Appendix
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7.12 Frequency Sweep
Frequency sweeping is similar to FM but no modulating waveform is used.
Instead, the function generator sets the output frequency based on either a
linear or logarithmic function. In a linear sweep, the output frequency
changes in a constant “hertz per second” manner. In a logarithmic sweep,
the output frequency changes in a constant “octaves per second” or
“decades per second” manner. Logarithmic sweeps are useful for covering
wide frequency ranges where resolution at low frequencies could be lost
with a linear sweep.
You can generate a sweep using an internal trigger source or an external
hardware trigger source. When the internal source is selected, the function
generator outputs a continuous sweep at a rate determined by the sweep
time specified. When the external source is selected, the function generator
will accept a hardware trigger applied to the front panel External-In
connector. The function generator initiates one sweep each time External-In
receives an active edge.
You can generate a sweep in combination with all trigger modes. Therefore,
it is possible to generate a continuous sweep as well as triggering or gating
a sweep. In triggered mode, one sweep will be generated for each trigger
event. In Gated mode, continuous sweeps will be generated while the gate
signal is active. A sweep will always be finished before starting a new one.
This does limit the maximum trigger rate or the gate timing to the sweep
time (or multiple in case of a gated sweep).
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