Elektronika 2009-11.pdf - Instytut Systemów Elektronicznych

Associated with every N-point M-dimensional vector quantizer
is a partition of R M into N regions or cells, R i , i =1,...,N. The
i-th cell is defined by:
For a given codebook Y of size N, the optimal partition cells
satisfy:
where i, j =1,...,N and i = j. That is, Q(x) = y i only if d(x,y i ) ≤
d(x,y j ). Thus given the codebook Y, the encoder contains
a minimum distortion or nearest-neighbor mapping with:
For making of measurement of distance, it is necessary qualification
of center of gravity of area, considered as similar. It
was defined the centroid cent(R o ), of any nonempty set
R o ∈ R M as the vector y o (if it exists) that minimizes the distortion
between a point X ∈ R o and y o , averaged over the
probability distribution of X given X ∈ R o . Thus:
for every y ∈ R M . For a given partition {R i ; i =1,...,N}, the optimal
code vectors satisfy:
(7)
(8)
(9)
(10)
Practical results
In this work, it was proposed use speech recognition method
to control the movement of the camera of closed-circuit television
system, and use user verification method to log on to
this system. Scheme of this system was showed on Figures.
In system, during the registering, user must enter his
unique login and read the three long randomly generated expressions.
When registered in the system user logs on, also
must enter his registered login and read one long randomly
generated expression. If this statement is similar to at least
two speeches given by the user login with highest probability,
the system accepts the login into the system correctly. After
adding a new user, the system makes code book, based on
the recorded speech. Next, user must learn in the selected
commands to control camera movement. It was selected the
following commands to control: left, right, top, bottom, zoom,
plus, minus, start, stop, recording, and the numerical values of
the angle of rotation. Each of the commands, during the learning
system, user must repeat five times. For the registered
user, system controls the movement of the camera, using the
database commands created by this user.
Samples were taken at frequency of 8 kHz and 16-bit encoding.
The system includes thirty five different posts, which
are randomly selected during registration or login. In aim to
eliminate harmful interference, the recording of expression is
effected by means of a microphone, equipped with the filter
code and the external processor DSP. For registered users,
the system correctly recognizes all the commands to control
the camera movement.
Area including similar elements, except center of gravity it has
to possess also boundary. Given the partition cells R i , i =
1,...,N, the boundary set is defined as:
for all i, j =1,...,N. Thus, the boundary consists of points that
are equally close to both y j and to some other y i and hence do
not have a unique nearest neighbor. A necessary condition for
a codebook to be optimal for a given source distribution is:
That is, the boundary set must be empty. Alter natively:
(11)
(12)
(13)
(14)
for all i, j = 1,...,N.
Suppose that the boundary set is non empty and hence
there is at least one x that is equidistant to the code vectors y i
and y j . Mapping x to y i or y j will yield two encoding schemes
with the same average distortion. By including the nonzero
probability input point x into either cell (R i and R j associated
with y i and y j , respectively) will necessarily modify the centroids
of R i and R j , meaning that the codebook is no longer optimal
for the new partition. Given a codebook Y of size N, it is desired
to find the input partition cells R i and codewords such that the
average distortion D = E {d(X,Q(X))} is minimized, where X is
the input random vector with a given PDF (Probability Density
Function). All method of vector quantization with use Lloyd algorithm
it was described on base work [4].
Scheme of closed-circuit television system with speech recognition
and and speaker verification
Schemat systemu telewizji przemysłowej z systemem rozpoznawania
mowy i głosowej weryfikacji użytkownika
Conclusion and future work
Now that speech signals are recorded with a frequency of
8000 Hz, the next step in the development of this system will
be able to log into the system and traffic control cameras by
the Internet. Encoded as the recorded sound, and send over
the network should not be a problem. Next, the system will be
equipped with a module to automatically locate the face, eyes
and mouth of person, contained in the frame of the camera.
The given data will be used to verify the identity of persons
on the basis of facial asymmetry.
ELEKTRONIKA 11/2009 67