Stanford Research Systems DS345, Manual

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Introduction
This section of the manual describes the DS345's modulation capabilities.
The DS345 has extremely powerful and flexible built-in modulation functions.
It is capable of AM (both simple and double sideband suppressed carrier
(DSBSC)), FM, PM, tone bursts, and frequency sweeps. The modulation
waveform may be a sine, square, ramp, or triangle wave. Frequency can be
swept up or down at a linear or logarithmic rate. A built-in trigger generator al-
lows triggering of single sweeps and bursts. For additional flexibility the
DS345 can also modulate the output waveform with an arbitrary pattern of
amplitude, frequency, or phase values.
SWEEPS AND MODULATION
MODULATION ON/OFF
The SWEEP ON/OFF key enables the DS345's modulation functions. Press-
ing the key toggles the modulation status. When modulation is on the
[MOD/SWP] LED will light. When modulation is enabled the modulation type
and modulation parameters are checked for consistency with the selected
output function. If the selected modulation is illegal (for example, FM frequen-
cy out of range for the function) the DS345 will display an error message and
not enable the modulation. The erroneous value must be changed before the
modulation is turned on.
MODULATION TYPE
The type of modulation is selected using the MODULATION TYPE [UP/
DOWN] arrow keys. Most of the output functions can be modulated by any
type of modulation. However, NOISE can only be modulated by the external
AM input, and ARB waveforms can only be modulated by AM and BURST
modulations. If an invalid choice is selected the message "funct error" is dis-
played.
MODULATION WAVEFORM
The waveform of the modulating function is selected with MODULATION
WAVEFORM UP/DOWN arrow keys. If no LEDs are lit the selected modula-
tion type has no associated waveform (BURST, for example, has no modula-
tion waveform). Not all modulation types may use all modulation waveforms.
The allowable combinations are listed on the following page. Note that ARB
modulation waveforms can only be downloaded via the computer interfaces.
2-13
SWEEP/MODULATE
LIN SWP SINGLE MOD/SWP
SWEEP
ON/OFF
BURST
RATE
BRST CNT
SWP CF
SPAN
(DEPTH)
STOP f
START
FREQ
ARB
TRIG
FM
AM (INT)
LOG SWP
m
I