Signal Averaging for Digitizer ADQ214

Abstract: Signal averaging is a signal processing technique applied in the time domain, intended to increase the strength of a signal relative to noise that is obscuring it. From a very long sequence of data, a number of smaller data sequences called records are collected. The form of averaging performed in this thesis was not among samples within a record, but among samples from different records. For example, let's say a sample x(n, k) which is a sample n from record k, where 1 <= n <= N and N is the record size, and 1 <= k <= K, where K is the total number of records it would perform the averaging. Input signals for multi-record is periodic, typically repeated pulses. These records are stored in the memory of the Signal Processing (SP) Devices Digitizer ADQ214. Averaging is being implemented in two ways: software implementation and hardware implementation. In a software implementation the stored records are read out from a Digitizer to PC over a USB interface and averaging is performed in a PC with Matlab. Averaging in a PC takes a significant amount of time because of reading out data through USB interface. The amount of records and number of samples per record play an important role in transferring a record from the Digitizer on board DDR memory to the PC through a USB interface. A large number of records and long record length increases the time to perform averaging. This limitation is removed by implementing averaging in hardware. Verilog, a hardware description language is being used for designing the averaging unit in one of the Virtex5 FPGAs available on the Digitizer ADQ214. Performing averaging in hardware takes much less time than averaging in software. In a hardware implementation it is required to transfer data, which is the result in this case, only once from the Digitizer board to the PC regardless of the number of records under consideration.