Chapter 6 - Measuring range
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When the DVB-S channel decoder receives a signal, the instrument shows its code rate and
modulation scheme in the parameter window. At the same time, bit error rate and MER measurement
is activated. The measured values are shown in the BER window and the MER window. The MPEG
window is also displayed; here you can follow the search for PSI (program service information) in the
transport stream. Further information can be found in the “MPEG Decoder” section.
6.2.4 BER
measurement
(bit error rate measurement)
As mentioned in the previous section, the BER measurement result is displayed in the BER window.
The measuring receiver can measure the bit error rate before Viterbi (CBER) and after Viterbi
(VBER) simultaneously. VBER is displayed in a smaller font on the top line of the BER window.
CBER is below in a large font.
6.2.5 MER
measurement
The MER value of the signal in the baseband (after the demodulator) is displayed in dB in the MER
window. The measuring range is between 2.0 and 20.0
dB. The resolution is 0.1 dB.
6.3 DVB-S2
mode
Use this mode to receive and measure QPSK/8PSK-modulated DVB-S2 signals.
DVB-S2 is a further development of DVB-S. In addition to QPSK a higher-quality modulation scheme
(8PSK) has been introduced. As an option, pilots can be transmitted to help the receiver synchronise
when reception conditions are not favourable. Furthermore, more efficient error protection
(LDPC/BCH) increases bandwidth effectiveness (bit rate/bandwidth at the same MER).
6.3.1 Symbol rate input
You must set the corresponding symbol rate before receiving a DVB-S2 signal. The instrument offers
the operator five preset symbol rates for rapid input.
MODE -> Symbol rate
opens the selection area
for the five preset symbol rates. Use the
Up/Down
arrow keys
to select the required symbol rate. The
new symbol rate is set when you press
ENTER
.
Press
->
to change the preset symbol rate between 2,000 kBd and 45,000 kBd (2000 - 45000
MSym/s). The default preset symbol rates are 27500, 22000, 5632, 4000 and 2400 kBd.
6.3.2 Scan
Use this function to scan the entire satellite frequency range (910 – 2,150 MHz) for DVB-S signals
whose symbol rates correspond to the value that is currently set in the instrument.
During the scan, the instrument alternates between the currently set symbol rate and the first two
preset symbol rates.
This means that the instrument scans the satellite range with a maximum of three different symbol
rates.
