Pulse or digital communications – Synchronizers – Self-synchronizing signal
Reexamination Certificate
1999-04-02
2003-05-27
Chin, Stephen (Department: 2634)
Pulse or digital communications
Synchronizers
Self-synchronizing signal
C375S362000, C375S372000, C370S509000, C710S120000
Reexamination Certificate
active
06570945
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a reception interface unit in a transmission system for putting time series digital data into a data packet and transferring the data packet at high speed.
2. Description of the Related Art
IEEE1394-1995 standard has been proposed as an interface standard for transferring time series data of audio signals, video signals, etc., in a data packet at high speed between electric devices such as audio devices, video devices, computers, etc.
However, in a data transfer system based on the IEEE1394-1995 standard, it is conceivable that received digital data cannot be reproduced at proper timing over a considerable period of time in a receiving party because of a change in the reference time in the system, a malfunction, etc.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above problem, and therefore an object of the invention is to provide a reception interface unit in a transmission system for enabling digital data sent by a transmitting party to be restored to a state in which the data can be reproduced immediately at proper timing in a receiving party.
To achieve the above object, according to a first aspect of the invention, there is provided a reception interface unit in a transmission system wherein time series data is divided into data groups and a data packet comprising reproduction specification time data specifying the time at which each data piece in the data groups should be reproduced, added to the data groups is transmitted on a transmission bus in a time division manner, the reception interface unit comprising a cycle timer for counting the reference time of a home device based on the reference time on the transmission bus, reproduction specification time data extraction means for extracting the reproduction specification time data in the data groups from a signal received via the transmission bus and storing the reproduction specification time data in a buffer, a reception buffer for inputting and storing the data pieces in the data groups in order and reading out the data pieces in the storage order in response to a reproduction clock, a match detection means for generating a reference clock pulse if the reference time of the home device matches the reproduction specification time, and a PLL circuit being responsive to the reference clock pulse for generating a clock signal which is phase synchronized with the reference clock pulse as the reproduction clock, wherein when the reference time on the transmission bus changes, the data stored in the buffer in the reproduction specification time data extraction means and the data stored in the reception buffer are all deleted.
According to a second aspect of the invention, there is provided a reception interface unit in a transmission system wherein time series data is divided into data groups and a data packet comprising reproduction specification time data specifying the time at which each data piece in the data groups should be reproduced, added to the data groups is transmitted on a transmission bus in a time division manner, the reception interface unit comprising a cycle timer for counting the reference time of the home device based on the reference time on the transmission bus, the cycle timer having at least two registers for temporarily storing the reference time of the home device before the reference time on the transmission bus changes and the reference time of the home device after the reference time on the transmission bus changes, reproduction specification time data extraction means for extracting the reproduction specification time data in the data groups from a signal received via the transmission bus and storing the reproduction specification time data in a buffer, a reception buffer for inputting and storing the data pieces in the data groups in order and reading out the data pieces in the storage order in response to a reproduction clock, a match detection means for generating a reference clock pulse if the reference time of the home device matches the reproduction specification time, and a PLL circuit being responsive to the reference clock pulse for generating a clock signal which is phase synchronized with the reference clock pulse as the reproduction clock, characterized in that when the buffer becomes empty of the data stored before the reference time on the transmission bus changes, either or both of the reproduction specification time data extraction means and the reception buffer output a control signal, that when the reference time on the transmission bus changes, the reproduction specification time data extraction means and the reception buffer interrupt write of the data and when each buffer becomes empty of the data stored before the reference time on the transmission bus changes, restarts write of the data, and that the cycle timer changes the reference time of the home device from the reference time of the home device before the reference time on the transmission bus changes to that after the reference time on the transmission bus changes based on the control signal and outputs the reference time of the home device to the match detection circuit.
According to a third aspect of the invention, there is provided a reception interface unit in a transmission system wherein time series data is divided into data groups and a data packet comprising reproduction specification time data specifying the time at which each data piece in the data groups should be reproduced, added to the data groups is transmitted on a transmission bus in a time division manner, the reception interface unit comprising a cycle timer for counting the reference time of the home device based on the reference time on the transmission bus, reproduction specification time data extraction means for extracting the reproduction specification time data in the data groups from a signal received via the transmission bus and storing the reproduction specification time data in a buffer, a reception buffer for inputting and storing the data pieces in the data groups in order and reading out the data pieces in the storage order in response to a reproduction clock, a match detection means for generating a reference clock pulse if the reference time of the home device matches the reproduction specification time, and a PLL circuit being responsive to the reference clock pulse for generating a clock signal which is phase synchronized with the reference clock pulse as the reproduction clock, characterized in that when the reference time on the transmission bus changes, the reproduction specification time data extraction means deletes all the reproduction specification time data stored in the buffer.
According to a fourth aspect of the invention, there is provided a reception interface unit in a transmission system wherein time series data is divided into data groups and a data packet comprising reproduction specification time data specifying the time at which each data piece in the data groups should be reproduced, added to the data groups is transmitted on a transmission bus in a time division manner, the reception interface unit comprising a cycle timer for counting the reference time of the home device based on the reference time on the transmission bus, reproduction specification time data extraction means for extracting the reproduction specification time data in the data groups from a signal received via the transmission bus and storing the reproduction specification time data in a buffer, dummy reproduction specification time data generation means for generating dummy reproduction specification time data from the reproduction specification time data extracted in the reproduction specification time data extraction means, selection means for selectively outputting either of the reproduction specification time data from the reproduction specification time data extraction means and the dummy reproduction specification time data from the dummy reproduction specification time data generation means, a reception buffer for inputting and
Hasebe Seiichi
Matsumaru Makoto
Minoshima Kunihiro
Murakoshi Sho
Ono Kinya
Chin Stephen
Ha Dac V.
Pioneer Electronic Corporation
Sughrue & Mion, PLLC
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