A-to-D converter and lookup table dimensioning for six- or five-port phase discriminators

In this paper the use of lookup tables as a means of accelerating the digital signal processing in systems based on six- or five-port interferometers is proposed. Furthermore, the influence of the quantization errors introduced by the conversion of the analog signals to digital as well as by the lookup table values truncation is analyzed. From this analysis the adequate choice of the analog-to-digital converter resolution and lookup table word length can be done to fulfill the system´s specification and cost requirements. Measurement results are presented in order to validate the proposed approach.