DS335 Synthesized Function Generator
DS335 Synthesized Function Generator
DS335 Synthesized Function Generator
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Sweeps & FSK 2-13<br />
FREQUENCY SWEEPS & FSK<br />
Introduction<br />
The <strong>DS335</strong> can perform frequency sweeps of the sine, square, triangle, and<br />
ramp waveforms. The sweeps may be up or down in frequency, and may be<br />
linear or logarithmic in nature. The frequency changes during the sweep are<br />
phase continuous and the sweep rate may be set between 0.01 Hz and<br />
1000Hz. The <strong>DS335</strong> has a SWEEP output that may be used to trigger an<br />
oscilloscope. The <strong>DS335</strong> is also capable of Frequency-Shift Keying (FSK).<br />
FSK can be implemented either through the internal rate generator or the<br />
back panel external input to toggle between two preset frequencies.<br />
Sweep/FSK Enable<br />
Sweep Type<br />
Sweep Waveform<br />
Sweeps are enabled by pressing [SHIFT][START FREQ] in the Frequency<br />
Sweeps menu. The <strong>DS335</strong> displays the "CONT SNGL" menu which allows<br />
the user to choose between continuous and single sweeps. The <strong>DS335</strong> will<br />
immediately start a continuos sweep unless the user presses the UP/DOWN<br />
arrow key to select SINGLE sweep. Once a single sweep is selected, the<br />
[SHIFT][START FREQ] key triggers the sweep. If the user has selected the<br />
FSK function from the "UNI/BI" (Unidirectional/Bidirectional/FSK) menu, the<br />
single/continuous sweep option is disabled and the "FS OFF" menu appears,<br />
giving the user the choice to enable or disable the FSK function. Once the<br />
FSK function is selected and enabled, the FSK output signal appears at the<br />
<strong>Function</strong> Out BNC.<br />
Pressing the [SHIFT] [STOP FREQ] key sets the sweep to either a linear or<br />
log mode. The UP/DOWN arrow toggles between the two sweep types. The<br />
output frequency of a linear sweep changes linearly during the sweep time.<br />
The output frequency in a logarithmic sweep changes exponentially during<br />
the sweep time, spending equal time in each decade of frequency. For<br />
example, in a sweep from 1 kHz to 100 kHz, the sweep will spend half the<br />
time in the 1 kHz to 10 kHz range and half the time in the 10 kHz to 100 kHz<br />
range). It should be noted that these are digital sweeps, and that the sweep<br />
is actually composed of 1500 to 3000 discrete frequency points, depending<br />
on the sweep rate.<br />
The type of sweep waveform may be set to UNIdirectional (ramp) or<br />
BIdirectional (triangle) by pressing the [SHIFT][SWEEP RATE] key and then<br />
pressing the UP/DOWN arrow keys. If FSK is selected, Frequency-Shift<br />
keying is enabled and the sweeps are disabled. If the waveform is UNI<br />
(Ramp) the <strong>DS335</strong> sweeps from the start to the stop frequency, returns to<br />
the start frequency and repeats continuously. For BI directional sweeps the<br />
<strong>DS335</strong> sweeps from the start to the stop frequency, then sweeps from the<br />
stop frequency to the start frequency, and repeats. If the <strong>DS335</strong> is set for a<br />
single sweep, the sweep occurs only once.<br />
<strong>DS335</strong> <strong>Synthesized</strong> <strong>Function</strong> <strong>Generator</strong>