EHF autodyne signals for tracking the parameters of moving objects

On principal impossibility of autosynchronization of an autodyne by radiation reflected from a moving target

“…In order to use these techniques in analyzing "Doppler autodynes", it appeared necessary to identify two different cases: 1) the case of a weak signal "whose amplitude is such that the reflected signal frequency is outside the synchronization band of the self-oscillating system under study, and the indices of modulation of the autodyne oscillations are quite small", then "the autodyne is a linear mixer", 2) the case of a strong signal, where the reflected radiation frequency is in the "line of synchronization" and "the behavior of autodyne is qualitatively changed", moreover "the change in the autodyne carrier frequency is nonperiodic and represents a continuous transition process", while "the rate of frequency variation is governed by the time constants of the system rather than by the frequency difference (Doppler correction) F D " [2,7]. However, the theoretical investigation and experimental results reported in a number of works [5,6,[9][10][11], as well as some practical application of autodynes in the measuring devices have demonstrated that the autodyne-based SRR successfully operate in a wide range of Doppler frequencies. Furthermore, in a limiting transition to the case of a zero Doppler frequency, for instance, the flight of a target perpendicular to the lobe of the antenna directional diagram during rocket tests [11], no particular problems in the behavior of autodyne oscillators have been revealed.…”

“…When describing the phenomenon under discussion, all the authors were unanimous only in the fact that in a linear approximation the value of the autodyne response is proportional to the reflected radiation amplitude. The phase aspect of the problem was, however, considered from principally different standpoints: in a number of works [2,7,8] it was assumed that the autodyne response results from the Doppler shift of the reflected radiation frequency, in other works [4,5,[9][10][11], the consideration relied on the phase delay of the reflected radiation and it was believed that formation of the autodyne response is controlled by the phase of the electromagnetic wave returned to the resonator of the oscillator.…”

Dynamic features of autodyne signals

“…System of equations (1) and (2) differs from that used in [7] by the presence of the parameter 11 ε that typically must be taken into account when analyzing millimeter-wave autodynes based on solid-state active elements [8,10]. In addition, the function of influence onto the oscillator in system (1) and (2) is represented by the pure "transport" delay of the reflected signal.…”

“…These distortions are manifested through changes of "wave slopes" of the autodyne characteristics depending on the direction of reflector motion and on the internal oscillator parameters [8,10]. The degree of distortion of the characteristics depends on the direction of reflector motion, which is caused by the dependence of the magnitude of autodyne frequency deviations on the sign of the Doppler shift (frequency dispersion of the autodyne frequency deviations [7]). The average oscillation frequency offset for the period of the autodyne response and the distance n 1 r << is absent, and the oscillator response on the amplitude variation contains the constant component whose polarity depends on the sign of the non-isodromous parameter ρ , and its value is determined only by the distortion parameter.…”

“…A large number of works are devoted to an analysis of the special features of signal formation under such conditions. The influence of inertia of oscillation amplitude changes [6] and oscillator anisochronous property was analyzed in [3,7]. In [8], in addition to the above-indicated oscillator properties, the non-isodromic oscillator property consisting in a dependence of the oscillation amplitude on the changes in the oscillation frequency was considered, and the special features of signal formation with allowance for the frequency dispersion of the autodyne frequency deviations and frequency auto-detection were studied.…”