HP 8981A Vector Modulation Analyzer

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HP 8981A Vector Modulation Analyzer

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The HP8981A is a wideband I/Q demodulator, combined with a two-channel ... format, and configuration of triggering (auto, free-run, or external bit-clock) ... – PowerPoint PPT presentation

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Title: HP 8981A Vector Modulation Analyzer

1
HP 8981A Vector Modulation Analyzer
Quick Reference Guide
Main Controls
The most often used buttons are listed below.
Many buttons bring up a softkey menu to the
right of the screen. Values are entered using
the numeric keypad followed by units on the
softkeys, or are changed with up/down buttons on
the left side of the keypad, or the dial on the
right.

PRESET This restores the analyzer to a known
state. This is a good place to start.
CONSTL Configures the display in an XY
constellation format where amplitude and phase of
the signal are shown in polar form. Use GAINOFS
and DEMOD buttons for further setup.
IQ Configures display into a 2-channel
oscilloscope format. Use TIMING button for
further setup.
TIMING Allows setting time/division in 2-channel
scope format, and configuration of triggering
(auto, free-run, or external bit-clock). Also
controls sampling speed in constellation mode.
GAINOFS Allows setting of full-scale value.
Defaults to 0 dBm and range extends to 20 dBm.
DEMOD Brings up MODE, REF-FREQ, and PHASE-ADJ
softkeys. MODE switches between demod and
baseband inputs. (Default is demod). When in
demod mode, set REF-FREQ to your input frequency.
PHASE-ADJ can be used to rotate the
constellation display.

Overview

The HP8981A is a wideband I/Q demodulator,
combined with a two-channel oscilloscope. It
allows you to examine BPSK, QPSK, QAM, and other
amplitude/phase modulated signals using either an
XY signal constellation diagram, or a traditional
oscilloscope-type eye-diagram display.
The input can be either RF (50 to 200 MHz), or
baseband. For an RF input, an unmodulated
coherent carrier reference must be provided in
addition to the signal being examined.
The RF input (as well as the coherent reference
input) is on the back panel (brought forward
using the coax seen on top of the instrument
above). The baseband I/Q signal and trigger
inputs are at the bottom of the front panel.