In this book we have reviewed two LPI radar signal waveforms, FMCW and phase-coded. The complexity of FMCW technology is minimal and it is very popular because of this reason. There are only two major obstacles that can be construed as a disadvantage in FMCW radars. These are the high time side lobes of the order of 13 dB down from the peak response and the nonlinearity in waveform generation for high bandwidths (and consequently high resolutions). The advantage of this waveform, however, lies in its Doppler tolerance, making it eminently suitable for use in aircraft target tracking radars. Phase-coded waveforms, on the other hand, are very easily adaptable to digital signal processing, being digital in nature, and polyphase codes produce relatively low time side lobes and as we have seen in some cases of polyphase codes, no time side lobes in the CW mode.

Chapter Contents:

• 6.1 Introduction
• 6.2 Frequency Hopped Signals as LPI Signals
• 6.3 Stepped Frequency Waveform
• 6.3.1 Range Resolution and Range Ambiguity
• 6.3.2 Effect of Target Velocity
• 6.4 Random Frequency Hopped Waveforms
• 6.5 Technology for SFCW
• 6.6 Hybrid FSK/LFM Technique

Inspec keywords: Doppler radar; spread spectrum radar; aircraft; target tracking; radar signal processing; waveform generators; radar tracking

Other keywords: Doppler tolerance; LPI radar signal waveforms; frequency hopped waveform; aircraft target tracking radars; waveform generation; FMCW; digital signal processing

Subjects: Signal processing and detection; Function generators; Radar equipment, systems and applications