SEFRAM 7849B User Manual page 109

usually use
some multiples of this unit: kilohertz (kHz), megahertz (MHz), gigahertz (GHz).
ex.: At Saint Etienne (Guizay), the TF1 frequency is 583.25 MHz
H
P/LP: high/low priority  possibility to transmit 2 multiplexes under the same channel in digit format (
ex.: in COFDM, we have a very robust high priority flow in QPSK; secondary flow in 16QAM)
G
UARD INTERVAL: The guard interval is the time when the signal is not emitted: all signals carrying
the same
information but coming from different sources (various emitters or through multiple reflections) won't dis-
turb
each other.
Value for DTT: 1/32 (28µs), that permits echoes lower than 8.4km
I
SOFREQUENCY: (or SFN: Single Frequency Network)
A DVB-T emitter network that emits on a whole region or a country at the same frequency.
 risk of echoes outside the guard interval
 moving reception
L
NB: Low Noise Block-converter
A LNB (or universal head) is a standard converter for the analogical and digital reception of a satellite.
18V
H
13V
Waves
V
The reception is made on 2 low/high frequency band and 2 horizontal/vertical polarizations of the received
wave.
The commutation of the band is made by a 13/18Volt voltage. The commutation of the polarization is
made by a 22kHz signal superimposed to this voltage (you can also use the DiSEqC commutation for
some LNB).
L
DPC: Low Density Parity Checker
An algorithm used to correct errors in transmissions of digital satellite transmissions DVB-S2 signals.
N
OISE MARGIN: Difference between the measured and the theoretical noise level before incorrigible
errors.
Difference in dB between the measured C/N and the minimum C/N for error-free transmission.
M
ER Modulation Error Ratio
:
Ratio in dB measuring the distance between the theoretical dot and the observed dot on a constellation
quarter. You can use it to control the reception: the higher this value, the better the image.
7849B – 7859B – 7817B
LNA+MIXER
Communication
control
Local Oscillator
10,6 GHz
22kHz
p.
Local Oscillator
9,75 GHz
0kHz
109
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