Geräte Informationen

Wandel & Goltermann SPM-19 Level Meter
Hersteller:
Wandel & Goltermann
Modell: SPM-19
Datum: 1981
Kategorie: Messgeräte
Gruppe: Level Meter
Beschreibung: Selective Level Meter
Informationen:
                                    While digital transmission systems are being used more and
more at the local and regional levels, FDM systems are still
the main systems for long distance traffic. Level
measurements play an important part in the measurement and
checking of the analog parameters of these systems and the
various modules. However, modern test equipment must be
available for additional measuring tasks. The selective
level meter SPM-19, in which the application of modern
circuit technologies and of a microcomputer provide a high
degree of accuracy and ease of use, is suitable for these
measuring tasks.
The frequency range of the meter extends from 50 Hz to 25
MHz if the coaxial input is used, and the frequency ranges
of the balanced inputs extend up to 620 kHz and 14 MHz. The
characteristics of the level meter make it equally suitable
for development, production, installation, and maintenance
of transmission systems with a maximum of 3,600 speech
channels, for measurements in the lower multiplex range of
single sideband radio link systems, and of single telephone
channels. Its remote control facilities also make it
suitable for use in automatic measuring systems.
As required by its intended application, the frequency of
the SPM-19 can be tuned, over the whole range, either
digitally with a keyboard or continuously, and with a
resolution of 1 Hz. The frequency can be stepped either
manually or automatically in preset steps, for example to
step from channel to channel. Up to 100 fixed frequencies
can be stored and recalled either sequentially or in any
required sequence for frequent measurements at fixed
frequencies. If required, further fixed frequencies can be
stored in a customer-specific PROM. Regardless of the type
of frequency tuning, the built- in synthesizer provides high
stability and accuracy of the selected frequency.
The signal to be measured is either connected to the coaxial
input (input impedance 75 Ohm) or to one of the two balanced
inputs with frequency ranges of 50 Hz to 520 kHz (150 Ohm,
600 Ohm) andlOkHz to 14 MHz (124 Ohm,
150 Ohm); each of these inputs can also be switched to high
impedance.
For high impedance, low capacitance measurements, the test
probe TK-11 or any other suitable test probe can be
connected as required. In selective mode, levels between
-140 and +22 dB. (-130 and +32 dBm) can be measured; in
wide-band mode, the limits are -60 and +22 dB (-50 and +32
dBm). The measured level is displayed either digitally with
automatic range selection, with a maximum resolution 0.01
dB, or on an analog meter. In the case of analog display,
the most suitable scale range of 1 dB, 20 dB or 80 dB can be
selected with three pushbuttons for the current measuring
task. Range switching is carried out either manually in
steps of 1 or 5 dB or automatically after depression of a
pushbutton.
In order to obtain the maximum possible measuring accuracy,
the microcomputer measures the total input level and adjusts
the input attenuator and IF attenuator such that
measurements are always carried out with the most favorable
settings. It is thus no longer necessary to fit the
changeover switch "low noise/low distortion", which has
previously caused some confusion.
In addition to measurement of absolute levels, the SPM- 19
permits simple measurement of relative levels. For this
purpose, a level which was previously measured digitally is
transferred to a memory as the reference value and the
difference between the measured value and this reference
value is displayed digitally or on the analog meter for all
subsequent measurements. In the case of measurements in
transmission systems, levels are often not specified
directly, but with reference to the relative level (dBr) of
a test point. In order to simplify evaluation of test
results in such cases, the relative level of the test point
can be preset in 0.1 dB steps and the result can then be
displayed as a reduced level in dBO (dBmO).
The pushbutton for the relative level is also useable for
setting any required reference value (e.g. for frequency
response measurements).
Various bandwidths are available for the various measuring
tasks. The pilot level, residual carrier signals or
frequency spectra are measured with the narrow 25 Hz filter.
Sensitive level measurements can be carried out with the 400
Hz bandwidth. A filter with a noise bandwidth of 1.74 can be
connected for weighted noise measurements in unused or
cleared speech channels at the CF level. A further posi tion
of the bandwidth switch permits level measurements with a
channel bandwidth of 3.1 kHz. Finally, the noise power of a
48 kHz primary group can be measured.
The built-in demodulator permits demodulation of single
sideband signals in the normal or inverted position. The
converted signal can either be assessed with the built-in
loudspeaker or extracted from the demodulator output for
further external processing. The demodulator is
characterized primarily by a very wide dynamic range, which
is necessary, for example, for precise measurement of noises
or pulse noise in converted speech channels. For assess™
ment of the transmission quality of telephone lines for data
transmission, phase jitter measurements can be carried out.
The weighting filter and the rectifier characteristic for
measurement of the peak to peak value comply with CCITT
recommendation 0.91. The phase jitter is displayed either
digitally or on a logarithmic scale of the analog meter in
the range 0.3 to 30 degrees. An automatic level control,
which makes manual calibration superfluous, guarantees high
measuring accuracy over the whole frequency range, a
considerable reduction in the measuring time, and a high
long-term stability. The level meter is thus also suitable
for continuous monitoring applications.
In addition to the above mentioned frequency settings, the
microcomputer control of the SPM-19 permits various other,
automatic frequency sequences. The automatic search
function, together with the rapid signal detector, is a
major aid in searching for interference or excessive levels.
The tuning, oscillator is tuned until a signal which exceeds
a preset level threshold falls within the display range of
the analog meter and stops the search.
At the same time, an automatic frequency control (AFC)
circuit is activated and tunes the oscillator precisely to
the frequency of the input signal. The search can be
restarted again either manually by depressing a pushbutton
or automatically after the level and frequency have been
printed out. The search speed is matched to the selected
bandwidth. The AFC circuit can also be switched on for
normal level measurements with all bandwidths. This circuit
ensures that the oscillator remains correctly tuned over the
whole frequency range.
For selective level measurements over a line, for example in
channel gaps of the system during normal operation, an
electronic circuit which is activated in the mode "track"
permits automatic tuning of the level meter to the frequency
of a sender with the same frequency steps.
The SPM-19 (BN 829/02) can be extended to form a panoramic
receiver by adding a display unit SG-2 or SG-3. Because of
the phase continuity during use of the sweep mode, the
frequency range can be searched completely in all chosen
operating modes, which means that all frequencies present in
the band can be clearly identified. The sweep facility
fitted in version BN 829/02 is characterised particularly by
the fact that the frequency sweep is carried out without
phase discontinuities, which means that precise measurements
are possible even of objects with extremely steep
attenuation edges. The two limit frequencies can be entered
via the keyboard to match the application. The signal
generators PS-19 and PSS-19 are suitable as signal sources
for the sweep measurements.
The combination of PS-19/SPM-19 permits measurements with
offset frequencies, e.g. the testing of channel translators.
Both types of measurements are possible, either
point-by-point or sweep measurements.
Many measuring tasks are particularly simple to solve if the
user can store complete equipment settings and recall them
when required. Depression of a pushbutton (address
selection) causes the unit to set up all previously selected
measuring conditions for a specific measuring task. The
supply voltage of the memory is buffered by a small battery
to maintain the stored data if the main supply fails or is
switched off.
All functions of the SPM-19 can be controlled by an external
computer which is compatible with the IEC bus via the
optionally available interface bus (lEC 625) board. The unit
can also be connected to an IEEE bus (IEEE Standard 488)
with an Adaptor IEC 625/IEEE 488, S 834. With the aid
further externally controllable peripheral units such as
signal generator, measuring point changeover switch, or
external memory systems, powerfull automatic level measuring
set ups can be constructed for use in test departments or
FDM monitoring systems.
The measuring point changeover switch MU-3 with a switching
unit MUE-31 and the IEC interface board can be used for
automatic testing of FDM modules with 12 channels (channel
converters). For measurements at higher frequencies, the
measuring point changeover switches MU-4 and MU-7 with
interface boards are available. Instead of the interface kus
(lEC 625) board, a printer interface for V.24/V.28 interface
can be fitted for recording the measured results in various
print formats.
Due to its excellent NPR value, the SPM-19 is suitable as a
selective receiver for measurement of intermodulation and
basic noise on FDM cable and radio link systems using the
white noise measuring method.
An optional white noise program is available to permit,
measurement of all noise parameters such as reduced noise
power (in pWOp), the reduced noise level (in dBmOp), or the
noise power ratio NPR (dB).
The test frequencies, in accordance with the recommendations
of CCITT/CCIR and INTELSAT, can either be entered via the
keyboard or stored in the 100 available fixed frequency
positions of the RAM; they can also be stored to customer's
specifications in a EPROM. The test modes and test
frequencies are recalled from the memories by suitable
address selection. The measured values and the corresponding
units are shown on the digital result display. The measuring
adapters RFZ-5, RFZ-14 (coaxial, above 10 kHz and 100 kHz,
respectively) and RFZ-12 (coaxial and balanced up to 4.5
MHz) and SDZ-12 are available as measuring accessories for
return loss or unbalance loss measurements. For apparent
resistance and return loss matching loss measurements, the
Impedance Measuring Attachment SFZ-1 (300 Hz to 612 kHz) is
available.
The Relay change-over Switch RU-3 permits digital level
difference measurements of higher relative accuracy.
The level meter can be switched from power level calibration
(dBm) to voltage level calibration (dB).
Inspite of the large number of functions, the SPM-19 is
installed in a relatively flat case. The connections,
controls, and displays are arranged clearly on an easy to
use front panel. LED's above or alongside the pushbuttons
signal the selected functions to the user. The unit is
available in versions for table-top use or 19" rack mounting.

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Dokumenttyp: Bedienungsanleitung Wandelgoltermann-8477-Manual-Page-1-Picture
Seitenanzahl: 208
Dateigröße: 5.44 Mbytes (5703848 Bytes)
Sprache: Englisch
Revision:
Dokument-ID/Nummer: 2798 GN v. 2772
Datum: 03 Juni 1981
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Informationen:
INTRODUCTION
1 TECHNICAL DATA
1.1 Frequency...................................... 1-1
1.1.1 Frequency range for selective and wide-band
measurements 1-1
1.1.2 Frequency display.................................1-1
1.1.3 Frequency tuning ...............................1-1
1.1.4 Automatic frequency sequences......................1-2
1.1.4.1 Frequency search.................................1-2
1.1.4.2 Auto step.......................................1-2
1.1.4.3 Tracking........................................1-2
1.1.4.4 Sweep frequency operation ........................1-2
1.1.5 Automatic frequency control (AFC)...................1-3
1.1.6 Error limits of the tuned frequency.................1-3
1.2 Level..........................................1-4
1.2.1 Measured parameters...............................1-4
1.2.2 Result indication, resolution, range selection........1-4
1.2.2.1 Result indication...............................1-4
1.2.2.2 Resolution of the digital display...................1-5
1.2.2.3 Range selection..................................1-5
1.2.3 Measuring ranges..................................1-6
1.2.3.1 Absolute level..................................1-6
1.2.3.2 Reduced level.,,.................................1-6
1.2.3.3 Reduced noise level {dBmOp) and
reduced noise power (pWOp).........................1-6
1.2.4 Automatic level calibration.......................1-6
1.2.5 Basic interference...............................1-7
1.2.5.1 Intrinsic noise level.............................1-7
1.2.5.2 Interference level of discrete, non-harmonic
signals...1-8
1.2.6 High-speed signal detector for rapid signal detection,
active only with analog display.....................1-8
1.2.7 Errors of the level indication.....................1-8
1.2.7.1 Error limits in selective mode.....................1-8
1.2.7.2 Total errors....................................1-9
1.2.7.3 Frequency response of the level indication..........1-10
1.2.7.4 Total error in wide-band mode,,....................1-12
1.3 Phase jitter....................................1-12
1.3.1 Measuring range.................................1-12
1.3.2 Error limits of the indication.....................1-12
1.3.3 Output for demodulated phase-jitter signal..........1-12
1.4 Selectivity and harmonic ratio......................1-13
1.4.1 Selectivity, switchable..........................1-13
1.4.2 Image frequency and IF suppression.................1-13
1.4.3 Distortion products..............................1-13
1.4.3.1 Harmonic distortion products......................1-13
1.4.3.2 Non-harmonic distortion products...................1-14
1.4.4 Noise power ratio (NPR)..........................1-14
1.5 Measurement periods..............................1-14
1.5.1 Level measurements with autoranging
calibrator switched off......................... 1-14
1.5.2 Level measurement with adjustment
of the measuring range...........................1-14
1.5.3 Lengthening of the measurement periods..............1-15
1.5.4 Phase jitter measurement..........................1-15
1.5.5 Data transfer, transfer time per character...........1-15
1.6 Inputs.........................................1-15
1.6.1 Coaxial in put...................................1-15
1.6.2 Balanced input 124/150 Ohms.......................1-15
1.6.3 Balanced input 150/600 Ohms.......................1-16
1.6.4 Maximum permissible input voltage for all inputs......1-16
1.7 Additional inputs and outputs.....................1-16
1.7.1 , Input for external standard frequency...............1-16
1.7.2 Output for standard frequency.....................1-16
1.7.3 Output for tuned frequency.........................1-17
1.7.4 IF output..................,....................1-17
1.7.5 X-output voltage (DC),............................1-17
1.7.6 X-output voltage (DC)...........................1-17
1.7.7 Demodulator output.............................1-17
1.7.8 Display unit connection socket.....................1-18
1-7-9 (IEC.625) Interface.:..,..,........................1-18
1.7.10 Digital interface....... „.w.......................1-18
1.7.11 Power supply connection for ;Test Probe
TK-11.........1-19
1.7.12 Tracking generator output..........................1-19
1.8 Memories for fixed frequencies and unit settings......1-19
1.8.1 Number of fixed frequencies......................1-19
1.8.2 Number of equipment settings..,-....................1-19
1.9 Power supplies and ambient conditions...............1-19
1.9.1 Power supplies....,..............................1-19
1.9.2 Ope'rating climate...............................1-20
1.10 Dimensions, weight.............................1-20
1.11 Optional accessories............................1-20
1.11.1 Standard frequency oscillator......................1-20
1.11.2 White noise program and fixed value memory...........1-21
1.11.2.1 White noise program without fixed value
memory.......1-21
1.11.3 (IEC 625 ) interface Bus Board.....................1-21
1.11.4 Printer interface...............................1-21
1.12 Measuring accessories...........................1-21
1.12.1 Test Probe TK-11, active test probe.................1-21
1.12.2 Test Probe TK-12 with Power Supply Unit TKN-12.......1-23
1.12.2.1 Test Probe TK-12................................1-23
1.12.2.2 Power Supply Unit TKN-12.........................1-25
1.12.3 Reflection Factor Measuring Bridge RFZ-14...........1-25
1.12.4 Adapter FEDA-1. . .................................1-26
1.12.5 Relay Changeover Switch RU-3.......................1-27
1.13 Ordering information.............................1-29
TECHNICAL DETAILS............... .........................2-1
2.1 Receiver section..................................2-2
2.1.1 Input circuit and frequency conversion...............2-2
2.1.2 IF amplifier, rectifier, and output circuit..........2-3
2.1.3 Automatic level calibration........................2-4
2.1.4 Rapid signal detector............................2-4
2.1.5 Phase jitter measuring adapter.....................2-5
2.1.6 Test probe connection..............................2-5
2.1.7 Outputs and inputs...............................2-5
2.1.9 Frequency tuning.................................2-7
2.2 Synthesizer.....................................2-7
2.3 Control section with microcomputer.................2-10
2.4 Printer interface...............................2-11
3 COMMISSIONING............................................3-1
3.1 Unpacking the unit...............................3-1
3.1.1 Notes for shipping...............................3-1
3.1.2. Transport in the Equipment Case TPK-4 or
Transport Case TPG-4..............................3-2
3.1.3 Use in 19“ racks.................................3-2
3.2 Installing the unit...............................3-3
3.3 Connection and switching on..................,,.....3-4
3.3.1 Mechanical zero setting..........................3-4
3.4 Power supply unit................................3-5
3.4.1 Replacing the fuse...............................3-5
3.5 Internal test...................................3-5
3.6 Standard set-up..................................3-6
4 OPERATION................................................4-8
4.1 Controls on the front and rear sides.................4-8
4.2 Equipment setting after switching on................4-9
4.3 Inputs, input impedances, and frequency ranges.......4-10
4.4 Tuning the receiver frequency.....................4-11
4.4.1 Digital tuning 12 ............ .................4-11
4.4.2 Continuous frequency tuning MAN .................4-12
4.4.3 Frequency tuning in steps.........................4-13
4.4.3.1 Manual stepping.,................................4-13
4.4.3.2 Automatic stepping...............................4-14
4.4.4 Transferring the frequency setting to the
memories for fsTEP anc^ sweeP limits.............4-15
4.5 Automatic level cal ibration "AUTO CAL”..............4-16
4.6 Selection of the operating mode analog/digital.......4-17
4.6.1 Digital level measurement..........................4-18
4.6.1.1 Absolute voltage or power level ABS.................4-19
4.6.1.2 Level difference................................4-19
4.6.1.3 Levels reduced to dBmO values.....................4-20
4.6.2 Analog level measurement..........................4-20
4.6.2.1 Measuring range selection........................4-21
4.6.2.2 Scale range.....................................4-22
4.6.2.3 Rapid signal detector............................4-23
4.6.3 Direction arrows in the level display...............4-24
4.6.4 Noise averaging AVRG ...........................4-25
4.7 Bandwidth......................................4-26
4.7.1 Wide-band section................................4-26
4.7.2 Selective section...............................4-27
4.8 Demodulator.....................................4-29
4.9.1
4.9.2
Phase jitter measurements......
Causes and effects of phase jitter Settings on the level
meter.....
4-31
4-32
4-32
4.10 Automatic frequency control AFC [Sj ................4-34
4.11 Track mode....................................4-35
4.11.1 Appl ications...................................4-35
4.11.2 Settings on the level meter......................4-37
4.12 Search........................................4-38
4.12.1 Single search F (Full range).....................4-39
4.12.2 Continuous search OPTimum........................4-40
4.13 Sweep.......................................4-41
4.13.1 Setting up the sweep limits......................4-42
4.13.2 Sweep sequence and time.........................4-43
4.13.3 Manual sweep..................................4-44
4.13.4 Display unit connection (421 .....................4-44
4,14 DC (Y-) output [24j ............................4-46
4.15 DC (X-) output 25 ............................4-46
4.16 10 kHz IF output [43] ..........................4-47
4.17 Remote control of the Level Generators PS-18,
PS-19, PSS-19..................................4-47
4.17.1 Tracking generator output........................4-48
4.18 Standard frequency input fsll ....................4-48
4.19 Digital interface 40 41 .....................4-48
4.20 Computer control...............................4-49
4.20.1 ' (TEC 625) Interface Bus .........................4-50
4.20.1.1 Interaction between the level meter and the
IEEE Bus Interface..............................4-51
4.20.1.2 Structure of the IEC Bus program...................4-53
4.20.2 Bus specification and bus plugs...................4-54
4.21 Printer connection.............................4-55
4.22 Memory functions (MEM)..........................4-55
4.22.1 Address organization............................4-56
4.22.2 The functions store and recall....................4-59
4.22.3 Storing the fixed frequencies.....................4-60
4.22.4 Recalling single fixed frequencies................4-60
4.22.5 Recalling a sequence of fixed frequencies...........4-61
4.22.6 Storage of equipment settings (set-ups)............4-63
4.22.7 Recall of equipment settings (set-ups) ...........4-63
4.23 White noise program and prom.....................4-64
4.23.1 Fixed frequencies and equipment settings...........4-65
4.23.2 Noise measurements...............................4-68
4.23.2.1 Measurement of the reduced noise level.............4-69
4.23.2.2 Measurement of the reduced noise power.............4-71
4.23.2.3 Measurement of the noise power ratio NPR...........4-72
4.23.3 Limits of noise measurement......................4-75
4.24 Measuring accessories...........................4-78
4.24.1 Test Probe TK-11...............................4-78
4.24.2 Test Probe TK-12...............................4-79
4.24.3 Adapter FEDA-1.................................4-80
4.24.4 Reflection and signal balance ratio measurements
....... 4-81
4.24.4.1 Reflection Loss Measuring Adapter RFZ-14...........4-81
4.25 Special modes of operation ......................4-83
4.25.1 Measurements with frequency offset ................4-83
4.25.2 Level difference measurement ....................4-83
4.25.3 Printer mode ..................................4-85
4.25.3.1 Demands placed on the printer ...................4-85
4.25.3.2 Printout format ...............................4-86
4.25.3.3 Printer release ...............................4-87
4.25.3.4 Operation ....................................4-89
4.25.3.5 Setting the level threshold at the SPM-19
..........4-89
4.25.3.6 Printout of white noise measurement results
.....,...4-91
4.25.3.7 Error annunciation in the printout ...............4-92
4.25.3.8 Dialog for modifying the printout ................4-92
5 MEASURING NOTES.......................................... .5-1
5.1 Selectivity curves of the level meter...............5-1
5.2 Measurement of high attenuation values..............5-3
5.3 Pulse noise and interruption measurements...........5-5
5.4 Psophometric weighting of noise voltages............5-6
5.5 Automatic drive level monitoring...................5-8
6 FUNCTIONAL TESTING, MAINTENANCE , AND
MISCELLANEOUS..............6-1
6.1 Functional test when switching on for the first time....6-1
6.1.1 Checking the internal noise.......................6-5
6.1.2 Checking the receiver selectivity..................6-5
6.1.3 Functional test of the test probe connector [Tô] ....6-6
6.2 Functional tests of important modules...............6-6
6.3 Maintenance and miscellaneous.....................6-14
6.3.1 Mechanical construction..........................6-14
6.3.2 Changing or installing the interface boards.........6-15
6.3.3 Installing the prom'.............................6-15
6.3.4 Universal connectors Versacon QR) 9................6-16
6.3.5 Rechargeable batteries for data retention...........6-17
6.4 Adaption of the V.24-printer interface ............6-17
6.4.1 Test of interface, S 1/3 ........................6-17
6.4.2 Automatic printout s 1/1 ........................6-18
6.4.3 Manual printout S 1/2 ..........................6-18
6.4.4 Modification of the printout S 1/4, S 1/5 ..........6-18
6.4.5 Paging S 1/8 .................................6-18
6.4.6 Waiting time ..................................6-18
6.4.7 Parity enable S 2/6 ............................5-19
6.4.8 Even parity S 2/7 ..............................6-19
6.4.9 Busy polarity S 2/8 .............................6-19
6.4.10 Busy enable S 2/9 ..............................6-19
6.4.11 Form feed enable S 2/10 .........................6-20
6.4.12 Baud rate S 3/1 to /3 ..........................6-20
6.4.13 Adaption to the basic unit S 3/5 to /8 ............6-20
Wandelgoltermann-8477-Manual-Page-1-Picture


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