UNIVERSAL ASYMMETRIC DIGITAL SUBSCRIBER LINE MODEM DEVICE FOR REDUCING AUDIBLE NOISES IN CASE OF TELEPHONE COMMUNICATION

摘要

PURPOSE: A universal asymmetric digital subscriber line modem device is provided to reduce audible noises in case of a telephonic communication by effectively reducing an upward transmission power by means of a voice band reflection quantity measuring device. CONSTITUTION: A universal asymmetric digital subscriber line modem device includes upward signal modulator(42), a transmission gain regulation amplifier(40), a high pass filter(32), a hybrid(34), a receiving gain regulation amplifier(36), and a telephone state diagnosis part. The upward signal modulator modulates upward transmission data. The transmission gain regulation amplifier regulates amplitude of upward signal, and regulates a transmission power. The receiving gain regulation amplifier regulates amplitude of downward signal generated from the hybrid. The telephone state diagnosis part senses an operation of internal automatic gain regulator according to an impedance variation of a telephone, and detects a telephone state detection signal. The downward signal modulates includes the telephone state diagnosis part, modulates a downward signal generated from the receiving gain regulation amplifier, outputs a downward receiving data, and controls a gain of the receiving gain regulation amplifier. A voice bandwidth reflection quantity measuring part includes a transmitting part gain regulation signal for attenuating a transmission power of upward signal to the transmission gain regulation amplifier.