On my usual hunt for a 33600 connect, Ludi Desouza and I ran a few more
tests tonight to see if we could manage a 33600 connection between our
modems (his being an M34F and mine a Courier). As usual, 31200 bps was the
most we could manage. An initial connect of 28800 (my USR calling his M34F)
happily shifted from 28800 to to 31200 once Ludi retrained. We managed a
3429/3429 symbol rate on the condition that my Courier placed the call.

I won't bother posting the complete link statisticss for that call, but
when I checked the stats both times, the carrier was 31200/31200, the
symbol rate was 3429/3429 and the preemphasis was 6/4. At one stage of the
call, the recv/xmit level was 27/16, while another time it had shifted to
47/16. There were still too many block errors for my liking (159); our call
lasted 21 minutes and 28 seconds, and the only data transferred were our
brief chats and link stats.

Both of us came to the conclusion that there is probably very little I can
do about the supposed problem. It's either a modem/SDL related problem or a
line and exchange related issue (at either end). From listening to David
Drummond (who AFAIK is running the same SDL as I am) and Russell Brooks,
both Courier owners, it's evident that 33600 connects are possible with the
V.Everything. Simple: it can't be a modem/SDL problem.

Ludi mentioned something about a post by Arthur which stated that there was
a lack of suitable bandwith for V.34 modems on AXE (or was it S12?)
exchanges.
(Please elaborate or correct me, Arthur.) I will be ringing Telstra
tomorrow (wish me luck) to find out what kind of exchange my line is
connected to.

As I stated before in another message, I'm fairly close to my exchange, so
it theoretically shouldn't be too hard to manage 33600 connects. Ludi is
around about 3kms away from his exchange, but he told me that he managed a
few 33600 connects on calls he made prior to ringing me.

Anyway, Ludi gave me a few numbers and suggested I call them and see what
kind of recv/xmit levels and connect speeds. One number was that of Cat
Attack BBS, and the other two belonged to a Sydney ISP called Triode. My
call to the BBS resulted in a boring 31200 bps connect. However, when I
called Triode, I was pleasantly surprised:

atdt93890823
CONNECT 33600/ARQ/V34/LAPM/V42BIS

[Welcome screen and login prompt omitted.]

OK
ati6i11
USRobotics Courier HST Dual Standard V.34+ Fax Link Diagnostics...

[Some stats omitted; no block errors, link timeouts or link naks.]

Data Compression       V42BIS 2048/32
Equalization           Long
Fallback               Enabled
Protocol               LAPM 244/6
Speed                  33600/33600
Current Call           00:00:21

Online
USRobotics Courier HST Dual Standard V.34+ Fax Link Diagnostics...

Modulation               V.34+
Carrier Freq (Hz)        1959/1959
Symbol Rate              3429/3429
Trellis Code             64S-4D/16S-4D
Nonlinear Encoding       ON/ON
Precoding                ON/ON
Shaping                  OFF/ON
Preemphasis (-dB)        6/6
Recv/Xmit Level (-dB)    23/16
Roundtrip Delay (msec)   4

OK
ato
CONNECT 33600/ARQ/V34/LAPM/V42BIS

After all this time, experimentation and frustration, what a great
surprise! Well, there is the proof: 33600 connects ARE in fact possible on
this line.

As I type, there's a user online, but as soon as he logs off, I'll dial
Triode again (as well as another number with the same modem) to see whether
or not I achieve a 33600 connect.

Triode's welcome screen mentioned that a NetComm 288 was the modem I
connected to. None of the other 33.6k modems I've connected to (Couriers,
NetComm M34Fs, Paul's Spirit Dragon, and the countless variety of modems my
users have) have done any better than 31200. Perhaps the copper between
Triode and its nearest exchange, combined with the relatively short
distance between here and my own local exchange, was what made a 33600
connect possible.

I'll post the (relevant) link stats as soon as I've dialled Triode again.

Comments from anyone?

John (japp{at}mpx.com.au)

--- FMail/386 1.22+