AP301-FULL-HD_rev.09_UK
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7.3.3.
NM (Noise Margin)
The Noise Margin is a calculated estimate (in dB) of how much the carrier/noise ratio can
deteriorate before reception will be compromised, based on the set reception parameters
and the measured MER.
The higher the noise margin, the lower the possibility of encountering any problems.
7.3.4.
RU
This parameter is not present for modulated signals in the DVB-T2 standard.
In fact, the DVB-T2 does not have the “REED SOLOMON” correction stage.
RU provides an indication of the signal quality over long time periods. In particular you can
observe the loss of some "blocks" of signal over time which are seen on the television, for
example, as mosaics of squares which are superimposed on the image.
RU (Reed Solomon Uncorrected) is a register that increases when events of this type take
place.
Obviously, the worse the BER, the more quickly the RU will increase.
The register value increases from 0 to 65535 and stops at the maximum value. It is reset
whenever there is a loss of signal lock, whenever new tuning operation is carried out or
whenever the position of the attenuator is changed.
7.3.5.
CSI (Channel Status Information)
The CSI, or Channel Status Information, indicates the sum of the disturbance signals (noise,
interference, etc.) with respect to the desired OFDM signal.
This measurement is expressed as a percentage: the higher the percentage value, the less
reliable the reception of the digital signal. The best theoretical value would therefore be
0%, while the worst would be 100%.
7.3.6.
USE OF THE CARD
Set the frequency like for that of a normal analogue channel. Although the measurement
can also be carried out in Measurement mode, it may be useful to visually check for the
presence of the digital signal by configuring the instrument in Spectrum Analyzer mode.
In order to activate the OFDM card, press the
DIGI
button.
In order for the card to function properly, the indicated “PWR index” level must be “OK”.
Adjust the attenuator if necessary. Use the lowest possible attenuation compatible with the
“OK” indication.
In order to be able to measure the tuned channel the
“MODE”
(indicates the DVB-T or
DVB-T2 selected) and
“CHBW”
(channel bandwidth,) parameters must be correctly set,
unique settings which are the user's responsibility. Proceed as follows for the settings:
press the
MENU
button and select PARAMETERS followed by
ENTER.
The cursor appears
on the screen to highlight the first of the parameters displayed. Rotate the knob to take the
cursor to the desired parameter and then press
ENTER.
Set the desired parameter by
rotating the Shaft Encoder and confirm the selection by pressing
ENTER
. The CARR
(carriers number), MOD (type of modulation), Code Rate (correction code), GUARD (guard
interval) and SPECT (spectrum polarity) parameters are automatically detected and set.
⇒
The CHBW bandwidth setting is extremely important for the card’s proper functionality.
This setting should normally be 8 MHz in UHF and 7 MHz in VHF.
