Model
8901B
Operation
RF
Frequency Error
FUNCTIONS
FREQ ERROR
DESCRIPTION
The Frequency Error function enables the Modulation Analyzer
to
measure the difference (in kHz)
between the RF input signal frequency
and
the frequency
to
which the instrument
is
tuned. This
function can be used
to
observe frequency
drift
of input signals, or
to
compare input frequencies against
a
keyboard-entered reference.
Display resolution
is
controlled by Special Function
7.
(Refer
to
RF Requency Resolution
on
page
3-131.)
PROCEDURE
To
make the RF frequency error measurement, connect the
RF
signal
to
the Modulation Analyzer’s
RF INPUT.
If
a
frequency
drift
measurement
is
to
be made,
first
allow
the Modulation Analyzer
to
automatically
tune
to
the signal, then select the MHz key
to
prevent retuning. Select FREQ ERROR (Shift, FREQ)
to
display the frequency error.
As
the
signal
drifts
the display indicates the magnitude and direction
of the
drift.
To make a frequency comparison, enter the reference frequency (in MHz) on the keyboard, then select
MHz. Select FREQ ERROR
to
display the difference frequency. The number is negative
if
the signal
frequency
is
lower than the reference, and positive
if
the signal frequency
is
higher than the reference.
Valid frequency error measurements are made
as
long
as
the down-converted signal remains
in
the
IF
passband. (Refer
to
RF Requency Zlming
on page
3-115.)
EXAMPLE
To
measure the error of
an
oscillator designed
to
operate
at
30
MHz, connect the oscillator’s output
to
the Modulation Analyzer’s RF INPUT connector and select the following keystrokes:
30
MZ
S5
Measurement
T
a
Data
(program
codes)
Function
RF Frequency Error
3-121
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