NewsCaster VT2 Operation
M17-0002-01A Rev 0.0 55 User Manual
COFDM PARAMETERS
The COFDM (digital) parameters consists
of five options:
1. Power - toggles the COFDM modulator
“On” or “OFF”.
2. Constellation - provides several different
methods of modulating the signal for
transmission:
• QSPK
• 16-QAM
• 64-QAM
3. Code Rate
Under the Code Rate sub-menu, the user can
set the amount of error correction. The
Code Rate (as well as Guard Interval,
Bandwidth, and Modulation) is instrumental
in setting the proper Data Rate. The options
for the Code Rate sub-menu are:
• 1/2 - code rate used for channels
with the greatest amount of noise.
• 2/3
• 3/4
• 5/6
• 7/8 - code rate used for channels
with the least amount of noise.
4. Guard Interval - COFDM carriers have a
precise spacing between each frequency.
This spacing ensures that only one carrier is
addressed at a time, and that no crosstalk
exists between carriers.
Under the Guard sub-menu, the user can set
the amount of delay interval between
symbols. The options for this sub-menu are:
• 1/32 - shortest delay between
symbols.
• 1/16
• 1/8
• 1/4 - longest delay between symbols.
5. Bandwidth - The bandwidth is the span
or width of a carrier frequency. Under the
Bandwidth sub-menu, the user can select the
size of the carrier bandwidth. The options
for this sub-menu are:
• 6 MHz - usually used for a “split-
channel” due to having the faster
“band re-growth” drop-off rate. The
signal must be offset by using either
+ or – channels.(This technique
works best in the lower RF power
equipment, which keeps re-growth to
a minimum.)
• 7 MHz
• 8 MHz - has the slowest “band re-
growth” drop-off rate.
Use Tables 14 through 16 to identify the
parameters required to set the desired
COFDM data rate:
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