Telestar SATPLUS 4 Operating Instructions Manual page 54

6. SAT MEASURING RANGE
6.2 DVB-S/S2 measurement
> Press the SAT button. The measured values of the selected program are displayed.
EN
PWR
The level measurement starts as soon as the measuring receiver is
tuned. The measured level is displayed in dBμV with 0.1 dB resolution
MER
MER measurement (Modulation Error Rate)
The MER is calculated from the constellation points.
It is the counterpart to S/N measurement for analog transmission methods. The measuring
range extends up to 20 dB with a resolution of 0.1 dB.
BER
The measurement of the bit error rate is used to assess the quality of a DVB signal.
The error correction mechanisms in the digital receiver are used to determine the bit error rate. The
data stream before and after correction is compared and the number of corrected bits is
determined. This number is set in relation to the total number of bits passed through and the
BER is calculated from this.
C/N
Carrier-to-noise , carrier-to-noise ratio
The distance between the carrier and the noise is measured. A good C/N is
a prerequisite for all other qualities BER, MER RollOff
The roll-off factor generally describes the edge steepness when filtering a signal. In satellite
transmission, the roll-off factors are used to define the edge steepness of the DVB-S2 signal. The lower
the number, the lower the required frequency bandwidth. However, this also reduces the signal-to-
noise ratio and therefore the transmission reliability. For DVB-S, a roll-off factor of 0.35 is generally
used.
CodeRate
The CodeRate shows information on the forward error correction (FEC) used for the DVB signal. Forward
error correction takes place as part of channel coding. Redundancy is added to the digital and initially
source-coded signal on the transmitter side in a channel encoder to enable the channel decoder in the
receiver to correct errors that have occurred on the transmission channel. The value of the FEC expresses
the ratio of useful bits to transmitted bits. In this image, 2 of the 3 transmitted bits are useful bits.
Demo
Displays the modulation method used on this transponder.
TELESTAR SATPLUS 4
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