Estimating the carrier frequency from a modulated waveform is one of the most
important functions of a coherent signal receiver. Good performance and low bit
error rates are obtained by coherent demodulation. Therefore, exact knowledge of the
received signal carrier frequency is critical for communication systems. Also due to
the spectral crowding, a high probability of channel interference can be observed.
Under moderate carrier frequency offsets, data-aided estimators have been developed
which have a high accuracy of estimation. However, for high frequency offsets the
frequency estimator does not have the information of data or timing. In this thesis we
propose a parametric based carrier frequency estimation of GMSK, which has
improved performance over ad-hoc methods (delay and multiply) and has high
resolution capability.
In this thesis three methods are implemented over GMSK data to improve the
performance and their results compared with the standard delay and multiply
method. Two of these methods are parametric based estimators and one is a fast
frequency estimator. Parametric based estimators were chosen partly due to their
high resolution capabilities and mainly for their proven performance. Parametric
based estimators were seen to have high computational load, and hence an alternate
fast frequency estimator was implemented. The tradeoffs involved with respect to
computational load and performance were shown.
The contributions of this thesis include the verification of the validity of
applying a parametric based approach on GMSK data, and compare the
performances of parametric methods and fast frequency estimator. It is showii that
such an approach has a better performance compared to non-data aided ad-hoc delay.
and multiply methods. A closed loop configuration of the open loop parametric
methods is suggested in the end. / Graduation date: 2004 / Best scan available. Figures are light on the original.
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29876 |
| Date | 09 June 2003 |
| Creators | Kandukuri, Ajay |
| Contributors | Magana, Mario E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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