Planar IT-088, Operating Manual

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The other area of the screen is divided into two fields for the measured parameters. The
first field is the modification error ratio MER . The second one is the bit error rate in the
digital stream after Viterbi decoder ( postBER ). The postBER value will be indicated
depending on achievement of the threshold value 2x10
-4
. If the postBER value is under
the threshold you will see pass (allowed value) message, otherwise you will see fail
message. Each parameter is represented both in numeric and graphic (as an indicator
line) form.
Frequency adjustment
To measure the signal quality parameters in a channel, select the required one by « »
and « » keys. To enter the channel number from the keypad, first press «F1» . enter
channel message will be for a short moment displayed on the screen. To enter the number
use the alphanumeric keys set. To enter special channels first press «C» key. After you
have entered the number press «MENU/ENTER» . If the number is incorrect, after you
pressed «MENU/ENTER» key the previously saved channel number value will be
restored. To enter the frequency value from the keypad, first press «F2» . enter frequency
message will be for a short moment displayed on the screen. To enter the frequency value
in MHz use the alphanumeric keypad. After you have entered the number, press
«MENU/ENTER» . If the frequency value is incorrect, after you pressed «MENU/ENTER»
key the previously saved value will be restored. The frequency value will scroll from max to
min with 0.125 MHz step. The value being edited will be highlighted in inverse colour and
flashing.
In «Channel plan operation» mode (4.3.10) pressing « » and « » keys will scroll the
digital channels, and in the top line you will see the name of a channel from this channel
plan. If there are no digital channels in the selected channel plan,
No digital channels in
selected ch. plan message will appear on the screen when you enter this mode, and the
Analyzer will switch to operation mode without channel plan. You can tune to any channel
or frequency entering its number by the alphanumeric keypad. If the channel does not
belong to the selected channel plan, its name will not be shown. If the frequency does not
belong to any channel in the selected channel allocation standard, «---» message will be
displayed on the screen instead of the channel name. If the entered frequency is not equal
to the value of frequency point in the frequency plan, the name of the frequency point is
displayed on white background (without color inversion).
If no channel plan is active, tuning to the channels and their numbering will be fulfilled in
accordance with the channel allocation standard (section 4.3.10).
Demodulation parameters adjustment
To perform measurement of the signal quality the DVB-T/H demodulator requires the
setting of the following parameters: subcarriers modulation type, channel bandwidth, the
number of subcarriers, guard interval, mode of hierarchical modulation, and FEC. These
parameters can be set through a channel plan or defined automatically while tuning to the
channel. If you operate a channel plan, the required parameters will be determined by this
plan. In case DVB-T/H demodulator cannot achieve synchronization with the input signal,
signal parameters auto detection mode is activated. If no channel plan is active, the
demodulator will immediately enable the parameter auto detection mode.
Channel synchronization process is shown as a progress bar. If the parameters have
not been determined in 20 seconds, it may mean that synchronization is impossible. After
synchronization is achieved,
«LOCK» message appears instead of the progress bar. If the
channel level is too low, then «NO SIG» message appears.