Modulation EN 8.1.6 Modulation Depth The modulation depth is a percentage that represents the amplitude variation. Press [Mod] > Depth softkey to set AM modulation depth. Modulation depth range: 0% to 120%. The default is 100%. At 0% depth, the amplitude is one-half of the carrier’s amplitude setting. At 100% depth, the output amplitude is equal to the specified value. In >100% modulation, the output amplitude of the instrument would not exceed 10Vpp (50Ω load). When external modulation source is select, the output amplitude of the instrument is also controlled by the ±4V signal level on the [FSK/Trig/Sync/Extmod] connector on the rear panel.
For example, set the modulation depth to 100%, the output amplitude is the maximum when the modulating signal is +4V and the minimum when the modulating signal is -4V. 8.2 DSB-AM Modulation 8.2.1 Select DSB-AM Modulation Press [Mod] > Type > DSB-AM softkey to enable DSB-AM function. ⚫ When Mod is enabled, Sweep or Burst will be disabled automatically. ⚫ After DSB-AM is enabled, the instrument will generate DSB-AM waveform with the currently specified carrier and modulating waveforms. To avoid multiple waveform changes, enable modulation after configuring the other modulation parameters. 8.2.2 Carrier Waveform Shape DSB-AM carrier shape:
Sine (default), Square, Ramp, Pulse, Arbitrary (except DC) or Harmonic waveform. ⚫ Press [Wave] button on the front panel to select the desired carrier waveform. ⚫ Noise and DC could not be used as carrier waveform. 8.2.3 Carrier Waveform Frequency For different carrier waveforms, the settable range of carrier frequency is different. please refer to "Frequency Characteristics" in Specifications. The default value is 1kHz. Copyright © Qingdao Hantek Electronics Co., LTD HDG3000B User manual 37 In the Double-sideband AM signal, there are only two side frequencies, and there is no carrier component. Its frequency bandwidth is still twice the frequency of the modulated signal.