User Manual

4.9.3. Modulation waveform:
Press【Menu】key to light “Shape” character, the current modulation waveform sequence No. is shown,
input modulation waveform No. with the numeric keys or adjusting knob to select modulation waveform, the
modulation waveform may be any one of the 16 kinds of waveforms listed in the waveforms table in section
4.2.9.
4.9.4. Sync output:
In PWM, the generator outputs a sync signal from the front panel “Sync” connector, which is a square wave
with TTL level and 50% duty cycle, its frequency is equal to modulating frequency and its phase is
referenced to the phase of the modulating signal.
In PWM, press【PWM】key, the “PWM” keyboard light will be off, and the generator exits PWM function and
returns back to continuity function.
4.10. Frequency shift keying（FSK）
In FSK, the frequency of the carrier shifts between “carrier frequency” and “hop frequency” alternately, the
rate at which the output shifts is determined by hop rate, all 16 waveforms could be used as carrier wave, Of
course, using DC or noise signal as carrier wave is invalid. Before entering into FSK, users should firstly set
the waveform, frequency and amplitude of carrier wave under continuity function.
Press【FSK】key to light “FSK” keyboard indicator, the generator enter into FSK function.
4.10.1. Hop rate:
Press【Menu】key to light “Rate” character, then set hop rate value. In FSK, the modulation waveform is
fixed as a square wave with 50% duty cycle, the frequency of the square wave is the hop rate.
4.10.2. Hop frequency:
Frequency shift keying is similar with FM whose modulating waveform is square. “hop frequency” is similar
with “frequency offset”, with the difference of, frequency offset is an offset value that the frequency of carrier
wave plus or minus, whose setting range is relational with the frequency of carrier wave, hop frequency
could be set arbitrarily within whole frequency range, it has no relationship with carrier frequency.
4.10.3. External trigger:
After entering into FSK function, the generator uses internal trigger source as default, outputs FSK signal
based on hop rate set. Press【trig】key, the “trig” keyboard indicator will be on and the generator enters into
FSK mode with external trigger. The trigger signal with TTL level is inputted from the rear panel “Trig In”
connector. If the level of the trigger signal is low, the frequency of the output signal is that of the carrier, if the
level of the trigger signal is high, the frequency of the output signal is the hop frequency. When using
external trigger, the setting of hop rate is ignored. When using external trigger, press 【FSK】key, the “trig”
keyboard indicator will be off and the generator resume to internal trigger mode.
4.10.4 Sync output:
In FSK, the generator outputs a sync signal from the front panel “Sync” connector, which is a square wave
with TTL level and 50% duty cycle, its frequency is equal to the hop rate. If the output signal is the carrier, a
low level sync signal is outputted. If the output is hop frequency, a high level sync signal is outputted.
In internal trigger FSK, press【FSK】key again, the “FSK” keyboard indicator will be off, the generator exits
FSK function and returns back to continuity function.
4.10.5. Output port:
There are two output ports on the front panel of the instrument, users must not input signal to the output port
as a possibility of damaging the instrument.
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