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Model 8902A
Operation
(program codes)
RF Frequency Error
I
Function
FUNCTIONS
FREQ ERROR
DESCRIPTION
The Frequency Error function enables the Measuring Receiver to measure the difference (in kHz)
between the R F 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 Freqirency Rcsolirlion on page
3-157.)
PROCEDURE
To make the R F frequency error measurement, connect the RF signal to the Measuring Receiver's
R F INPUT.
If a frequency driA measurement is to be made, first allow the Measuring Receiver 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 Fr~~qitcncy Timing on page
3-141.)
EXAMPLE
To measure the error of an oscillator designed to operate at 30 MHz, connect the oscillator's output
to the Measuring Receiver's R F I N P U T connector and select the following keystrokes:
LOCAL
(keystrokes)
5
FREO
ERROR
30
MZ
S5
~ a t a
L T -
Measurement
3-147
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