 Training of level learning modems |
| FIG. 1 shows, at the left, an analog modem 101 connected to the public switched digital network (PS... |
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| Method and apparatus for a low voltage high current bi-directional termination voltage regulator |
| Accordingly, the present invention provides a low voltage high current bi-directional termination ... |
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| Time domain equalizer for ADSL |
| The invention provides an equalization technique that relies on time domain lms, has lower ... |
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| Automatic gain control circuit for a modem receiver |
| An object of the present invention is to provide an automatic gain control circuit for a modem ... |
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| All-digital method and apparatus for demodulating an analog signal |
| It is an object of the invention to provide a demodulator that is totally digital in structure, and ... |
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| Test circuit of multiplex equipment |
| An object of the present invention is to provide a test circuit for multiplex equipment to be used ... |
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| Echo canceller |
| OF THE EMBODIMENTS FIG. 1 is a block diagram illustrating an embodiment of an echo canceller of ... |
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| Listener echo cancellation |
| The listener echo cancellation means of the present invention employs a finite impulse response (FIR... |
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| Semiconductor integrated device |
| In the integrated service digital network, the training mode for getting the echo data is carried ... |
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Protective relay system and sampling synchronizing method therefor
| Details |
Inventors: Yamaura, Mitsuru; Shuto, Ituo;
Assignee: Kabushiki Kaisha Toshiba (JP)
Primary Examiner:
Assistant Examiner:
Attorney, Agent or Firm:
In a protective relay system for an electric power system having two terminals at which electrical quantity is sampled in synchronism with a clock signal produced at each terminal, and the sampled electrical quantity data are exchanged for protection at said opposite terminal: a synchronous signal is transmitted from each terminal toward the opposite terminal; time data T1 is transmitted from a first terminal SS2 toward a second terminal SS1, the time data T1 indicating a time point t.sub.1 of the transmission of the synchronous signal toward the second terminal SS1 with reference to the clock signal; the time data T0 is transmitted from the second terminal SS1 toward the first terminal SS2, subsequent to reception of the synchronous signal from the first terminal SS2, the time data T0 indicating a value t.sub.0 -T1+t.sub.2 where t.sub.0 represents a time point of the reception of the synchronous signal with reference to the clock signal at the second terminal SS1, T1 represents the value as indicated by the time data T1, and t.sub.2 represents a time point of the transmission of the synchronous signal with reference to the clock signal; a time deviation .DELTA.T in the occurrence of the clock signal between the two terminals is determined from the time data T0 and a time point t.sub.3 of the reception of the synchronous signal with reference to the clock signal; and the timing of the occurrence of the clock signal at said one terminal is adjusted in accordance with .DELTA.T. |
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DETAILED DESCRIPTION An object of the invention is to minimize the delay in the transmission of the electrical quantity data, and to minimize the amount of information or data to be transmitted for the purpose of the synchronization, and to reduce restriction on the time point of transmission of the electrical quantity data.
According to the invention, there is provided a sampling synchronizing method for use in a protective relay system for an electric power system having two or more terminals at which electrical quantity is sampled, two of the terminals being coupled to form a pair, said sampling at each terminal being made in synchronism with a clock signal produced at each terminal, and electrical quantity data obtained by the sampling at each terminal of said pair is transmitted to the opposite terminal of said pair to be used for protection at said opposite terminal, the clock signals at the terminals of said pair having the same frequency, wherein a synchronous signal is transmitted from each terminal of said pair toward the opposite terminal; time data T1 is transmitted from one terminal SS2 of said pair toward the other terminal SS1 of said pair, in association with the synchronous signal, the time data T1 indicating a time point t.
sub.
1 of the transmission of the synchronous signal toward said other terminal with reference to occurrence of the clock signal at said one terminal; time data T0 is transmitted from said other terminal toward said one terminal, in association with the synchronous signal F0 is an M.
sub.
0 -th clock period (M.
sub.
0 being a predetermined natural number) after the reception of the synchronous signal F1 associated with the time data T1 from said one terminal, the time data T0 indicating a value given by: t.
sub.
0 -T1+t.
sub.
2 where t.
sub.
0 represents a time point of the reception of the synchronous signal F1 associated with the time data T1 from said one terminal SS2 with reference to occurrence of the clock signal at said other terminal SS1, T1 represents a value indicated by the time data T1, and t
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Multiplexer-related 
