# PROCESSING OF NON-STATIONARY SIGNAL USING LEVEL-CROSSING SAMPLING

### Modris Greitans

#### Abstract

The spectral characteristics of multimedia signals typically vary with time. Preferably, the sampling density of them would comply with instantaneous bandwidth of signal. The paper discusses the level-crossing sampling principle, which provides such capability for analog-to-digital conversion. As the captured samples are spaced non-uniformly, the appropriate digital signal processing is required. The non-stationary signal is characterized by time-frequency representation. Its classical approaches are inspected for applicability to analyze the data obtained by level-crossing sampling. Several enhancements of short-time Fourier transform approach are proposed, which are based on the idea to minimize the reconstruction error not only at sampling instants, but also between them with the same accuracy. Additional benefits are gained if the instantaneous spectral range of analysis is complied with local sampling density: artifacts are removed, complexity of calculations is decreased. The performance of algorithms is demonstrated by simulations. Presented research can be attractive for clock-less designs, which receive now an increasing interest. Their promising advantages can play a significant role in future electronicsâ€™ development.

#### References

- Akay, M., editor (1998). Time frequency and wavelets in biomedical signal processing. IEEE Press.
- Baraniuk, R. G. and Jones, D. L. (1993). A signaldependent time-frequency representation: Optimal kernel design. IEEE Trans. Signal Proc., 41(4):1589- 1602.
- Chui, C. K. (1992). Wavelet Analysis and its Applications. Academic Press, Boston, MA.
- Cohen, L. (1995). Time-frequency analysis. Prentice-Hall.
- E. Allier, G. Sicard, L. F. and Renaudin, M. (2003). A new class of asynchronous a/d converters based on time quantization. In Proc. of International Symposium on Asynchronous Circuits and Systems ASYNC'03, pages 196-205, Vancouver, Canada.
- Ellis, P. H. (1959). Extension of phase plane analysis to quantized systems. IRE Transactions on Automatic Control, AC(4):43-59.
- Gabor, D. (1946). Theory of communication. Journal of the IEE, 93(3):429-457.
- Greitans, M. (2005). Spectral analysis based on signal dependent transformation. In Proc. of the International Workshop on Spectral methods and multirate signal processing, pages 179-184, Riga, Latvia.
- Hauck, S. (1995). Asynchronous design methodologies: An overview. Proc. of the IEEE, 83(1):69-93.
- Mark, J. W. and Todd, T. D. (1981). A nonuniform sampling approach to data compression. IEEE Trans. on Comm., 29(1):24-32.

#### Paper Citation

#### in Harvard Style

Greitans M. (2006). **PROCESSING OF NON-STATIONARY SIGNAL USING LEVEL-CROSSING SAMPLING** . In *Proceedings of the International Conference on Signal Processing and Multimedia Applications - Volume 1: SIGMAP, (ICETE 2006)* ISBN 978-972-8865-64-1, pages 170-177. DOI: 10.5220/0001569001700177

#### in Bibtex Style

@conference{sigmap06,

author={Modris Greitans},

title={PROCESSING OF NON-STATIONARY SIGNAL USING LEVEL-CROSSING SAMPLING},

booktitle={Proceedings of the International Conference on Signal Processing and Multimedia Applications - Volume 1: SIGMAP, (ICETE 2006)},

year={2006},

pages={170-177},

publisher={SciTePress},

organization={INSTICC},

doi={10.5220/0001569001700177},

isbn={978-972-8865-64-1},

}

#### in EndNote Style

TY - CONF

JO - Proceedings of the International Conference on Signal Processing and Multimedia Applications - Volume 1: SIGMAP, (ICETE 2006)

TI - PROCESSING OF NON-STATIONARY SIGNAL USING LEVEL-CROSSING SAMPLING

SN - 978-972-8865-64-1

AU - Greitans M.

PY - 2006

SP - 170

EP - 177

DO - 10.5220/0001569001700177