Dual port interface for a computer-based multifunction personal communication system

Claim 3

A method as claimed in claim 2, in which the step of invoking a data communication connection further comprises the step of sending CCITT standard modem data packets and supervisory packets constructed as a CCITT standard modem standard data packet using a header undefined by the CCITT standard.

Claim 4

A method as claimed in claim 2 or claim 3, in which the step of enabling a voice over data connection between a local site equipped with a local modem and a first remote site equipped with a first remote modem, includes the steps of: (a) creating an outgoing data packet containing conventional digital data; (b) creating an outgoing voice packet containing digital voice data; (c) detecting substantially silent periods having absence of voice information in the digital voice data and producing in response thereto a silence flag; (d) transmitting only outgoing data packets when the silence flag indicates the absence of voice information; and (e) transmitting both the outgoing voice packets and the outgoing data packets when the silence flag indicates the presence of voice information.

Claim 7

A personal communication system for use with a telephone network and a personal computer, comprising: (a) data interface means connected for transferring data to and from the personal computer; (b) first telephone line interface means for connection to a first telephone line; (c) second telephone line interface means for connection to a second telephone line; (d) telephone handset means for receiving local voice signals from a local user and for conveying remote voice signals from a remote user to the local user; (e) full-duplex conversion means connected to the telephone handset means for converting the local voice signals into outgoing digital voice data and for converting incoming digital voice data into the remote voice signals; (f) voice compression means connected to the full-duplex conversion means for compressing the outgoing digital voice data into compressed outgoing digital voice data, and for decompressing compressed incoming digital voice data into the incoming digital voice data; (g) main control means connected for: receiving the compressed outgoing digital voice data from the voice compression means, receiving outgoing conventional digital data from the personal computer through the data interface means, multiplexing and transmitting compressed outgoing digital voice data with the outgoing conventional digital data, and passing the remote voice signals to the second telephone line.

Claim 8

A system as claimed in claim 7, in which the main control means is further operable for detecting silent periods in the outgoing digital voice data and for producing in response thereto a silence flag, and wherein the main control means is further operable for transmitting outgoing conventional digital data on the telephone line when the silence flag indicates the absence of voice information, and wherein the main control means is further operable for multiplexing and transmitting both the compressed outgoing digital voice data and the outgoing conventional digital data on the telephone line when the silence flag indicates the presence of voice information.

Claim 9

A module as claimed in claim 7 or claim 8, in which the telephone line includes a cellular telephone link, and wherein the main control means is further operable for periodically transmitting a cellular supervisory packet on the telephone line and for maintaining the link to the remote site over the telephone line if the remote site acknowledges receipt of the cellular supervisory packet within a predetermined period of time and for dropping the link to the remote site over the telephone line if the remote site fails to acknowledge receipt of the cellular supervisory packet within a predetermined period of time.

Claim 10

A module as claimed in any one of claims 7 to 9, in which the digital signal processor means is further operable for compressing the outgoing digital voice data into compressed outgoing digital voice data by performing the steps of: (a) removing any DC bias in the outgoing digital voice data to produce a normalized outgoing digital voice signal; (b) pre-emphasizing the normalized outgoing digital voice signal to produce a pre-emphasized outgoing digital voice signal; (c) dividing the pre-emphasized outgoing digital voice signal into segments to produce a current segment and a past segment; (d) predicting the pitch of the current speech segment to form a pitch prediction; (e) calculating the gain of the pitch of the current speech segment to form a prediction gain; (f) reconstructing the past speech segment from a compressed past segment to produce a reconstructed past segment; (g) finding the innovation in the current speech segment by comparing the pitch prediction to the reconstructed past segment to produce an error signal; (h) determining the maximum amplitude in the current speech segment; (i) quantizing the error signal using a code book generated from a representative set of speakers and environments to produce a minimum mean squared error matching the form of an index into the code book; and (j) recording the pitch prediction, the prediction gain, the maximum amplitude and the index into the code book in a packet as the compressed outgoing digital voice data.