Operating Manual Vol 1 - ES Documentation

SMIQDigital Modulation2.10.6 Envelope ControlFor TDMA radio networks, in addition to digital modulation, a time-synchronous control of the envelopeof the RF output signal is required. To this effect, SMIQ is equipped with an analog envelope modulatorwhich can be driven via connector POWER RAMP. Instead of the analog control signal the digitalsignals BURST GATE and LEV ATT can be used to control the envelope modulator. In the modulationcoder, a ramp with settable slope is obtained from data changes from high→low or low→high of thedigital BURST GATE signal. The resulting analog signal is taken to the envelope modulator and isprovided at connector POWER RAMP. The LEV ATT signal serves for a defined level reduction.POWER RAMPBURST GATELEV ATTRF Π RF OUTx dBLevel attenuationEnvelope controlFig. 2-59Envelope control in SMIQ with modulation coderThe digital envelope control signals can be fed in externally via connector PAR DATA. With option DataGenerator SMIQB11 provided, the signals can also be generated internally by programming them in theCONTROL LIST (see Section "Modulation Data from Lists").The following table shows the logic function of the two signals BURST GATE and LEV ATT.Table 2-12Logic function of signals BURST GATE and LEVEL ATTBURST GATE LEV ATT Remark1 0 Full level1 1 Level reduced by the value set in dB under POWER RAMP CONTROL -ATTENUATION0 X Maximum level reduction1125.5555.03 2.99E-9