Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1993-12-30
1995-09-19
Coles, Sr., Edward L.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358442, 358434, 379100, H04N 132
Patent
active
054521068
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a facsimile device for connecting a facsimile transceiver to a computer. The facsimile device may also be connected to a telephone network.
DESCRIPTION OF THE PRIOR ART
According to the prior art it is known to have facsimile modems and data modems for performing facsimile transmission of documents or file transfers using facsimile protocols. Such devices may be either internal or external devices which can be connected to computer provided with the appropriate software. However, such devices may not be easily interconnected with an existing facsimile transceiver at the same local site. Prior art devices provide only for connection to a facsimile device at a remote site over a telephone network. Therefore, any connection between the computer and the local facsimile transceiver is only possible via the telephone network. In such a case, a telephone exchange and telephone lines are required to communicate between the computer and the facsimile transceiver.
BACKGROUND TO THE INVENTION
In order to describe the scope of the current invention it is desirable to briefly outline the operational procedures of facsimile communications and the incorporation of file transfer within these procedures. This may be done with reference to the five Phases in a facsimile transmission:
Phase A is the call establishment and line connection of equipment,
Phase B is the pre-message signalling and capability selection,
Phase C is the facsimile message transfer,
Phase D is the post-message signalling, and
Phase E is the call disconnection.
In particular Phase B is the low speed (300 baud) pre-message signalling in which the capabilities of the respective machines are indicated and selected. In particular the called station first responds with a Digital Information Signal (DIS) in which its capabilities in terms of group type, speed, resolution, and other special capabilities are indicated. At this time file transfer capabilities may also be indicated. The calling machine then responds with a Digital Command Signal (DCS) in which, in line with its own capabilities, the capabilities required for the forthcoming transmission are selected. This is followed by a high speed training sequence related to synchronisation, equalisation and other functions.
When the receiving machine indicates its readiness to receive, Phase C is entered during which the transfer of facsimile information takes place. At this time the transmitting machine will progressively scan the input document, code and compress the pixel information according to the selected resolution and transmit the information at the selected speed. The receiving machine will correspondingly decompress and decode the received information and print the required image.
At the completion of each page, Phase D is entered. This post-message signalling determines if there are more pages to transmit, in which case Phase C is repeated. If there are no more pages then Phase E is entered at which time the call is terminated and the line disconnected.
It is necessary to refer to recent modifications to the standards for facsimile telecommunications as determined by the Study Group VIII of the CCITT. These allow for improvements in speed, resolution, network addressing procedures and also for file transfer to be accomplished as an alternative facsimile data type.
The procedures for non-facsimile image data transfer within the facsimile call are defined in modifications and appendices to the CCITT Recommendations T.4 and T.30 which govern facsimile telecommunications. In particular the file transfer modes permitted are:
Of these, BFT is considered most general and most suitable for widespread application for PC compatible communications. This is because the binary file mode allows the transfer of any type of file including those indicated by the other modes. The first two transfer modes are more appropriate for integration with telex or similar communications, whereas the fourth relates specifically to the standard form for electronic data i
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Coles Sr. Edward L.
Exfax Technologies Ltd Pty
Vu Kim Yen
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