Marc email (remove spam text)
> Re the replies to my enquiry about Manchester Code. Thank you, it's
> been very clear and informative, and I see how it works. AND it looks
> like (after more experimentation) that I'm going to have to attack it,
> as I have to send code over a radio link, and the radio link prefers
> close to fixed length hi's and lo's. Not only that, the instructions
> say Manchester is preferable! (A rarity - I've read the instructions!)
I haven't followed the thread, but I assume you consider Manchester
because of it not having much DC component, and the self-clocking
If so, you might be better off with convolutional coding. That can
provide you with selfclocking data and little DC component (though
not zero), too. But additional to that it gains you forward error
correction of burst errors.
Convolution coding is quite simple and documented on the web (try
altavista). Just remember to send the parity bits inverted for
self-clocking data. I have done implementations that work on streams,
so the RAM requirements are very low and don't limit the block size.
Actually I think it's as simple to implement as Manchester, but
more desirable for radio links.
See also: www.piclist.com/techref/index.htm?key=manchester+code
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