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User Guide
Local Analog Loopback Test (V.54 Loop 3)
In this test, data from your computer or terminal is sent to your mo- dem’s transmitter, converted into analog form, looped back to the mo- dem’s receiver, converted into digital form, and then sent to your monitor for verification. No connection to the phone line is required.
AT&T1
CONNECT
UUUUUUUUU
UUU
Digital Analog
Computer or Terminal | Local MultiModem |
Figure C-1. Local analog loopback test.
Test procedure
1.Connect the modem to your computer. Using your communication program, set the desired baud rate and go into terminal mode.
2.Type AT&T1 and press ENTER. This places your modem in analog loopback mode in the originate mode. A CONNECT message should appear on your display. The modem is now out of command mode and in a
3.Note that the CD LED is on. If you are set for 14,400 bps or higher, a speed LED should be on. If the CD LED is not on, there is a defect in your modem.
4.Enter characters from your keyboard. For this test, typing multiple uppercase U characters is a good way to send an alternating test pattern of binary ones and zeros. The characters entered should be