User Manual DDS200 Digital Demodulation System 070-9952-00
User Manual DDS200 Digital Demodulation System 070-9952-00
User Manual DDS200 Digital Demodulation System 070-9952-00
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<strong>Manual</strong> OperationFigure 2–27: STATUS menuSAW FILTER. The <strong>DDS2<strong>00</strong></strong> has three slots for accommodating SAW filters. Oneor two filters can be inserted in addition to the 8-MHz filter, which is standard.The required filter is selected by pressing the SAW FILTER BW soft key severaltimes. Unused slots are automatically identified. They are displayed in italics andcannot be selected. When the internal noise generator is active (refer to MEA-SURE Menu on page 2–46), the noise power is automatically increased so that aconstant noise level is obtained in the selected filter bandwidth.SYMBOL RATE. The SYMBOL RATE... soft key is used for configuring thesymbol rate of the QAM demodulator. The rate is calculated from the net datarate D according to the formulaSymbol Rate D 204188 1log 2 (M) ,with M being the order of QAM (M = 4, 16, 32, 64, 128, 256). The factor of204/188 is the result of the Reed-Solomon error protection. This can be seen inthe following diagram.<strong>DDS2<strong>00</strong></strong> <strong>Digital</strong> <strong>Demodulation</strong> <strong>System</strong> <strong>User</strong> <strong>Manual</strong> 2–31
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