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Chapter 06 – Measuring range 23
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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 device.
During the scan, the device alternates between the currently set symbol rate and the first two preset symbol rates.
This means that the device scans the satellite range with a maximum of three different symbol rates.
Start the scan by tuning the measuring receiver to a frequency at which the scan should begin (see “Frequency input”).
Pressing
ENTER begins the process, as indicated by the “SCAN” message in the frequency window. When the device
finds a transponder, the search is halted and the measuring receiver measures the frequency found. You can stop the
scan by pressing a number key, an arrow key (
Up/Down ) or the ESC key.
During the scan, the device also detects DVB-S and DVB-S2 signals and adjusts the measuring receiver to the relevant
operating mode.
Note:
In the UNICABLE and JESS operating mode the scan function is deactivated.
6.3.3 DVB-S2 parameters
The parameters are shown in the parameter window. If the measuring receiver is tuned to a frequency (see “Frequency
input”), the DVB-S2 channel decoder attempts to synchronise with the signal that is present; this activity can be traced
using the “SCAN” message in the parameter window.
The receiver first attempts to synchronise to the DVB-S2 signal that is present using the set symbol rate. If this is not
successful, all of the preset symbol rates are set one after another. In addition, the device automatically detects the
DVB-S/DVB-S2 operating modes.
If a QPSK/8PSK signal with the set symbol rate is present, the channel decoder locks and LOCKED is displayed in the
parameter window. Otherwise, the UNLOCKED message is shown. This may be caused by the following: none of the
set symbol rates fit; the receive level is too low; the signal is too noisy; or there is no DVB-S2 signal at this frequency.
When the DVB-S2 channel decoder receives a signal, the device 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.
6.3.4 AFC (Automatic Frequency Control)
Siehe oben unter DVB-S Betrieb.
6.3.5 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 LDPC (CBER) and afterwards (LBER) at the same time.
The LBER is displayed in a smaller font on the top line of the BER window. CBER is below in a large font.