Robotics Sportster Flash x2 Manual de usuario descargar pdf (Pagina 7)

High-End Rolloff

Examine the values of 3300 and 3750 from the Y11 screen. These values indicate the

degree of “rolloff” in signal power at the high end of the frequency spectrum.

Subtract the value for 3300 and from the value of 3750. If the difference is equal to or

greater than 25, that is very good evidence of an additional analog-to-digital conversion

(codec). An additional codec pair in the path makes achieving x2 either not possible or

extremely unlikely.

Signal Attenuation at 3750 Hz

Another criteria that should be looked at is the value of 3750. If it is greater than 50-55,

this is a sign of a poor local loop, and it’s likely to cause poor performance or prevent x2

from being achieved.

NOTE: in the field trials, we found several sites that had greater than 50 dB attenuation

at 3750, but did get x2. Most of the sites with greater than 50 had low connect rates

(30s, low 40s) and often retrained back to V.34. (Many of those who obtained 30s were

thrilled, as they were only able to get low 20s with V.34.)

Other Important Values

Other values to collect (if it is not practical to obtain the I-screens in their entirety) are

SNR and round-trip delay (from I11) and 150 and 300 from Y11.

6. Disconnect any other devices that share the analog line.

Although the following actions should not be necessary for normal operation, they will

aid troubleshooting.

Disconnect (not just hang up) all other phones, answering machines, caller ID boxes,

and modems, from all telephone wall jacks at the location. Use only one standard

telephone cable (usually silver and 7ft long) between the modem and a wall jack.

Telephone cable extenders and Y-adapters can have adverse affects on x2 (and V.34 for

that matter) connections. Multiple devices sharing the same line may affect x2

performance, especially if they are daisy-chained. Disconnect the other devices and

connect the modem directly to the wall jack.

7. Contact U.S. Robotics Technical Support.

To expedite your request, please collect the following data first:

❏ The phone number for the POP being called.

From a call to the service provider, preferably while online:

❏ From the Y11 screen, the values for 150, 300, 3300, and 3750.

❏ From the I11 screen, the Round-trip delay and SNR values.

From a call to a known-good x2 host, the same parameters.

❏ From the Y11 screen, the values for 150, 300, 3300, and 3750.

❏ From the I11 screen, the Round-trip delay and SNR values.

If practical, the full I4, I6, I7, I11, Y11 online screen captures, obtained 45 seconds after

connect are best!

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Robotics Sportster Flash x2 Manual de usuario Pagina 7