3156B User Manual
Getting Started 1-16
Racal Instrument © 2005
Modulated
Waveforms
Using the latest DDS technology, the 3156B is capable of producing
an array of modulation which, places this generator in-line with high
performance, modulation generators. The 3156B can produce: Sweep,
FSK, Frequency Hops, AM, FM and the most advanced modulation
function - Arbitrary FM. When modulation is used from one channel,
the other channel can either be in the same modulation mode, or
generate an AC continuous function such as standard or arbitrary
waveforms. Description of the various modulation functions is given
below.
Figure 1-10 WaveCAD Example - Modulation panel
Sweep
Sweep modulation allows carrier waveform (CW) to sweep from one
frequency, defined by the sweep start parameter to another frequency,
defined by the sweep stop parameter. Note that CW is sinewave only.
The start and stop frequencies can be programmed with 10 digits
throughout the entire frequency range of the instrument, from 100
μ
Hz
to 25MHz. There are other parameters that control how the waveforms
are swept, these are:
Sweep Time
– defines the time that will lapse from sweep start to
sweep stop frequencies. Sweep time is programmable from 1.4
μ
s to
40s.
Sweep Step
– selects between linear or logarithmic steps.
Sweep Direction
– defines if the carrier will sweep from start to stop
or from stop to start frequencies.
