Research And Implementation Of High-speed Data Transmission Technology In Telemetry Seismic Acquisition Stations

Telemetry digital seismic acquisition station is designed as single-channel single-station, analog signal output from geophone is changed into digital signal in every station, no analog signal weakening, noise disturbance, the user can select the channel number for each acquisition station chain. Seismic acquisition station plays an important role. Geophone data collection is mainly responsible for Seismic acquisition station, synchronization of data transmission, asynchronous data transmission and other tasks. Data transmission performance and synchronization performance is directly related to the acquisition system with a channel capacity.In this thesis, with fully study , research and understand the background, we proposed a system of seismic acquisition station for telemetry, high-speed low-power data transmission program, and adopted the preliminary experiment. Data transmission between stations using Manchester coding, which has a 16.384Mbps data transfer rate, the sender uses 32.768MHz crystal. Manchester encoding is a self-written program, serial data conversion parallel data, code and add header in the FPGA. Receiver using oversampling clock 131.072MHz, Manchester decoder can identify the data header, the Manchester-encoded data into serial data, and then serial data into parallel data.Power supply is similar to POE (Power Over Ethernet), just use 4 core cable to complete the task of two-way data transmission and power supply , and voltage isolation between the stations. In the same time of data transmission, customization of a synchronous reset protocol. AC signal in the transmission line delay is 5.13ns / m (AC signal in the wire transfer speeds of about 195,000 km per second), a two thousand meters chain, signal transmission delay is 10.26μs , coupled with the delay in each acquisition station 4μs, the delay will reach tens of milliseconds, so send synchronous acquisition command alone can not achieve high-precision synchronization. Synchronous reset agreement also must be able to respond to any changes in the length of the transmission line, the synchronization process is like this, synchronization test frame is sent back and forth in the acquisition of a chain, each acquisition station can receive the frame from two directions simultaneously testing positive and negative, by calculating , acquisition station will wait with their positions corresponding delay after the synchronous acquisition command arrived. After the actual test, the synchronization precision can be achieved 200ns.To test the telemetry seismic acquisition station with data transmission performance, we made the power station with only data relay function, after tested, data transmission performance reached the design requirements.