QubeFlex handles a wide range of common space packets protocols as well as unformatted data, and helps Operators cope easily with the large Doppler frequency
shifts that are common to LEO satellites.
Here, L is the total number of possible propagation paths, [f.sub.Dj] is the [j.sup.th] path Doppler frequency
shift which creates ICI of the received signals, [h.sub.j] is the complex impulse response of the [j.sup.th] path and [[tau].sub.j] is the [j.sup.th] path time delay and [a.sub.n] is the complex path attenuation factor which gives the time varying complex amplitude, defined as the exponential term [mathematical expression not reproducible].
For example, when the L-band radar operating wavelength X > 15 cm, the speed of a conventional aircraft is less than Mach (Ma) 3; thus, the Doppler frequency
is less than 5.4 kHz, while the L-band signal bandwidth is several MHz.
This change in frequency is known as the Doppler frequency
Herein, the Doppler frequency
is estimated due to phase change undergone by the beat signal along a series of ramps of the FMCW signal, considering the null intra-pulse movement .
On this foundation, the current study analyzes and builds models for the principle of ultrasound reflection in drilling mud and explains the relationship between mud flow rate and Doppler frequency
shift under the condition of continuous nonoriented ultrasound reflection.
Because BeiDou GEO satellites are almost stationary relative to Earth, they cannot use relative motion to produce Doppler frequency
shift of DDM and are not considered in simulation experiments.
In , a cooperative antenna system is built on separated train carriages and a Doppler frequency
offset estimation and joint channel estimation algorithm exploited multiantenna diversity gains are put forward.
That is, when the velocity of a moving target is more than [V.sub.max]/K, the detected Doppler frequency
of this target is placed in the wrong frequency domain.
Compared with ambient noise and reverberation has its unique characteristics, one of the most important, the reverberation is caused by the emission signal, and has close relation with the environment, and the waveguide, therefore spectral properties of the reverberation and the target echo signal under the condition of the Doppler frequency
shift is correlation is very strong, and present a strong non-stationarity.