| 摘要 |
PURPOSE:To attain quality measurement of a telephone line while keeping the connection of a MODEM and a data terminal equipment only by providing a generator of a test pattern generator, a data memory, a comparator and an adder to the inside of the modulator-demodulator. CONSTITUTION:When a request of a remote digital loopback test is issued from a personal computer 3 to a MODEM 1, a microcontroller 4 sends a remote digital loopback test start data to a MODEM section 6. The opposite MODEM forms a loop of the remote digital loopback test. Then the microcontroller 4 generates a test pattern. The sent test pattern is subject to loopback by the opposite MODEM and the microcontroller 4 receiving the test pattern returned through the telephone line, discriminates whether or not the pattern is the test pattern sent by a comparator 8. |
