Thanks to the Advanced Testing of Automotive Radars project, our microwave laboratory was equipped with a R&S FS-Z90 harmonic mixer, which allows us to measure the spectrum of signals in the 60–90 GHz band in conjunction with the R&S FSW26 spectrum analyzer. This is actively utilized in our microwave group at the department for the development of artificial radar target simulators.
If we have a car radar that we need to test, we paradoxically often know almost nothing about it. Automotive component information is often unavailable due to safety and competition. To test such a radar using an artificial target simulator, we need to know at least the basic parameters of the transmitted signals. Current commercially available automotive radars transmit FMCW signals in the band normally 76–81 GHz, and the analysis of these signals is quite complicated in the frequency and time domains.
First, we need to perform the frequency conversion of radar signals to the intermediate frequency band around units of GHz so that we can sample the signals correctly with the available AD converters. The lengths of individual chips are in the order of only tens of µs and it is difficult to analyze them in real time. In addition, radars often switch between different modes of operation, where the slopes, durations and periods of the transmitted chips change, so that a simple time base trigger known from conventional oscilloscopes cannot be used. Thus, the analysis is usually performed offline from the measured samples, which are usually several tens of GB from a few seconds of measurement.
