An efficient structure of multi-rate interpolation in digital storage oscilloscope

Interpolation is a common means of signal processing in digital storage oscilloscope (DSO), which is used to satisfy the time base whose sampling rate is larger than the real-time sampling rate. An interpolation algorithm based on a polyphase filter bank structure is proposed for DSO with multiple interpolation time bases, which are corresponding to multiple interpolation rates. Adopting this algorithm, the interpolation process avoids the meaningless multiplication of zero saving the time consumption of computation. Only a set of coefficients of the maximum interpolation rate need to design, while the coefficients of other interpolation filter are the decimation of this set of coefficients. Based on the Field Programmable Gate Array (FPGA) simulation and the experiment of self-made DSO, the interpolation of multiple rates of 2,5 and 10 is achieved. The results show that this algorithm can effectively realize the interpolation of multiple rates in DSO.