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C
: Control mean for the quality of the signal by a group of points making spots on the
ONSTELLATION
screen of
the field meter. The more circular and distinct the spots of the constellation, the better the quality
of the
signal. In addition, according to the shape of the spots, you can evaluate the kind of error. This function is
available on field meters that enable the display of the constellation for any type of digital signal QAM,
QPSK
and COFDM.
Typically:
-QAM (cable) : 64 spots (16 spots per quarter)
-COFDM (TNT) : 64 spots (16 spots per quarter)
-QPSK (Satellite) : 4 spots (1 spot per quarter)
-8PSK (Satellite) : 8 spots (on a circle)
C
OUNTER-POLARIZATION: Ratio between the levels received from the desired polarization and the
opposed polarization (it should be as high as possible). To adjust the counter-polarization, you have to
turn the head of
the dish.
D
AB: Digital Audio Broadcasting.
The Digital Audio Broadcasting is a standardized audio broadcasting system (coded in COFDM).
It exists on the following bands:
L Band: 1452-1492Mhz
3 Band: 223-230Mhz
D
VB-T: Broadcasting norm for the terrestrial digital television, COFDM modulation
D
VB-C: Broadcasting norm for the cable digital television, QAM modulation
D
VB-C2: Broadcasting norm for the cable digital television by cable (based on DVB-T2)
D
VB-S: Broadcasting norm for the satellite digital television, QPSK modulation
D
VB-S2: Broadcasting norm for the satellite digital television, QPSK or 8PSK modulation
D
SE
C: Digital Satellite Equipement Control.
I
Q
Control norm for the equipment of reception for satellite signals. Uses a 22kHz signal superimposed to
the
remote supply voltage of the satellite dish.
F
REQUENCY: Parameter that characterizes the radio-electrical wave. It is measured in "Hertz". We
7849B – 7859B – 7817B
p.
108
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