Description
of
the
HP
83447A
The
HP
83447A
lightwave
trigger
receiver
is
used
to
generate
an
electrical
trigger
signal
from
an
optical
waveform.
A
typical
usage
is
for
eye-diagram
analysis
of
telecommunications
optical
signals
where
an
external
electrical
clock
signal
is
not
available
as
a
timing
reference
.
F
or
more
information
on
using
the
lightwave
trigger
receiver
refer
to
Chapter
3.
Learning
the
inside
story
.
.
.
The
block
diagram
for
the
HP
83447A
is
shown
in
Figure
1-1.
The
optical
input
uses
9
m
single-mode
ber
.
The
optical
signal
to
be
measured
is
routed
to
the
HP
83447A.
Inside
the
HP
83447A,
the
signal
is
passed
through
an
asymmetric
coupler
,
where
approximately
10%
of
the
power
is
tapped.
The
remaining
90%
of
the
optical
signal
is
sent
directly
out
of
the
HP
83447A
and
can
be
connected
to
the
measuring
instrument.
The
10%
signal
is
detected
by
a
high-gain
avalanche
photodiode
(APD).
The
electrical
signal
from
the
APD
is
amplied
by
an
A
C-coupled,
two-stage
limiting
amplier
.
The
output
can
be
used
as
a
timing
reference
,
such
as
a
trigger
signal
for
an
instrument
like
the
HP
83480A
digital
communications
analyzer
.
This
technique
is
similar
to
\splitting"
an
electrical
signal
from
an
optical-electrical
(O/E)
converter
to
trigger
an
oscilloscope
.
However
,
a
key
advantage
to
using
the
HP
83447A
technique
is
that
the
optical
signal
to
be
measured
experiences
only
a
minor
level
of
attenuation,
typically
1
dB
o
.
Splitting
an
electrical
signal
usually
results
in
a
6
dB
e
loss
.
Because
the
O/E
element
of
the
HP
83447A
is
an
APD
and
two
stages
of
amplication,
a
preamp
and
a
limiting
amplier
,
the
output
electrical
signal
exceeds
200
mV
p-p
with
input
optical
modulation
powers
lower
than
20
W
p-p
,
(such
as
a
020
dBm
average
power
with
a
10
dB
or
higher
extinction
ratio).
Placing
an
electrical
splitter
after
an
O/E
converter
can
degrade
the
frequency
response
of
the
measurement
channel,
resulting
in
inaccurate
measurements
.
The
HP
83447A
triggering
technique
preserves
the
integrity
of
the
electrical
signal
path.
1-3
Summary of Contents for 83447A
Page 1: ...User and Service Guide HP 83447A Lightwave Trigger Receiver ...
Page 3: ...Printing History HP Part Number Edition Date 83447 90002 Edition 1 April 1996 iii ...
Page 10: ......
Page 15: ...1 General Information ...
Page 25: ...Declaration of Conformity 1 11 ...
Page 29: ...2 Installation and Preparation for Use ...
Page 51: ...3 Using the HP 83447A ...
Page 55: ...4 Servicing the HP 83447A ...
Page 95: ...Servicing the HP 83447A Replaceable parts Figure 4 9 HP 83447A replaceable hardware 4 41 ...
Page 97: ...Index ...
Page 102: ...W warranty 2 13 warranty information viii waveform test measuring eye diagram 3 3 Index 6 ...
