Tektronix 067-1049-00 User manual

. 070-3850-00
•·
ronoo
COMMITTED
TO
EXCELLENCE
Instructi
ns
OPTICAL CALIBRATION
SIGNAL GENERATOR
067
-1
049-00
m1
OUTPUT
CAL
t
« »
30
OPTICAL
OUTPUT
0
CURRENT
mt
OUTPUT
GENERATOR
~it
(i)
3850-00
The 067-1049-00 Optical Calibration Signal Generator.
First Printing NOV
1981

Optical
Calibration
Signal
Generator
N s
Page
Section 1 GENERAL INFORMATION AND
SPECIFICATION
Product Description
................
1-1
Specification
.....................
1-1
Optical and Electrical Characteristics
1-1
Environmental Characteristics
.....
1-2
Physical Characteristics
..........
1-3
Standard Accessories
...........
1-3
Section 2 OPERATION
Controls and Connectors
...........
2-1
Output Level (dB)
...............
2-1
Cal/Run
.......................
2-1
Optical Output
.................
2-1
Current Source
.................
2-1
Adjustments
.....................
2-2
Optical Source
.................
2-2
Pulse Width
...................
2-2
Preparation for Use
................
2-2
Equipment.
....................
2-2
Installation (for OCSG calibration)
..
2-2
Calibration
.......................
2-3
Check Optical Signal Pulse Widths . 2-3
Check and Adjust Power
of
Optical
Output Levels
...................
2-4
Configuration
of
the OCSG as a Calibra-
tion Fixture for use with the OF150
...
2-4
Section 3 CIRCUIT DESCRIPTION
Current Pulse Generator
............
3-1
Optical Pulse Generator
............
3-1
Section 4 REPLACEABLE ELECTRICAL PARTS
Section 5 DIAGRAM AND CIRCUIT BOARD
ILLUSTRATION
Section 6 REPLACEABLE MECHANICAL PARTS
CHANGE INFORMATION
@

Optical Calibration Signal Generator
SAFETY SUMMARY
TERMS
In
This Manual
CAUTION statements identify conditions or practices that
could result
in
damage to the equipment or other property.
WARNING statements identify conditions or practices that
could result
in
personal injury
or
loss
of
life.
As Marked
on
Equipment
CAUTION indicates a personal injury hazard not immediate-
ly accessible
as
one reads the marking, or a hazard to prop-
erty including the equipment itself.
DANGER indicates a personal injury hazard immediately ac-
cessible as one reads the marking.
SYMBOLS
In
This Manual
ii
This symbol indicates where applicable cau-
tionary or other information is to
be
found.
As Marked
on
Equipment
DANGER-High
voltage.
Protective ground (earth) terminal.
ATTENTION-refer
to manual.
Do
Not.
Service Alone
Do not perform internal service or adjustment
of
this prod-
uct unless another person capable of rendering first
aid
and
resuscitation is present.
Use Care When Servicing With Power
On
Dangerous voltages exist at several points
in
this product.
To
avoid personal injury, do not touch exposed connections
and components while power is on.
Disconnect power before removing protective panels, sol-
dering, or replacing components. ·
@

Section 1-0ptical Calibration Signal Generator
GENERAL INFORMATION AND SPECIFICATION
PRODUCT DESCRIPTION
The Optical Calibration Signal Generator (OSCG) is a
calibration fixture for the OF150 Fiber Optic Time Domain
Reflectometer. The OCSG supplies three optical signal lev-
els that may be used to verify the vertical scale of the
OF150 display. These signal levels are 50 dB, 60 dB, and
70 dB, referenced to the bottom of the display. Nine electri-
cal signal levels are provided for calibration of the OF150
Log Amplifier circuit. These signals are provided in 1OdB
steps from
20 dB to 100 dB.
The OCSG has two operating modes. CAL, when select-
ed, allows the OCSG optical output levels to be adjusted
and their power content verified with an optical power me-
ter. RUN, when selected, allows the OCSG to be used as a
signal generator for calibration of the OF150. The OF150
is
the power source for the OCSG.
NOTE
The OCSG will need to be recalibrated if the Fiber
Optic Cable is removed.
SPECIFICATION
The following list of instrument characteristics and fea-
tures apply to the Optical Calibration Signal Generator after
a 10 minute warmup in 20°C ambient air.
The Performance Requirement column describes the lim-
its of the characteristic and the Supplemental lnformati0n
column describes features and typical values
of information
that may be useful to the user.
Table 1-1
OPTICAL AND ELECTRICAL CHARACTERISTICS
Characteristic Performance Requirement Supplemental Information
Optical Output Amplitude
CAL mode
at 70 dB 0.110
µW average power out of fiber, After adjustment
±5%
at 60 dB match 70 dB output, ± 1% After adjustment
at 50 dB match 70 dB output, ± 1% After adjustment
RUN mode
at 70 dB 0.550
µW average power out of fiber,
23.1 µW peak
±10%
Optical Pulse Width After adjustment
Measured in 4.900 ns/m on the OF150 DIS-
TANCE CAL
CAL mode
at 70 dB 100 meters, ± 5% 1
µs pulse width
at
60 dB 10 X 70 dB pulse width, ± 1% 1O
µs pulse width
at 50 dB 100 X 70 dB pulse width, ± 1% 100
µs pulse width
RUN mode 510 meters,
±5% 5 µs pulse width
@ 1-1

General
Information-Optical
Calibration Signal Generator
Characteristics
Optical Output Step Accuracy
Electrical Output Amplitude
at 100 dB
at 90 dB
at
80
dB
at 70 dB
at 60 dB
at 50 dB
at 40 dB
at 30 dB
at 20 dB
Electrical Pulse Width
Characteristic
Temperature
Operating
Non-operating
Altitude
Operating
Non-operating
Vibration
Shock, operating and non-operating
Bench handling
Fungus inert
Package transit vibration
Package drop
Electrostatic discharge
Table
1-1
(cont)
Performance Requirements Supplemental Information
±
0.1
dB when calibrated to optical power
meter, tor ambient temperature variations of
less than ± 5°
Measured with
an
external
de
supply set to
8
V,
±1%
8.0
V,
±5%
into 499 n
4.05
v,
± 2% into 499 n
1.11
V,
±2%
into 499 n
3.95
v,
±2%
into 24.9 kn
0.73
V,
±2%
into 24.9 kn
0.079
v,
±2%
into 24.9 kn
7.50
V,
±2%
open
0.74
V,
±2%
open
0.0755
V,
±2%
open
50
µS,
± 10%
Table
1-2
ENVIRONMENTAL CHARACTERISTICS
Description
+10°C
to
+40°C
-25°C
to +
75°C
3.050 meters
12,000 meters
5 to
55
Hz,
2 g maximum
30g
1
O
cm
topple, 45°, or point of balance
Materials used are fungus inert
Tektronix Standard 062-2858-00, paragraph
9.1
Tektronix Standard 062-2858-00, paragraph 9.2
Tektronix Standard 062-2862-00
This instrument meets the specifications of MIL-T-28800B, Type Ill, Class
6,
Style
E,
with the exception of the Non-operating
Temperature specification, and the Humidity specification.
1-2
@

General
Information-Optical
Calibration Signal Generator
Characteristic
Weight
Table
1-3
PHYSICAL CHARACTERISTICS
Description
(including standard accessories, except Instruction manual) 0.4
Kg
(0.9 lbs)
Dimensions
Description
Optical Interface Cable
Electrical Interface Cable
7600 X 6400 X 1780 mm
(3.04 X 2.56 X 7.12 inches)
Table
1-4
STANDARD ACCESSORIES
Qty
Refor to the Replaceable Mechanical Parts list for Tektronix Part Number.
@
1-3

@
Section
2-0ptical
Calibration Signal Generator
OPERATION
CONTROLS AND CONNECTORS
{see Figure
1)
1 OUTPUT
LEVEL
(dB).
Nine
selections
in
1
O
dB steps, from
20
to 100.
All
nine selections
are
active for the CURRENT OUTPUT
(electrical signals). Only the
50
dB, 60 dB,
and
70 dB
selections are active for the OPTICAL OUTPUT sig-
nals. When
an
optical signal level
is
selected, the
equivalent electrical signal level
is
selected.
2
CAL/RUN.
This switch
is
located
on
the circuit board
and
it
is
accessible through a hole
in
the top cover of the
OCSG. When looking at the front of the OCSG, push
(TOP VIEW SHOWING ACCESS HOLE)
the switch to the right to select CAL. This configures
the
OCSG
for calibration of its optical output signals.
The
RUN
selection (push to left) configures the OCSG
for operation as a signal generator.
3
OPTICAL OUTPUT.
Source of calibrated optical signals at 50 dB,
60
dB,
or
70
dB levels.
4
CURRENT SOURCE.
Source of electrical signals
in
10
dB steps from
20
dB
to 100 dB (typical) levels.
::::~;;;;~AL
i ,
!I
~•:~··
CURRENT
OUTPUT
~
Tektronix
CALI
BRAT
ION
GENERATOR
067-1049-00
-
FRONT PANEL
3850-01
Fig. 2-1. OCSG Controls, Connectors, and Adjustments.
2-1

Calibration-Optical
Calibration Signal Generator
ADJUSTMENTS
1 OPTICAL SOURCE.
These three screwdriver adjustments are used to set
the power output
of
the optical signal level selections.
2 PULSE WIDTH.
These two screwdriver adjustments are located
on
. the circuit board and they are accessible through the
hole
in
the top cover of the OCSG. The front potenti-
ometer, R1044,
is
used to adjust the pulse width of
the 50 dB optical signal. The rear potentiometer,
R1045,
is
used to adjust the pulse width of the 60 dB
optical signal.
NOTE
The
voltage andcurrent levels
of
the electrical signals
from the CURRENT SOURCE are
set
by
fixed resis-
tors and are
not
adjustable.
PREPARATION FOR USE
The following procedure calibrates the pulse widths
and
power levels of the optical output signals. If this function
is
not required for a particular application, omit this procedure,
set the CAL/RUN switch to
RUN,
insert the OCSG
in
the
OF150 chart recorder compartment,
and
refer to the OF150
manual for setup and use instructions.
Equipment
.The items required tor calibration of the optical signals
include:
Extender Module 068-1071-00
J6502 lrradiance Probe
J16 Photometer/Radiometer
Screwdriver, flat, 6 in; with 1/8
in.
tip
Installation
(for
OCSG calibration)
1.
Remove the chart recorder from the OF150.
2.
Insert the Extender Module
in
the OF150 chart re-
corder compartment.
3.
Attach the Extender Module cable to the circuit board
connector at the rear of the OCSG
(see
Fig.
2-2).
CAL/RUN
SWITCH,
RI45
ACCESS
CIRCUIT BOARD
2-2
<O
(0
a::n
flEAR
OF OCSG UNIT
Fig. 2-2. OCSG to Extender Module cable connector.
EXTENDER MODULE {Plug)
3850-02
@

~
The
circuit board connector is
not
keyed.
When
cor-
rectly connected to the Extender Module cable, the
connector thatis used with the chartrecorderis locat-
ed
above the OCSG connector as shown in
Fig.
2-2.
4.
Remove the protective dust caps and connect the Op-
tical Interface cable to the Optical Output port of the OF150.
NOTE
A. Always keep these caps in place when the optical
connectors are
not
in
use,
as the optic fiber con-
nectors have an oil film
and
must
be protected
from foreign matter.
B.
Do
not
sharply bend the Optical Interface cable.
CALIBRATION
1. Check Optical Signal Pulse Widths:
70 dB
=
100
meters,
±5%
60
dB=
10 X
70
dB width,
±1%
(R1045)
50 dB = 100 X 70 dB width, ± 1%(R1044)
a.
Control Settings
CAL/RUN
OUTPUT LEVEL
(dB)
Dist/Div
Filter
Vertical Scale
Readout Mode
Power
Marker
OCSG
CAL
70
OF150
Fast
10 dB/Div
Dist (meters)
On
Set to zero
b.
Press the OF150 Sweep control. A waveform show-
ing
the leading edge
and
the beginning of the 70 dB
OCSG
output pulse should
be
displayed. Adjust the vertical Posi-
tion control to align the top ofthe displayed waveform with a
graticule line to facilitate finding the point of the waveform's
leading edge that
is
-10
dB from the peak (steady state)
value.
@
Calibration-Optical
Calibration Signal Generator
c.
Read
and
note the distance
in
meters between the
-10
dB point
and
the zero Marker. This distance
is
typically
3 meters.
d. Change the OF150 Dist/Div to 20
and
move the Mark-
er to the trailing edge of the 70 dB waveform.
e.
Return the OF150 Dist/Div to 1
and
move the Marker
to the
-10
dB point of the waveform.
Read
and note the
distance
in
meters at which the
-10
dB below peak value
occurs.
f.
Add the distance found
in
part c to the distance found
in
part
d.
This
sum
is
the
-10
dB pulse width of the 70 dB
OCSG output. The pulse width should equal 100 meters,
±5%.
NOTE
The
check and adjustment procedure for the 60
dB
optical output pulse width,
10
X the 70
dB
pulse
width, begins with
part
g.
g.
Set the OUTPUT LEVEL (dB) to
60.
h.
Set the OF150 Dist/Div to 200 and move the Marker
to the
end
of the pulse.
i.
Change the OF150 Dist/Div to 10.
j.
Adjust the OF150 Marker control to produce a readout
that
is
1
OX
the pulse width of the 70 dB optical signal
output.
k.
Position the display vertically to facilitate finding the
-1
OdB point
on
the trailing edge of the displayed
waveform.
I.
Read
and
note the point
on
the trailing edge of. the
waveform that
is
10 dB below the peak (steady state)
value.
m.
If the reading
at
the
-10
dB point
is
outside the lim-
its, 10 X 70 dB pulse width, ± 1
%,
press
and
hold Sweep
and
adjust R1045
as
necessary.
NOTE
At
this Dist/Div setting, one graticule division equals
1
%
of
the Readout.
2-3

Calibration-Optical
Calibration Signal Generator
NOTE
The
check and adjustment procedures for the
50
dB
optical output pulse width, 100 X the 70
dB
pulse
width, begins with
part
n.
n.
Set the OUTPUT LEVEL to 50.
o.
Set the OF150 Dist/Div
to
1000.
p.
Use the OF150 horizontal Position control to move
the trailing edge of the waveform on screen and set the
Marker to the trailing edge.
q.
Set the OF150 Dist/Div to 100.
r.
Adjust the OF150 Marker control to produce a readout
that
is
100 X the 70 dB pulse width.
s.
Position the display vertically to facilitate finding the
-10
dB point of the displayed waveform.
t.
Read
and note the point
on
the trailing edge of the
waveform that
is
-10
dB below peak value.
u.
If the reading
is
outside the limits of 100 X the
70
dB
pulse width, ± 1%, press and hold Sweep
and
adjust R1044
as necessary.
2.
Check and Adjust Power
of
Optical Output
Levels
70
dB=
0.110
µW,
±5%
60
dB
=
70 dB Power, ± 1%
50
dB
=
70 dB Power, ± 1%
a.
Disconnect the Optical Interface cable from the
OF150 (replace cap on port) and connect the cable to the
input connector of the J6502 lrradiance Probe.
b.
Set the OUTPUT LEVEL to 70 dB.
c.
Set the OF150 Filter to Slow.
d.
Note the photometer (J16) reading and, if necessary,
use a screwdriver
and
adjust OPTICAL SOURCE, 70 dB,
for a (J16) display of 0.110
µW,
± 5%.
2-4
NOTE
1.
If
the OpticalInterface Cable connection is improp-
erly aligned with the OCSG OPTICAL OUTPUT
port, the Optical Power Out cannot be adjusted to
0.
110µ
W.
To
align, loosen the cable connector,
then while viewing the photometer, rotate the cable
for maximum
power
indication. Tighten the con-
nectorand repeat
part
d.
2.
The
OCSG OPTICAL OUTPUTpulse is active only
during an OF150 sweep function.
When
adjusting
the POWER SOURCElevels, press Sweep as nec-
essary to maintain an optical outputpulse.
e.
Set the OUTPUT LEVEL to
60
dB.
f.
Note the J16 reading and,
as
necessary, adjust OPTI-
CAL SOURCE,
60
dB, for a J16 reading equal to the 70 dB
power
±1%.
g.
Set the OUTPUT LEVEL to
50
dB.
h.
Note the J16 reading and,
as
necessary, adjust OPTI-
CAL SOURCE,
50
dB, for a J16 reading equal to the 70 dB
power
±1%.
i.
Disconnect the Optical Interface cable
and
replace the
protective caps.
CONFIGURATION OF
THE
OCSG
AS A
CALIBRATION FIXTURE
FOR
USE
WITH
THE
OF150
1.
Set the CAL/RUN switch to
RUN.
2.
Set the OUTPUT LEVEL to 70 dB.
3.
Remove the chart recorder from the OF150.
4.
Insert the OCSG into the chart recorder
compartment.
5.
Remove the protective caps from the Optical Inter-
face cable
and
the OF150 Optical Output port, and connect
the cable to the port.
6.
Refer to the OF150 Instruction manual for OF150 cali-
bration procedures.
@

(
The OC8G contains two pulse generators to produce
calibration signals for the OF150. Both generators are trig-
gered by the PULSTRIG signal from the OF150, allowing
them to
be
synchronized with the OF150 sampling system.
CURRENT PULSE GENERATOR
The current output pulse
is
generated
by
the monostable
multivibrator, UF150B. The
50
µsec
wide output pulse
is
then level shifted by VR2030 to drive output switch 02024.
The collector of 02024
is
switched between ground and
+
8
volts (supplied
by
U2052). The output pulse
is
applied to the
output cable through
81
OOOA
and
resistor network R2010
through R2017. This resistor network,
in
conjunction with a
network located on the OF150 Input Log Amplifier, gener-
ates a current pulse to
be
connected
in
place of the Ava-
lanche Photo Diode for calibrating the OF150 vertical scale
display.
OPTICAL PULSE GENERATOR
The optical pulse
is
generated by switching the drive cur-
rent to
an
infrared
LED,
0810. The width of the pulse
is
set
@
Section
3-0ptical
Calibration Signal Generator
by
U1050A
and
is
a function of 81040 (CAL/RUN)
and
81000E.
In
the
RUN
position, the pulse width
is
approxi-
mately 5
µsec
and
independent of the 81000E position.
In
CAL mode, the pulse width
is
selected by
81
OOOE
(1
µsec,
10
µsec,
and
100
µsec
at 70 dB,
60
dB, and 50 dB,
respectively).
The output of U1050A drives a current switch formed by
02042
and
02044. The current that
is
switched by the
FETs
is
generated
by
the current source consisting of U2038,
02032,
and
a current sense resistor selected
by
810000.
Transistor 02034 buffers the output of the current source
from high speed switching transients.
The reference voltage for the current source
is
developed
across a resistor (R10, R12, or
R14)
selected by 81000C.
The reference current that develops this voltage
is
generat-
ed
by a temperature-compensated current source formed by
U1056, 01056, U1058,
and
resistor network R1053-R1058.
Temperature compensation
is
used to stabilize the optical
output
as
a function
of
temperature.
3-1