Promax PRODIG-3 Manual Del Usaurio página 124

Figure 29.- Screen of VBER measurement (QPSK signals).
The BER measurement is provided in scientific notation (i.e. 2.0 E-3 means
-3
2.0x10 , that is to say two incorrect bits of every 1.000) and through an analogue bar
(as its length is smaller the signal quality will be better). The analogue representation is
done on a logarithmic scale (not linear).
With the aim to have a reference about the signal quality, it is considered that a
system has a good quality when it decodes less than one non-correctable error for
every transmission hour. This border is known as QEF (Quasi-Error-Free) and it
corresponds approximately to a BER after Viterbi of 2.0E-4 BER (2.0x10
is marked on the measurement bar of the BER after Viterbi and therefore, BER for
acceptable signals must be at the left side of this mark.
Next it is shown the tuning frequency and the frequency deviation in MHz
between the tuned frequency and the one which optimizes the BER (i.e. Freq: 1777.0
+1.2 MHz).
Finally it is shown a status line with information about the detected signal. The
possible messages that can appear and its meaning are shown in the following list. The
messages are exposed from less to more fulfilment of the MPEG-2 standard:
No signal received
Any signal has been detected.
Signal received
A signal is detected but it can not be decoded.
Carrier recovered
A digital carrier has been detected but it can not be decoded.
Page 48
-8 -7 -6
FREQ: 1781.94 MHz
5037 kHz
DL-Ku: 12382.0 MHz
CH: 99 MHz
MPEG-2
USER'S MANUAL. PRODIG-3
-5 QEF -4
C/N: 0.2
POWER: 51.5 dBµV
MER: 10.9
CBER: 9.7E-4
» VBER: 5.2E-8
-3
dB
dB
-4
). This value
03/2008