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Modem Testing Standards

Floyd Kling 

(3/15/07)


 

There are standards for testing modem performance

 


 

I will say from the start, I am not really a fan of these tests unless there is a valid reason you feel they are necessary.  Most analoge modems today are in chip form, pre-designed and are so integrated there is little or almost nothing you can do to improve the performance from the IC.  At best, you must follow good layout guidelines and pay VERY CLOSE ATTENTION TO GOOD GROUNDING AND A QUIET VCC. 

 

Today, most modems are made from highly integrated modem chipsets.  They are like a microprocessor, 99% of of the design is inaccessible.  Also, there are many... MANY different ways to apply performance tests... who's modem are you testing against (as your reference)?, what characteristics of the line will you use?, (there are many), what speeds will you test?, are you originating or answering (again, to who's modem)?, should you use "like" modems at both ends?, (there are many reasons to say NO!... analogue/digital "like" modems are designed for optimum performance to themselves), what defines marginal connection?, (in what combination of all the variables?)... the questions go on and on.  Results are up to interpretation and vary tremendously.

 

Before you start any testing program, you might ask the big question... what will you do if the performances is 'under par'???  (Don't forget to define 'par').

Disclaimer... This information is only for your reference, it is not 'gospel'.  Actual tests available vary greatly depending on performance concerns. I suggest you generate a clear definition of your intent before you begin this process.

Anyway, here is a terse list of some performance certifications for PSTN (dial-up) modems.  At the very bottom of this page, are two links for more information... I am not associated with those links and I only give you them for your reference.

 


 

1.  ANSI/TIA TSB-37A and TSB38

TSB37A specifies the telephone network model intended to be representative of the transmission impairment conditions encountered in North America (US and Canada).

 

TSB38 specifies the standardized procedures for testing 2-Wire 4-Kilohertz Voiceband Duplex Modems that operate over PSTN.
 

2.  ITU-T Recommendation V.56bis and V.56ter

V.56ter specifies the standardized procedures for testing 2-Wire 4-Kilohertz Voiceband Duplex Modems that operate over PSTN.

V.56bis specifies the telephone network model intended to be representative of the transmission impairment conditions found on networks within North America, Europe and Asia. Additionally, it has been adjusted to account for the presence of the large PBX (Private Branch Exchange) system commonly found in business environments.
 

3.  ANSI/TIA SP-3857 and TSB38 (for testing to V.90 speeds)

SP-3857 North American Telephone Network Transmission Model for Evaluating Analog Client and Digitally Connected Server Modems” (if approved in 2007), will be reaffirmed as TIA/EIA-793)

 

TSB38 specifies the standardized procedures for testing 2-Wire 4-Kilohertz Voiceband Duplex Modems that operate over PSTN.

 

4.  TBD

In Process... visit later

5.  TBD

In Process... visit later

6.  TBD

In Process... visit later

7.  TBD

In Process... visit later

 

8.  TBD

In Process... visit later

 


 

 

Here are the links I promised:

http://www.fluent-access.com/wtpapers/tsb38rat.html

 

http://citywd.com/E/henderso/n-index.htm

Please be careful with this.  You could needlessly stop your projects momentum by not using this information prudently.

End

 

 

Copyright © 1997-2011 Floyd Kling 
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