Telemetry system incorporating synchromization of receiver with transmitter

Claim 2

A time division demultiplexing signal system for demultiplexing a plurality of time division signals comprising a programmer for Producing a signal at the end of a predetermined sequence of time slots, each time slot adapted to contain a time division signal; a ramp generator triggered by said programmer signal; gate means responsive to the next occurring time division signal after said predetermined time slot sequence to transmit the amplitude of said ramp generator output at the time of said time division signal; a variable frequency circuit, the output frequency of which is controlled in response to said gated ramp output; switch means for segregating said multiplexed signals in accordance with an established cycle of switch operation; and further circuit means responsive to said next occurring time division signal for initiating said cycle of switch operation.

Claim 3

A transmission system for a logging tool comprising: a plurality of signal sources in said logging tool for producing a plurality of data signals representative of various subsurface characteristics; storage means for temporarily storing said data signals; downhole control means for periodically generating a plurality of signals including a synchronization signal and control signals representative of time periods during which signals form each of said sources are to be transmitted to the surface of the earth, said synchronization signal having a predetermined time relationship to said time periods; means responsive to said control signals for interrogating said storage means for the presence of data signals and transmitting representations of said stored data signals and synchronization signal to the surface of the earth; means at the surface of the earth for receiving and identifying said transmitted signals, including clock means for generating a clock signal, surface control means responsive to said clock signal for generating signals which include identification signals which identify the time periods when transmitted signals corresponding to each source are expected, and means responsive to a generated signal from said control means for causing a selected transmitted signal received at the surface of the earth to synchronize the operation of said clock or surface control means with that of said downhole control means.

Claim 4

A transmission system for a logging tool comprising: a plurality of signal sources in said logging tool for producing a plurality of data signals representative of various subsurface characteristics; storage means for temporarily storing said data signals; downhole control means for periodically generating a plurality of signals including a synchronization signal and control signals representative of time periods during which signals form each of said sources are to be transmitted to the surface of the earth, said synchronization signal having a predetermined time relationship to said time periods; means responsive to said control signals for interrogating said storage means for the presence of data signals and transmitting representations of said stored data signals and synchronization signal to the surface of the earth; means at the surface of the earth for receiving and identifying said transmitted signals, including clock means for generating a clock signal, surface control means responsive to said clock signal for generating signals which include identification signals which identify the time periods when transmitted signals corresponding to each source are expected, and means responsive to a generated signal from said control means for causing a selected transmitted signal received at the surface of the earth to synchronize the operation of said clock or surface control means with that of said downhole control means.

Claim 5

In a transmission system for a logging tool, apparatus for demultiplexing a transmission signal which is characterized by a repetitive sequence which includes a plurality of time periods individually allotted to a data signal from each of a plurality of information sources and a synchronization signal wherein there exists a probability of non-recurrence of a data signal in those time periods allotted to data signals comprising: means for receiving the transmission signal, clock means for generating a clock signal; control means responsive to said clock signal for generating signals which include identification signals which identify the time periods of said transmission signal corresponding to each information source; synchronization means responsive to a generated signal from said control means for causing a selected received signal to synchronize said clock signal or identification signals with said transmission signal.

Claim 6

In a transmission system for a logging tool, apparatus for demultiplexing a transmission signal which is characterized by a repetitive sequence which includes a plurality of time periods individually allotted to a data signal from each of a plurality of information sources and a synchronization signal wherein there exists a probability of non-recurrence of a data signal in those time periods allotted to data signals comprising: means for receiving the transmission signal, clock means for generating a clock signal; control means responsive to said clock signal for generating signals which include identification signals which identify the time periods of said transmission signal corresponding to each information source; synchronization means responsive to a generated signal from said control means for causing a selected received signal to synchronize said clock signal or identification signals with said transmission signal.

Claim 7

The apparatus of claim 3 wherein said synchronization means includes gate means responsive to a signal from said control means for gating a received signal to said clock means during a time period when a synchronization signal is expected to enable synchronization of said clock and transmission signals.

Claim 8

The apparatus of claim 3 wherein said synchronization means includes gate means adapted to inhibit application of said clock signal to said control means; means responsive to a signal from said control means for energizing said gate means to inhibit application of said clock signal to said control means at the beginning of a time period during which a synchronization signal is expected, the next received signal during said time period when a synchronization signal is expected operating to cause said gate means to pass said clock signal to said control means.

Claim 9

The apparatus of cLaim 3 wherein said synchronization means includes gate means responsive to a signal from said control means for passing a received signal, frequency control means responsive to said passed signal from said gate means and a signal from said control means for generating an output signal representative of the time interval between said two signals applied to said frequency control means, and means for applying said output signal to said clock means to control the frequency of said clock signal.

Claim 10

The apparatus of claim 3 wherein each transmission signal sequence comprises a first time period for a synchronization signal and a plurality of subsequent time periods for data signals from said information sources, and wherein said control means produces a termination signal at the end of each transmission signal sequence, and wherein said synchronization means includes gate means responsive to said termination signal from said control means for gating a received signal to said clock means during a time period at the end of said transmission signal sequence to enable phase synchronization of said clock and transmission signals.

Claim 11

The apparatus of claim 3 wherein each transmission signal sequence comprises a first time period for a synchronization signal and a plurality of subsequent time periods for data signals from said information sources, and wherein said control means produces a termination signal at the end of said transmission signal sequence, and wherein said synchronization means includes gate means adapted to inhibit application of said clock signal to said control means; means responsive to said termination signal from said control means for energizing said gate means to inhibit application of said clock signal to said control means during a time period beginning with the end of said sequence, the next received signal after said termination signal operating to cause said gate means to pass said clock signal to said control means.

Claim 12

The apparatus of claim 3 wherein each transmission signal sequence comprises a first time period for a synchronization signal and a plurality of subsequent time periods for data signals from said information sources, and wherein said control means produces at least one termination signal at the end of each transmission signal sequence, and wherein said synchronization means includes gate means responsive to a termination signal from said control means for passing a received signal, frequency control means responsive to said passed signal from said gate means and a termination signal from said control means for generating an output signal representative of the time interval between said two signals applied to said frequency control means, and means for applying said output signal to said clock means to control the frequency of said clock signal.

Claim 13

The apparatus of claim 3 and further including a plurality of utilization devices, each adapted for individually receiving the data signals from an information source, means responsive to said identification signals from said control means for gating the data signals corresponding to each information source to corresponding utilization devices.