54
2)
External source
When using an external modulation source, the rate will not be shown in the parameter list, when an external waveform
will be used to modulate carrier waveform. FSK output frequency is determined by logic level on the external digital
modulation interface (FSK Trig connector). For example, when external input logic is low, carrier frequency is output;
when external input logic is high, hopping frequency is output.
Set hopping frequency
After you use FSK function, the default hopping frequency is 1MHz. You can change it with the multi-functional control and
direction keys on the interface for using FSK function or by pressing Hop Freq. The range of hopping frequency depends
on the carrier waveform. See the table below for frequency range of carrier wave:
Table 4- 6
Carrier waveform
Frequency
72-14120
72-14122
72-14126
Sine wave
1μHz~ 80MHz
1μHz ~ 120MHz
1μHz ~ 160MHz
Square wave
1μHz ~ 30MHz
1μHz ~ 40MHz
1μHz ~ 50MHz
Sawtooth wave
1μHz ~ 30MHz
1μHz ~ 40MHz
1μHz ~ 50MHz
Pulse wave
1μHz ~ 2MHz
1μHz ~ 3MHz
1μHz ~ 4MHz
Arbitrary wave
1μHz ~ 30MHz
1μHz ~ 30MHz
1μHz ~ 30MHz
Set FSK rate
The frequency between carrier frequency and hopping frequency can be set in case of internal modulation source. After
you use FSK function, you can set FSK rate, which is in the range of 2mHz~100kHz and 100Hz by default. You can
change it with multi-functional control and direction key on the interface for using FSK function or by pressing Rate.
Note: FSK rate can only be changed after FSK function is used. Press MOD, Type and FSK in sequence (press soft key
“Type” to select ) to use FSK function.
Comprehensive example
First set the instrument to run in FSK mode, and then set an internal sine wave of 2kHz and 1Vpp as carrier signal. Set
hopping frequency to be 800Hz. Finally set frequency between carrier frequency and hopping frequency to be 200Hz. The
specific steps are as follows:
3)
Use FSK function
Press MOD, Type and FSK in sequence (press soft key “Type” to select ) to use FSK function.
