In chapter 12, we learned pulse delay ranging. We have seen that for getting the best detection range, the best radar operation is to use a high PRF (HPRF), which gives the largest average power. HPRF is by nature ambiguous in range, very highly ambiguous. With a typical ambiguous range on the order of 500 meters, HPRF would have to resolve through more than 100 ambiguities in most radars, and more than 500 in some. This has been very difficult to achieve without some rough range information from which to start. Fortunately, there are two other techniques.
The first of these is frequency modulation ranging. As you learned in the text, applying a frequency modulation on the tranmsitted signal will cause a frequency modulation on the return signal, but there will be a time delay on the returned signal. For reasons which will become clear as you do the problems, a linear frequency modulation is used. Mixing the exciter signal with the returned signal will cause a frequency shift proportional to range to be added to the received signal. You will work out the rest in the problems.
Problem 1 - Derive the equations for HPRF Frequency Modulation Ranging (FMR)
Problem 2 - Apply the FMR equations to get range and velocity to a target
Problem 3 - Apply the FMR equations to resolve ghosts with two targets
Problem 4 - FMR Ranging Accuracy
The second technique is FSK ranging, developed by Thomson-CSF Detexis. This technique resolves ambiguous phase from two different RFs (radio frequencies) separated by about 1 kHz. This material is not in your text book, so read the problems carefully.
Problem 5 - Help Martine with her two watches
Problem 6 - FSK Ranging Implementation
Problem 7 - FSK Ranging Accuracy