Two TV Programs on One Channel

New approach to TV broadcastirg techniques may double channel facilities.

A NEW television broadcasting technique that might provide an additional program on each of the TV channels now in use was announced by Blonder-Tongue Laboratories, Inc. of Newark, N. J. The company has recently presented its plan to the FCC.

The new method, called Bi-Tran, requires modification of present TV, station equipment to enable two programs to be transmitted simultaneously on the same channel. Channel 2, for example, could be designated 2A and 2B; channel 4 could be designated 4, 4A and 4B, etc. The doubling of facilities is accomplished by a special multiplexing process that allows two different pictures to be produced within the same channel width. A series of positive or negative signals enable picture A or picture B to be visible on the TV screen while the other picture is canceled.

The Bi-Tran system may also be applied to pay-TV programming. In this case the primary free program would be received normally by the TV receiver. The alternate program, however, would only become visible and audible by the addition of coded electronic signals.

These coding and decoding signals would be carried via existing telephone wires in the home, Without disturbing regular telephone service. The viewer could switch to the B portion of the channel, thereby selecting a pay-TV program. The decoding signals would be brought to the set and at the same time information would be transmitted back to the telephone central office, indicating the program selected.

Radio and Television News/December 1957