On Oct 16, 1996 at 16:54 hrs, Ray Mcconnell of 3:632/309 wrote to John Clarke:

Hello Ray,

RM>> In actual fact, the 28800 number is in bits so it should be divided 
RM>> by 8 to make it bytes.

JC>> Wrong.  Divide by 10 - each byte (8 bits) is sent out wrapped inside 
JC>> 1 start  and 1 stop bit making 10 bits all up.  Error correction 
JC>> modems usually can achieve higher thoughput than the BPS/10 
JC>> since they strip off the start and stop bits but lose 
JC>> throughput in the error correction/detection process 
JC>> averaging out at about 115% to 116% of the BBS rate.

 RM> Well, 28800 divided by 8 makes 3600 cps, so why when it's divided by 
 RM> 10 it only makes 2880 cps, and why is it that you're supposed to get 
 RM> 3300 cps? So many lines are pathetic you don't even get 3300 cps, and 
 RM> Telstra expect to be able to charge people by time online when it's 
 RM> their fault that we spend so much time online.

Er, did you READ what I wrote?   Start with a 28800/Lap-m connect.  You
send across the port to the modem data comprising 1 start bit, 8 data bits
and 1 stop bit - 10 bits in all for each byte of data.  The modem strips
off the start and stop bits which should yield a transfer rate of
(28800/10)*10/8 or 1.25 x 2880.  The modem uses some bits for its error
detection and control which effectivel reduces the multiplier from 1.25 x
down to 1.15 x.  The final transfer rate (under good conditions) will be
1.15 x 2880 = 3312 cps.

 RM> So why am I only getting 2700-3000 cps recently? Error Correction is 
 RM> enabled and it always connects at 28800.

Your modem has speed shifted to the next lower speed - 26400bps.

Regards ... John
@EOT:

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