Telephonic communications – Telephone line or system combined with diverse electrical... – To produce visual-graphic copy
Reexamination Certificate
1995-06-20
2001-05-15
Chan, Wing F. (Department: 2743)
Telephonic communications
Telephone line or system combined with diverse electrical...
To produce visual-graphic copy
C379S093080, C358S434000, C370S282000
Reexamination Certificate
active
06233324
ABSTRACT:
BACKGROUND OF THE INVENTION
The terminal equipment of facsimile group 3 connectable to a communication network via analog interfaces are mainly used for the transmission of digital still images. The still pictures to be communicated via the telecommunication networks are composed of a great plurality of minute black and white mosaic squares having the same shape and size (called pixels). The original still pictures are either scanned by a scanner and resolved into black or white pixels or are generated by a computer as a result of a document/graphics production. The pixels are converted into digital code in the transmitting facsimile terminal equipment. First, they are compressed in order to reduce the quantity of information to be transmitted and, then, they are divided into information data frames and communicated block-by-block over the telecommunication network. In the receiving facsimile terminal equipment, the received information are decompressed and decoded into the original black and white pixels, an image being thus composed that is similar to the original (and is therefore displayed as a “facsimile” thereof). The receiver terminal equipment usually prints the received image out on paper or displays it in some instances on a display picture screen or stores it on local, digital storage equipment such as on a magnetic disk.
Instead of or in addition to the pixel-coded image, it is also optimally possible with terminal equipment of facsimile group 3 to send character-coded information. This service referred to as mixed mode has to operating modes, namely character-coded communication of texts and pixel-coded communication of images. It is suitable, for example, for economical transmission of letters with a letterhead and signature in fax format and with text in text format.
The described mixed mode is enabled by identifying the individual information data frames in a facsimile control field defined according to ITU-T T.4.Annex E. It is also known to send general computer data files.
The method employed by terminal equipment of facsimile group 3 has been standardized in the corresponding ITU-T recommendations for group 3 (ITU-T T.4, CCITT T.6, ITU-T T.30) (last revision 1994) according to the international telecommunication union (ITU).
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a simple method for audio signal transmission via a communication network that can be simply realized and that enables the realization of auxiliary communication services regardless of whether the communication terminal equipment are connection to the communication network via analog or digital interfaces.
In general terms the present invention is a method for transmitting audio signals from one communication terminal equipment via a communication network to another communication terminal equipment using a facsimile transmission protocol of ITU-T.T.4 and ITU-T.T30. A digital input audio signal is compressed in the sending communication terminal equipment. The compressed audio signal is divided into data frames according to ITU-T.T4 Annex A and ITU-T.T30 Annex A. Every data frame is identified as an audio information data frame. The audio information data frames are transmitted from the sending communication terminal equipment to the receiving communication terminal equipment using the facsimile transmission protocol and are stored in the receiving communication terminal equipment. The stored audio information data frames are output as digital audio signal after application of a decompression method or are further-processed.
In the data transmission the transmission duration of the compressed audio signals is shorter than the duration of the digital input audio signal dependent on the data frame transmission rate between the communication terminal equipment.
The audio signal is a voice signal.
Identification as an audio information data frame is undertaken in the facsimile control field defined according to ITU-T.T4 Annex E. An identification is provided for audio information data frames and an identification is also provided for voice information data frames. The audio information data frames are transmitted in a mixed mode alternating with appropriately identified written character information data frames, being transmitted from the sending communication terminal equipment to the receiving communication terminal equipment. Facsimile information data frames are transmitted alternating with information data frames of this type in mixed mode, being transmitted from the sending communication terminal equipment to the receiving communication terminal equipment.
The use of the facsimile transmission protocol according to ITU-T.T4 and ITU-T.T30 includes the error correction mode according to ITU-T.T4 Annex A and ITU-T.T30 Annex A.
The present invention is also an arrangement for the implementation of the method described above and has a communication network, as well as of sending communication terminal equipment and receiving communication terminal equipment, that respectively have at least the standard telephone terminal equipment. The communication terminal equipment also have a communication control means for controlling the data transmission using the facsimile transmission protocol and have at least one fax modem. At least the sending communication terminal equipment also has an audio coding means for compressing the audio input digital signal. At least the receiving communication terminal equipment has an audio decoding means for decompression of the received audio information data.
The present invention is also a facsimile apparatus for the implementation of the method described above having an image scanner means, a printer means, a modem, a communication controller and a facsimile coding/decoding means, as well as an audio input/output means. The facsimile apparatus also has an audio signal coding/decoding means for the compression and decompression of audio input/output signals.
The identification of the data frames to be transmitted as audio information data block or voice information data block in the facsimile control field defined according to ITU-T T.4.Annex E enables a mixed mode wherein voice/audio information alternate at least block-by-block but can be transmitted within one transmission procedure together with facsimile information and/or written character information.
As a result thereof, audio information and image information can be transmitted in common not only via a digital telephone network but also via an analog telephone network.
When real-time transmission can be foregone, a bidirectional information exchange is possible given employment of the inventive method in both directions—usually with a respectively renewed call setup.
Given bidirectional information exchange upon employment of the inventive method, the call address of the terminal equipment initiating a call setup and that is usually communicated within the framework of the signaling to the called terminal equipment can be stored in the calling terminal equipment in an especially beneficial embodiment of the invention and can be employed in the setup of a call-back by the previously called terminal equipment.
For realizing an inventive method, it is proposed to send a digitally compressed and coded voice or audio information in the information stream usually transmitted between facsimile terminal equipment instead of the pixel-coded image or in addition thereto.
Individual embodiments of the invention, dependent on the individual embodiment, make use of some of the special characteristics of facsimile group 3 recited below:
the optional error correction mode (ECM) of the facsimile group 3 introduced in 1988 (ITU-T T.4 Annex A, ITU-T T.30 Annex A) enables error-free transmission of facsimile information frames with a size of 64 (or 256) octets.
increasing the transmission speeds of the facsimile group 3 by optionally attaching high-speed modems (up to 30 kbit/s).
the optional mixed mode (MM) for facsimile group 3 introduced in 1992 (ITU-T T.4 Annex E, ITU-T T.30) distinguishes b
Chan Wing F.
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
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