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Parameter
Modulation
RF Switch/Pol
Carrier
Data_rate
Fec_rate
Tag_site
[program]
Label
4.4 Frequency Tagging
General
Frequency Tagging is a mechanism that is used to ensure that an IRD is locked to desired
Rules
carrier settings. Sometimes, due to minor offsets in LNB and frequency errors, tuning may
be off by a couple of MHz. To prevent locking to some other near by (adjacent) carrier while
looking for an intended carrier, the acquired carrier contains "frequency tags." These tags
are inserted in Compel control stream at the uplink to identify the intended carrier frequency.
Traditionally, the tags have been sent at a rate of every 100 or 125 ms.
The Unity 552 supports both single and multiple tags. A carrier settings with "Tag Site"
number, specifies which of the possible tags the IRD need to use. The Unity 552 allows for
Tag Site designations from 0 to 15, inclusive. The tag '15' is reserved for an exception. If the
Carrier Setting shows Tag Site '15', the Carrier Tags are not required.
The SCPC Frequency Tag Protocol Functional Specification (WCI #16803) gives more
details.
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Table 4.3: Signal Quality Information
8PSK/QPSK/S1
If IRD is configured for Universal LNB, H or V are valid. Specify RF port 1-4
for four-port RF configuration.
The downlink frequency specified in MHz with up to two decimal places.
This value's absolute difference with the LNB LO frequency is used as
specified in the technical specifications.
Data rate is specified in Mbps with up to three decimal places. See the
technical specifications for the applicable range.
The inner FEC code ratio and can have one of the values specified in the
technical specifications.
Value of 0-14 (15 is a special NO Tag case) specifying the location of this
carrier's tag frequency
The program number from the MPEG Program Association Table. This must
be number from 1 to 65535. If omitted or an '*' is entered, the unit will select
the first available program stream. Note that this number points to the PID
for the Program Map Table for what we might call a "service" (a single video
channel and associated audio signals).
A string of characters for identification.
800089-01 Rev. C
Unity 552 User's Manual
Description
41
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