Ok guys I have hijacked this thread enough and this will be my last post HERE on the subject. I am getting close, I think, to a solution, but I may yet open another thread if I deem it necessary.
Now if anyone is still reading this you may be saying what the hell is this guy going on about?
Well the issue basically is that I and many others have printed out encoders for NBTV sync and used them quite successfully. I, being the good Samaritan I am
introduced Harry to what I believe to be a very simple and easily implemented sync detection system. Alas, for Harry it didn't work, and the fact it didn't work has cost both Harry and myself more time and effort than a more conventional detection system (a hole in the disk) would have taken.
*Nowhere* in the literature, that I am aware of, is there an explanation for why it doesn't work for Harry.
Eventually Graham came along and pointed out that he too had problems when printing out similar encoders (or whatever) on an INKJET printer. Well, I use a monochrome laser printer and so I said sorry I didn't realise it didn't work with with inkjet printers and we all carried on as if nothing had happened.
Well over time, and also because Harry has had to revert to cutting out encoders etc, which is really no easier than punching holes in the disk and having an opto fork etc. caused me to ponder more on the subject and I just couldn't believe that there could be a pigment/dye that just happened to absorb the entire visual spectrum, but annoyingly, didn't absorb the IR spectrum.
Now there are a number of ways to create black, one of them, indirectly explained by M3DVQ is to use a series of "notch" filters (CMY). This would explain the IR reflectivity because together the perform a perfect "notch" over the visible spectrum. The problem with that is, as is often the case, it is not so perfect in practice as it is in theory, and that method is rarely used (if at all) in an inkjet printer where black is produced by a separate ink cartridge (K).
So here we are, a laser printer toner (carbon black), and an inkjet ink/dye/pigment ALSO usually carbon black, behave differently - WTF? (I says to meself).
Now, I attach a graph which basically shows my quandary. It shows the response of carbon black and it indicates what I have previously been ranting about (ad nauseum to most I am sure). It is flat over the visible spectrum AND the IR spectrum.
Ok, ok, black ink may be made of something else I suppose (although why I can't guess as carbon black must be the cheapest ever thing to produce), AND - I said AND it *may* have that peculiar characteristic, quite unlike carbon black, of nulling out the visible spectrum but no part of it's adjacent spectrum - IR.
Well, to me that's quite a stretch, sorry.
The penny dropped with Harry's last post - his printer is a "photo" printer (Graham - can you confirm whether or not yours is also?).
I have found a reference that indicates that *digital photo printers* exhibit high IR reflectivity - why this is I am yet to determine but rest assured I will find out.
If I haven't already put you to sleep - you can go to bed now
PS: The image is from an article on the development of an IR absorbing ink - a topic unrelated to this matter - but the important thing is the carbon black ink graph.
PPS: I am also asserting that inkjet printers that *aren't* specifically photo printers should also work for these encoders.