Software for OCR'ing paper tape? (was: Question about Military

You do not need a sproket wheel, it fact it's better (for the tape) if you don't use one. What you need is the photodiode array. Paper tape is friendly in that firstly there is a 'clock' for each dta word, namely the sprocket track. The holes i nthat are smalelr, so you can use them (with a smaller apperture sensor) as a clock for the data holes. The second friendly feature is that the holes are on a 0.1" pitch in both direcitons, prototpying board makes a usful jig for making parts. Now, the pphotidode array could be a problem. If you can find some photodiodes (or phototranssitors, slower, but that may not be a major problem) which are small enough, you cna mount them on 0.1" centres. if not, then you can use a trick that was done in an early Elliot reader which seems to use OCP71 phototransitors, namely fibre optics. The Elliot has glass rods and light guides from the read head to the phototransistors. These days you could use plasic fibre optic cable and suitable snesors. That's the hard part. The other part is moving the tape. This is hard if you want to be able to stop on a character, but as I said last night, for archiving tapes this may not be a problem. In the latter case, a simple capstan and pinch roller will feed the tape past the head, or you coudl even just turn the takeup spool (with a week brake o nthe feed spool) if you don't mind the data rate changing. -tony