Tdk Systems, Inc.

Tdk U.s.a. Corporation

Gregory S Gillespie

Thomas J Glad

James T Schley-May

David R Kissinger

William L Harris

The present invention provides apparatus and method for connecting Data Terminal Equipment (DTE) to communication networks. The present invention provides an adaptable universal modem that can be reconfigured to meet different specifications in different countries, thereby allowing a user to use a single universal modem across different specifications in different countries. The universal modem includes a microcontroller, a programmable data pump, and a programmable DAA. A user reads a particular country code on each country's unique identifier and provides the information to a modem setup program. The modem setup program configures the universal modem according to the country information entered by the user, thereby permanently storing the home country code in modem flash memory. The universal modem of the present invention reverts to a default home configuration upon power-up to meet the requirements of various PTT (Postal Telephone & Telegraph) authorities. The country code can be changed after power-up by entering a country code change command in the modem setup program.

Method and apparatus for initial country selection in a universal modem

Method and apparatus for controlling the volume of an internal PC speaker. In the present invention, pulse width modulation (PWM) techniques are used to selectively reduce the signal power generated at the speaker. By substituting a high frequency signal having a symmetric duty cycle for portions of the digital audio signal, the average signal power is reduced. The frequency of the substitute signal is much higher than the speaker bandwidth, contributing negligible power to the output. The ratio of audio signal to high frequency signal determines the output signal level. In the preferred embodiment of the present invention, a three bit counter is used to separate the audio signal into intervals having eight states apiece. A signal providing -6 dB of attenuation is generated by substituting the toggling output from the least significant bit of the counter during four out of the eight states. A signal providing -12 dB of attenuation is generated by substituting the same toggling output during six out of the eight states. A multiplexer is provided to select between the two attenuated signals, an unattenuated signal and a DC signal (off).

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Nevada City, CA, United States of America

Gregory S Gillespie