University of Twente Student Theses


Design & Implementation of Digital Channel Selection Filters for a Combined Bluetooth and Hiperlan/2 Receiver

Mourik, L.C. van (2002) Design & Implementation of Digital Channel Selection Filters for a Combined Bluetooth and Hiperlan/2 Receiver.

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Abstract:In the context of a Software Defined Radio (SDR) receiver, digital channel selection filters were researched for Bluetooth and HiperLAN/2 signals. The goal was to derive the specifications and find suitable implementations, as well as building a simulation model. This model includes the digital channel selection system for both Bluetooth and HiperLAN/2 with analog front-end and demodulators. For HiperLAN/2 the proposed filter system is based on poly-phase low-pass FIR filters and theoretical specifications. Due to late availability of a demodulator, this system was not further researched. For Bluetooth, The real and The complex filter systems were researched including the feasibility of using (non linear phase) IIR filters. The real design was implemented and improved and is proposed as the optimal solution for the current requirements with respect to the derived performance figure. The incoming quadrature signals are low-pass filtered by a pair of (real) FIR filters, implemented in polyphase. Then, they are converted to a bandpass signal by using a FIR Hilbert transformer and adder. Changing the sign bit of the adder is the first stage of channel selection. Then, the signals are band-pass filtering by a variable 4th order Chebyshev Type II IIR filter. The filter is variable in the sense that filter coefficients must be updated every time the Bluetooth signal hops to another frequency. Then the filtered signal is mixed to the required frequency for demodulation. After a second band-pass filter (6th order Butterworth IIR filter) the signal is decimated again and ready for demodulation. The choice for IIR filters was made to reduce filter operations. A FIR-only design was also proposed and can be used in case IIR filters are not suitable for implementation. Both systems meet BER requirements as specified in the Bluetooth documentation.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:53 electrotechnology
Programme:Electrical Engineering MSc (60353)
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