Operating Manual Vol 1 - ES Documentation

SMIQDigital Standard 3GPP W-CDMA (FDD)2.14.2.3 WCDMA/3GPP Menu - Display of CCDFFig. 2-111DIGITAL STD – WCDMA/3GPP – CCDF menu with a traceA complementary cumulative distribution function" can be generated from the filtered I/Q samples. Thisfunction gives the probability of the magnitude of a complex sample exceeding a predefined threshold.The complete waveform, i.e. the sum for all (max. 4) stations is used to calculate the CCDF.If this threshold is thought of as the radius of a circle centered on the origin, the radius is plotted along thehorizontal axis and the probability of the samples lying outside this circle along the vertical axis. Only radiithat correspond to values that are at least as great as the average power are considered.The crest factor can be read off at the intersection of the trace with the x axis. The precise value isobtained from the displayed levels (PEP-LEVEL).Fig. 2-112Reading off the crest factor from LEVEL displaysIn this example, the crest factor is 7.8 dB.The number of simultaneously displayed traces can be set with the menu item NUMBER OF CCDFTRACES. Displaying several traces shows the effect of the parameters on the envelope. The basebandfilter, the timing offsets and the channelization codes in particular have an effect on the CCDF.The last three traces are distinguished in the following way:Current trace:Last trace:Last but one trace:Fig. 2-113DIGITAL STD – WCDMA/3GPP – CCDF menu with three traces1125.5555.03 2.191E-9