TABLE OF CONTENTS Chapter 4 introduced the concept of the four-dimensional radar resolution cell covering specific regions in azimuth, elevation, range (measured by time delay t d), and radial velocity (measured by doppler frequency f d). Most radar systems exhibit resolution properties in t d and f d that are separable from those in azimuth and elevation. These properties are described by the response function, or cross-ambiguity function, ?( t d, f d) expressed mathematically by
| (5.1) |  |
where A 2( f) is the energy spectrum of the modulation on the transmitted signal, a( t) is the corresponding waveform, H( f) is the response of the receiving filter, and h( t) is its impulse response. These functions are, in general, complex (having phase as well as amplitude variation). In the frequency integral of (5.1) the function A( f - f d) is the spectrum of the doppler-shifted echo signal, while exp( j2 ? ft d) is the phase shift of the spectral component transmitted at f. The time integral of (5.1) contains the product of the delayed waveform a( t - t d) and h( -t), the weighting function applied by the filter to a signal component arriving at time t with phase shift exp( j2 ? f dt). The output voltage ? varies as a function...
