High-speed logging cable telemetry system transceiver circuit design based on FPGA

Abstract

The telemetry system is critical in the application of geophysical exploration technology. The efficiency and accuracy of the entire logging system will be directly affected by whether the signals captured by the downhole acquisition equipment can be transferred reliably and at a high rate to the surface receiver for data processing. Now, for the problems of slow cable transmission speed, signal attenuation, and severe distortion, the transmission system is studied in this paper based on orthogonal frequency division multiplexing (OFDM) technology. The logging cable telemetry system's overall plan is designed, and the OFDM communication system is completed according to IEEE802.11a physical layer standard, detailing the transmitter and receiver's circuit structure, functional roles, and implementation methods, and instituting each transmitter and receiver module using XILINX Field Programmable Gate Arrays (FPGA). Scrambler, convolutional encoder, interleaver, 16QAM modulator, IFFT module, insert CP module, and training sequence module is all included in the transmitter. Time synchronizer, CP removal module, FFT module, deinterleaver, demodulator, Viterbi decoder, and descrambler are all included in the receiver. RTL level simulation on the Vivado platform is used to verify the communication system. The results demonstrate that the communication time per frame of 128bit data communication is 130us and that this telemetry system can communicate at a rate of more than 7600Kbit/s without using a cable. The FPGA-based telemetry system has advantages over typical digital signal processor telemetry systems regarding communication rate and real-time performance.