TI-H: Data Transfer Idea


[Prev][Next][Index][Thread]

TI-H: Data Transfer Idea



TI>    Ok, all this time, we've been trying to use both lines for data
TI>transfer.  If we use both, then we are esentially using sterio sound, but
TI>modems work great on mono.  Sure if you are hard wired to gether, then the
TI>connection goes red-red, and white-white.  But in a radio transmitter, we
TI>can transmit on one, and recieve on the other.  Or we could just use one
TI>line and employ a protocol that modems use to transfer.  This is where you
TI>guys come in...  The most efficient transfer protocol is by far Xmodem CRC,
TI>right (assume that were leaving out isnd and T3 lines).  Does somebody know
TI>EXACTLY how it takes care of errors?  Don't reply saying that it has
TI>something to do with a checksum bit, I know that.  Then you could leave you
TI>calc on waiting for a signal, and when you get a request, you could play a
TI>game, or chat, or whatever.


       Okay.. First of all, modems are BI-directional.. They send AND
recieve at the same time over the same line.
       As for fastest protocols, Xmodem CRC is one of the slowest (next
to some old KERMIT implememntations).  It has a SMALL packet size, it is
not streaming, and has no compression routines.. Also the CRC it uses is
fairly weak.  As for the CRC, it hashes the data to comes out with a
checksum ( I can get the exact algorithm if necessary).  I would suggest
something closer to Y-Modem:  A good compromise between data speed and
error checking.  A streaming protocl like Zmodem isn't as good in such a
intermittant environment as an IR link.


Zarquon
Sysop of Imperial Realm (410) 799-8616
<a href="http://members.tripod.com/~Zarquon/">http://members.tripod.com/~Zarquon/</a>                        zarquon@gaianet.net