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22 01-0870-401B 01/03
Front Panel
LO Freq Sets the frequency to match your LNB downconverter local
oscillator frequency.
Note: The IF frequency is the absolute value of the difference
between the RF frequency and the LO frequency. The
demodulator has a valid IF frequency in the range of 2150 MHz
and 950 MHz. Entering values for RF or LO that equal an out of
range IF frequency value will result in an IF value that is either
the maximum or the minimum IF frequency.
2000 to 15000MHz
Code Rate Sets the Viterbi code rate ■ QPSK: 1/2, 2/3, 3/4, 5/6, or 7/8
■ 8PSK: 2/3, 5/6, 8/9
■ 16QAM: 3/4, 7/8
Sym Rate Sets the demodulator to the frequency of the incoming RF signal.
Note: If an out-of-range value is entered the TDR6 will not
accept the new value and will revert to the previous value
entered.
Since the data rate is proportional to the symbol rate, entering a
data rate value might fail if the corresponding symbol rate is out
of range.
Converting a symbol rate to data rate and vice versa may be
subject to a small rounding error. The error is less than
0.00001%. It is advisable to use the symbol rate representation
when entering parameters if a conversion error cannot be
tolerated.
In cases where the demodulator is not locking on the carrier, it is
necessary to add an offset to the symbol rate. This compensates
for the symbol rate drift. The range of the offset is between
0.0002% and 0.0006%; in general a value of 0.0004% proves
successful to lock on the carrier in these cases.
37500000 sps and 1000000 Sps
To convert symbol rate to data rate, use the
following equation:
Symbol rate x 2 x (188/204) x FEC code rate
Data Rate Sets the data rate of the transport data stream 2 to 48Mbps
To convert data rate to symbol rate, use the
following equation:
Data rate x 1/2 x (204/188) x 1/FEC code rate
LNB Power Sets the voltage of the LNB Off, 13 V, 18 V
Acq Range Defines the size of the frequency range over which the
demodulator will search for the carrier.
0 to 7500000 Hz
Details>Input>Config>Filter: allows you set the PCR filter
PCR Filter Sets the PCR (program clock reference) filter for normal
operations or operations over an ATM network.
■ Normal: set for normal operations
■ ATM: set for operations over an ATM network
Details>Input>Status>RF: allows you to query the receive signal E
b
/N
0
level, the carrier offset, and the current lock status of the
demodulator, decoder, and transport stream; this menu only applies to the currently active RF input.
E
b
/N
0
Query-only; displays the E
b
/N
0
of the RF receive signal
Note: E
b
/N
0
is only available when
Details>Input>Config>Select>Input is set to RF.
Displays the value in dB; value is ± 2 dB
Eb/No values above 16 dB are not significant.
Offset Query-only; displays the RF offset.
The Offset measures the difference, in MHz, between the actual
carrier frequency received by the TDR6 and the carrier
frequency the TDR6 calculates by subtracting the LO parameter
from the RF parameter. For optimum performance, the Offset
parameter should be as close to zero as possible.
For more information regarding the offset, refer to the chapters
on configuration and troubleshooting. Also refer to the appendix
on the QPSK demodulator.
Note: Offset is only available when
Details>Input>Config>Select>Input is set to RF.
Frequency in MHz
Demod Query-only; displays the lock status of the demodulator
Note: Demod is only available when
Details>Input>Config>Select>Input is set to RF.
Locked, Unlocked
Decoder Query-only; displays the lock status of the decoder
Note: Decoder is only available when
Details>Input>Config>Select>Input is set to RF.
Locked, Unlocked
Transport Query-only; displays the lock status of the transport stream Locked, Unlocked
Rate Query-only; displays the output rate for the QPSK demodulator value in bps
Command Description Parameters / Response Values