Transmitter and receiver synchronization for wireless telemetry systems

Abstract

An acoustic modem for communication in a network of acoustic modems via a communication channel. The acoustic modem comprises a transceiver assembly, transceiver electronics, and a power supply. The transceiver assembly is adapted to convert acoustic messages into electrical signals. The transceiver electronics is provided with transmitter electronics and receiver electronics. The transmitter electronics cause the transceiver assembly to send acoustic signals into the communication channel. The receiver electronics comprises at least one microcontroller adapted to execute instructions to (1) enable the receiver electronics to receive electrical signals indicative of the acoustic message from at least one other acoustic modem via the transceiver assembly, (2) estimate a carrier frequency of the electrical signals by analyzing an estimation frame of the electrical signals, (3) estimate a starting time of a data frame of the electrical signals by synchronizing with a synchronization frame of the acoustic message in parallel with at least two bit rates, and (4) decode the data frame. The power supply supplies power to the transceiver assembly and the transceiver electronics.

1 . A method of transmitting data along tubing in a borehole, the method comprising the steps of:
 (i) transmitting an acoustic message containing data by a first modem at a first location on the tubing at a first frequency and a first bit rate selected from a predetermined group of at least two frequencies and at least two bit rates;   (ii) receiving the acoustic message by a second modem at a second location on the tubing, and detecting the first frequency of the acoustic message by receiver electronics of the second modem; and   (iii) synchronizing the acoustic message with the detected first frequency and in parallel with at least two bit rates by the receiver electronics of the second modem.   
     
     
         2 . The method of  claim 1 , wherein step (i) further comprises adjusting a frequency of the acoustic message to one of the at least two frequencies in the predetermined group of at least two frequencies and at least two bit rates. 
     
     
         3 . The method of  claim 2 , wherein the predetermined group of at least two frequencies and at least two bit rates comprises the first frequency and more than two further frequencies, the method further comprising iterating steps (i)-(iii) through the group of frequencies. 
     
     
         4 . The method of  claim 1 , wherein step (i) comprises adjusting the bit rate of the acoustic message to a lower bit rate. 
     
     
         5 . The method of  claim 4 , wherein the step of adjusting the bit rate follows adjustment of frequency of the acoustic message. 
     
     
         6 . The method as of  claim 1 , further comprising the step of re-transmitting the data within the acoustic message received by the second modem to a third modem. 
     
     
         7 . The method of  claim 1 , further comprising the step of determining whether the step of synchronization is successful utilizing a predetermined selection algorithm; and wherein the predetermined selection algorithm is selected from a group of at least one signal quality parameter consisting of signal distortion, signal strength, ambient noise, signal-to-interference noise ratio, signal-to-noise ratio, channel response time, signal amplitude, and signal auto-correlation. 
     
     
         8 . A method, comprising the steps of:
 converting an acoustic message into an electrical signal by a transceiver assembly of an acoustic modem attached to a tubing within a borehole, the acoustic message including a synchronization frame and transmitted at a first frequency and a first bit rate selected from a group of multiple frequencies and bit rates;   receiving the electrical signal by receiver electronics of the acoustic modem; and   synchronizing, in parallel by the receiver electronics of the acoustic modem, a synchronization frame of the electrical signal with at least two frequencies and at least two bit rates of the group of multiple frequencies and bit rates.   
     
     
         9 . The method of  claim 8 , wherein the multiple frequencies and bit rates within the group are predetermined. 
     
     
         10 . An acoustic modem for communication in a network of acoustic modems via a communication channel, the acoustic modem comprising:
 a transceiver assembly adapted to convert acoustic messages into electrical signals;   transceiver electronics, comprising:
 transmitter electronics to cause the transceiver assembly to send acoustic signals into the communication channel; 
 receiver electronics comprising at least one microcontroller adapted to execute instructions to (1) enable the receiver electronics to receive electrical signals indicative of the acoustic message from at least one other acoustic modem via the transceiver assembly, (2) estimate a carrier frequency of the electrical signals by analyzing an estimation frame of the electrical signals, (3) estimate a starting time of a data frame of the electrical signals by synchronizing with a synchronization frame of the acoustic message in parallel with at least two bit rates, and (4) decode the data frame; and 
   a power supply supplying power to the transceiver assembly and the transceiver electronics.   
     
     
         11 . The acoustic modem of  claim 10 , wherein the at least one microcontroller of the receiver electronics enables the transmitter electronics to transmit an acknowledgement. 
     
     
         12 . The acoustic modem of  claim 10 , wherein the at least one microcontroller executes instructions to cause (2) and (3) to execute sequentially. 
     
     
         13 . An acoustic modem for communication in a network of acoustic modems via a communication channel, the acoustic modem comprising:
 a transceiver assembly adapted to convert electrical signals into acoustic messages;   transceiver electronics, comprising:
 transmitter electronics coupled to the transceiver assembly; 
 receiver electronics coupled to the transceiver assembly; 
 at least one microcontroller executing instructions to (1) enable the transmitter electronics to enter a training phase where the transmitter electronics transmit a training message having an estimation frame, a synchronization frame and a data frame to the transceiver assembly, and (2) enable the transmitter electronics to enter a data communication phase where the transmitter electronics transmits a data message to the transceiver assembly having a synchronization frame and a data frame without an estimation frame; and 
   a power supply supplying power to the transceiver assembly and the transceiver electronics.   
     
     
         14 . An acoustic modem for communication in a network of acoustic modems via a communication channel, the acoustic modem comprising:
 a transceiver assembly adapted to receive an acoustic message having a synchronization frame and a data frame and to convert the acoustic message into an electrical signal;   transceiver electronics, comprising:
 transmitter electronics to cause the transceiver assembly to send acoustic signals into the communication channel; 
 receiver electronics having at least one microcontroller executing instructions to (1) receive the electrical signal indicative of the acoustic message; (2) synchronize, in parallel, a synchronization frame of the electrical signal with at least two frequencies and at least two bit rates of a group of multiple frequencies and bit rates; and (3) decode the data frame; and 
 a power supply supplying power to the transceiver assembly and the transceiver electronics. 
   
     
     
         15 . An acoustic modem for communication in a network of acoustic modems via a communication channel, the acoustic modem comprising:
 a transceiver assembly adapted to convert an electrical signal into an acoustic message;   transceiver electronics, comprising:
 receiver electronics coupled to the transceiver assembly; 
 transmitter electronics coupled to the transceiver assembly and including at least one microcontroller adapted to execute instructions to generate a sequence of electrical signals directed to the transceiver assembly with different carrier frequencies and with the sequence ordered based upon a model of a particular, planned tubing for a borehole; and 
   a power supply supplying power to the transceiver assembly and the transceiver electronics.   
     
     
         16 . A computer system, comprising:
 one or more input device;   one or more output device;   one or more non-transitory computer readable medium storing instructions for (1) receiving a priori information of a particular, planned tubing for a borehole from the one or more input device, (2) predicting optimal carrier frequencies for acoustic communication utilizing the particular, planned tubing as a communication channel between two or more modems, and (3) outputting information to the output device indicative of the optimal carrier frequencies;   at least one processor in communication with the one or more non-transitory computer readable medium for executing the instructions based upon a message from the one or more input device; and   one or more power supply supplying power to the input device, the output device, the one or more non-transitory computer readable medium and the one or more processor.