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Getting Started 1-9
Backplane
Synchronization
Multiple Model 3152s may be synchronized and operated together
inside one VXIbus chassis. With one instrument configured as
master and the rest of the instruments configured as slaves, the
instruments are phase-locked to the start phase on the master
module. The slave modules may be configured to have phase offsets
within the range of 0
E
to 360
E
. There is no need to install multiple
Model 3152 modules in adjacent slots to be able to phase
synchronize modules.
Front-Panel PLL
Model 3152 may be phase locked to an external reference and
phase shifted from the start phase of the external reference from -
180
E
to +180
E
. The reference signal is applied to a front-panel input
BNC. In this way, the same reference can be applied to multiple
modules to generate multi-phase signal patterns. The reference
signal for the PLL function is applied to the TRIG IN. It shares the
same characteristics as the trigger input, programmable trigger level
and programmable slope. When placed in this mode, the model
3152 scans the TRIG IN connector for a valid signal. Once sensed,
the model 3152 measures its frequency and centers its lock-in range
around this frequency. The model 3152 then locks automatically on
the frequency of the external signal. There is no need for manual
initiation or operator intervention for locking the model 3152 to an
external reference. The PLL range is 500 Hz to 10 MHz.
Frequency Counter
The Model 3152 uses an autoranging counter circuit to measure
frequencies of reference signals at the trigger input. This built-in
counter is made available for you in PLL mode. Thus, you can use
the 3152 as a frequency counter provided that the signal at the
trigger input is valid and the PLL ON LED illuminates. Frequencies
are measured from 500 Hz to 10 MHz. External frequency query
returns four digits with a decimal point and suffix multiplier.
Phase Modulation
When the Model 3152 is placed in PLL mode, there are two ways to
control the phase offset. The first option is to modify the phase offset
setting using SCPI commands. This method is extremely accurate
while permitting phase offset adjustments with 0.01
E
increments. The
PM IN provides another option for changing phase offsets. Applying
voltage to this input changes the start phase of the synthesizer
continuously, depending on the voltage level at the phase modulation
input. The applied voltage range is DC to 10 kHz, depending on the
lock frequency and the number of waveform samples.
Filter
Three filters are built into the Model 3152, each having a different
cutoff frequency and rise time properties. These filters are available
for use in various applications, depending on the specific
requirement. The 20 MHz Gaussian filter has a gaussian response
which smooths fast transitions and eliminates ringing and
aberrations. The 25 MHz and the 50 MHz filters are elliptical with a
very sharp cutoff frequency. They are useful for removing the
staircase effect from waveforms that are generated with high
frequency clock rates.
Front Panel Indicators
There are three LEDs on the front panel. The FAIL LED (Red)
illuminates at power-up until the Model 3152 has passed its self-test.
If the Model 3152 self-test fails, the FAIL LED remains illuminated.
Содержание 3152
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