2.4 Determination of spectral components
Let’s discuss methods of obtaining information
about optical picture making use of neuron networks.
Envisage some neuron network with nonlinear
interconnections. Assume that optical signal
influences on each neuronlike element. Besides,
magnitude of electrical signal in network is enough
that nonlinearity would be able to reveal itself.
Suppose that only part of all quantity of elements
are lighted up.This group located at the begining of
network.Another part of neurons have no influence of
light and connected with lighted section only
electrically.Such example one can find in /9/.There
non linearity is realized using capacity. After
exposition a set of solitins forms along the network
and besides of this there appears a component of
continuous spectrum. After a while solitons, moving
along the network, reach to its darked part.And
continuous component forms as linear interaction
between neurons.Hence it distributes along whole
line, decreasing own amplitude.Consequently we can
suggest that main part of information contains in
solitons which move with different velocities.Center
of soliton is at
: nt
x = § -c (qt
where B; - const
Its Velorıly is equal to C(- n°) .More strong soliton
moves quicker than weak one.
With the aid of neuron system it is possible to
devide weak solitons which correspond to high
frequency spectrum part from strong ones which
characterize low frequency components of spectrum.
All discussed solitons have different velocities.
Hence at the darked end of network strong pulses
appear earlier. One can offer method of
soliton characteristics determination.Most important
are amplitude and width.But they have one-to-one
correspondence.
Let’s find derivative of signal with respect to
time for two neibouring neurons and compare moments
when y = 0. This procedure enables to get time
interval between apparence of solitons at first and
second neurons.Beometrical distance one can choose
taking into account information about brightness of
source and its extent.Thus at darked end of network
all solitons are identified sequently.
Becouse we envisage situation when process has
become settled, it is possible to realize
identification by control soliton which moves to
meet information ones.It can be recieved from other
networks as well.During collision of two solitons
they acquare phase shifts which depend on components
of discrete spectrum corresponding to them.
Furthemore, these phase shifts may be stated as
following relation
ou Loo "ts S = + Lo Nat Na
Go) 5, d gel AM se
Introduce additional function
F = arctan (e I)
After collision due to phase shifts function F
suffers jump, characterizing by big value of time
derivative.Counting up all those jumps along network
and knowing in advance amplitude of control soliton,
set of discrete components are determined without
fails.
Besides, signal measurement in a single network
the same operation is possible using information,
containing in several networks. Imagine two
identical networks, for example, two neighbour ones.
20
First, light distribution at every of them is
identical too. Let us fix two pairs of neurons at
each network with the same number. And choose those
pairs at a short distance. Begin to calculate
function F using signals from every pair for this
operation. If illuminances are identical as supposed
above, then we will obtain as a result F = 45 in
every moment. The same signal will be observed at
the next output, connected with the next pair.
Examination of pair with another number, different
from those, shows that there are not change of
initial picture. This result shows as well
coincidence of signals at both networks.
Imagine situation when at the second network
initial picture has small differences from first
one. Then , as we have seen above, discrete spectrum
will suffer changes too. Several solitons will
increase or decrease their amplitudes and
accordingly their velocities. That pair of neurons
which number is the least, will acquire
insignificant change. The more number of next pair
is different from initial one, the more function F
acquires change. It can be explained by different
coordinates of two corresponding solitons in some
moment. It is advisable to introduce such parameter
as length of identity. It can be defined taking into
consideration permissible level of difference F from
au",
Üne and the same 2 D network can have different
discrete spectrum structure depending on topology of
all subnetworks. Calculation of function F will
enable to produce optimal topology. Choose minimum
of equivalent length as a criterion of identity. In
that situation discrete spectrum is most rich. Let
us place several pairs of neurons for measurement of
Fat 2D photodetector plane. And envisage several
standart topologies to choose optimal type. This
task was solved for 12x12 matrix with the aid of
digital computer. It Was examined following
types of possible networks : horizontal lines,
vertical lines, rectangulars and spirals. For
different light distribution optimal topology should
be determined.
Algorithm, represented above, evidently is
suboptimal one, because we examined only standart
types of networks. More complex task is to form
network by changing this network through several
steps, leading criterion to minimum.
Several values, corresponding to discrete
spectrum, characterize received optical signal, its
parameters.Comparison with the standart image will
enable to estimate difference in their spectrums.If
it is necessary one can rehabilitate initial image
making use the method of inverse scattering
transform (/10/),
2.5 Signal distortion
Special question of influence of different
distortions of initial image on discrete spectrum
components should be discussed. Assume that light
distribution at the detector plane suffered a small
increment 5 yGO. Then after substitution of it into
Schredinger equation and making some transformations
we get 2
Gy gars ES f$) v Zoe
Hence increments of discrete spectrum component
depend on type of optical signal, i.e. how many
elements there are in the series corresponding to
this signal. Coefficients Yk are time independent.
In other situations it is possible to correct
initial signal with the aid of spectral correction.
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