Time-locking method for stations which form part of a local loop network, and local loop network for performing this time-locking method
First Claim
1. In a local loop network comprising a plurality of stations which are distributed along a bus, each station being connected to the bus by way of a coupler, said bus comprising a looping unit inserted in the bus, a method for the time-locking of the stations, said method including an initialization phase for allocating to each station a time reference with respect to a master clock of the looping unit, characterized in that the initialization phase forms part of a transmission phase which comprises the following steps:
- (a) the transmission of a frame, referred to as the transmission frame, by the looping unit, said transmission frame comprising;
a synchronization word which initializes the transmission and initialization phase,at least one slot which initially does not contain data and which has for each station a different position with respect to the position of the synchronization word, said position corresponding to the time position occupied by each station in the transmission frame;
(b) the generating of a transmission command by at least one station after the transmission of the synchronization word;
(d) the insertion, by the station and under the control of the transmission command, of a word into the empty slot allocated to the station;
said transmission phase being followed by a receiving phase which comprises the following steps;
(a) the demodulation of the transmission frame by the looping unit;
(b) the retransmission, in the form of a frame which is referred to as the receiving frame, of said demodulated transmission frame by the looping unit,(c) the measurement by the station of the delay, with respect to the beginning of the slot allocated thereto, with which the word has been inserted into the allocated slot by the station during the transmission phase;
(d) the storage by the station of the measured delay value in order to enable the station to advance the insertion of the word into the allocated slot during a next transmission by a period which corresponds to the delay value.
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Accused Products
Abstract
A method for use in a local loop network comprising a plurality of stations which are distributed along a bus, each station being connected to the bus via a coupler which is inserted in the bus. The time-locking method for these stations comprises a transmission phase during which a looping unit which is also inserted in the bus transmits a frame (transmission frame) which consists of a synchronization word and one or more slots which initially do not contain data and which correspond to the time position occupied by each of the stations, a receiving phase during which the demodulation of the transmission frame by the master clock of the looping unit is performed after the retransmission in the form of a frame which is referred to as the receiving frame, of this frame to the coupler of each of the successive stations and, after the receiving phase, new transmission and receiving phases until the insertion of the data on the bus by each station during a transmission phase takes place with the desired accuracy.
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Citations
12 Claims
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1. In a local loop network comprising a plurality of stations which are distributed along a bus, each station being connected to the bus by way of a coupler, said bus comprising a looping unit inserted in the bus, a method for the time-locking of the stations, said method including an initialization phase for allocating to each station a time reference with respect to a master clock of the looping unit, characterized in that the initialization phase forms part of a transmission phase which comprises the following steps:
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(a) the transmission of a frame, referred to as the transmission frame, by the looping unit, said transmission frame comprising; a synchronization word which initializes the transmission and initialization phase, at least one slot which initially does not contain data and which has for each station a different position with respect to the position of the synchronization word, said position corresponding to the time position occupied by each station in the transmission frame; (b) the generating of a transmission command by at least one station after the transmission of the synchronization word; (d) the insertion, by the station and under the control of the transmission command, of a word into the empty slot allocated to the station; said transmission phase being followed by a receiving phase which comprises the following steps; (a) the demodulation of the transmission frame by the looping unit; (b) the retransmission, in the form of a frame which is referred to as the receiving frame, of said demodulated transmission frame by the looping unit, (c) the measurement by the station of the delay, with respect to the beginning of the slot allocated thereto, with which the word has been inserted into the allocated slot by the station during the transmission phase; (d) the storage by the station of the measured delay value in order to enable the station to advance the insertion of the word into the allocated slot during a next transmission by a period which corresponds to the delay value. - View Dependent Claims (2, 3, 4, 5)
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6. A local loop network comprising a plurality of stations which are distributed along a bus, each station being connected to the bus by way of a coupler, said bus comprising a looping unit which comprises;
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first transmission means for transmitting a transmission frame comprising a synchronization word and at least one slot which initially does not contain data and which has for each station a different position with respect to the position of the synchronization word, said position corresponding to the time position occupied by each station in the transmission frame; receiving means for receiving a receiving frame comprising a transmission frame which has made at least one revolution through the loop and which comprises at least one slot wherein a word has been inserted by a station which did receive the transmission frame; a demodulator for generating a demodulated frame of said receiving frame; second transmission means for transmitting said demodulated frame; and each station comprises; insertion means for inserting a word into the empty slot allocated to the station; measuring means for measuring in a demodulated frame the delay, with respect to the beginning of the slot allocated thereto, with which the word has been inserted by the station into the allocated slot of a transmission frame; storage means for storing said measured delay; and enabling means connected with said insertion means and said storage means, said enabling means being provided for enabling said insertion means to advance said insertion by a time duration which corresponds to the stored delay value. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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Specification