User Manual DDS200 Digital Demodulation System 070-9952-00

Manual OperationTable 2–3: Suitable limit values for QAM parametersOrderof QAM416Phase rippleand PE in theC/N for BER passband range< 10 -4 (max)12 dB18.5 dB< 10°< 4°Amplituderipple and AI inthe passbandrange (max)< ± 1 dB< ± 0.4 dBIntermodulationproducts(max)Discrete andgeneralinterferenceand CS (max)Linearity (3rdorder mode)ÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ326421.5 dB24.5 dB< 3°< 2°< ± 0.3 dB< ± 0.2 dBÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ27 dB34 dB37 dB27 dB34 dB37 dB< – dB< 1 dB< 0.5 dBÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ128 ÁÁÁÁÁÁ< 1.5° ÁÁÁÁÁÁ43 dB ÁÁÁÁÁ43 dB ÁÁÁÁÁÁ< 0.2 dBÁÁÁÁÁÁ40 dB27.5 ÁÁÁÁÁÁdB < ± 0.15 ÁÁÁÁÁÁdB30.5 ÁÁÁÁÁÁdB < ± 0.1 ÁÁÁÁÁÁdB40 dB< 0.3 dBÁÁÁÁÁÁ256 < ÁÁÁÁÁÁ1° 46 ÁÁÁÁÁdB 46 ÁÁÁÁÁÁdB < 0.1 dBÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁConditions:ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ1. Abbreviations: PE = phase error (modulator), AI = amplitude imbalance(modulator), CS = carrier suppression2. Deviation from linear phase; depends on whether an equalizer is used.3. Deviation from ideal amplitude-frequency response; depends on whether anequalizer is used.4. The C/N ratio only applies if all other conditions are ideal.5. For the specified linearity, the level drop for a basic signal constellation isspecified.6. All values are based on experience, calculation and simulation. Specifiedlimit values guarantee acceptable reception, provided no other types of erroroccur.Valuable information on the definition of parameters, calculation methods, andinterpretation are given in Explanation of Calculated Parameters, Formulas andLimit Values on page 2–68.Spectrum Measurement and Echo Display. A SPECTRUM and an ECHOPATTERN function are available to help understand the characteristics of yourtransmission channel. Both functions rely on the capability of the instrument toadapt to receiving conditions via the integrated, self-adapting equalizer. Theinternal equalizer coefficients are accessible in the instrument are mathematicallyevaluated to create these displays. With both functions, the calculation isperformed only once, since reading out the coefficients takes several seconds.Another press of the SPECTRUM or ECHO PATTERN key causes the display tobe updated.DDS200 Digital Demodulation System User Manual 2–55