V.90 Known Issues
With BayDSP V.90 Modems

The BayDSP V.90 digital modem technology has been extensively tested with all popular V.90, X2, K56flex, and V.34 client modems.  The V.90 implementation is subject to some interpretation differences during the coding process by the variety of organizations that are releasing products for the client modem user.

Consequently, incompatibilities exist between the central site V.90 modem releases and certain client modem implementations, as follows: 

  • V.FC (Fast Class) modems are not supported by BayDSP digital modems.
  • V.32terbo operation (a 19.2Kb/s modem of operation similar to V.FC) may operate with some modems but is not supported in this release.
  • The version of BayDSP Digital Modem code included in this release supports speeds from 2400 (V.22bis) up through 33.6 Kb/s (V.34 with extended rates) up to V.90 56Kb/s.
  • The following modems are known to exhibit connectin reliability problems with the BayDSP Digital Modems:
    • AT&T Paradyne Comsphere 3810
    • AT&T Paradyne 3740-A1-201
    • Motorola Codex 3261
    • UDS V.3225
    • Racal V.34 models 3292 and 3264
    Ongoing client modem flash upgrades resolve many of these issues; however, the following chipsets/client modems have been found to exhibit limited compatibility with the BayDSP V.90 modem implementation.
    ESS x2 Chipset
    The ESS x2 chipset previously had a bug that affected transmission and detection of the x2 signature with the handshake.  Consequently, connections with the BayDSP modem would fall back to V.34 modem.  ESS has since fixed the x2 signature requirements; however, not all manufacturers that use the ESS chipset have incorportated these changes in their client modem releases.  One client modem in this category is the Netcom ESS56K.
    Cirrus Logic Chipset
    The Cirrus Logic chipset previously had a bug affecting x2 training sequence timings.  Consequently, connections with the BayDSP modem would fall back to the V.34 modem.  Cirrus Logic has since fixed this problem; however, not all manufacturers that use the Cirrus Logic chipset may have incorporated these changes in their client modem relesases.  Client modem manufacturers who use the Cirrus Logic chipset in some of their modems models are Digicom, GVC, Atlas and Zoltrix.
    Racal ALM 3239
    The Racal ALM 3239 modem does not connect with the BayDSP modem.  During the handshake sequence, INFO sequences are incompatible between the 3239 and the BayDSP digital modem.  Consequently, the handshake sequence does not progress to data modem and the modems disconnect the line.
  • It is very important that the client modem user check the client modem manufacturer's Web site for any upgrades that may be available.  A good site for links to client modem manufacturers is http://modems.rosenet.net/ . or check out ECSIS.NET Modem Information Pages .


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Electronic Communication Systems
640-I Highway 51 ByPass East
Dyersburg, TN 38024
Phone: (901) 285-5936 Fax: (901) 285-2240