Tabor 8020, User Manual

Page: 33 / 111

SWEEP UP - The function generator, when triggered,
sweeps from value set by FREQ to value set by STOP.
Sweep time is determined by TIME. At the end of the
sweep, the output waveform remains at the stop fre-
quency. Following another trigger, the output jumps
quickly to its start frequency and the above cycle is re-
peated. In normal mode the generator repeats its sweep
cycle continuously.
SWEEP DN - The sweep down mode is similar to the
sweep up mode except that the output waveform, when
triggered, sweeps from frequency set by the sweep stop
(STOP) parameter to frequency set by the sweep start
(FREQ) parameter. Sweep time is determined by the
TIME parameter. At the end of the sweep, the output
waveform remains at the start frequency. Following an-
other trigger, the output jumps quickly to its stop fre-
quency and the above cycle is repeated. In normal mode
the generator repeats its sweep cycle continuously.
SWEEP UP-DN - The function generator, when trig-
gered, sweeps from value set by the FREQ parameter to
value set by the STOP parameter and back to the FREQ
value. Sweep time is doubled than the displayed TIME
parameter. At the end of the sweep, the output waveform
remains at the start frequency. Following another trig-
ger, the above cycle is repeated. In normal mode the gen-
erator repeats its sweep cycle continuously.
SWEEP DN-UP - The sweep down mode is similar to the
sweep up mode except that the output waveform, when
triggered, sweeps from value set by the STOP parameter
to value set by the FREQ parameter and back to the STOP
value. Sweep time is doubled than the displayed TIME
parameter. At the end of the sweep, the output waveform
remains at the stop frequency. Following another trig-
ger, the above cycle is repeated. In normal mode the gen-
erator repeats its sweep cycle continuously.
Selecting one of the above sweep directions is de-
scribed in the following. The same procedure is used for
both linear and logarithmic sweep scales.
1. Depress the [2nd] push-button and observe that the
display is modified to indicate the following:
2nd ?
(? appears flashing)
2. Depress the [SWP MODE] push-button in the MODE
group and observe that one of the following read-outs is
displayed:
UP, dn, U-d or d-U
This reading indicates the selected sweep mode. To
modify the selected sweep mode to one of the above modes
depress the [x1 UP] modifier push-button until the se-
lected mode is displayed.
3. Depress the [EXE] push-button. The output waveform
now sweeps with the selected sweep mode.
3-12-3. Voltage Controlled Oscillator Mode
Placing the function generator in VCO (voltage control-
led oscillator) operating mode removes the frequency
control from its output connector. The frequency of the
selected waveform is then proportional to an amplitude
level of a signal which may be applied to the VCO IN
connector. VCO mode may also be used as FM (fre-
quency modulation) mode. In this case, an applied sine-
wave at the VCO IN connector determine modulation
characteristics.
The generator is placed in VCO operating mode when
the light next to VCO illuminates.
3-12-4. Pulse Generator Mode (model 8021 only)
Model 8021 offers additional capability to the basic
function generator by allowing modification of its out-
put duty cycle (WID). Ramp and Square waveforms at
the output connector remains symmetrical (50 % duty
Cycle) in normal operating mode. Placing the generator
in PULSE mode replaces output symmetry to that pro-
grammed for WID. Width to frequency relation should
be observed. When error conditions exists the light next
to the selected waveform blinks.
PULSE mode may also be used as PWM (pulse width
modulation) mode. In this case, an applied sinewave at the
PWM IN connector determine modulation charac-
teristics. Model 8021 is placed in PULSE operating mode
when the light next to PULSE illuminates.
Operating Instructions Model 8020
Page 3-10