I have been doing a lot of research in recent months on television
signals in terms of both radio frequency and video after demodulation. A lot
of facinating components make up a color television signal. If the signal has
been scrambled to prevent unauthorized reception, it is even more intriguing.
I have examined the signals of two cable companies in West Virginia who
employ scrambling techniques and find that no actual scrambling is being done.
That is, the signals are not "mixed up" in any way. All that has been done is
the horizontal sync and blanking pulses have been suppressed about 6 db below
the peak video level. Except for that modification all the signal components
are intact and in proper sequence. The scrambling occurs inside the TV
receiver because of its inability to locate and lock on to the horizontal sync
pulses.
If you are interested in this kind of experimenting, an excellent series
of articles began in the June 1986 issue of "Radio Electronics" and is
continuing as of this date (August 1986). It may also be of value to know
where the signals you want to work on are located in terms of frequency. If
you have ever wondered where those mid band and super band cable channels are
located, the following table will be enlightening.
