The frequencies that will be used for digital tv transmission over the air are the VHF high band (Ch 7 thru 13) and UHF (ch 14-69). The low band VHF will be allocated to telecom use, which that part of the spectrum has already been auctioned off.



In order for sub-carriers to work, the receiver must be able to receive them, ie..must have the circutry to be able to tune to those subcarriers.



The digital tv standards that comprise the system being used only has so much it can carry, as well as the receivers being built to only decode what the standards are.



For example, lets say xyz covert co. wants to transmit some extra sub signal over Fox network. Well first they have to find an empty slot or data chunk that can squeeze into the data stream, and insert that without altering the decoding at the individual tv stations re-transmitting the network on their channels, plus not mess up people's digital tv decoding circutry at the same time. Plus they would have to rely on manufacturers of tv receivers putting in the extra capacity to decode the extra data chunks (bits). Since the adopted standard for digital tv transmission cant be changed this late in the game, xyz covert co. is SOL simply because there is no way to add any extra sub channels to an already filled allotment of bandwidth usage and the limit built into each receiver.



What could be done is lets say Fox there isnt transmitting 5.1 surround during a news program or other program. At that point, since receivers can decode 5.1, and they are only using 2 or 1 audio channels at that time, the remaining 4 could be used for something else.



For the video, putting in 1 frame per every 30 or 60 is one way to do subliminal messaging. 1 frame passing every 30 frames per second is like seeing something in the wink of an eye. You probably wont see it but your mind will.



Now this kind of stuff can also be done through the analog world. But if there is any xyz covert co. out there wanting to do this, they have already been doing it and the digital switch over come Feb 17th is irrelavent because it is already happening.



But since these kinds of things can be measured, analog or digital, and it only takes a simply oscilliscope to measure it, xyz covert co. would still have a very difficult time masknig their dirty deed from the ones out in the general public with the ability to detect it and record it and then bring it to the public's notice.



I really do not think that there is anything to worry about, particularly the Feb 17th switch over date. All it really amounts to is that on that day, the old analog broadcast signals for television will simply be turned off for good.







Cheers!!!!