Operating Manual R&S SMIQ - Volume 1 - Rohde & Schwarz

SMIQTest Procedures5.3.10 Broadband Amplitude ModulationTest equipment - Spectrum analyzer (Table 5-1, item 2)- Signal generator (Table 5-1, item 5)Test setupNoteMeasurement Connect the RF output of the SMIQ to the spectrum analyzer, connectthe signal generator to the I (broadband AM) input of the SMIQ. If the measurement of the modulation frequency response has beensuccessfully performed for vector modulation, only a functional testis required here. Settings on SMIQ:- Test level 0 dBm, test frequency > 30.3 MHz- Select STATE ON in the menu ANALOG MOD/BB-AM. Setting on signal generator:- Level 0.20 V (Vpeak) corresponding to -4 dBm for a modulationdepth of 80% Functional test:Vary the frequency from 1 MHz to 30 MHz on the signal generatorand measure the sidebands referred to the carrier at SPAN 3 MHz.They should be 8 +- 1.5 dB below the carrier level.Repeat the measurement at a frequency of 30 MHz on the signalgenerator and SPAN 70 MHz on the analyzer. The sidebands shouldnow be 8 +-4.5 dB below the carrier level. Complete measurement:Setting on analyzer and measurement as for vector modulation,modulation frequency response, but the level is first to be measuredas reference at the test frequency. Since the sidebands have an offset of m/2 from the carrier, an offsetof -6 dB corresponds to 100% AM. The modulation depth is calculated with the formulam = 2*10 (sideband offset/20) . The frequency response is the difference between thegreatest and the smallest modulation depth.5.3.11 Pulse Modulation5.3.11.1 ON/OFF RatioTest equipment - Spectrum analyzer (Table 5-1, item 2)- Pulse generator (Table 5-1, item 17)Test setupMeasurementRecommended test frequenciesRecommended test level To determine the ON/OFF ratio, connect the spectrum analyzer tothe RF output socket of the SMIQ and the pulse generator to thePULSE socket on the rear of the SMIQ. Setting on SMIQ:- Select SOURCE EXT in the menu ANALOG MOD/PULSE. Determine the output level of the SMIQ at various carrierfrequencies with a "high" and a "low" signal applied. The difference between the output level with a "high" signalapplied and that with a "low" signal applied is the ON/OFF ratio.400 MHz, 1 GHz, 2.2 GHz, 3.3 GHz, 4.4 GHz, 6.4 GHzPcw max1125.5555.03 5.33E-9