Racal Instruments 3152A, Руководство пользователя

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3152A User Manual
Racal Instruments
©
2001 Getting Started 1-13
When placed in this mode, the model 3152A scans the TRIG IN
connector for a valid signal. Once sensed, the model 3152A
measures its frequency and centers its lock-in range around this
frequency. The model 3152A then locks automatically on the
frequency of the external signal. There is no need for manual
initiation or operator intervention for locking the model 3152A to
an external reference. The PLL range is 500 Hz to 10 MHz.
Frequency
Counter
The Model 3152A 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 3152A 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 3152A 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 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 3152A, 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.