Walter Banks bytecraft.com> writes: > I wrote a Morse decode for demonstration for a friend for a ham > convention in the early 70's on a PDP8/e. It was designed to be > speed tracking and worked quite well on hand sent code. The > algorithm I used was to base the starting speed on the the last > received character and analyse the speed of the received > character to update the received speed. I remember two > things debugging the code. For a while small noise pulses > were interpreted as dots and were hard (at the time) to filter > out in software. the second thing that should not have been > a surprise was the dit / dah ratio in hand sent code was far > from close and we did some tracking on the ratio as well. Yes I know about timing issues. Inspecting my own ham (pun!) fist (re-pun!) output on a waterfall display does not show anything promising wrt. to easy decoding by machine. I was thinking along the lines of 'listening' for a while, measuring timings, and then setting a set of discrimination levels and starting decoding, while continuing to track average timings and tweaking the discrimination levels to follow. I have no intention to base this on standard timings at all. As a rough guide from my waterfall 'analysis' I'd say anything from 50% to 200% dot is a valid dot, ditto symbol-symbol breaks, dashes from 220% to 500% dot and character-character gaps the same. > It was a weekend project I wrote the code and Roger Grant > created a interface to a receiver. It was a hit around the ham > convention. One of the attendees was an old railway telegraph > operator whose code on a straight key might as well have been > machine generated. The console on this old computer was > a teletype and his code might as well have been typed from > a file. > The code is somewhere in the historical records department > at Byte Craft then all I need is to find a paper reader that > has been run in the last 20 years. I think that that could be helped. There is a way to transfer paper tapes into computers using a scanner and a black sheet of paper as backing. The computer assembles the parts by itself and decodes the info. Somebody wrote software for that (*nix probably). There is also the same for punched cards I think. Nowadays this could work with a webcam (on *nix the scanner interface permits 'scanning' from *any* video source - that includes webcams, video cards and screenshots by the way). thnaks for posting, Peter P. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist