If the input signal is like PRN-23 or a video signal, the BER and VBER
measurement are considered as acceptable when BER/VBER ≤ 3*10E-6 and SER-
ERR/s ≤ 2 being SER value the number of wrong packets taken as reference
measurement.
A signal is considered acceptable when SER-ERR/s ≥ 20 dB. This border is know
as TOV (Threshold Of Visibility) and it corresponds to an error rate after Viterbi of
3.0*10E-6 and a MER of 15 dB. This value is marked on the measurement bar of the
SER and therefore, SER for acceptable signals must be at the left side of this mark.
-8
FREQ:
CH:
MPEG-2
Figure 37.- Screen of SER measurement (8-VSB signals).
Finally it is shown a status line with information about the detected signal. The
possible messages that can appear and its meaning are showing the following list. The
messages are exposed from less to more fulfillment of the MPEG-2 standard:
No signal received
No signal has been detected.
Timing recovered
Only it is possible to recuperate the symbol time.
AFC in lock
The system automatic frequency control can identify and lock a digital
transmission (TDT) but its parameters can not be obtained. It can be due to a
transitory situation previous to the TPS identification (Transmission Parameter
Signaling) or well to a TDT transmission with an insufficient C/N ratio.
TPS in lock
The TPS (Transmission Parameter Signaling) are decoded. The TPS are carriers
containing information related to the transmission, modulation and codification:
Modulation type, Viterbi Code Rate, and Number of the received frame.
MPEG-2
Correct detection of a MPEG-2 signal.
Page 58
-6
TOV
57.00
MHz
C/N:
-3
kHz
POWER:
A02
MER:
»
SER:
VBER:
USER'S MANUAL. US TV EXPLORER
ERR.SEG/s
>3
-2
0
>21.3
dB
55.8
dBµV
19.5
dB
1.0E-5
1.0E-8
II
11/2013