Vizualogic Headrest and visor system.

[Tiger Bait]

Phil, the FM modulator phyically connects in line to your antenna input on the back of the radio. You must take the dash apart to get to that input wire. The FM modulator does not broadcast "over the air" to that frequency on the radio. If so other cars nearby would get your dvd soundtrack instead of the station they were listening to on their radio. The FM modulators are set in the low band range (generally some variant off of 88Mhz) where few stations broadcast. There are some in that range that are sometimes used. SO instead of inadvertently sending out on that frequency, a direct input feed is selected. There is a filter that blocks out all other frequencies when it is switched in line. That is what causes some interference to other frequencis on the radio when installed even if switched off.