modulating signal source “external” is selected, the symbol “Ext” is displayed and parameters FM
DEVIA, FM FREQ and FM WAVE do not apply (disabled)
Start and stop of FM modulation
An FM signal is generated once FM function mode is selected. The instrument will automatically
output a signal according to the preset parameters. If you do not want to output the FM signal,
simply press the 【output】key to disable the signal output (LED above Output button is OFF). Once
all the parameters are set, you can turn make the FM signal available at the output by pressing the
Output button again.
FM example:
Example configuration: Carrier signal is square, frequency is 1MHz, amplitude is 2V, modulating
signal is generated internally. Carrier waveform is sine (No. 1), Frequency is 5kHz. Peak frequency
deviation is 200kHz.
Press【FM】
Press【frequency】then【1】【 MHz】 (set carrier frequency)
Press【amplitude】, then【2】【 V】 (set carrier amplitude)
Press【Shift】and 【square】 (set carrier waveform)
Press【menu】, select “FM DEVIA”, enter【2】【 0】【 0】【 kHz】 (set FM deviation)
Press【menu】, select “FM FREQ”, press【5】【 kHz】 (set FM frequency)
Press【menu】, select “FM WAVE, press【1】【 N】 (set FM waveform as sine)
Press【menu】, select “FM SOURCE”, press【1】【 N】 (set FM source as internal)
4.6.3 AM modulation
AM stands for amplitude modulation.
Press【AM】to enable AM modulation. The carrier frequency and the AM annunciator is displayed.
Frequency, amplitude, waveform and DC offset of the carrier signal can be set as described in the
previous section of this chapter. The parameters carry over from the parameter settings of the main
waveforms sine and square. In AM only sine and square waves can be selected for carrier.
Press the 【menu】 key repeatedly to cycle through the AM modulation parameters listed below.
AM LEVEL: Modulation depth
AM FREQ: Frequency of modulating signal
AM WAVE: Waveform of modulating signal
AM SOURCE: internal or external modulating signal
In AM mode, to ensure normal signal output at 100% modulation depth, the instrument reduces the
peak-to-peak value of the carrier by 50%. Only sine and square waves can be selected as AM
carrier.
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