Page 298 - Fundamentals of Radar Signal Processing

long so that a scatterer will only influence measurements in one coarse range

bin, avoiding range ambiguities. On the other hand, the shorter τ is made, the
greater the potential straddle loss for targets located between coarse range
samples. A detailed consideration of these tradeoffs is in Keel and Baden
(2012).
Details of the Doppler response and ambiguity function of the linearly
stepped frequency waveform are available in Levanon and Mozeson (2004). A

small central portion of the ambiguity function is shown in Fig. 4.41 for the case
M = 8 pulses, PRI T = 10τ, and a frequency step size of ΔF = 0.8/τ. The
resulting bandwidth is β = M · ΔF = 6.4/τ Hz. The AF displays both the skewed
response typical of a linear FM modulation, and the range and Doppler
ambiguities typical of pulse burst waveforms. Ambiguities in delay (range) are
evident at intervals of T seconds, corresponding to 1/8 = 0.125 on the
normalized scale of the figure. The first zero in Doppler of the main ridge

occurs at 1/MT Hz, corresponding to 1 on the normalized Doppler scale.

FIGURE 4.41 Contour plot of the central portion of the ambiguity function of a

pulse burst waveform. M = 8, T = 10τ, and ΔF = 0.8/τ.

Figure 4.42a further magnifies the delay coordinate of this AF. The delay

coordinate now covers the interval ± τ = ± 0.0125 (± 1/80) on this normalized
scale. The zero-delay and zero-Doppler axes are highlighted by the heavier gray
lines. The expected Rayleigh resolution in delay is 1/ΔF = τ/6.4, which