takes a slightly different route to get to you.

Television networks now transmit their broadcasts up to a satellite, which rebroadcasts the signal; cable TV companies now use satellite dishes instead of antennas to receive the broadcast.  Cable TV providers then bundle it, and transmit it across their hybrid fiber-coaxial (HFC) networks, delivering digital cable and 1080i HDTV to your house.