From: dbd@urartu.sdpa.org (David Davidian)
Subject: Re: modem for Russia 
Organization: S.D.P.A. Center for Regional Studies
Date: Thu, 31 Dec 1992 16:20:39 GMT

In article <92362.143645DLVGC@CUNYVM.BITNET> DLVGC@CUNYVM.BITNET (Dimitri Vulis) writes:
>In article <BzwH3A.JAn@world.std.com>, ralex@world.std.com (Aleksey Y Romanov)
>says:
>>A friend of mine would like to buy a modem to use it in Russia.
>>What is a reasonable speed he should look for ?
>>Are hays modems popular in Russia ?
>>Can fax modem work over Russian telphone lines ?
>Don't get HAYES brand modem, unless you have lots of money to blow.
>Hayes is an excellent choice for U.S. because of good support and warranty
>but you're not going to get them in xSU anyway, so go for a Hayes compatible
>(actually, it's hard to find a modem that's not Hayes compatible these
>days :).  Because Russian phone lines are so dirty, it's a good idea
>to get a modem with some sort of error correction/detection: MNP 5 and/or
>CCITT. (Note that the modem on the other end must support it too).
>I've heard particularly good reports about ZyXEL modems' performance
>in the USSR.  For about $320 you get an up to 14.4K modem and fax,
>all sorts of protocols, and unlike Hayes, you can raise the transmit
>level (the volume at which the modem shouts into the phone line) ---
>very helpful there. :)
>
>But if you're going to communicate, say, only within Moscow city limits,
>then a $30 2400 bps modem with no error correction may do as well.
>
>Dimitri
>Disclaimer: CUNY/UCC and modems are two things incompatible :)

There are a multitude of issues when dealing with modem-based communications
in the X-USSR. The first is that the cross-talk at the local switch is
horrible, causing all sorts of integrety problems. The main problem is the
frequency of the busy tone is at (or really near) the V.22bis tones. This is
a real problem during crosstalk. Another major problem is, as was stated above,
the transmit power which, if not programmable, has to be increased several
db up to at least -7db (if not mistaken) which a US Robotics uses, and which
other modems can be modified for. And further, signal bandwidth falls off 
sharply with a bad connection (the norm, rather than the exception), resulting
in an effective throughput of nearly 200 bps with a interface speed of 1200 
(avoid a 2400 connection if possible) with MNP Level 5. Also note that 
increasing the xmit power will really eat into other conversations at high 
crosstalk times, which is why there are regulations in the US regarding maximum
xmit power. 

I am reporting this after discussions with ARMINCO (connected to RELCOM) in
Yerevan, Armenia and SPRINT Moscow (who always pick the "best" lines to
demonstrate "reliable 1200 bps")!

This may sound rather barbaric, but an old 1200 bps modem with no error
correction and Z-Modem software with MNP Level 5 is an effective combination!




-- 
David Davidian <dbd@urartu.sdpa.org> |"The massacres? Oh well! They merely  
S.D.P.A. Center for Regional Studies | amuse me!"  -Talaat Pasha, architect of 
P.O. Box 382761                      | Turkish the genocide of Armenian people. 
Cambridge, MA 02238                  | (Four Years Beneath the Crescent, p 208) 
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