>I was wondering whether or not anyone would be kind enough to
>translate into english the following modem jargon for me.
>Technical-ish replies will be understood.
>No doubt this isn't the first time these questions have been posed,
>but I can't find anything in the group that covers them.
I'll give it a shot...
Quote:>1) "long space disconnect"
I believe that a "long space" is also known as a 'BREAK' signal. Essentially,
it's a signal that can't be confused for any legal data value on an
asynchronous serial connection (i.e. one with start and stop bits). I also
believe that some modems can be configured to hang up on receiving it.
Quote:>2) "Guard Tone" and what purpose does it serve?
It's just an extra tone played on the phone line so that telecom equipment
knows that there's a data connection under way and won't be tempted to hang
Quote:>3) "Pulse make/break ratio" what purpose does it serve?
When you pulse dial, you're shorting (well, nearly) the two telephone wires
together ('making' the loop) and un-shorting them ('breaking' the loop) in
order to make a pulse. The phone system expects a certain ratio of time
shorted and time not shorted, as well as a certain dial speed (approx. 10
pulses per second, though 20 works on some equipment). The European and North
American phone systems expect a slightly different ratio, though I'd be
surprised if their tolerances weren't enough to overlook an incorrect setting.
Quote:>4) "Auto-reliable fallback"
The modem will try to establish an error-correcting (LAP-M or MNP) link, but
will stay connected if it doesn't work out. 'Reliable' mode will hang up even
a perfectly good connection if the error correction negotiation doesn't
succeed, e.g. the modem on the other end doesn't support error correction...
or its an RPI modem running without the WinRPI driver. <grin>
Quote:>5) "disconnect buffer delay"
When an error-correcting link is established, the modem buffers a fair amount
of data internally. This causes a problem when, for instance, a BBS sends you
a logout screen and then hangs up; the data that the BBS sent may not have
been transmitted by the time it hangs up, so the caller gets half a screen
ending with the words "NO CARRIER", usually in some odd colour. <grin> By
forcing a delay before disconnecting, the modem increases the chances that the
data will actually be sent before it hangs up.
Quote:>6) "Automatic rate adaption"
The dynamic adjustment of the communications speed to compensate for changing
line conditions as evidenced by data errors.
Quote:>7) "Automatic rate adaption"-low BER
>8) "Automatic rate adaption"-medium BER
>9) "Automatic rate adaption"-high BER
BER = Bit Error Rate (formally; it may be used to represent the Block Error
Rate, though some manufacturers - including USRobotics - use the more formal
symbol "BLER" for that). These settings probably allow you to tell the modem
how tolerant you want it to be of errors before it changes the data transfer
Quote:>10) "LAPM with MNP fallback"
>11) "LAPM with MNP normal fallback"
Can I presume that you know that the Link Access Protocol for Modems and
Microcom Networking Protocol are?
#10: If LAP-M negotiation fails, try MNP. If that fails, hang up. (*)
#11: If LAP-M negotiation fails, try MNP. If that fails, stay connected with
no error correction protocol.
(*) Some documentation may speak of an MNP fallback _without_ implying that
the alternative is to hang up; i.e. if #11 is not an explicitly mentioned
alternative, you should assume that the words beside your #10 above mean what
I said about #11.
Quote:>Thanks, in advance, for any help which may be forthcoming.
In retrospect, I think that I got most of them near-right. I got better as I
could see the end looming in the distance.
Geoffrey Welsh, Developer, InSystems Technologies Inc.
TYPING IN ALL CAPS IS GROUNDS FOR IMMEDIATE DISMISSAL.