TABLE OF CONTENTS F.E. Nathanson
M.N. Cohen
This chapter includes a discussion of the most widely used forms of pulse compression, those that fall into the general class of frequency modulation. Frequency-modulated (FM) waveforms can entail linear (LFM) or nonlinear (NLFM) modulation of the frequency of the transmit waveform. These modulations can be implemented either within a single coded pulse (intrapulse modulation) or on a pulse-to-pulse basis (interpulse modulation). Also, the frequency modulation may be achieved via either an analog (continuous) or a digital (discrete) process.
Since both frequency and phase modulation are forms of angle modulation, the discussion begins with an example relating FM and phase-coded waveforms. In the rest of the discussion, the formulation, generation, and processing of classical coded pulse LFM as well as more recently developed NLFM and interpulse waveforms are treated.
It was shown in the chapter on signal processing concepts and waveform design that the basis of improved range resolution is some form of modulation or coding within the envelope of the transmit pulse that widens the signal spectrum. While binary or 0-to-180 phase coding accomplishes this same end, it is not categorized as frequency modulation, and was therefore treated separately in Chap. 12.
It is interesting to note that the Frank polyphase codes (Sec. 12.5) are actually a phase approximation to a frequency code. If the Frank code for 64 segments is written as an 8 8 matrix with segments 1 through 8 making up the first row; segments...
