Synthesis of multilevel and binary sequences with good correlation properties
In radar systems the very low side lobes that can be achieved with amplitude and phase modulated pulse trains especially particularly in systems requiring a large dynamic range. Moreover, the excellent self-clutter rejection performance is obtained without sacrificing the ability for the separation...
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| Format: | Thesis |
| Language: | English |
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| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44111/1/p.1-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44111/2/full%20text.pdf |
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| Summary: | In radar systems the very low side lobes that can be achieved with amplitude and phase
modulated pulse trains especially particularly in systems requiring a large dynamic range. Moreover, the excellent self-clutter rejection performance is obtained without sacrificing the ability for the separation of close targets (no main lobe widening). The additional expense of encoding and decoding in amplitude and phase may be justified for radars that must cope with land clutter or operating in a dense-target environment. To choose a
suitable transmit waveform is an important problem in radar design. This is so because, the
waveform controls resolution, clutter performance and also bears heavily on the system
cost. Theoretical studies which provide the basis for technical advances have not so far
solved the general signal design problem. The knowledge about the properties of the pulse
trains shows that, a class of signals particularly well suited to digital processing of
increasing practical importance. Two properties of such sequences are of interest. One is
the energy ratio (ER) defined as the ratio of the total energy of the sequence to the energy
of the largest pulse. The other property is the total side lobe energy (SLE) which is the
energy in the side lobes of the autocorrelation function of the sequency. The work
presented in this research is mainly concerned with the synthesis of multilevel and binary
waveform of any desired length that has high energy ratio and low side lobe in their
autocorrelation function (ACF). For the design of multilevel sequences in iterative
technique is proposed, this techniques employed the properties of optimum inverse filtering
and shown to be effective for the generation of multilevel sequences in any desired lengths.
The method of clipping proposed in this research converts a multilevel sequence to binary
sequence in same lengths while it is still retaining at low side lobe in autocorrelation
function. It is shown that the iterative method based on inverse filtering and the method of
clipping provide effective techniques for the generation of multilevel sequences that have
high energy ratio and low side lobe energy in their autocorrelation function. Such
sequences can then be effectively used to improve the range and Doppler resolution of
radars. |
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