Kathrein 9986492 User Manual
Const Menu
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Const Menu
The function constellation diagram can be called up in the operation types, SAT
(DVB-S), TV (DVB-C and DVB-T), TV-IF or return path (DVB-C). Operating the
constellation functions is principally the same in the various operating types. The
differences are described below.
(DVB-S), TV (DVB-C and DVB-T), TV-IF or return path (DVB-C). Operating the
constellation functions is principally the same in the various operating types. The
differences are described below.
Colour representation of I/Q value pairs
The colour representation of the I/Q value pairs should
simplify the analysis of the constellation diagram in regards to
the occurring error. The colour of the I/Q value pairs changes
with the number of hits on one point within the decision field.
In an ideal case, the I/Q value pairs are always in the middle
of the decision field. However the I/Q value pairs are
influenced by interference on the transmission paths or in the
modulator on the transmitting side. As long as the I/Q value
pairs lie within the decision waves, a clear relation of valence
in the receiver can occur. The decision field is subdivided into
signal subsurfaces, also called pixels. For a black/white
representation, one could not represent the frequency of the
hits of a I/Q value pair on the surface of a pixel. The colour
representation of the MSK 33 allows the frequency of the hits
of a I/Q value pair on the surface of a pixel to be described by
the changing of colour. If many I/Q value pairs meet on a
pixel, RED is represented, however if very few I/Q value pairs
meet on a pixel, blue is represented. Four colours are avail-
able for the assessment of the „scores.“
simplify the analysis of the constellation diagram in regards to
the occurring error. The colour of the I/Q value pairs changes
with the number of hits on one point within the decision field.
In an ideal case, the I/Q value pairs are always in the middle
of the decision field. However the I/Q value pairs are
influenced by interference on the transmission paths or in the
modulator on the transmitting side. As long as the I/Q value
pairs lie within the decision waves, a clear relation of valence
in the receiver can occur. The decision field is subdivided into
signal subsurfaces, also called pixels. For a black/white
representation, one could not represent the frequency of the
hits of a I/Q value pair on the surface of a pixel. The colour
representation of the MSK 33 allows the frequency of the hits
of a I/Q value pair on the surface of a pixel to be described by
the changing of colour. If many I/Q value pairs meet on a
pixel, RED is represented, however if very few I/Q value pairs
meet on a pixel, blue is represented. Four colours are avail-
able for the assessment of the „scores.“
RED – very many hits
YELLOW – many hits
GREEN – few hits
BLUE – very few hits
YELLOW – many hits
GREEN – few hits
BLUE – very few hits
Constellation diagram for QPSK (DVB-S)
For the digital transmission via satellite,
the modulation type QPSK (Quadrature
Phase Shift Keying) is used. Every 2 in-
formation bits are put together to one
symbol and modulate one carrier in its
phase. With this, four conditions are pos-
sible, which a receiver must recognise.
the modulation type QPSK (Quadrature
Phase Shift Keying) is used. Every 2 in-
formation bits are put together to one
symbol and modulate one carrier in its
phase. With this, four conditions are pos-
sible, which a receiver must recognise.
A crosshair with four clouds, which repre-
sent the possible symbols or their fre-
quency in the quadrants appear on the
colour screen.
sent the possible symbols or their fre-
quency in the quadrants appear on the
colour screen.
Measurement of the bit error rate (BER)
Since it deals with transmission of binary data for DVB-S, the bit error rate can be
considered as measurement for the occurred transmission error in the data stream.
In the MSK 33, a BER measurement is carried out before the viterbi decoder and
displayed on the screen. The bit error rate is the ratio of the number of received de-
fected bits divided by the entire number of the received bits. The lowest bit error
considered as measurement for the occurred transmission error in the data stream.
In the MSK 33, a BER measurement is carried out before the viterbi decoder and
displayed on the screen. The bit error rate is the ratio of the number of received de-
fected bits divided by the entire number of the received bits. The lowest bit error