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Many different modem models show an estimated maximum attainable sync speed on the GUI pages, but the Speedstream modems do not include this capability. The Speedstream 5100b/4100/4100b modem analysis tool (aka DMT tool) programmed by deblin can estimate the upload/download maximum attainable sync speeds for a line if provided with a link to a saved copy of the Technician Readout page on the user's hard drive. The 5100b/4100 modem must be using software version to provide the complete results for the upload side. The 4100b modem uses the factory software. This DMT tool also works for the Motorola 2210-02-1002 modem (firmware 7.7.3r5) as well as the Speedstream 5100b, 4100, and 4100b modems.

If the DMT tool link is broken, please use the original DMT tool beta test site instead and the instructions in this FAQ.

First you must be able to access the modem's GUI either by connecting directly to the modem or by letting the modem do the PPP and issuing a public/private IP to wan/internet port of router: »AT&T Midwest/Ameritech FAQ »Funhouse 5100b Setup and Reference Info or by one of the other advanced methods: »SBC DSL FAQ »How do I access the modem GUI thru a router - advanced methods?.

To save a copy of the Technician Readout page, », on a Speedstream modem with a non-IE browser, simply use the Save as command. If you are using any version of Internet Explorer, then after using the Save as command, you must change from the default setting on the Save as type: drop down box to the Web Page, HTML only (*.htm,*.html) choice and then save the Technician Readout Page.

On IE, alternatively you can use the View -> Source menu item on the Technician Readout page. This will open up the HTML source in notepad (or whatever your default text file viewer is). Save this file as "techreadout.htm" (the file name doesn't matter).

For a Motorola 2210 modem, save the Technician Readout page from » by the one of the above methods instead.

These estimates will under report the actual maximum attainable sync speeds if the modem is not running at full output power. Because these modems do not report the output power levels, there is no way to compensate for this possibility.

Also note at the slower speed plans such as 3008/512 and below, the modem only lists the statistics for tone bins (frequencies) it is using. So the speed estimates made from limited tone bin data tend to be slower than the real potential of the line.

The chart below (click for full image) was produced by the modem analysis tool for a good 768/384 connection on a relatively short loop. It is an extreme illustration of the limits of these maximum attainable speed calculations. Although this line is known to be running at the maximum allowed power levels, no data is reported by these modems for the unused, higher tone bins, and without that data, the DMT tool can make no estimate of the speed capacities of those tone bins. AT&T techs estimate this line's maximum attainable sync speed at 6976 kbps instead of the tool's estimate of 4596.

If you are asked to post the tool's results in a thread and you don't have the ability to make a graphic capture such as the above shot, then you can post a copy of the DMT chart link address (with Firefox you right click on the chart and 'Copy Image Location' and with IE you right click on the chart, select Properties, and then copy the entire Address:(URL)) and a simple cut-and paste of the text such as done below. This will make viewing your results much easier for those reading your thread:

»/users/deblin? ··· aph=true

Downstream Current Rate (Reported): 768
Downstream Maxrate (Estimated): 4596
Downstream Bit Margin (Calculated): 252

Upstream Current Rate (Reported): 384
Upstream Maxrate (Estimated): 1058
Upstream Bit Margin (Reported): 92

Bit tones with notches/missing bits:

bit(s) 38:43 163.875 - 189.75 KHz
bit(s) 110 474.375 - 478.6875 KHz
bit(s) 123 530.4375 - 534.75 KHz
bit(s) 137 590.8125 - 595.125 KHz
bit(s) 143:255 616.6875 - 1104 KHz

The sync speeds for the total of the upload tone bins (to left of tone bin 32) and the download bins (to right of tone bin 32) can be calculated. These calculated sync speeds exceed the actual modem sync speeds the modem reports to the user. This excess speed is listed as the "Bit Margin" by the DMT tool and is extra bit load capacity the modem must have for bit swapping and ATM signaling overhead. The actual Bit Margin speed varies from 252 for 768 sync speeds to 480 for 6016 sync speeds. Sync stability is impaired if the modem can't reserve the appropriate Bit Margin speed for the sync speed the modem is trying to achieve.

Note: The upload tone bins (the leftmost group) for the 2210 modems are not shown on the DMT chart because they do not list that data in their techreadout pages. The maxrates listed by the DMT tool for the 2210 modem are those actually reported on the modem's techreadout page.

Feedback received on this FAQ entry:
  • Good one!!!

    2009-11-22 11:14:51

  • RedMatrix: the fancy chart shows the DMT bit bin layout. This shows the actual radio frequencies used to transmit/upload (left hump) data and receive/download data (right hump/plateau). You normally want to see a nice smooth feature. A few holes are ok, but huge missing hunks usually mean there is something impairing those radio frequencies. The fancy chart can be used by forum members to suggest possible problems that they've seen before.

    2009-03-19 10:41:56 (justbits See Profile)

  • I don't know how to read the actual chart. I 'get' the max rates at the bottom. But what does that fancy chart mean? Thanks. -dave RedMatrix

    2008-08-16 04:07:07 (RedMatrix See Profile)

Expand got feedback?

by d_l See Profile
last modified: 2011-09-23 10:37:43