A possible solution is to transmit simultaneously the Golay pair at the same carrier frequency using a space-diversity concept. In order to do this, an array antenna is needed, with the possibility of simultaneous operation with two or more subarrays, as is the case in a multifuction phased array radar (MPAR). The antenna array is subdivided in two subarrays to transmit (receive) the Golay codes. In this case it is not necessary to use a modified Golay pair because a conventional Golay pair is sufficient. With such a solution, the impairments due to frequency diversity can be avoided, and, in principle, sidelobes may be perfectly cancelled even for complex targets. However, this new approach requires a very stringent calibration of the pair of subarrays and their receive channels. G. GALATI G. PAVAN Tor Vergata University Department of Electronic Engineering and Vito Volterra Centre Via del Politecnico 1 Roma Italy 00133 E-Mail: (gaspare.galati@uniroma2.it) REFERENCES [1] Levanon, N. and Mozeson, E. Radar Signal. Hoboken, NJ: Wiley, 2004. [2] Searle, S. J., Howard, S. D., and Moran, W. Formation of ambiguity functions with frequency-separated Golay coded pulses. IEEE Transactions on Aerospace and Electronic Systems, 45, 4 (Oct. 2009), 1580—1597. [3] Edde, B. Radar: Principles, Technology, Applications. Upper Saddle River: NJ, Prentice Hall PTR, 1993. [4] Skolnik, M. I. Introduction to Radar Systems. New York: McGraw-Hill International Editions, 2001. [5] Eaves, J. L. and Reedy, E. K. Principles of Modern Radar. New York: Van Nostrand Reinhold, 1987. [6] Borwein, P. B. and Ferguson, R. A. A complete description of Golay pairs for lengths up to 100. Mathematics of Computation, 73, 246 (2003), 967—985. [7] Searle, S. J. and Howard, S. D. A novel nonlinear technique for sidelobe suppression in radar. Presented at the IET International Conference on Radar Systems 2007, Edinburgh, United Kingdom, Oct. 15—18, 2007. Code Tracking Variance Analysis for GNSS Receivers with “Strobe Correlators” To measure noise performance of various correlation techniques, a generic theoretical code variance expression is provided here for arbitrary signal spectra and additive white Gaussian noise. The expression is valid for code discriminators using noncoherent dot-product type structures whose coherent component is based on linear reference waveform shaping. The variance of the proposed BOC-gated-PRN (BOC-GPRN) discriminator and other existing “strobe correlators” are analysed theoretically and validated empirically. Parameter selections are suggested for their optimum noise performance. I. INTRODUCTION Recently, the design of receivers tailored for modernised GNSS signals has become a hot topic. In the interests of interoperability and compatibility between systems, the L1 Open Service channel is being shared by most GNSS and the newly developed regional satellite systems. Updates of the satellites’ direct sequence spread-spectrum signals have been made for improving the synchronisation precision in the code tracking loop by using binary offset carrier (BOC) modulations. Although existing code tracking techniques are also valid for BOC signals, it is desirable to tailor designs for their unique features, e.g. an auto-correlation function (ACF) with a sharper main peak and multiple side peaks. This has triggered new code tracking loop algorithm research and development, particularly in code discriminator design. The design challenges lie mainly in the compromise between multipath mitigation, narrowband interference mitigation and tracking jitter resistance, as well as tracking ambiguity (bias tracking) elimination. Among these error sources, the multipath effect is still dominant for most ground-based applications [1]. However, noise performance also plays an important role in high-precision applications (e.g. aircraft landing, surveying and flight reference systems) [1]. Particularly when side peak cancellation techniques Manuscript received September 2, 2010; revised June 11, 2011; released for publication February 8, 2012. IEEE Log No. T-AES/48/3/944052. Refereeing of this contribution was handled by M. Braasch. The work of the first author was supported during her Ph.D. studies by the Australian Research Council (ARC) under ARC Discovery Project DP0556848. 0018-9251/12/$26.00 c ° 2012 IEEE 2760 IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS VOL. 48, NO. 3 JULY 2012