Skybuck's Universal Code 2

Jun 06, 2006 2 Replies

Hello,



Instead of using a binary system a tertiary system could be used for Skybuck's Universal Code.



For example:


-5 voltage would mean 0


0 voltage would mean 1


5 voltage would mean 2



The data is still in binairy. (0,1)



However a marker can now be added to the information stream, indicating the end of the field.



For example:


01110110110110112100110101001120110110110112112010101012

So this would make the encoding more efficient and still flexible.



Bye, Skybuck.


In particular systems, yes, this could be efficient and flexible (and it's not altogether unlike the sync pulses used in NTSC and PAL video). Strictly from the communications theory point of view, though, you've just added 58.5% overhead to your channel (3 states is 1.585 bits) to signal what I'm going to assume is (statistically) a relatively uncommon event (framing); there are more efficient schemes available, even something as simple as a 9th bit per byte (12.5% overhead).

You do see a lot of ICs that use this sort of tertiary encoding for, e.g., configuration bins: Low means one thing, open means another, and high means a third. Internally they're presumably using (roughly) 0v, 2.5V (bias), and 5v.

---Joel

Skybuck Flying skrev:

USB kinda does that, data is normally differential but "single ended zero" i.e. both data lines low are used for EOP and RESET signalling

-Lasse

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