Digital signal processing and numerical analysis for radar in geophysical applications

Numerical solutions for signal processing are described in this work as acontribution to study of echo detection methods for ionospheric sounder design. The ionospheric sounder is a high frequency radar for geophysical applications. The main detection approach has been done by implementing the spread-spectrum techniques using coding methods to improve the radar’s range resolution by transmitting low power. Digital signal processing has been performed and the numerical methods were checked. An algorithm was proposed and its computational complexity was calculated.
The proposed detection process combines two channels correlations with the local code and calculates threshold (Vt) by statistical evaluation of the background noise to design a detection algorithm. The noisy signals treatment was performed depending on the threshold and echo amplitude. In each case, the detection was improved by using coherent integration. Synthetic signals, close loop and actual echoes, obtained from the Advanced Ionospheric Sounder (AIS-INGV) at Rome Ionospheric Observatory, were used to verify the
process.
The results showed that, even in highly noisy environments, the echo detection is possible.
Given that these are preliminary results, further studies considering data sets corresponding to other geophysical conditions are needed.

Aho, A.V., Hill, M., Hopcroft, J.E., Ullman, J.D. Data Structures and
Algorith ms. Addison -Wesley, New York, 1987.
Barry, G.H. A low power vertical incidence ionosonde. IEEE Trans. Geosci. Electron. 9 (2),86–89,1971. Barton, D.K., Leonov, S.A. (Eds.). Radar Technology Encycloped ia.
Artech House, USA, 1998.
Bianchi, C., Sciacca, U., Zirizzotti , A., Zuccheretti, E., Baskarad as, J.
Signal processin g techniques for phase-coded HF-VHF radars. Ann.
Geoph ys. 46 (4), http://dx.d oi.org/ 10.4401/ag- 4369, 2003 .
Cabrera , M., Zucchere tti, E., Ezquer, R., Sciacca, U., Lopez, J., Molina,
M., Baskarad as, J. Some consideratio ns for different time-domain
signal processing of pulse compressio n radar. Ann. Geophys. 53 (5–6),
1–11, http://dx.d oi.org/ 10.4401/ag- 4758, 2010 .
Curry, G.R. (Ed.). Radar System Performance Modeli ng, second ed
Artech House, Norwood , MA, 23–25,2005.
Ghebrebrh an, O., Luce, H., Yamamoto, M., Fukao, S. Interferen ce
suppress ion factor characterist ics of compleme ntary codes for ST/
SMT radar applicatio ns. Radio Sci. V39, RS3013, http://dx.d oi.org/
10.1029/ 2003RS002 910, 2004 .
Golay, M.J.E. Compl ementary series. IRE Trans. Inf. Theory 7, 82–87,
1961.
Ioannid is, G., Farley, D.T. Incoheren t scatter observations at Arecibo
using compressed pulses. Radio Sci. 7, 763–766,1972.
Mahafza, B.R. (Ed.),Radar systems analysis and design using MATLAB ,
Chapman & Hall/CRC, USA, 2000.
Rastogi, P.K. Signal processing and data analysis in middle atmosphere
radar. Radio Sci. 25 (5),1071–1086, 1990.
Rastogi, P.K., Sobolew ski, G. New quasi-comp lementary code sets for
atmosphe ric radar applicatio ns. Radio Sci. V25 (5),1087–1094,1990.
Reinisch, B.W. Radio sounding of geospac e plasmas. Fisica de la Tierra,
105–126,ISSN: 0214-4557 , 2000.
Richards, M.A. (Ed.). Fundame ntals of Radar Signal Process ing.
McGraw-H ill, New York, 2005.
Rishbeth, H., Garriot, O.K. Introduction to Ionospher ic Physics.
Academi c Press, England, 1969.
Skolnik, M.I. (Ed.).Introduct ion to Radar Systems. McGraw-H ill, USA,
1980.
Skolnik, M.I. (Ed.).Radar Handboo k. McGraw-H ill, USA, 1990.
Sultzer, M.P., Woodman, R.F. Quasi-com plementary codes: anew
techniqu e for radar sounding. Radio Sci. 19, 337–344,1984.
Wirth, W. Radar techniques using array antennas. The Institution of
Electrical Engineer, United Kingdom, London, 2001.
Zucchere tti, E., Tutone, G., Sciacca, U., Bianchi, C., Arokiasamy, B.J.
The new AIS-ING V digital ionosonde . Ann. Geophys. 46 (4),647–659, 2003.