Page 304 - Fundamentals of Radar Signal Processing
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FIGURE 4.46 Spectra of a 13-bit Barker coded pulse and a simple pulse of the
same length.
Because of the increased bandwidth, the signal processing gain due to
pulse compression with the Barker codes in particular, and phase codes in
general, is the same factor G = βτ that applied for the LFM waveform. This is
sp
again because a simple pulse must be shorter than a phase-coded pulse by the
factor βτ to achieve the same Rayleigh resolution in time. Note that in the case
of phase codes, βτ can also be expressed as τ/τ .
c
One of the major disadvantages of Barker codes is that there are not very
many of them. Barker codes have been found only for N up to 13. Sample Barker
codes of all known lengths are listed in Table 4.1; more than one code exists for
some lengths, while none exist for N = 6, 8 – 10, and 12. The table also lists the
peak sidelobe level (PSL) relative to the mainlobe peak, which is simply 20
log (1/N). Because of the modest lengths, low PSLs are not attainable.
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