Real time seismic telemetry system
First Claim
1. A synchronizing system for a seismic telemetry system, comprising:
- a central station;
means at said central station for receiving and processing digitally encoded data from a plurality of channels in real time;
a data link connected to said central station for accommodating said channels;
means at said central station for transmitting a synchronizing signal over said data link referenced to a common time base;
a plurality of remote data acquisition units each associated with one of said channels for transmitting digitally encoded data over said data link, each of said data acquisition units having;
means for generating a local clock, each of said means for generating being asynchronous with respect to the others of said means for generating,receiver means for synchronizing said synchronizing signal,synchronizing means for synchronizing each of said generating means to said common time base in response to the presence of said synchronizing signal, each of said generating means maintaining its asynchronous operation when said synchronizing signal is removed, andmeans for collecting and digitally encoding data for transmission to said central station over said data link on said associated channel at a data rate referenced to said local clock after synchronization.
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Accused Products
Abstract
A real time seismic telemetry system includes a central station (10) for communication with a plurality of remote data acquistion units (14). The command station (10) has a command unit (34) for controlling the operation of a transmitter (40) for providing instructions to the data acquistion units (14). The data acquistion units (14) receive the data on a receiver (80) and process the data in a logic control circuit (88). Remote data is picked up with a hydrophone (30) and converted to digital data for transmission through a transmitter (78) which is tuned to a discrete channel for each data acquistion unit (14). The command station (10) has a PCM receiver (62) tuned to each of the channels for demodulating the data stream therefrom. A digital receiver (66) is provided for synchronizing and processing the data. The digital receiver (66) synchronizes both to the bit rate and to the beginning and ending of the digital word such that data contained in the digital word can be multiplexed onto a data bus (68). The data bus (68) is controlled by an external storage/control (70) for storage of the data from all of the digital receivers (66) for all of the discrete channels.
121 Citations
20 Claims
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1. A synchronizing system for a seismic telemetry system, comprising:
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a central station; means at said central station for receiving and processing digitally encoded data from a plurality of channels in real time; a data link connected to said central station for accommodating said channels; means at said central station for transmitting a synchronizing signal over said data link referenced to a common time base; a plurality of remote data acquisition units each associated with one of said channels for transmitting digitally encoded data over said data link, each of said data acquisition units having; means for generating a local clock, each of said means for generating being asynchronous with respect to the others of said means for generating, receiver means for synchronizing said synchronizing signal, synchronizing means for synchronizing each of said generating means to said common time base in response to the presence of said synchronizing signal, each of said generating means maintaining its asynchronous operation when said synchronizing signal is removed, and means for collecting and digitally encoding data for transmission to said central station over said data link on said associated channel at a data rate referenced to said local clock after synchronization. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for synchronizing a seismic telemetry system, comprising:
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a data link for accommodating a plurality of channels; a central command station having; means for receiving digitally encoded data from said plurality of channels through said data link, and means for transmitting a synchronizing signal over said data link; a plurality of remote data acquisition units, each of said remote data acquisition units associated with one of said channels and having; means for generating a clock frequency, means for collecting seismic data, means for digitally encoding said collected seismic data, said encoded data having the bit rate thereof referenced to said clock frequency, means for transmitting said encoded data over said data link, means for receiving said synchronous signal, and synchronizing means for synchronizing the phase of said clock generating means in response to said synchronizing signal such that the clock frequencies in all of said data acquisition units are synchronized when said synchronizing signal is present and asynchronous when said synchronizing signal is not present. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A system for synchronizing a seismic telemetry system, comprising:
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a data link for transmission of digitally encoded data over a plurality of channels; a command station having; means for receiving encoded data from said data link, and means for transmitting a synchronizing signal referenced to a common time base and a pre-synchronizing signal over said data link; a plurality of remotely disposed data acquisition units, each of said data acquisition units associated with one of said channels and having; a reference oscillator, a divider circuit for dividing the frequency of said reference oscillator to a desired clock frequency, means for digitally encoding seismic data, said encoded data having the bit rate thereof referenced to said clock frequency, a transmitter for transmitting said encoded data over said data link, a receiver for receiving said synchronization signal and said pre-synchronization signal from said data link, a timer for initiating a pulse with a predetermined width in response to reception of said pre-synchronization signal, means for generating a plurality of reset pulses in response to the presence of said synchronization signal during the time interval that said pulse would be generated by said timer, said reset pulses input to said divider for resetting thereof such that the division of the output of said reference oscillator is begun upon the occurrence of a predetermined phase of said reference oscillator after said divider has been reset by said reset pulses wherein the maximum error between the clock frequency in said data acquisition units and the synchronization signal is equal to one period of said reference oscillator.
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18. A method for synchronizing data transmission in a real time seismic telemetry system, comprising:
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receiving encoded data at a central location from a plurality of remote data acquisition units over a data link; transmitting a synchronizing signal referenced to a common time base over the data link to the data acquisition units; generating a clock frequency at each of the data acquisition units on a separate time base; digitally encoding seismic data having the bit rate thereof referenced to the generated clock frequency; transmitting the encoded data over the data link; receiving the synchronization signal; and synchronizing the phase of the clock frequency in response to the synchronizing signal such that all of the clock frequencies in all of the data acquisition units are synchronized to the common time base when the synchronizing signal is present and asynchronous when the synchronizing signal is not present, synchronization occurring before transmitting of data. - View Dependent Claims (19, 20)
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Specification