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Service Hints & Tips |
Document ID: LWIK-3T7R3V |
TP 600,770 - Internal modem performance
Applicable to: World-Wide
SYMPTOM:
Modem speeds not appearing as expected in your communications application.
CONFIGURATION:
ThinkPad 600 or 770 with the internal ACP modem.
ADDITIONAL INFORMATION:
This tip will provide information on the functioning of the ACP internal modems and an explanation of some of the modem speeds that will be displayed by modem applications.
Many modem dialer applications, such as IBM Global Network Dialer, will display the COM port speed for the connection speed. So, a connection speed of 115200 bps can be displayed for a 56K modem. The connection speeds of the modem across the phone lines may be less or equal to the COM port speed.
The actual connection speed can be viewed by opening the Modem application in the ThinkPad Modem folder from the Start menu. This application shows the speed at which the modem is transmitting data. Typical initial values range from 30666 to 41333 bps. Connection speeds for 56K modems are highly sensitive to the phone lines being used for the connection and can vary from location to location. 56K is predicated on bypassing the analog to digital conversion on the downloading side, thereby giving a faster possible connection. The uploading side of the connection is still limited to V.34 speeds. So, data will usually be received at a much faster rate than the system is sending data.
The internal modems in the 770 and 600 are designed to establish a stable connection first, so the initial connection speed may be slower than expected. The modem will then attempt to increase the connection speed as high as possible while still maintaining a quality connection. A slower connection speed that yields minimal errors can be as efficient or better than a higher connection speed that yields large quantities of errors. So, the number that is displayed as the connection speed may not necessarily be as important as the actual performance of the modem.
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Hint Category |
Communications | |
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Date Created |
03-04-98 | |
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Last Updated |
19-01-99 | |
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Revision Date |
19-01-2000 | |
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Brand |
IBM ThinkPad | |
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Product Family |
ThinkPad 600, ThinkPad 770 | |
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Machine Type |
2645, 2646, 9549 | |
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Model |
Various | |
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TypeModel |
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Retain Tip (if applicable) |
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