UNAOHM
42
EP2500 (Rev. 0)
9.1.3
OFDM Display Description
Figure 20
Typical OFDM BER &MER display
When the OFDM module is operating, the screen indicates, from top to bottom, (see Figure 20):
•
The indication of the
CH BER
followed by the card status:
LOCKED
when the signal has been
locked,
UNLOCKED
when the parameters are not in the correct range of values and
NO
CARRIER
in the absence of an input signal.
•
The
ANALOGUE BAR
on the line below moves in a logarithmic scale to shows instantaneous
variations of the BER. This bar becomes longer from left to right in proportion to the better quality
of the signal as the BER decreases (improves). For a BER of 1E-2 (1 error out of 100) or worse, the
printing character of the BER readings become smaller. This limit is only indicative, the decoder
may still be operative although at its extreme limits.
The BER measurement is valid only when the signal is locked.
•
The indication of the
post Viterbi BER (pV BER)
.
•
Further below, is the
number of uncorrected errors
RU
followed by the reading (in parenthesis) of
the amount of time taken to count the errors. The chronometer, like the RU error reading, is reset to
zero when the QPSK signal is not locked. The maximum RU count is 65535.
•
On the line below
MER
(Modulation Error ratio) of the digital channel is shown
in dB. This
measurement too, is valid only when the carrier is locked.
•
The
“CFO”
(Center Frequency Offset) indicates the difference between the carrier frequency set
and the effective operating value.
•
On the same line,
“PWR index”
and a writing:
OK
,
HIGH
or
LOW
are shown. They indicates if
the signal has too high a level, or too low or just appropriate for the card to measure.
•
The tuning frequency , its related channel, if available, and the current program are shown on next
line down.
•
CHBW
and the channel bandwidth, then
CARR
and the number of carriers (or operating mode).
•
Next line down we find
MOD
and the type of constellation, then
CODE
and the Code Rate. On the
same lime
M
followed by the attenuation engaged.
•
SPECT
and the polarity, then
GUARD
and the guard interval are shown on next line down.
•
On the right side of the display, from top to bottom, we have the designations of the softkeys. The
functions the softkeys offer will be described in the section related to how to use the OFDM card.
CH BER: 2.23 E -7 LOCKED
pV BER: 2.12 E-5
RU : 00000 (00h20m03s)
MER: 24.5 dB
CFO: 0.1 PWR index: OK
599.25 CH 37 PR02
CHBW :8M CARR :2K
MOD :64QAM CODE :2/3 M00
SPECT:DIR GUARD:1/32
BACK
AUTO
PRMT
