Page - 14 - in Integration of Advanced Driver Assistance Systems on Full-Vehicle Level - Parametrization of an Adaptive Cruise Control System Based on Test Drives

2. Adaptive Cruise Control 1A 2A A∆ t 0 0 1 1 1− 1− Figure 2.6.: Distance measurement through phase comparison, adapted from [Men99] FSK RADAR The Frequency Shift Keying (FSK) RADAR sends electromagnetic waves alternating between twoconstant frequenciesf1,2 =f0±∆fFSK2 . Thenormalized signals readA1,2 = sin(2pif1,2 t), see fig. 2.6. The RADAR sensor measures the phase angles ρ1,2 of the two signals received and then calculates the phase difference ρ2−ρ1 = 2pi(f2−f1)τ, (2.6) with the corresponding normalized amplitude ∆A= sin(ρ2−ρ1), as depicted in fig. 2.6. Using eq. (2.1), the phase difference of eq. (2.6) is rearranged to ρ2−ρ1 = 4pi c (f2−f1)r, (2.7) where the distance to the object r can be found. Due to the fact that ∆fFSK f0, the relative speed can be calculated using the frequency shift of the Doppler Effect (∆fr˙), as described in eq. (2.2). Chirp Sequence Modulation RADAR TheChirp Sequence Modulation RADAR combines theadvantagesof theRADARsensor types mentioned above, [Win09]. It sends a high number of identical frequency ramps, 14