UNAOHM
EP2500 (Rev. 0)
33
Figure 16
OFDM display
Pressing additional multifunction key
(36)
allows the desired modulation (16QAM, 64QAM, QPSK),
the number of carriers (2K, 8K), the Guard interval (1/4, 1/8, 1/16 and 1/32) and the Code Rate (1/2,
2/3, 3/4, 5/6, 7/8) to be set. To return to the display as per
Figure 16
, press the additional multifunction
key
(36)
.
For BER estimation it is necessary to proceed as follows:
1. Check the reference frequency for noise measurement on the lower box at the middle-to-left hand side
of the display. If the reference frequency is not the desired one, press
CARR
to have
NOISE
shown
on the display: this makes the correct setting of the noise frequency possible by means of the keypad
or the knob. Press
↵
ENTER (21)
to confirm the new setting of the noise frequency.
2. Pressing
EXEC
starts measuring: it will take a few seconds for the CH BER reading to show on the
higher box at the middle-to-left hand side of the display. As we said, the CH BER is derived from
measuring the C/N which, in turn, is indicated on the middle box at the middle-to-left hand side of
the same display.
3. Press
BACK
to exit this operational mode.
7.19.5.2
QAM BER Estimation
As far as QAM BER estimation is concerned, the same procedure as that we described for OFDM
signals (see 7.19.5.1.) applies.
Notice though the only difference is the parameter setting: you only have to set the modulation
constellation here viz, QAM64, QAM128 or QAM256.
7.20
DATA LOGGER
The data logger featured by the instrument makes it possible to carry out measurements and store their
results. Stored data are available for further analysis on the picture tube of the instrument and by means
of the RS232 serial port.
A maximum of 700 acquisitions may be stored.
In addition to the frequency and channel, it is possible to store:
•
level, V/A, C/N for analogue signal measurements.
•
DCP, BER, MER for digital signal measurements per acquisition.
Following data acquisition, all data may be simultaneously cancelled or each acquisition one by one.
The acquisition of analogue and/or digital programs is possible, up to 100 programs per acquisition.
BER
842.00 CH 67 pr 00
650.00 M20
EXEC
OFDM
CARR
BACK
[1.1 E- 7]
CH BER preViterbi
[41 dB]
CND:
