Digital television tuning with the virtual channel

Since the inception of television in the late 1920s, the consumer has selected the channel they want to watch by selecting a number on the television, such as channels 2-13 for VHF and channels 14-69 for UHF. With the advent of cable television, this has changed a bit with channel options from 2 to about 99. The average consumer has become very comfortable with this system.

When the industry began to develop digital television and compression, they had to develop a new system. The standard that was developed was established by the Advanced Television Standards Committee (ATSC).

Because compressed digital television can now transmit more than one program on a television channel, it was decided to assign the program a main channel number and a minor channel number separated by a period (.).

For example, a digital program that airs on VHF channel 6 would be called 6.1. If a second or third program were being broadcast, they would be called 6.2 or 6.3. If they were transmitted on a UHF channel they would be 45.1, 45.3 and 45.7. To make things even more confusing, the FCC ordered television stations that air on channels 2-6 to move to another frequency. This often resulted in a channel that was known for 50 years as Channel 3 to be broadcast on UHF channel 26 but called 3.1 … Very confusing indeed.

When these shows were picked up by the local cable company, it tended to be even more confusing until the virtual channel numbering system was introduced. This is because in a cable system, there can be up to 10 or 12 programs on a channel and the channel may be irrelevant to the program number or the traditional channel number.

With the introduction of a virtual channel number system, a number is assigned to a program from where the channel is actually transported in the system. This means that the number displayed on the TV or cable box will be between 2 and 999 and will not have duplicates or minor numbers like a.1 or 2. The system operator can assign any virtual number.

For example, when we watch channel 3 mentioned above, it is broadcast by the station on UHF channel 26. The cable company may put it on channel 57.3, but has set it to virtual channel number 3. This way, when you select channel 3 on your cable box, the old channel 3 you watched for years is what you get.