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

Test ProceduresSMIQ5.3.13.3 PhiM Frequency ResponseTest assemblyMeasurementSee section "Test Assemblies", standard test assembly for analogmodulations with audio analyzer Settings on SMIQ:- Carrier frequency 1000 MHz- Level 0 dBm- Select EXT1 in the menu MODULATION/PM/PM1 SOURCE.- Deviation 5 rad Setting on audio analyzer:- Generator level 1 V (V peak ) Vary the generator frequency of the analyzer to determine themodulation frequency response. The modulation frequency response is the difference between thegreatest and the smallest modulation depth.Note: For the FMB, it is recommended that the measurement be carriedout as frequency modulation measurement as this provideshigher accuracy; conversion to phase deviation with formulam = deviation/f mod . Since no frequency response can occur belowfmod 1000 Hz because of the DC coupling, it is sufficient tomeasure the response starting from 1000 Hz (measurementsbelow 1000 Hz are problematic since deviations are very small). Repeat the measurement with the setting PM2 SOURCE EXT2. Repeat the measurement with the setting PM1 SOURCE INT andvariation of the frequency of the internal modulation generator.5.3.14 Digital Modulation (Option SMIQB20)The basic functioning of the module can be checked by calling up the built-in test. To do this, selectUTILITIES/TEST TEST MCOD in the menu. No fault messages should occur.5.3.14.1 Level Error and Residual Carrier with Digital ModulationTest equipment Spectrum analyzer (Table 5-1, item 2).Test setupConnect spectrum analyzer to the RF socket of the SMIQ.Measurement Settings on SMIQLevel 0 dBm, test frequencyDigital modulation, switch on standard GSMSOURCE PATTERNPATTERN 0SYMBOL RATE 300 kHzSTATUS first on OFF. Settings on analyzerCENTER FREQUENCY 1 GHzREFERENCE LEVEL 5 dBmSPAN 1 MHz Measure the level of the unmodulated signal as reference. Settings on SMIQDIGITAL MOD/STATUS ONNow measure the carrier offset by the modulation by ¼ of thesymbol rate.• It should not deviate by more than 0.3 dB of the reference value. Residual carrier = the spectral line remaining at the carrier frequency.• It should be more than 50 dB below the reference value.Recommended test frequencies 100, 1472, (2200), 3300, 4400, 6400 MHz1125.5555.03 5.38E-9