Electronic digital logic circuitry – Signal sensitivity or transmission integrity – Bus or line termination
Reexamination Certificate
2002-01-31
2004-06-01
Chang, Daniel D. (Department: 2819)
Electronic digital logic circuitry
Signal sensitivity or transmission integrity
Bus or line termination
C326S082000
Reexamination Certificate
active
06744276
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a serial digital audio data port with multiple functional configurations.
AES3-1992 prescribes a signal format for digital audio data. A signal in this format is sometimes known as an AES
3
signal, or simply as an AES signal, and has two channels which may be related, for example as left and right stereo channels.
AES3-1992 specifies that the AES signal should be transmitted in balanced form over a shielded twisted pair cable. AES3-1992 specifies that in this case the cable should have a characteristic impedance of 110 ohms at frequencies from 100 kHz to 128 times the maximum frame rate, or 6.144 MHz for a frame rate of 48 kHz, that the driver should have a balanced output with an internal impedance of 110 ohms +/−20% over the same frequency range and that the receiver should present an essentially resistive impedance of 110 ohms +/−20% over the same frequency range.
SMPTE 276M-1995 describes a point-to-point coaxial cable interface for the transmission of AES digital audio signals throughout television production and broadcast facilities. In accordance with SMPTE 276M, the generator or driver must have a source impedance of 75 ohms over the frequency band 0.1 MHz to 6.0 MHz and the receiver must present an impedance of 75 ohms over the same frequency band. In a given facility, AES signals may be transmitted both in balanced form and in unbalanced form.
SMPTE 259M-1993 (hereinafter referred to simply as SMPTE 259) defines the serial digital interface (SDI) signal format for video. The SDI signal format specifies locations at which ancillary data can be accommodated in the field of a composite digital video signal or a component digital video signal.
SMPTE 272M-1994 (hereinafter referred to simply as SMPTE 272) defines the mapping of AES digital audio data into the horizontal ancillary data space of the SDI data stream, resulting in a serial data stream including both video data and audio data. The process by which AES digital audio data is inserted in the horizontal ancillary data space of the SDI data stream is referred to as embedding or multiplexing. Conversely, the process by which digital audio data is extracted from the horizontal ancillary data space of a serial data stream including both video data and audio data is referred to as disembedding or demultiplexing. See, for example, D. K. Fibush, “Integrating Digital Audio into the Serial Digital Video Signal,”
SMPTE JOURNAL
, September 1994, 574-579 and U.S. Pat. No. 5,483,538.
Powerful digital signal processing techniques allow different configurations of a given product to perform different functions. For example, with relatively minor variations in control and software, a given functional module may be used either to embed digital audio data in a digital video data stream, according to SMPTE 272M, or to disembed digital audio data from a digital video data stream. Operating as an embedder, this module would require one or more audio inputs (as well as a video input and a video output), whereas it would require an audio output rather than an audio input when operating as a disembedder. A port that could be configured either as an audio input or as an audio output could be used to provide an audio connection to either module.
U.S. patent application Ser. No. 09/977,655 filed Oct. 12, 2001, discloses a routing switch having variable input/output configuration. This function requires that some ports should operate selectively either as input ports or output ports, depending on the required configuration.
U.S. Pat. No. 6,256,686 discloses a bidirectional serial video port.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the invention there is provided a bidirectional port for digital audio data, comprising an I/O circuit including a connector having at least one signal terminal and also including a coupling circuit connected to said signal terminal and having first and second coupling circuit terminals, and a transceiver having first and second I/O terminals connected to said first and second coupling circuit terminals respectively and including a receiver having a first input terminal connected to the first I/O terminal, a second input terminal connected to the second I/O terminal, and at least one signal output terminal, a termination circuit connected between said first and second I/O terminals and including a resistor and a switch connected in series, the switch having an open state and a closed state, and a driver having at least one signal input terminal and also having first and second output terminals connected respectively to the I/O terminals of the transceiver, the driver having an enabled state and a disabled state, whereby the transceiver has multiple modes of operation depending on at least the state of the driver and the state of the switch.
In accordance with a second aspect of the invention there is provided a modular product for audio and video processing, comprising a digital video input port for receiving a digital video data stream, a processor for processing the digital video data stream and a digital audio data stream, and a digital audio transceiver for receiving or outputting the digital audio data stream, said digital audio, transceiver having first and second I/O terminals and including a receiver having a first input terminal connected to the first I/O terminal, a second input terminal connected to the second I/O terminal, and at least one signal output terminal connected to the processor, a termination circuit connected between said first and second I/O terminals and including a resistor and a switch connected in series, the switch having an open state and a closed state, and a driver having at least one signal input terminal connected to the processor and also having first and second output terminals connected respectively to the I/O terminals of the transceiver, the driver having an enabled state and a disabled state, whereby the digital audio transceiver has multiple modes of operation depending on at least the state of the driver and the state of the switch.
In accordance with a third aspect of the invention there is provided apparatus for audio and video processing, comprising a digital video input port for receiving a digital video data stream, a processor for processing the digital video data stream and a digital audio data stream, and a digital audio I/O port for receiving or outputting the digital audio data stream, the digital audio I/O port including an I/O circuit including a connector having at least one signal terminal and also including a coupling circuit connected to said signal terminal and having first and second coupling circuit terminals, and a digital audio transceiver having first and second I/O terminals connected to said first and second coupling circuit terminals respectively and including a receiver having a first input terminal connected to the first I/O terminal, a second input terminal connected to the second I/O terminal, and at least one signal output terminal connected to the processor, a termination circuit connected between said first and second I/O terminals and including a resistor and a switch connected in series, the switch having an open state and a closed state, and a driver having at least one signal input terminal connected to the processor and also having first and second output terminals connected respectively to the I/O terminals of the transceiver, the driver having an enabled state and a disabled state, whereby the digital audio transceiver has multiple modes of operation depending on at least the state of the driver and the state of the switch.
In accordance with a fourth aspect of the invention there is provided a method of making an active circuit assembly, said method comprising providing an active circuit module having an interconnection means for receiving an input signal and having an output for providing an output signal, providing a first interface module, said first interface module being a balanced interface module having two input terminals for
Costa David R.
Hauke Michael T.
Miller Steven E.
Pacak Jerzy
Chang Daniel D.
Fried Harvey D.
Grass Valley (US) Inc.
Levy Robert B.
Tripoli Joseph S.
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