Racal Instruments 3162A/B, User Manual

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User Manual 3162A/B
Getting Started 1-13
frequency and centers its lock-in range on this frequency. The Model 3162B
then locks automatically onto the frequency of the external signal. There is no
need for manual initiation or operator intervention to lock the instrument to an
external reference.
Frequency Counter
The Model 3162B uses a built-in, auto-ranging counter circuit in PLL mode to
measure the frequency of the reference signal at the trigger input. Regardless
of whether you want to lock the 3162B to another source or not, you can use
the counter circuit to measure frequency. There are three things to be done: 1)
place the generator in PLL mode, 2) adjust the trigger level, and 3) make sure
that the PLL ON LED illuminates. Frequencies are measured from 500Hz to 31
MHz. An external frequency query returns six digits with a decimal point and
suffix multiplier.
Phase Modulation
When the Model 3162B 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. This input is voltage sensitive. Applying voltage to
this input changes the start phase of the generator. The bandwidth of the PM
input is DC to 10kHz.
Filters
Two filters are built into the Model 3162B, one for each channel. These filters
are available for use in various applications like the creation of high frequency
sine waves. The elliptical 150 MHz filter has very sharp cutoff frequency. It is
very useful for removing the staircase effect from waveforms that are generated
with high frequency clock rates.