Notice - Keysight

Notice - Keysight
Notice
Hewlett-Packard to Agilent Technologies Transition
This documentation supports a product that previously shipped under the HewlettPackard company brand name. The brand name has now been changed to Agilent
Technologies. The two products are functionally identical, only our name has changed. The
document still includes references to Hewlett-Packard products, some of which have been
transitioned to Agilent Technologies.
Printed in USA
March 2000
Making Measurements
with the HP 11757B
Multipath Fading Simulator
SERIAL NUMBERS
Attached to the rear panel of the instrument is a
serial number plate. The serial number is in the form:
0000A00000. The rst four digits and the letter are
the serial number prex. The last ve digits are the
sux. The prex is the same for identical instruments; it
changes only when a conguration change is made to the
instrument. The sux, however, is assigned sequentially
and is dierent for each instrument.
This manual applies to instruments with serial numbers
prexed 3108A and above.
ABCDE
HP Part No. 11757-90050
c
HEWLETT-PACKARD COMPANY 1992
5301 Stevens Creek Blvd., Santa Clara, California 95052
Printed in USA
Contacting Agilent
By internet, phone, or fax, get assistance with all your test and measurement needs.
Table 1-1 Contacting Agilent
Online assistance: www.agilent.com/find/assist
United States
(tel) 1 800 452 4844
Latin America
(tel) (305) 269 7500
(fax) (305) 269 7599
Canada
(tel) 1 877 894 4414
(fax) (905) 282-6495
New Zealand
(tel) 0 800 738 378
(fax) (+64) 4 495 8950
Japan
(tel) (+81) 426 56 7832
(fax) (+81) 426 56 7840
Australia
(tel) 1 800 629 485
(fax) (+61) 3 9210 5947
Europe
(tel) (+31) 20 547 2323
(fax) (+31) 20 547 2390
Asia Call Center Numbers
Country
Phone Number
Fax Number
Singapore
1-800-375-8100
(65) 836-0252
Malaysia
1-800-828-848
1-800-801664
Philippines
(632) 8426802
1-800-16510170 (PLDT
Subscriber Only)
(632) 8426809
1-800-16510288 (PLDT
Subscriber Only)
Thailand
(088) 226-008 (outside Bangkok)
(662) 661-3999 (within Bangkok)
(66) 1-661-3714
Hong Kong
800-930-871
(852) 2506 9233
Taiwan
0800-047-866
(886) 2 25456723
People’s Republic
of China
800-810-0189 (preferred)
10800-650-0021
10800-650-0121
India
1-600-11-2929
000-800-650-1101
2
Chapter 1
1
Digital Radio Testing
Note
BERT
This guide contains detailed instructions for performing
digital radio tests with the HP 11757B Multipath Fading
Simulator. The tests detailed in this chapter include:
Static M-Curve Measurement
Dynamic M-Curve Measurement
Dynamic S-Curve Measurement
Hysteresis M-Curve Measurement
Recovery Time Test
Bit Error Rate Test
If you have an option 001 HP 11757B Multipath Fading
Simulator, this guide does not apply to your instrument.
Use the Operating and Programming Reference.
The tests detailed in this guide use a Bit Error Rate
Test Sets (BERT) to supply and receive data, and count
errors. There are other alternatives. Some digital radio
systems have their own internal error checking scheme
with an error pulse output. This will allow elimination
of the BERT. Another possibility is simply using the
Alarm Output of the radio, and simplifying tests to
lock/out-of-lock transition measurements.
1-1
Digital Radio Testing
Connecting the HP
11757B to a BERT
HP 11757B
The HP 11757B can work with many dierent types
of Bit Error Rate Test Sets (BERT). However, not all
BERT operate the same way and it is important for you
to understand how to correctly interface dierent types
of BERTs to the HP 11757B.
Triggering
The 4RADIO SETUP5 key can be used to adjust the
triggering of the ERROR PULSE INPUT and ALARM
INPUT connectors to coincide with the BERT you
are using. The ERROR PULSE INPUT line can be
terminated in ECL/75
, TTL/75
, or TTL/ 10k
. In
addition, an ERROR PULSE INPUT variable threshold
can be selected instead of ECL or TTL thresholds.
ERROR PULSE INPUT variable threshold is only
available in serial prexes 3235A and above. The HP
11757B will always trigger on the rising edge of signals
applied to the ERROR PULSE INPUT connector.
The ALARM INPUT connector is always terminated
in TTL/10k
. However, the edge (positive or negative
going) that the Fader triggers on can be chosen by you.
Select the one that works with your BERT.
Error Pulse Signals during Out-of-Lock Situations
It is very important to understand what kind of
\ERROR PULSE" signal your BERT puts out when
the radio is out-of-lock. Ideally, when the radio is
out-of-lock, the BERT will put out a very fast stream
of pulses indicating a very high Bit Error Rate (BER).
If this is the case with your BERT, all you need do for
BER Criteria measurements is connect the \ERROR
PULSE" of your BERT to the ERROR PULSE INPUT
connector on the front panel of the Fader.
On the other hand, some BERTs turn o their \ERROR
PULSE" signal when an out-of-lock state is detected.
If this is the case with your BERT, you not only need
1-2
HP 11757B
Digital Radio Testing
to connect the \ERROR PULSE" of the BERT to the
ERROR PULSE INPUT of the Fader, you must also
connect an Alarm line from either your radio or your
BERT to the ALARM INPUT line of the Fader. This
is because when no errors are present on the ERROR
PULSE INPUT line, the Fader cannot tell the dierence
between an out-of-lock situation and one were the bit
error rate is truly zero. The Fader needs the ALARM
INPUT line to determine which of these situations is
occurring.
1-3
Digital Radio Testing
HP 11757B
Static M-Curve
Measurement
Equipment Setup
Note
1. The basic setup for all measurements involves
interrupting the IF path of the digital radio with a
fading simulator. If a Bit Error Rate Tester (BERT)
is used, connect the appropriate data channels. In
the gure below, the DS3 data out from the BERT
is connected to the DS3 input of the transmitter,
and the BASEBAND output of the receiver to the
DS3 data input of the BERT. DS3 is used only as an
example; if your radio requires another data format,
use a BERT that produces it. The ERROR OUTPUT
of the BERT is connected to the ERROR PULSE
INPUT of the Fader. This input can be set to match
the impedance of the BERT.
Some digital radios have their own error outputs and
internal data checking schemes that limit the need for
a BERT. See the manual for your radio if you wish
to connect the ERROR PULSE INPUT of the Fader
directly to the radio. There may be a connection that
must be made between two ports of the radio system for
this to work.
2. The RF output of the transmitter is connected to the
RF input of the receiver. Appropriate attenuation is
used to protect the RF input of the receiver. Check
the manual of the receiver and the transmitter to
insure safe levels for the receiver input.
3. The Alarm Output on the receiver can be connected
to the Alarm Input on the Fader. This connection is
only needed for recovery tests, and tests where no
BERT is available and you want to use the ALARM
INPUT to indicate failure.
1-4
HP 11757B
Digital Radio Testing
Figure 1-1. Static M-Curve Measurement Test Setup
4. Connect the Fader, BERT and Digital Radio as
shown in gure 1-1.
5. Press 4MEAS TYPE5. Use the 485 key until the display
shows
, then press 4ENTER5.
STATIC
Radio Setup
1. Press 4RADIO SETUP5.
2. The rst item displayed reads
. Press
4ENTER5 to see what the bit rate is set to. The
preset value is 44.7 MHz (DS3). If you want to set
another bit rate use the arrow or data keys and press
4ENTER5.
3. The display then reads
. Press
4ENTER5 to nd the present setting. Use the 485 key
to toggle to the termination appropriate for your
BERT, then press 4ENTER5.
4. The display then reads
. Press
4ENTER5 to see what the variable error threshold is
set to. If you want to set a dierent threshold use
the arrow or data keys. Choose a threshold setting
(combined with the ERROR TERM setting) that
is appropriate for your BERT, then press 4ENTER5.
0 BIT RATE
1 ERROR TERM
1.1 ERROR THR
1-5
Digital Radio Testing
HP 11757B
5.
6.
Error pulse input variable threshold is only available
in serial prexes 3235A and above.
The display next reads
. You will not
need to set this unless you are planning to use the
ALARM INPUT for this test. Press the 485 key to
advance to the next feature.
The display should read
. The
PRESET scale factor is 1.0, and this should only be
changed if your BERT's error output is sending out
error pulses at a rate other than it is detecting them.
For instance, if the error output of your BERT is
sending one pulse for every four errors, set the scale
factor to four. To set the SCALE FACTOR press
4ENTER5 when
is displayed, then use
the 485 arrow key to display the factor your want,
then press 4ENTER5 again.
The display should now read
. AGC
(Automatic Gain Control) maintains the power level
of the spectrum sent through the Fader. You may
want the power level to remain constant even though
a notch is sweeping through the band. If you are
interrupting the digital radio after its own internal
ALC or AGC circuitry, you may have to use the
Fader's internal AGC circuitry to prevent non-fade
eects from distorting measurement results. Press
4ENTER5, then use the 485 key to display AGC ON if
AGC OFF is displayed. Press 4ENTER5 to exit.
The display should now read
. If the
AGC is ON, you should ensure that you have the
proper AGC center frequency set. Press 4ENTER5
and the display will change \
" or
whatever frequency may have been set previously.
Use the arrow or data keys to set the desired
frequency, then press 4ENTER5.
The display should now read \
". This
allows you to set the bandwidth to distribute the
2 ALARM POL
3 SCALE FACT
3 SCALE FACT
7.
8.
4 AGC ON/OFF
5 AGC FREQ
AGC FRQ 070.0
9.
1-6
6 AGC BW
HP 11757B
Digital Radio Testing
AGC power over. Press 4ENTER5 to see what value
this is set to. Use the arrow or data entry keys to
set a value. Use a value close to the radio's channel
bandwidth, then press 4ENTER5.
10. The display should now read \
". This
allows you to set the wait time after every notch
movement. This wait allows your radio some settling
time before a Bit Error Rate measurement is made
by the Fader. Press 4ENTER5 to see what value this is
set to. Use the arrow or data entry keys to set a new
value if desired, then press 4ENTER5.
11. The display should now read \
". This
allows you to set the notch's maximum slew rate
during measurements. Press 4ENTER5 to see what
value this is set to. Use the arrow or data entry keys
to set a new value if desired, then press 4ENTER5.
12. The display should now read \
".
This allows you to set the symbol time of your radio.
You will not need to set this unless you are planning
to perform a CCIR DFM calculation. The radio
setup is now complete. CCIR DFM is only available
in serial prexes 3215A and above.
7 WAIT TIME
8 MAX SLEW
9 SYMBL TIME
Measurement Setup
1. Press 4MEAS SETUP5. This will access a series of
parameters to enter to set the Fader up for a
measurement.
2. The rst item displayed under 4MEAS SETUP5 is \
". This species the number of linearly
spaced frequencies to calculate and measure in the
band you have selected. Press 4ENTER5 to access, then
use the arrow or data keys to enter a value, then
press 4ENTER5 to get the next parameter. 11 is a good
value to enter to keep the measurement time down.
3. The second and third items will be \
"
and \
". These access the start and stop
0
DATA PTS
1 STRT FRQ
2 STOP FRQ
1-7
Digital Radio Testing
HP 11757B
frequencies for the notch. Press 4ENTER5 to access
STRT FR, then use the arrow or data keys to set a
value in MHz (use 45 for this example), then press
4ENTER5. The display should show
.
Press 4ENTER5 and set a value using data or arrow
keys (95 for this example), then press 4ENTER5.
The next two items displayed are \
"
and \
". These parameters are used
for S-Curve measurements and will be ignored when
making M-Curve measurements. Press 495 until the
display reads \
".
determines the number of errors that
are counted before a nal bit error rate calculation is
made. You may enter powers of 2 from 2 to 15 (4 ,
8, . . . , 32768). Press 4ENTER5 to access and use the
485 arrow key to get 211 , which equals 2048. Press
4ENTER5.
The next displayed item is \
". Press
4ENTER5 and use the 485 arrow key to toggle between
the three options:
.
When both is displayed, press 4ENTER5.
The Fader will then display \
",
which indicates the decision criteria for drawing an
M-Curve. Press 4ENTER5 and use the 485 arrow key
to toggle through the options: ALARM, 1E-3, 3E-4,
1E-4, 3E-5, 1E-5 and 1E-6. Unless you have opted to
use the ALARM INPUT to make the measurement,
select one of the other criteria and press 4ENTER5.
The display will then read \
". This applies
only to Dynamic M-Curve, and will be ignored for
Static M-Curve measurements. Press 495 to move to
the next feature.
The display will now read \
". This
applies only to Dynamic M-Curve, and will be
2 STOP FRQ
4.
3 START RATE
4 STOP RATE
5 ERROR BITS
5.
6.
ERROR BITS
6 PHASE
MIN, NON-MIN and BOTH
7.
8.
9.
1-8
7 CRITERIA
8 SPEED
9 DEVIATION
HP 11757B
Digital Radio Testing
ignored for Static M-Curve measurements. Press 495
to move to the next feature.
10. The display should then read \
".
This feature increases measurement resolution near
the edges of the measurement, but will only be
activated if you have specied at least 15 data points
(we specied just 11 earlier in this example). Use
the 495 key to move to the next feature.
11. The display will now read \
".
This algorithm will initiate worst case searches
during the measurement. For a full description see
MK SEARCH in the Local and Remote Reference
Manual. Since this feature can increase measurement
time press 4ENTER5 to ensure that it is set to OFF,
then press 4ENTER5 again.
12. The display will now read \
". This
allows selection of the type of DFM calculation
performed. For a full description see MEAS in the
Local Reference. The measurement setup is now
complete. DFM TYPE is only available in serial
prexes 3215A and above.
10 EDGE ZOOM
11 MK SEARCH
12 DFM TYPE
Measurement
You are now ready to make the actual measurement.
Press 4MEAS5. The display will indicate that the
measurement is in progress. When the measurement
has nished, the display will return to normal. If you
press the 4PRESET/LOCAL5 key on the Fader front panel
during the measurement, the measurement will be
interrupted and stop.
Printing Results
1. After the measurement has been completed, you can
print the results. First, set the printer destination.
Press 4SHIFT5 4MEAS5 (PRINTER), then use the 485
arrow key to select between
and
.
Press 4ENTER5 on
to set the destination.
Use 485 to select between
and
.
1 DEST
2 PRINT
1 DEST
EXTERN
INTERN
1-9
Digital Radio Testing
HP 11757B
Press 4ENTER5 on
to set the printout for the
internal thermal printer.
INTERN
Note
Once the destination has been set, you do not need to
reset it before every printing.
is the PRESET
setting.
NONE
2. Next, print the parameters. Press 4SHIFT5 4MEAS5, then
toggle the 485 key to get
. Press 4ENTER5. Use
the 485 key to display
, the press 4ENTER5.
The printer will print the parameters you used to
make the measurement.
3. Next, print the data (graphic results). Press 4SHIFT5
4MEAS5, then toggle the 485 key to get
. Press
4ENTER5. Use the 485 key to display
, then press
4ENTER5. The printer will now print the results.
2 PRINT
PRVIEW
2 PRINT
DATA
1-10
HP 11757B
Digital Radio Testing
Dynamic M-Curve
Measurement
Equipment Setup
Note
1. The basic setup for all measurements involves
interrupting the IF path of the digital radio with a
fading simulator. If a Bit Error Rate Tester (BERT)
is used, connect the appropriate data channels. In the
gure below, the DS3 data out from the BERT is
connected to the DS3 input of the transmitter, and
the BASEBAND output of the receiver to the DS3
data input of the BERT. The ERROR OUTPUT
of the BERT is connected to the ERROR PULSE
INPUT of the Fader. This input can be set to match
the impedance of the BERT.
Some digital radios have their own error outputs and
internal data checking schemes that limit the need for
a BERT. See the manual for your radio if you wish
to connect the ERROR PULSE INPUT of the Fader
directly to the radio. There may be a connection that
must be made between two ports of the radio system for
this to work.
2. The RF output of the transmitter is connected to the
RF input of the receiver. Appropriate attenuation is
used to protect the RF input of the receiver. Check
the manual of the receiver and the transmitter to
insure safe levels for the receiver input.
3. The Alarm Output on the receiver can be connected
to the Alarm Input on the Fader. This connection is
only needed for recovery tests, and tests where no
BERT is available and you want to use the ALARM
INPUT to indicate failure.
1-11
Digital Radio Testing
HP 11757B
Figure 1-2. Dynamic M-Curve Measurement Test Setup
4. Connect the Fader, BERT and Digital Radio as
shown in gure 1-2.
5. Press 4MEAS TYPE5. Use the 485 key until the display
shows
, then press 4ENTER5.
DYNM M
Radio Setup
1. Press 4RADIO SETUP5.
2. The rst item displayed reads
. Press
4ENTER5 to see what the bit rate is set to. The
preset value is 44.7 MHz (DS3). If you want to set
another bit rate use the arrow or data keys and press
4ENTER5.
3. The display then reads
. Press
4ENTER5 to nd the present setting. Use the 485 key
to toggle to the termination appropriate for your
BERT, then press 4ENTER5.
4. The display then reads
. Press
4ENTER5 to see what the variable error threshold is
set to. If you want to set a dierent threshold use
the arrow or data keys. Choose a threshold setting
(combined with the ERROR TERM setting) that
is appropriate for your BERT, then press 4ENTER5.
0 BIT RATE
1 ERROR TERM
1.1 ERROR THR
1-12
HP 11757B
Digital Radio Testing
5.
6.
Error pulse input variable threshold is only available
in serial prexes 3235A and above.
The display next reads
. You will not
need to set this unless you are planning to use the
ALARM INPUT for this test. Press the 495 key to
advance to the next feature.
The display should read
. The
PRESET scale factor is 1, and this should only be
changed if your BERT's error output is sending out
error pulses at a rate other than it is detecting them.
For instance, if the error output of your BERT is
sending one pulse for every four errors, set the scale
factor to four. To set the scale factor press 4ENTER5
when
is displayed, then use the 485
arrow key to display the factor your want, then press
4ENTER5 again.
The display should now read
. AGC
(Automatic Gain Control) maintains the power level
of the spectrum sent through the Fader. You may
want the power level to remain constant even though
a notch is sweeping through the band. If you are
interrupting the digital radio after its own internal
ALC or AGC circuitry, you may have to use the
Fader's internal AGC circuitry to prevent non-fade
eects from distorting measurement results. Press
4ENTER5, then use the 485 key to display AGC ON if
AGC OFF is displayed. Press 4ENTER5 to exit.
The display should now read
. If the
AGC is ON, you should ensure that you have the
proper AGC center frequency set. Press 4ENTER5
and the display will change \
" or
whatever frequency may have been set previously.
Use the arrow or data keys to set the desired
frequency, then press 4ENTER5.
The display should now read \
". This
allows you to set the bandwidth to distribute the
2 ALARM POL
3 SCALE FACT
3 SCALE FACT
7.
8.
4 AGC ON/OFF
5 AGC FREQ
AGC FRQ 070.0
9.
6 AGC BW
1-13
Digital Radio Testing
HP 11757B
AGC power over. Press 4ENTER5 to see what value
this is set to. Use the arrow or data entry keys to
set a value. Use a value close to the radio's channel
bandwidth, then press 4ENTER5.
10. The display should now read \
". This
allows you to set the wait time after every notch
movement. This wait allows your radio some settling
time before a Bit Error Rate measurement is made
by the Fader. Press 4ENTER5 to see what value this is
set to. Use the arrow or data entry keys to set a new
value if desired, then press 4ENTER5.
11. The display should now read \
". This
allows you to set the notch's maximum slew rate
during measurements. Press 4ENTER5 to see what
value this is set to. Use the arrow or data entry keys
to set a new value if desired, then press 4ENTER5.
12. The display should now read \
".
This allows you to set the symbol time of your radio.
You will not need to set this unless you are planning
to perform a CCIR DFM calculation. The radio
setup is now complete. CCIR DFM is only available
in serial prexes 3215A and above.
7 WAIT TIME
8 MAX SLEW
9 SYMBL TIME
Measurement Setup
1. Press 4MEAS SETUP5. This will access a series of
parameters to enter to set the Fader up for a
measurement.
2. The rst item displayed under 4MEAS SETUP5 is \
". This species the number of linearly
spaced frequencies to calculate and measure in the
band you have selected. Press 4ENTER5 to access, then
use the arrow or data keys to enter a value, then
press 4ENTER5 to get the next parameter. 11 is a good
value to enter to keep the measurement time down.
3. The second and third items will be \
"
and \
". These access the start and stop
0
DATA PTS
1 STRT FRQ
2 STOP FRQ
1-14
HP 11757B
Digital Radio Testing
frequencies for the notch. Press 4ENTER5 to access
STRT FRQ, then use the arrow or data keys to set a
value in MHz (use 50 for this example), then press
4ENTER5. The display should show
.
Press 4ENTER5 and set a value using data or arrow
keys (95 for this example), then press 4ENTER5.
The next two items displayed are \
"
and \
". These parameters are used
for S-Curve measurements and will be ignored when
making M-Curve measurements. Press 495 until the
display reads \
".
determines the number of errors that
are counted before a nal bit error rate calculation is
made. You may enter powers of 2 from 2 to 15 (4 ,
8, . .. , 32768). Press 4ENTER5 to access and use the
485 arrow key to get 211 , which equals 2048. Press
4ENTER5.
The next displayed item is \
". Press 4ENTER5
and use the 485 arrow key to select between the three
options:
. When both is
displayed, press 4ENTER5.
The Fader will then display \
", which
indicates the decision criteria for drawing an
M-Curve. Press 4ENTER5 and use the 485 arrow key
to toggle through the options: ALARM, 1E-3, 3E-4,
1E-4, 3E-5, 1E-5 and 1E-6. Unless you have opted to
use the ALARM INPUT to make the measurement,
select one of the other criteria and press 4ENTER5.
The display will then read \
". This
parameter determines the peak frequency per second
at which the notch oscillations will take place for
Dynamic M-Curve measurements. Press 4ENTER5 to
access. Speed is entered in megahertz per second.
The PRESET is 300 MHz per second. Use the 495
arrow key to toggle between the allowable values: 10,
2 STOP FRQ
4.
3 START RATE
4 STOP RATE
5 ERROR BITS
5.
6.
ERROR BITS
PHASE
MIN, NON-MIN and BOTH
7.
8.
CRITERIA
8 SPEED
1-15
Digital Radio Testing
HP 11757B
30, 100, 300, 600 and 1200 MHz per second. Choose
a value and press 4ENTER5. Refer to gure 1-3.
9. The display will now read \
". This
refers to the maximum deviation of frequency the
notch will take as it makes a measurement. See
gure below. Use the arrow or data keys to select a
value (61, 62, 64, 66, 610 and 620 MHz). Do not
set a value that will cause the starting or stopping
frequency for your measurement to exceed allowable
bounds. For instance, if you set the start frequency
at 45 MHz, and set the deviation at 620 MHz, an
error message will result (45 0 20 = 25, and 25
MHz is below the minimum frequency for Fader).
There is a guardband of 64 MHz that should be
used to prevent errors. The formula for calculating
acceptable deviation values is:
START FREQ 0(jDEVIATIONj+4 MHz)40
MHz
STOP FREQ +(jDEVIATIONj+4 MHz)100
MHz
Use the arrow keys to set 65 MHz, then press
4ENTER5.
9 DEVIATION
1-16
HP 11757B
Digital Radio Testing
Figure 1-3. Speed and Deviation
10. The display should then read \
".
This feature increases measurement resolution near
the edges of the measurement, but should only be
activated if you have specied at least 15 data points
(we specied just 11 earlier in this example). Use
the 495 key to move to the next feature.
11. The display will now read \
".
This algorithm will initiate worst case searches
during the measurement. For a full description see
MK SEARCH in the Local and Remote Reference
Manual. Since this feature can increase measurement
time press 4ENTER5 to ensure that it is set to OFF,
then press 4ENTER5 again.
12. The display will now read \
". This
allows selection of the type of DFM calculation
performed. For a full description see MEAS in the
Local Reference. The measurement setup is now
complete. DFM TYPE is only available in serial
prexes 3215A and above.
10 EDGE ZOOM
11 MK SEARCH
12 DFM TYPE
1-17
Digital Radio Testing
HP 11757B
Measurement
You are now ready to make the actual measurement.
Press 4MEAS5. The display will indicate that the
measurement is in progress. When the measurement
has nished, the display will return to normal. If you
press the 4PRESET/LOCAL5 key on the Fader front panel
during the measurement, the measurement will be
interrupted and stop.
Printing Results
1. After the measurement has been completed, you can
print the results. First, set the printer destination.
Press 4SHIFT5 4MEAS5 (PRINTER), then use the 485
arrow key to select between
and
.
Press 4ENTER5 on
to set the destination.
Use 485 to select between
and
.
Press 4ENTER5 on
to set the printout for the
internal thermal printer.
1 DEST
2 PRINT
1 DEST
EXTERN
INTERN
INTERN
Note
Once the destination has been set, you do not need to
reset it before every printing. NONE is the PRESET
setting.
2. Next, print the parameters. Press 4SHIFT5 4MEAS5, then
toggle the 485 key to get
. Press 4ENTER5. Use
the 485 key to display
, the press 4ENTER5.
The printer will print the parameters you used to
make the measurement.
3. Next, print the data (graphic results). Press 4SHIFT5
4MEAS5, then toggle the 485 key to get
. Press
4ENTER5. Use the 485 key to display
, then press
4ENTER5. The printer will now print the results.
2 PRINT
PRVIEW
2 PRINT
DATA
1-18
HP 11757B
Digital Radio Testing
Dynamic S-Curve
Measurement
Equipment Setup
Note
1. The basic setup for all measurements involves
interrupting the IF path of the digital radio with a
fading simulator. If a Bit Error Rate Tester (BERT)
is used, connect the appropriate data channels. In the
gure below, the DS3 data out from the BERT is
connected to the DS3 input of the transmitter, and
the BASEBAND output of the receiver to the DS3
data input of the BERT. The ERROR OUTPUT
of the BERT is connected to the ERROR PULSE
INPUT of the Fader. This input can be set to match
the impedance of the BERT.
Some digital radios have their own error outputs and
internal data checking schemes that limit the need for
a BERT. See the manual for your radio if you wish
to connect the ERROR PULSE INPUT of the Fader
directly to the radio. There may be a connection that
must be made between two ports of the radio system for
this to work.
2. The RF output of the transmitter is connected to the
RF input of the receiver. Appropriate attenuation is
used to protect the RF input of the receiver. Check
the manual of the receiver and the transmitter to
insure safe levels for the receiver input.
3. The Alarm Output on the receiver can be connected
to the Alarm Input on the Fader. This connection is
only needed for recovery tests, and tests where no
BERT is available and you want to use the ALARM
INPUT to indicate failure.
1-19
Digital Radio Testing
HP 11757B
Figure 1-4. S-Curve Measurement Test Setup
4. Connect the Fader, BERT and Digital Radio as
shown in gure 1-4.
5. Press 4MEAS TYPE5. Use the 485 key until the display
shows
, then press 4ENTER5.
DYNM S
Radio Setup
1. Press 4RADIO SETUP5.
2. The rst item displayed reads
. Press
4ENTER5 to see what the bit rate is set to. The
preset value is 44.7 MHz (DS3). If you want to set
another bit rate use the arrow or data keys and press
4ENTER5.
3. The display then reads
. Press
4ENTER5 to nd the present setting. Use the 485 key
to toggle to the termination appropriate for your
BERT, then press 4ENTER5.
4. The display then reads
. Press
4ENTER5 to see what the variable error threshold is
set to. If you want to set a dierent threshold use
the arrow or data keys. Choose a threshold setting
(combined with the ERROR TERM setting) that
is appropriate for your BERT, then press 4ENTER5.
0 BIT RATE
1 ERROR TERM
1.1 ERROR THR
1-20
HP 11757B
Digital Radio Testing
5.
6.
Error pulse input variable threshold is only available
in serial prexes 3235A and above.
The display next reads
. You will not
need to set this unless you are planning to use the
ALARM INPUT for this test. Press the 495 key to
advance to the next feature.
The display should read
. The
PRESET scale factor is 1, and this should only be
changed if your BERT's error output is sending out
error pulses at a rate other than it is detecting them.
For instance, if the error output of your BERT is
sending one pulse for every four errors, set the scale
factor to four. To set the scale factor press 4ENTER5
when
is displayed, then use the 485
arrow key to display the factor your want, then press
4ENTER5 again.
The display should now read
. AGC
(Automatic Gain Control) maintains the power level
of the spectrum sent through the Fader. You may
want the power level to remain constant even though
a notch is sweeping through the band. If you are
interrupting the digital radio after its own internal
ALC or AGC circuitry, you may have to use the
Fader's internal AGC circuitry to prevent non-fade
eects from distorting measurement results. Press
4ENTER5, then use the 485 key to display AGC ON if
AGC OFF is displayed. Press 4ENTER5 to exit.
The display should now read
. If the
AGC is ON, you should ensure that you have the
proper AGC center frequency set. Press 4ENTER5
and the display will change \
" or
whatever frequency may have been set previously.
Use the arrow or data keys to set the desired
frequency, then press 4ENTER5.
The display should now read \
". This
allows you to set the bandwidth to distribute the
2 ALARM POL
3 SCALE FACT
3 SCALE FACT
7.
8.
4 AGC ON/OFF
5 AGC FREQ
AGC FRQ 070.0
9.
6 AGC BW
1-21
Digital Radio Testing
HP 11757B
AGC power over. Press 4ENTER5 to see what value
this is set to. Use the arrow or data entry keys to
set a value. Use a value close to the radio's channel
bandwidth, then press 4ENTER5.
10. The display should now read \
". This
allows you to set the wait time after every notch
movement. This wait allows your radio some settling
time before a Bit Error Rate measurement is made
by the Fader. Press 4ENTER5 to see what value this is
set to. Use the arrow or data entry keys to set a new
value if desired, then press 4ENTER5.
11. The display should now read \
". This
allows you to set the notch's maximum slew rate
during measurements. Press 4ENTER5 to see what
value this is set to. Use the arrow or data entry keys
to set a new value if desired, then press 4ENTER5.
12. The display should now read \
".
This feature is not available for Dynamic S-Curve
measurements. The radio setup is now complete.
7 WAIT TIME
8 MAX SLEW
9 SYMBL TIME
Measurement Setup
1. Press 4MEAS SETUP5. This will access a series of
parameters to enter to set the Fader up for a
measurement.
2. The rst item displayed under 4MEAS SETUP5 is \
". This species the number of linearly
spaced rates to calculate and measure in the band
you have selected. Press 4ENTER5 to access, then use
the arrow or data keys to enter a value, then press
4ENTER5 to get the next parameter. 11 is a good
value to enter to keep the measurement time down.
3. The second and third items will be \
"
and \
". These access the start and stop
frequencies for the notch. Press 4ENTER5 to access
STRT FR, then use the arrow or data keys to set a
value in MHz (use 45 for this example), then press
0
DATA PTS
1 STRT FRQ
2 STOP FRQ
1-22
HP 11757B
Digital Radio Testing
. The display should show
.
Press
and set a value using data or arrow
keys (95 for this example), then press 4ENTER5.
The next two items displayed are \
"
and \
". These parameters are used for
S-Curve measurements. The start rate and stop rate
refer to the range of rates at which the notch sweeps
throughout the measurement. The range of values
0
j MHz per
is 1 MHz per second to j
01
second. The Fader will linearly distribute rates from
your start rate to your stop rate using the number of
data points selected. If you selected 11 data points,
the measurement will use 11 dierent rates from
your start rate to your stop rate. Press 4ENTER5 to
access the start rate. Use the arrow or data keys
to set the value at 5 MHz per second. Then press
4ENTER5 to move to
. Press 4ENTER5
again to access and set the rate to 2000 MHz per
second, the press 4ENTER5.
The next parameter,
, determines the
number of errors that are counted before a nal bit
error rate calculation is made. You may enter powers
of 2 from 2 to 15 (4 , 8, . . . , 32768). Press 4ENTER5
to access and use the 485 arrow key to get 211, which
equals 2048. Press 4ENTER5.
The next displayed item is \
". Press 4ENTER5
and use the 485 arrow key to select between the three
options:
. When both is
displayed, press 4ENTER5.
The Fader will then display \
", which
indicates the decision criteria for drawing an
M-Curve. Press 4ENTER5 and use the 485 arrow key
to toggle through the options: ALARM, 1E-3, 3E-4,
1E-4, 3E-5, 1E-5 and 1E-6. Unless you have opted to
use the ALARM INPUT to make the measurement,
select one of the other criteria and press 4ENTER5.
4ENTER5
4ENTER5
4.
2 STOP FRQ
3 START RATE
4 STOP RATE
StartF req
StopF req
:
4 STOP RATE
5.
6.
ERROR BITS
PHASE
MIN, NON-MIN and BOTH
7.
CRITERIA
1-23
Digital Radio Testing
HP 11757B
8. The display will then read \
". This
parameter determines the peak frequency per second
at which the notch oscillations will take place for
Dynamic M-Curve measurements. It does not apply
to S-Curve Measurements. Press 495.
9. The display will now read \
". This
applies only to Dynamic M-Curve Measurements.
Press 495.
10. The display should then read \
".
This feature is not useful for S-Curve measurements
and will be ignored. Press 495.
11. The display will now read \
".
This feature is not available for Dynamic S-Curve
measurements.
12. The display will now read \
".
This feature is not available for Dynamic S-Curve
measurements. The measurement setup is now
complete.
8 SPEED
9 DEVIATION
10 EDGE ZOOM
11 MK SEARCH
12 DFM TYPE
Measurement
You are now ready to make the actual measurement.
Press 4MEAS5. The display will indicate that the
measurement is in progress. When the measurement
has nished, the display will return to normal. If you
press the 4PRESET/LOCAL5 key on the Fader front panel
during the measurement, the measurement will be
interrupted and stop.
Printing Results
1. After the measurement has been completed, you can
print the results. First, set the printer destination.
Press 4SHIFT5 4MEAS5 (PRINTER), then use the 485
arrow key to select between
and
.
Press 4ENTER5 on
to set the destination.
Use 485 to select between
and
.
Press 4ENTER5 on
to set the printout for the
internal thermal printer.
1 DEST
2 PRINT
1 DEST
EXTERN
INTERN
1-24
INTERN
HP 11757B
Digital Radio Testing
Note
Once the destination has been set, you do not need to
reset it before every printing. NONE is the PRESET
setting.
2. Next, print the parameters. Press 4SHIFT5 4MEAS5, then
toggle the 485 key to get
. Press 4ENTER5. Use
the 485 key to display
, the press 4ENTER5.
The printer will print the parameters you used to
make the measurement.
3. Next, print the data (graphic results). Press 4SHIFT5
4MEAS5, then toggle the 485 key to get
. Press
4ENTER5. Use the 485 key to display
, then press
4ENTER5. The printer will now print the results.
2 PRINT
PRVIEW
2 PRINT
DATA
1-25
Digital Radio Testing
HP 11757B
Hysteresis
M-Curve
Measurement
Note
Equipment Setup
Note
The Hysteresis M-Curve measurement uses the same
parameters and setup as the Static M-Curve Test.
1. The basic setup for all measurements involves
interrupting the IF path of the digital radio with a
fading simulator. If a Bit Error Rate Tester (BERT)
is used, connect the appropriate data channels. In the
gure below, the DS3 data out from the BERT is
connected to the DS3 input of the transmitter, and
the BASEBAND output of the receiver to the DS3
data input of the BERT. The ERROR OUTPUT
of the BERT is connected to the ERROR PULSE
INPUT of the Fader. This input can be set to match
the impedance of the BERT.
Some digital radios have their own error outputs and
internal data checking schemes that limit the need for
a BERT. See the manual for your radio if you wish
to connect the ERROR PULSE INPUT of the Fader
directly to the radio. There may be a connection that
must be made between two ports of the radio system for
this to work.
2. The RF output of the transmitter is connected to the
RF input of the receiver. Appropriate attenuation is
used to protect the RF input of the receiver. Check
the manual of the receiver and the transmitter to
insure safe levels for the receiver input.
3. The Alarm Output on the receiver can be connected
to the Alarm Input on the Fader. This connection is
only needed for recovery tests, and tests where no
1-26
HP 11757B
Digital Radio Testing
BERT is available and you want to use the ALARM
INPUT to indicate failure.
Figure 1-5. Hysteresis Measurement
4. Connect the Fader, BERT and Digital Radio as
shown in gure 1-5.
5. Press 4MEAS TYPE5. Use the 485 key until the display
shows
, then press 4ENTER5.
HYSTER
Radio Setup
1. Press 4RADIO SETUP5.
2. The rst item displayed reads
. Press
4ENTER5 to see what the bit rate is set to. The
preset value is 44.7 MHz (DS3). If you want to set
another bit rate use the arrow or data keys and press
4ENTER5.
3. The display then reads
. Press
4ENTER5 to nd the present setting. Use the 485 key
to toggle to the termination appropriate for your
BERT, then press 4ENTER5.
4. The display then reads
. Press
4ENTER5 to see what the variable error threshold is
set to. If you want to set a dierent threshold use
0 BIT RATE
1 ERROR TERM
1.1 ERROR THR
1-27
Digital Radio Testing
HP 11757B
5.
6.
the arrow or data keys. Choose a threshold setting
(combined with the ERROR TERM setting) that
is appropriate for your BERT, then press 4ENTER5.
Error pulse input variable threshold is only available
in serial prexes 3235A and above.
The display next reads
. You will not
need to set this unless you are planning to use the
ALARM INPUT for this test. Press the 495 key to
advance to the next feature.
The display should read
. The
PRESET scale factor is 1.0, and this should only be
changed if your BERT's error output is sending out
error pulses at a rate other than it is detecting them.
For instance, if the error output of your BERT is
sending one pulse for every four errors, set the scale
factor to four. To set the scale factor press 4ENTER5
when
is displayed, then use the 485
arrow key to display the factor your want, then press
4ENTER5 again.
The display should now read
. AGC
(Automatic Gain Control) maintains the power level
of the spectrum sent through the Fader. You may
want the power level to remain constant even though
a notch is sweeping through the band. If you are
interrupting the digital radio after its own internal
ALC or AGC circuitry, you may have to use the
Fader's internal AGC circuitry to prevent non-fade
eects from distorting measurement results. Press
4ENTER5, then use the 485 key to display AGC ON if
AGC OFF is displayed. Press 4ENTER5 to exit.
The display should now read
. If the
AGC is ON, you should ensure that you have the
proper AGC center frequency set. Press 4ENTER5
and the display will change \
" or
whatever frequency may have been set previously.
2 ALARM POL
3 SCALE FACT
3 SCALE FACT
7.
8.
4 AGC ON/OFF
5 AGC FREQ
AGC FRQ 070.0
1-28
HP 11757B
Digital Radio Testing
9.
10.
11.
12.
Measurement Setup
Use the arrow or data keys to set the desired
frequency, then press 4ENTER5.
The display should now read \
". This
allows you to set the bandwidth to distribute the
AGC power over. Press 4ENTER5 to see what value
this is set to. Use the arrow or data entry keys to
set a value. Use a value close to the radio's channel
bandwidth, then press 4ENTER5.
The display should now read \
". This
allows you to set the wait time after every notch
movement. This wait allows your radio some settling
time before a Bit Error Rate measurement is made
by the Fader. Press 4ENTER5 to see what value this is
set to. Use the arrow or data entry keys to set a new
value if desired, then press 4ENTER5.
The display should now read \
". This
allows you to set the notch's maximum slew rate
during measurements. Press 4ENTER5 to see what
value this is set to. Use the arrow or data entry keys
to set a new value if desired, then press 4ENTER5.
The display should now read \
".
This allows you to set the symbol time of your radio.
You will not need to set this unless you are planning
to perform a CCIR DFM calculation. The radio
setup is now complete. CCIR DFM is only available
in serial prexes 3215A and above.
6 AGC BW
7 WAIT TIME
8 MAX SLEW
9 SYMBL TIME
1. Press 4MEAS SETUP5. This will access a series of
parameters to enter to set the Fader up for a
measurement.
2. The rst item displayed under 4MEAS SETUP5 is \
". This species the number of linearly
spaced frequencies to calculate and measure in the
band you have selected. Press 4ENTER5 to access, then
use the arrow or data keys to enter a value, then
0
DATA PTS
1-29
Digital Radio Testing
HP 11757B
3.
press 4ENTER5 to get the next parameter. 11 is a good
value to enter to keep the measurement time down.
The second and third items will be \
"
and \
". These access the start and stop
frequencies for the notch. Press 4ENTER5 to access
STRT FRQ, then use the arrow or data keys to set a
value in MHz (use 45 for this example), then press
4ENTER5. The display should show
.
Press 4ENTER5 and set a value using data or arrow
keys (95 for this example), then press 4ENTER5.
The next two items displayed are \
"
and \
". These parameters are used
for S-Curve measurements and will be ignored when
making Hysteresis M-Curve measurements. Press 495
until the display reads \
".
determines the number of errors that
are counted before a nal bit error rate calculation is
made. You may enter powers of 2 from 2 to 15 (4 ,
8, . . . , 32768). Press 4ENTER5 to access and use the
485 arrow key to get 211 , which equals 2048. Press
4ENTER5.
The next displayed item is \
". The
Hysteresis M-Curve measurement uses BOTH
phases. You do not need to select a phase because
the instrument will always choose BOTH. Use the
495 key to move to
.
The Fader will then display \
", which
indicates the decision criteria for drawing an
M-Curve. Press 4ENTER5 and use the 485 arrow key
to toggle through the options: ALARM, 1E-3, 3E-4,
1E-4, 3E-5, 1E-5 and 1E-6. Unless you have opted to
use the ALARM INPUT to make the measurement,
select one of the other criteria and press 4ENTER5.
The display will then read \
". This applies
only to Dynamic M-Curve, and will be ignored for
1 STRT FRQ
2 STOP FRQ
2 STOP FRQ
4.
3 START RATE
4 STOP RATE
5 ERROR BITS
5.
6.
ERROR BITS
PHASE
CRITERIA
7.
8.
1-30
CRITERIA
8 SPEED
HP 11757B
Digital Radio Testing
9.
10.
11.
12.
Measurement
Hysteresis M-Curve measurements. Press 495 to
move to the next feature.
The display will now read \
". This
applies only to Dynamic M-Curve, and will be
ignored for Hysteresis M-Curve measurements. Press
495 to move to the next feature.
The display should then read \
".
This feature increases measurement resolution near
the edges of the measurement, but will only be
activated if you have specied at least 15 data points
(we specied just 11 earlier in this example). Use
the 495 key to move to the next feature.
The display will now read \
".
This algorithm will initiate worst case searches
during the measurement. For a full description see
MK SEARCH in the Local and Remote Reference
Manual. Since this feature can increase measurement
time press 4ENTER5 to ensure that it is set to OFF,
then press 4ENTER5 again.
The display will now read \
". This
allows selection of the type of DFM calculation
performed. For a full description see MEAS in the
Local Reference. The measurement setup is now
complete. DFM TYPE is only available in serial
prexes 3215A and above.
9 DEVIATION
10 EDGE ZOOM
11 MK SEARCH
12 DFM TYPE
You are now ready to make the actual measurement.
Press 4MEAS5. The display will indicate that the
measurement is in progress. When the measurement
has nished, the display will return to normal. If you
press the 4PRESET/LOCAL5 key on the Fader front panel
during the measurement, the measurement will be
interrupted and stop.
1-31
Digital Radio Testing
Printing Results
HP 11757B
1. After the measurement has been completed, you can
print the results. First, set the printer destination.
Press 4SHIFT5 4MEAS5 (PRINTER), then use the 485
arrow key to select between
,
and
. Press 4ENTER5 on
to set the
destination. Use 485 to select between
and
. Press 4ENTER5 on
to set the
printout for the internal thermal printer.
1 DEST
NONE
2 PRINT
1 DEST
EXTERN
INTERN
Note
INTERN
Once the destination has been set, you do not need to
reset it before every printing. NONE is the PRESET
setting.
2. Next, print the parameters. Press 4SHIFT5 4MEAS5, then
toggle the 485 key to get
. Press 4ENTER5. Use
the 485 key to display
, the press 4ENTER5.
The printer will print the parameters you used to
make the measurement.
3. Next, print the data (graphic results). Press 4SHIFT5
4MEAS5, then toggle the 485 key to get
. Press
4ENTER5. Use the 485 key to display
, then press
4ENTER5. The printer will now print the results.
2 PRINT
PRVIEW
2 PRINT
DATA
1-32
HP 11757B
Digital Radio Testing
Recovery Time
Test
Note
In the recovery time test the Fader breaks the IF path of
the digital radio and then measures the time the radio
takes to recover lock. The time the radio is out of lock is
measured at the ALARM INPUT of the Fader.
There are two variations on this test that you may want
to try. You can measure the time it takes to recover
when a notch is in the IF path after a break in lock.
You may also measure the time it takes to recover to a
specied bit error rate (requires Bit Error Rate Tester).
The procedure that follows covers all three variations.
The BERT is only required for return to bit error rate
testing.
Some radios have their own internal error checking
scheme. This would eliminate the need for a BERT in
bit error rate checking.
Figure 1-6. Recovery Time Test Setup
1-33
Digital Radio Testing
Equipment Setup
HP 11757B
1. Connect the Fader, Digital Radio, and BERT if used
as shown in gure 1-6.
2. Press 4MEAS TYPE5. Use the 485 key until the display
shows
, then press 4ENTER5.
RECVRY
Radio Setup
1. Press 4RADIO SETUP5.
2. The rst item displayed reads
. This
need only be entered if you are using a BERT to
measure recovery time to a bit error rate. Press
4ENTER5 to see what the bit rate is set to. The preset
value is 44.7 MHz (DS3). If you want to set another
bit rate use the arrow or data keys and press 4ENTER5.
3. The display then reads
. Press
4ENTER5 to nd the present setting. Use the 485 key to
toggle to the termination appropriate for your BERT,
then press 4ENTER5.
4. The display then reads
. Press
4ENTER5 to see what the variable error threshold is
set to. If you want to set a dierent threshold use
the arrow or data keys. Choose a threshold setting
(combined with the ERROR TERM setting) that
is appropriate for your BERT, then press 4ENTER5.
Error pulse input variable threshold is only available
in serial prexes 3235A and above.
5. The display next reads
. Press 4ENTER5
to display the current setting. Use the 485 key to
toggle between positive and negative edge polarity
triggering. You may need to refer to the ALARM
OUTPUT of your radio, or the manual for your radio
to nd out which polarity to use. Select the polarity
and press 4ENTER5.
6. The display should read
. This is not
needed unless you are using a BERT for recovery to
a bit error rate, and the BERT does not put out a
pulse for each error it detects. For instance, if the
0 BIT RATE
1 ERROR TERM
1.1 ERROR THR
2 ALARM POL
3 SCALE FACT
1-34
HP 11757B
Digital Radio Testing
error output of your BERT is sending one pulse for
every four errors, set the scale factor to four. To set
the scale factor press 4ENTER5 when
is
displayed, then use the 485 arrow key to display the
factor your want, then press 4ENTER5 again.
7. The display should now read
. You
do not need to use AGC or set anything in the next
three steps unless you intend to have a notch in the
band before the start of a test. If you are not using a
notch, go to
. AGC (Automatic
Gain Control) maintains the power level of the
spectrum sent through the Fader. You want the
power level to remain constant even though a notch is
sweeping through the band. If you are interrupting
the digital radio after its own internal ALC or AGC
circuitry, you may have to use the Fader's internal
AGC circuitry to prevent non-fade eects from
distorting measurement results. Press 4ENTER5, then
use the 485 key to display AGC ON if AGC OFF is
displayed. Press 4ENTER5 to exit.
8. The display should now read
. If the
AGC is ON, you should ensure that you have the
proper AGC center frequency set. Press 4ENTER5
and the display will change \
" or
whatever frequency may have been set previously.
Use the arrow or data keys to set the desired
frequency, then press 4ENTER5.
9. The display should no read \
". This
allows you to set the bandwidth to distribute the
AGC power over. Press 4ENTER5 to see what value
this is set to. Use the arrow or data entry keys to
set a value. Use a value close to the radio's channel
bandwidth, then press 4ENTER5. The radio setup is
now complete.
3 SCALE FACT
4 AGC ON/OFF
Measurement Setup
5 AGC FREQ
AGC FRQ 070.0
6 AGC BW
1-35
Digital Radio Testing
Measurement Setup
HP 11757B
1. Press 4MEAS SETUP5. This will access a series of
parameters to enter to set the Fader up for a
measurement.
2. Use the 495 to display \
", which can be
used with the recovery test to measure the time it
takes to recover to a specied bit error rate. This
is not needed if you are simply using the ALARM
INPUT to measure recovery time. Press 4ENTER5 and
use the 485 arrow key to toggle through the options:
ALARM, 1E-3, 3E-4, 1E-4, 3E-5, 1E-5 and 1E-6.
Unless you have opted to use the ALARM INPUT to
make the measurement, select one of the other criteria
and press 4ENTER5.
3. If you want to test recovery time when a notch
exists in the IF path (or some other path), press
4NOTCH FREQ5 and use the arrow or data keys to set
the notch frequency you want to test at. Then press
4NOTCH DEPTH5 and use the arrow or data keys to set
the depth you want to test at.
CRITERIA
Note
Measurement
1-36
If you set a depth too deep and have set a bit error rate
criteria for recovery, the radio may not recover. Make
sure that the notch depth and frequency you have chosen
for recovery test is one that would pass on the Static
M-Curve test for the criteria you have set.
You are now ready to make the actual measurement.
Press 4MEAS5. The Fader display will show the recovery
time.
HP 11757B
Digital Radio Testing
Printing Results
You cannot print the data in this test. However, you can
print the parameters.
1. After the measurement has been completed, you
can print the parameters. First, set the printer
destination. Press 4SHIFT5 4MEAS5 (PRINTER), then
use the 485 arrow key to select between
and
. Press 4ENTER5 on
to set the
destination. Use 485 to select between
and
. Press 4ENTER5 on
to set the
printout for the internal thermal printer.
1 DEST
2 PRINT
1 DEST
INTERN
INTERN
EXTERN
Note
Once the destination has been set, you do not need to
reset it before every printing. NONE is the PRESET
setting.
2. Next, print the parameters. Press 4SHIFT5 4MEAS5, then
toggle the 485 key to get
. Press 4ENTER5. Use
the 485 key to display
, the press 4ENTER5.
The printer will print the parameters you used to
make the measurement.
2 PRINT
PRVIEW
1-37
Digital Radio Testing
HP 11757B
Bit Error Rate Test
In the bit error rate test the Fader monitors the ERROR
PULSE INPUT and measures the bit error rate for
approximately 1 second. When started using the 4MEAS5
key, this test runs continuously until the 4PRESET/LOCAL5
key is pressed.
Some radios have their own internal error checking
scheme. This would eliminate the need for a BERT in
bit error rate checking.
Note
Figure 1-7. Bit Error Rate Test Setup
Equipment Setup
1. Connect the Fader, Digital Radio, and BERT if used
as shown in gure 1-7.
2. Press 4MEAS TYPE5. Use the 485 key until the display
shows
, then press 4ENTER5.
BER
1-38
HP 11757B
Digital Radio Testing
Radio Setup
1. Press 4RADIO SETUP5.
2. The rst item displayed reads
. This
need only be entered if you are using a BERT to
measure recovery time to a bit error rate. Press
4ENTER5 to see what the bit rate is set to. The
preset value is 44.7 MHz (DS3). If you want to set
another bit rate use the arrow or data keys and press
4ENTER5.
3. The display then reads
. Press
4ENTER5 to nd the present setting. Use the 485 key
to toggle to the termination appropriate for your
BERT, then press 4ENTER5.
4. The display then reads
. Press
4ENTER5 to see what the variable error threshold is
set to. If you want to set a dierent threshold use
the arrow or data keys. Choose a threshold setting
(combined with the ERROR TERM setting) that
is appropriate for your BERT, then press 4ENTER5.
Error pulse input variable threshold is only available
in serial prexes 3235A and above.
5. The display next reads
. You will not
need to set this for this test. Press the 485 key to
advance to the next feature.
6. The display should read
. The
PRESET scale factor is 1.0, and this should only be
changed if your BERT's error output is sending out
error pulses at a rate other than it is detecting them.
For instance, if the error output of your BERT is
sending one pulse for every four errors, set the scale
factor to four. To set the SCALE FACTOR press
4ENTER5 when
is displayed, then use
the 485 arrow key to display the factor your want,
then press 4ENTER5 again.
7. The display should now read
. AGC
(Automatic Gain Control) maintains the power level
0 BIT RATE
1 ERROR TERM
1.1 ERROR THR
2 ALARM POL
3 SCALE FACT
3 SCALE FACT
4 AGC ON/OFF
1-39
Digital Radio Testing
HP 11757B
8.
of the spectrum sent through the Fader. You may
want the power level to remain constant even though
you have a notch. If you are interrupting the digital
radio after its own internal ALC or AGC circuitry,
you may have to use the Fader's internal AGC
circuitry to prevent non-fade eects from distorting
measurement results. Press 4ENTER5, then use the 485
key to display AGC ON if AGC OFF is displayed.
Press 4ENTER5 to exit.
The display should now read
. If the
AGC is ON, you should ensure that you have the
proper AGC center frequency set. Press 4ENTER5
and the display will change \
" or
whatever frequency may have been set previously.
Use the arrow or data keys to set the desired
frequency, then press 4ENTER5.
The display should now read \
". This
allows you to set the bandwidth to distribute the
AGC power over. Press 4ENTER5 to see what value
this is set to. Use the arrow or data entry keys to
set a value. Use a value close to the radio's channel
bandwidth, then press 4ENTER5.
The display should now read \
". This
allows you to set the wait time after every notch
movement. This wait allows your radio some settling
time before a Bit Error Rate measurement is made
by the Fader. Press 4ENTER5 to see what value this is
set to. Use the arrow or data entry keys to set a new
value if desired, then press 4ENTER5.
The display should now read \
". This
allows you to set the notch's maximum slew rate
during measurements. Press 4ENTER5 to see what
value this is set to. Use the arrow or data entry keys
to set a new value if desired, then press 4ENTER5.
If you want to test bit error rate when a notch
exists in the IF path (or some other path), press
5 AGC FREQ
AGC FRQ 070.0
9.
10.
11.
12.
1-40
6 AGC BW
7 WAIT TIME
8 MAX SLEW
HP 11757B
Digital Radio Testing
and use the arrow or data keys to set
the notch frequency you want to test at. Then press
4NOTCH DEPTH5 and use the arrow or data keys to set
the depth you want to test at.
4NOTCH FREQ5
Measurement
You are now ready to make the actual measurement.
Press 4MEAS5. The Fader display will show the bit error
rate approximately every 1 second.
Printing Results
You cannot print the data in this test. However, you can
print the parameters.
1. After the measurement has been completed, you
can print the parameters. First, set the printer
destination. Press 4SHIFT5 4MEAS5 (PRINTER), then
use the 485 arrow key to select between
and
. Press 4ENTER5 on
to set the
destination. Use 485 to select between
and
. Press 4ENTER5 on
to set the
printout for the internal thermal printer.
1 DEST
2 PRINT
1 DEST
INTERN
INTERN
EXTERN
Note
Once the destination has been set, you do not need to
reset it before every printing. NONE is the PRESET
setting.
2. Next, print the parameters. Press 4SHIFT5 4MEAS5, then
toggle the 485 key to get
. Press 4ENTER5. Use
the 485 key to display
, the press 4ENTER5.
The printer will print the parameters you used to
make the measurement.
2 PRINT
PRVIEW
1-41
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising