Alcad DM-102, Техническая записка

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10
Attenuation is the dropdown box that allows you to adjust the power level output of the
modulator.
Press transmit button on the programmer to send the change through to module.
Offset is the dropdown box that gives you the option to add or subtract either 0.166 or
0.125MHz of the output digital RF frequency. Look at table to give you the decimal
conversion.
Fraction
Offset Decimal
Offsets
+ 1 / 6 +0.166
- 1 / 6 -0.166
+ 1 / 8 +0.125
- 1 / 8 - 0.125
Bandwidth in Australia must
‘ALWAYS’ be set to 7 MHz .
Press transmit button on the programmer to send the change through to module.
Mode can be set to either 2K or 8K. DVB-T offers a choice of two options for the number of
carriers, each with the same fundamental data capacity. In
"2K" mode , 1705 carriers are used
to carry symbols with a useful duration of 224m s, whereas in "8K" mode there are 6817
carriers with a useful symbol duration of 896m s. The reason for having two modes is to allow
a trade-off to be made between receiver complexity and the ability to withstand long echoes.
Press transmit button on the programmer to send the change through to module.
Modulation has 3 modulation options QPSK, 16QAM, 64QAM. There is a balance between the
amount rate at which data can be transmitted and the signal to noise ratio that can be
tolerated. The lower order modulation formats like QPSK do not transmit data as fast as the
higher modulation formats such as 64QAM, but they can be received when signal strengths
are lower.
Press transmit button on the programmer to send the change through to module.