Test methods for nonlinear parameters of seismic data recorders and their effect analyses

Total harmonic distortion （THD） and intermodulation distortion （IMD） characteris-tics are two important nonlinear parameters of seismic data recorders. Input signal mode and peak value of sine-wave can affect the test results of these two characteristics. In order to deter-mine these effects, the basic principles on THD and IMD were introduced in this paper, and then test methods, data processing methods and effect analyses on THD and IMD were fully presented. Finally, some different kinds of sine-waves were input into the seismic data recorder to test THD and IMD. The test results show that the two signals with the same peak value but different input-mode have great impact on THD, and those with the same frequency but different peak value of sine-wave have great impact on IMD. However, signal frequency variation has no impact on THD and IMD. The research in this paper is of great value for quality test of seismic data recorder, which can be applied to test THD and IMD of seismic data recorders.