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Model 8902A
General Information
input Power Protection The Measuring Receiver is equipped with input power protection
to
prevent
damage from the accidental application of excessive power. (This is a common cause of damage in
equipment used
to
measure transmitters.) The Measuring Receiver is tested for inputs up to 2W.
Protection is provided by limiting diodes and an RF relay. When excessive power is applied, the relay
opens and protects sensitive components, and the Measuring Receiver displays an error message. The
circuit automatically resets whenever a key is depressed.
RF Power Calibration
RF
Power Calibration is accomplished with the 50 MHz, 1 mW standard
available in every instrument. Also, the front-panel ZERO function enables you to zero the sensor
module without removing it from the source-under-test. After the ZERO key is pressed, the new zero
offsets are stored automatically.
RF Power Calibration Factors
RF Power Calibration Factors can be entered from the power sensor
into the Measuring Receiver's non-volatile memory. The instrument automatically compensates for the
power sensor's efficiency and mismatch loss at each frequency.
Tuned RF Level The Measuring Receiver has a minimum sensitivity of -127 dF3m with exceptional
accuracy. Relative-level measurements with accuracy expected only from a transfer standard can be
made.
High Selectivity Measurements Options 030-037 add selective power measurement capability
to
the
HP 8902A Measuring Receiver. Used with a low-noise external
LO,
the HP 8902A performs fast,
accurate single-sideband
(SSB)
carrier noise measurements to 1.4 GHz.
RF Frequency Measurements
In automatic operation, the Measuring Receiver has the performance of a high-quality, 150 kHz to 1300
MHz frequency counter. The frequency counter automatically adjusts itself
as
the input level changes.
There is no need to manually set or adjust the input attenuator. Because the Measuring Receiver is
usually used to measure modulated signals, its frequency counter also accurately measures signals with
significant levels of AM.
Modulation Measurements
The Measuring Receiver has extremely low internal noise. Incidental AM, FM, and cPM can be measured
on a wide range of simple and complex modulated signals. To complement its modulation measurement
capability, the HP 8902A characterizes audio signal level, frequency, and distortion. (These features
are also available for external audio signals.)
Filters, De-emphasis Networks and Modulation Calibrators
Post-Detection Audio Filters The Measuring Receiver has two high-pass and three low-pass post-
detection audio filters for filtering the recovered modulation. These filters can be selected individually or
in combination. Their cutoff frequencies have been chosen
to
match those needed for applications such
as transmitter or signal generator testing. The $ 0 kHz filter is a Bessel filter. It minimizes overshoot
for square-wave modulation so that this type of modulating waveform can also be accurately measured.
De-Emphasis Networks The Measuring Receiver contains four de-emphasis networks that can be
used in addition to the audio filters. These are the ones commonly used in FM communications-25,
50, 75, and 750
ps.
When selected, the de-emphasis networks always affect the demodulated output.
You can select whether the de-emphasis network affects the deviation measured. The ability to select
either the actual or "de-emphasized deviation" increases the usefulness of the Measuring Receiver in
many applications.
reu.24A
UG87
1-7
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