Multistage Implementation of Narrowband LPF by Decimator in Multirate DSP Application

Decimator is an important sampling device used for multi-rate signal processing in wireless communication systems. Multirate systems have traditionally played the important role in compression for contemporary communication application.In this paper it demonstrated that a multistage implementation of sampling rate conversion often provides for a more efficient realization, especially when filter specifications are very tight (e.g., a narrow pass band and narrow transition band) and there are a audio-band of 4kHz bandwidth and compression by decimator to isolate the frequency component 80Hz.The LPF used by the decimator are acquire by two different approaches: first is the window method and other is frequency sampling method,Multistages implementations are used to further reduce the computational load. This approach drastically reduces the filter order and also reduces computational cost. Here it have reduce the overall computational complexity at single stage is 50 times and for second stages is near about 9 times reduce by the decimator factor is 50.