GSS PTDT 1000, Руководство по сборке

Страница: 27 / 48

- 27 - PTDT 1000
h
ier arChiCal modul ation
In order to attain with less field strength a greater range for broadcasters,
with DVB-T so-called "hierarchical modulation" can be used. In this process,
several data streams are modulated onto a DVB-T data stream using "Quad-
rature Amplitude Modulation" (QAM). The robust "High Priority" data stream
(HP) with a lower data rate is modulated onto the more sensitive "Low Priority"
data stream, which possesses a higher data rate. If "hierarchical modulation"
is used by the transmission, in good reception conditions, the receivers can
receive both data streams; in poorer reception conditions, only the "HP" por-
tion.
Bx 4A
Priority:
high
INPUT
• By pressing set to " high " or " low " (not relevant in the case of stand-
ard modulation).
• Press the button.
—> The menu "Station filter " – " PROGRAM " is activated.
s
tation filter
The default setting for the station filter is " off ". In this menu you define the sta-
tions received to be transmitted. If stations are activated the output data rate
increases.
If the station filter is switched off (factory default) all stations of the transport
stream passes the station filter. As soon as the station filter is activated all sta-
tions are inactive and can be added to the transport stream selectively.
The figure of the menu below is dependent on the setting of the "Selecting the
input signal path" menu (page 7).
The menu shows the setting " A+B+ASI = 1 ASI = 2 ".
With this setting the transport stream of channel strip " B " is routed to the trans-
port stream of channel strip " A " and therefore cannot be set in channel strip
" B ". Programming channel strip " B " the transport stream coming from the ASI
input can be processed only.