Emulation of analog modem signaling over IDSN for translation-less interoperability with PSTN based H.324 system

• US 5,961,589 A
• Filed: 09/09/1997
• Issued: 10/05/1999
• Est. Priority Date: 09/09/1997
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Hansen, Carl Christian
• Primary Examiner(s): Pan, Daniel H.
• Application Number:
  US08/926,413
• Time in Patent Office: 756 Days
• Field of Search: 395/200.61, 395/200.34, 395/200.36, 395/200.35, 370/260, 370/352, 370/309, 370/496, 370/264, 455/416, 399/90.01, 399/202, 399/219, 399/93.21, 348/17, 348/15, 345/330, 300/10, 709/205, 709/204, 709/203, 709/206, 709/207
• US Class Current: 709/205
• CPC Class Codes: G06F 13/105 where the programme performs an input/output emulation function
• CPC Class Codes: H04M 11/06 Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors
• CPC Class Codes: H04M 3/56 Arrangements for connecting several subscribers to a common circuit, i.e. affording conference facilities video conference systems H04N7/15
• CPC Class Codes: H04N 7/148 Interfacing a video terminal to a particular transmission medium, e.g. ISDN
• CPC Class Codes: H04N 7/15 Conference systems

Abstract

What is disclosed is a system for translationless videoconferencing interoperability between an analog modem based node and an Integrated Services Digital Network (ISDN) node having a videoconferencing engine coupled to the ISDN node, the videoconferencing engine generating videoconferencing data according to an analog modem protocol. Further the system has a modem emulator coupled to the videoconferencing engine, the modem emulator configured to model said data as analog modem data interpretable by the analog modem based node.

Claims

1. A system for translationless videoconferencing interoperability between an analog modem based node and an Integrated Services Digital Network (ISDN) node comprising:

a first videoconferencing engine coupled to said ISDN node, said first videoconferencing engine generating videoconferencing data according to an analog modem videoconferencing protocol; and

a modem emulator coupled to said first videoconferencing engine, said modem emulator configured to model said videoconferencing data as analog modem data interpretable by said analog modem based node, said analog modem based node incapable of ISDN communication, said ISDN node incapable of analog modem based communication.

2. A system according to claim 1 further comprising an ISDN adapter coupled to said modem emulator, said ISDN adapter configured to transmit digitally said analog modem modeled data.

3. A system according claim 1 further comprising a second videoconferencing engine coupled to said analog modem based node, said second videoconferencing engine of a protocol compatible to said first videoconferencing engine.

4. A system according to claim 3 wherein said protocol conforms to H.324.

5. A system according to claim 1 wherein said modem emulator emulates V.34 signaling.

6. A method for translationless videoconferencing interoperability between an analog modem based node and a ISDN based node comprising the steps of:

receiving a first set of signals from said analog modem based node on said ISDN based node, said first set of signals compatible with an analog modem videoconferencing protocol;

generating on said ISDN based node a second set of signals from said first set of signals, said second set of signals resembling analog modem data; and

generating on said ISDN based node a third set of signals from said second set of signals, said third set of signals characteristic of videoconferencing information.

7. A method according to claim 6 wherein said step of generating said second set of signals includes the steps of:

simulating the demodulating of said first set of signals into a bitstream; and

descrambling said bitstream into said second set of signals.

8. A method according to claim 6 wherein said step of generating said third set of signals includes the step of removing start, stop and parity bits from said second set of signals to generate said third set of signals.

9. A method for translationless videoconferencing interoperability between an analog modem based node and a ISDN based node comprising the steps of:

generating on said ISDN based system a first set of signals characteristic of videoconferencing information, said first set compatible with an analog modem videoconferencing protocol;

modeling said first set of signals into a second set of signals, said second set of signals encoded as analog modem signals; and

transmitting from said ISDN based node to said analog modem based node a third set of signals, said third set of signals sampled digitally from said second set of signals.

10. A method for translationless videoconferencing interoperability according to claim 9 wherein the step of modeling further comprises the steps of:

affixing start, stop and parity bits to selected portions of said first set of signals to generate transfer blocks;

scrambling said transfer blocks into scrambled data; and

simulating the modulating of said transfer blocks into analog modem signals.

11. A modem emulator for coupling to an ISDN device, said emulator comprising:

a UART module;

a receiver module coupled to said UART module, said receiver module configured to receive samples from said ISDN device and generate a first set of data transfer blocks, said first set of data transfer blocks passed to said UART module;

a transmitter module coupled to said UART module and said ISDN device, said transmitter module configured to receive a second set of data transfer blocks from said UART module and to generate analog-modem compatible data in the form of digital samples, said ISDN device having no analog modem capability.

12. A modem emulator according to claim 11 wherein said transmitter module consists of:

a scrambler module coupled to said UART, said scrambler module configured to scramble said second set of data transfer blocks into a sequence of bits;

a modulator module coupled to said scrambler module to generate analog modem compatible data from said sequence of bits; and

a dynamic rate adapter coupled to said modulator module, said dynamic rate adapter modifying the sample rate of said analog-modem compatible data to a sample rate compatible with said ISDN device.

13. A modem emulator according to claim 11 wherein said receiver module consists of:

a dynamic rate adapter coupled to said ISDN device, said dynamic rate adapter modifying the sample rate of said samples to a sample rate compatible with an analog modem device,

a demodulator module coupled to said dynamic rate adapter, said demodulator module configured to generate from said modified sample rate samples a scrambled bitstream; and

a descrambler module coupled to said demodulator module, said descrambler module configured to descramble said scrambled bitstream into said first set of transfer blocks.

14. A modem emulator according to claim 11 configured to generate videoconferencing information compatible with an analog-modem videoconferencing protocol.

15. ISDN-based computer system comprising:

a memory configured to store a first set of instructions corresponding to a videoconferencing engine and to store a second set of instructions corresponding to performing the function of a modem emulator; and

a processor coupled to said memory, said processor configured execute said first set of instructions and said second set of instructions, said processor further configured to provide and interpret videoconferencing information to and from an analog modem based computer system, said first and second set of instructions modeling said videoconferencing information in analog form, and sampling said modeled information digitally for use by the ISDN device of said systems.