29-04-2022, 11:45 AM
To give more detail, the ignition current waveform has a finite risetime, so its energy diminishes with frequency above roughly 50 Megahertz. On the other hand, the effectiveness of the plug leads as a radiating antenna diminishes at lower frequencies, where they become only a small fraction of a wavelength. The net result of these two opposing factors is that the largest radiation of energy is in the low VHF range, say 30 to 100 Megahertz, which is right where the old Band 1 TV was placed.
Adding resistance to the plug leads increases the risetime, which causes the energy to diminish more rapidly with frequency.
Reception quality with digital radio and TV systems tends not to degrade progressively with weakening signals, instead reception is either perfect or poor with a fairly rapid transition from one to the other. Susceptibility to impulse interference follows a similar pattern, slight interference is handled fairly well, but if the interference is too strong everything goes to pieces.
Adding resistance to the plug leads increases the risetime, which causes the energy to diminish more rapidly with frequency.
Reception quality with digital radio and TV systems tends not to degrade progressively with weakening signals, instead reception is either perfect or poor with a fairly rapid transition from one to the other. Susceptibility to impulse interference follows a similar pattern, slight interference is handled fairly well, but if the interference is too strong everything goes to pieces.