Active remote-sensing methods and instruments such as microwave radars, optical radars (lidars), and acoustical radars (sodars, sonars) have widely been used for in-depth or surface probing of atmosphere, ocean and earth (Doviak & Zrnic, 1984; Measures, 1984; Kovalev & Eichinger, 2004; Van Trees, 2001; Marzano & Visconti, 2002). The recent active sensing methods are based mainly on the so-called lidar (LIght Detection And Ranging) or Time-OfFlight (TOF) principle (Measures, 1984; Kovalev & Eichinger, 2004). This principle consists in the detection of backscattering-due radiative returns (at angle π) from the probed media after irradiating them by penetrating narrow-beam pulsed radiation. Then, the return signal profile detected in the time domain contains range-resolved information about the radiation-matter interaction (absorption and scattering) processes and the related material characteristics along the line of sight (LOS). The range-resolution scale (along the LOS) is determined by the (larger of the) characteristic pulse response length and the sampling interval Δz0=cΔt0/2 of the lidar system, and by the noise level and bandwidth (Gurdev et al., 1998, 1993); Δt0 is the sampling interval (the digitizing step) in the time domain. The value of Δz0 is usually assumed to be less than the least variation scale of the investigated extinction and backscattering inhomogeneities. Thus, a “hardware” way of improving the accuracy and resolution of lidars is to use as fast as possible analog-to-digital converters (ADC) and as short as possible sensing laser pulses. Consequently, the realization of the hardware approach depends on the development of the electronic and laser technologies and is connected with overcoming different technological difficulties. For instance, shortening the laser pulses is often connected with lowering the pulse energy or increasing the (peak) pulse power. Then, in the former case one should amplify the shortened pulses while in the latter case the pulse power should be restricted to avoid nonlinear disturbance of the investigated (sensed) medium. Let us also note that in coherent heterodyne lidars the sensing pulse length should be above a threshold determined by the required resolution of measuring the Doppler velocity and the wavelength of the sensing radiation (Hannon & Thomson, 1994). The only way of improving the range resolution in this case is to use shorter laser pulses of proportionally shorter radiation wavelength. As another example one may consider GRAYDAR (Gamma RAY Detection