KOSS-19 Technique for sounding and communication with superwide-band signals

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KOSS-19 Technique for sounding and communication with superwide-band signals

At present stage of progress of radar systems and sounding systems, specific interest has been brought out to technique with superwide-band signals. Great information volume being born by reflected superwide-band signals allows not only to detect remote objects, but successfully perform their recognition at some distance. In the application related to problems of sounding subterranean areas and water depth, flaw detection and tomography, the technique of superwide-band signals allows to achieve positive results, since unpredictable suppressions of some spectral components could not completely destroy a signal.

The main obstacle to inculcate the technique of sounding with superwide-band signals at present is in absence of adequate algorithm of receiving and estimating parameters of reflected signals. Classical radar and sounding theory and technique are built on algorithms of receiving reflected signals using matched filters, which algorithms assume exact information on a form of signals being received. Provided use of superwide-band signals, a form of reflected signals is distorted in unpredictable way. It is substantially affected by configuration, location, reflectivity of objects and propagation conditions in environment. Moreover, monitored object(s) often is (are) disposed at some angle to the sounding direction, which leads to additional distortion of total reflected signal and to origin of "spreading" effect in time. As result, conventional methods of receiving become ineffective or useless.

Concern KOSS has developed conditions which permit to realize the combined algorithm of detecting and estimating parameters (delay and direction) of reflected superwide-band signals arrival, which algorithm allows arbitrary forms of signals being received.

Said adaptive combined algorithm has been obtained as a solution of statistic synthesis problem and meet the asymptotic optimality criterion.

The proposed algorithm of receiving sounding superwide-band signals supposes a realization on the base of antenna array having delay lines in channels.

Analysis of the developed adaptive combined algorithm in the mode of detecting reflected signal and estimating parameters has shown that its operation characteristics in the form of effective signal-to-noise ratio is only 6 dB lower than for ideal situation of receiving with the help of matched filter. However, in contrast to ideal situation, the developed algorithm does not require exact information on reflected signal form and maintains its operability in arbitrary distortions.

At the same time, a new unique possibility inherent to the technique of superwide-band sounding was established and confirmed. This is a capability, using the developed algorithm, to estimate in accordance with responses to one-shot radiation not only distances, but also directions to objects disposed at once in a whole sector. In conventional location methods, objects are detected exclusively in the direction of sounding. At permissible energy losses of the order of 2-2.5 dB, it is possible, using a 10-element linear antenna array with the half-wavelength element spacing, to sound at once all objects in an angle sector of the order 45 -50 at one-shot radiation. Exact ratios establishing a relation between permissible energy losses and sounding sector size bound with chosen direction of superwide-band signal radiation are obtained.

 
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