User Manual DDS200 Digital Demodulation System 070-9952-00

Manual OperationThe magnitude of the DC component is equal to the radius of a circle thatwould be obtained in the event of a frequency offset of the interferencerelative to the carrier signal. In the constellation diagram, a residual carriershows up as a shifting of the signal states corresponding to the DC componentsof the I and Q components. See Figure 2–51.Figure 2–51: Constellation diagram of 64QAM signal with residual carrier inI component (CS = 17.6 dB)Additive Gaussian NoiseNoise can disturb the digitally modulated signal during analog transmission.Additive superimposed noise normally has a constant power density and aGaussian amplitude distribution throughout the bandwidth of a channel. If noother error is present at the same time, the points representing the idealsignal status are expanded to form circular “clouds.” See Figure 2–52.2–66 DDS200 Digital Demodulation System User Manual