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That shit was legend. I mean, we were still using BBSs and phone phreaking. Here's this ubernerd that BROKE INTO the television signal. We bow before you, kinky ubernerd.
The power required to do it is impressive to say the least.
I guess the other option would be that the signal was created with very close proximity to the broadcast tower requiring much less power, but they probably had a limited area to search.
To me it almost reads like this was a "we technically can, let's test it out!" And it worked.
It would require as much, or more, power to drown out a TV broadcast signal at the source. I believe many of the old towers were 200kW-1000kW so it would have taken one hell of a pirate signal if interfering close to the main source. However, RF follows the same principle as light using the inverse square law so the further you get from the primary transmitter, the signal quickly becomes exponentially weaker for any receiver.
If you had a TV transmitter on a small hill that is a fair distance away from the target audience, like many were, splitting the distance with a directional antenna wouldn't require nearly as much power from the pirate signal to overtake the original transmission.
If I wanted, I could interfere with ham radio signals with as little as a watt of power (in my immediate local area) even though people might be communicating through a ham radio repeater that transmits at a couple of thousand watts that is many miles away. (It's actually a permitted emergency technique to "break into" active conversations. Actually, other ham radio operators are familiar with what interference sounds like, even for signals that can't fully overtake a transmission. It's customary to stop the conversation if detected and wait for the "break".)
Yeah, growing up there were people with illegal high power CB radios that would bleed into the TV signals near me. And I don't even know if they're close to the same band.
Doesn't need to be in the same band due to harmonics and power. If you keep splitting the 11m band (CB) into "fractional-frequencies", you are going to get a cross-over somehow, especially if the fundamental is at super-high power.
Using a piano as an example, if you play a C2 at 62.41Hz it still expresses harmonics at C3 (130.81Hz), G3 (196.22Hz) and C4 (261.63Hz) and at least in theory, to infinity and beyond! Each harmonic away from the fundamental will be expressed in decreasing levels of power. (It's like 1/3 power per, I think. The proper math is out there though.)