Power Reflection Meter NRT
200 kHz to 4 GHz 0.3 mW to 2000 W
• Power measurement on transmitters,
amplifiers, industrial RF and microwave generators
• Simultaneous display of power and
reflection
• Measurement of average power irrespective of modulation mode
• Measurement of peak power, crest
factor and average burst power
• Compatible with all main digital standards, eg GSM/EDGE, 3GPP
(W-/TD-CDMA), CDMA (IS-95),
CDMA2000, PHS, NADC, PDC, TETRA,
DECT, DAB, DVB-T...
• Intelligent sensors: simply plug in and
go
• IEC625 (IEEE488) bus and
RS-232 interface
• Digital interface between sensor and
basic unit
• Direct connection of sensor to a PC
Power Reflection Meter NRT ...
• For mobile use, service, development, production and
quality management
• Up to 3 (4) measurement channels
• Digital sensor interface
• Sensor operation directly on PC
• Entire range of sensors of predecessor model NAP connectible
Directional power meters are connected between
source and load and measure the power flow in
both directions. The power applied to the load and
the reflection can thus be measured.
Compared to low-cost instruments, power meters
like NRT provide a number of benefits: most importantly high measurement accuracy through excellent
directivity and a measurement method that determines the average power like a thermal power meter.
The instruments thus provide correct measurement
results even in case of modulation or in the presence
of several carriers. Power Sensors NRT-Z43/-Z44 feature low insertion loss, very good matching and
excellent intermodulation characteristics: the signal
to be measured is virtually unaffected, the sensor is
fully transparent.
Directional power meters are used to
measure power and reflection under
operational conditions. Typical applications are in installation, maintenance and
monitoring of transmitters, antennas and
RF generators in industrial and medical
fields.
Versatile measurement functions ...
Power Reflection Meter NRT is the right
choice: rugged, accurate and compact.
Due to the large variety of measurement
functions and high accuracy it is suitable
for classic applications in mobile use as
well as for use in research, development,
production and quality management.
2 Power Reflection Meter NRT
... from HF through to digital radiocommunications
With Power Sensors NRT-Z43 and NRTZ44, NRT is tailor-made to present and
future requirements of radiocommunications: the wide frequency range from
200 (400) MHz to 4 GHz covers all relevant
frequency bands, the measurement
method is compatible with all common
analog and in particular digital modulation standards: GSM/EDGE, 3GPP
(W-/TD-CDMA), CDMA (IS-95),
CDMA2000, PHS, NADC, PDC, TETRA,
DECT, DAB, DVB-T and many more. The
complete range of sensors of the predecessor model NAP is available for the customary frequency ranges, eg shortwave;
the sensors can be connected via an
option.
Measurement directly on PC
While conventional power sensors can
only be used in conjunction with a basic
unit, the NRT family is a step further
ahead: the sensors are self-contained
measuring instruments which are able to
communicate with the basic unit or with
a PC via a standard serial data interface.
Apart from the possibility of operating the
sensor directly at the RS-232 or PC Card
interface of a PC, this concept provides a
number of further benefits: practically
maintenance-free basic unit, high immunity to radiated interference – an important feature for measurements in the near
field of antennas – and remote operation
over very long distances (up to 500 m).
... a concept satisfying highest demands
Forward power
G
Source
NRT-Z43/-Z44
NRT-Z3
RS-232-C
NRT-Z4
Ba tter y, NAP sen sor c onn ecto r an d two NRT s ens or co nne ctors are accessible on the rear panel
Reverse power
AC line
DC
PC Card
Ease of operation
With its large display and a manageable
nu mbe r of clear ly l aid -ou t keys , op erati on
of the NRT basic unit is extremely easy.
Switchover between the main functions
NRT
Load
.
POWER REFLECTION METER N RT
SENSOR POWER MENU REFLECTION
SCALE SCALE
AVG
ENV
AUTO AUTO
dBm
REF
W
PC
Laptop
SWR
CORR
CONF
RFL
LOCAL
SEL
UTIL
ON / ST B Y
Power and reflection measurement with NRT-Z43/
-Z44: readout of results
either on basic unit or
directly on PC
is made at a keystroke. Additional settings are selected in three clearly
arranged menus, each of which can be
accessed at a keystroke.
A large variety of functions is available for
daily routine measurements:
• Choice between average power,
average burst power, peak envelope
power (PEP) and peak-to-average
power ratio (crest factor)
• Switchover between forward power
and absorbed power
• Measurement of power differences in
dB or %
• Choice between return loss, SWR, reflection coefficient and reverse-to-forward power ratio in % in reflection
measurements
• Display of amplitude distribution
(CCDF) for modulated signals
• Consideration of cable loss between
sensor and load
• Acoustic SWR monitoring
• Indication of maximum and minimum
values
• Quasi-analog bargraph display
• Choice between measurement at the
source or at the load
Versatile through options
The NRT basic unit comes with an IECbus (IEEE488) and RS-232 interface, both
to SCPI standard. Three options allow the
NRT to be adapted to different applications:
• An additional test input allows the
sensors of predecessor model NAP to
be connected, thus covering the frequency range from 200 kHz with power up to 1 kW and above (NRT-B1)
• Two additional test inputs for sensors
of type NRT-Z (option NRT-B2) allow
monitoring of up to three test points
(to be scanned by manual or remote
control)
• Battery and built-in charger enable
mobile use (NRT-B3)
Power Reflection Meter NRT 3
Sensor with PC interface
Directional Power Sensors
NRT-Z43/-Z44
Power Sensors NRT-Z43 and NRT-Z44 can
be used as self-contained measuring
instruments with digital interface even
without the basic unit. In addition to a
directional coupler and analog section,
they comprise a processor kernel for control of the hardware and remote interface
and for processing the measured data
(temperature compensation, linearization, zeroing
and frequencyresponse correction). This
compact
concept
allows a
ensures of
measurement
functions without the restrictions of conventional analog solutions.
Average power (rms value)
This measurement function returns for
any type of test signal – whether modulated, unmodulated or several carriers –
the average value of the power, ie a result
as provided by a thermal power meter. It
features a measurement range of 35 dB
to 40 dB as well as high measurement
accuracy.
Peak envelope power (PEP) and crest
factor
These two parameters provide information on the peak power of a modulated
envelope and thus describe the overdrive
characteristics of transmitter output
stages. The result of the crest factor
measurement is referred to the average
power and read out in dB. The measurements are carried out with a video bandwidth adjustable in several steps and
allow determination even of short-time,
high power peaks generated, for example, by CDMA base stations.
Average burst power
This function can be used for measuring
modulated and unmodulated bursts. The
measurement is based on the average
power and the duty cycle, which may be
defined by the user or determined automatically by the power sensor.
Complementary cumulative distribution
function (CCDF)
This function measures the probability of
the peak envelope power exceeding a
preset threshold so that the amplitude
distribution of transmitted signals with
non-determined envelope can be determined.
Matching
The power sensor calculates the matching of the load from the average values of
forward and reverse power. This
parameter can be output in all
common representations – as
return loss, SWR, reflection coef-
ficient or power ratio in %. Since
the reverse power measurement channel is 10 dB more sensitive than the forward channel, matching measurements
can already be made at very low powers.
Excellent shielding
The power sensors feature excellent
shielding so that emissions from the
microprocessor or from the digital data
stream on the connecting cable are completely blocked out. Any radiated emissions at the RF connectors are below the
limit of detection. The excellent intermodulation characteristics keep unwanted
frequency components resulting from the
insertion of the power sensor to a minimum. These are all good reasons to use
NRT-Z43 and NRT-Z44 not only for testing
but also in fixed installations.
PEP
Power
0
4 Power Reflection Meter NRT
CF =
BRST.AV
AVG
PEP
AVG
Time
The main parameters of modulated RF shown in the example of a TDMA signal (one active timeslot) with
modulation:
average power (AVG)
peak envelope power (PEP)
crest factor (CF)
average burst power (BRST.AV)
π/4DQPSK
Direct power
monitoring on PC
This is the most economical way of performing
high-precision power and
reflection measurements
with Power Sensors NRTZ43 and NRT-Z44. Via Interface Converters NRT-Z3
and NRT-Z4, the two sensors can be operated on
the serial RS-232 or PC
Card interface of any PC. In addition to
purely remote-controlled applications, eg
power monitoring in transmitter stations
and EMC test systems, this solution is
ideal where the data are to be collected
by a computer. This may be in the development laboratory as well as in the maintenance of base stations, where in addition to power and reflection other parameters have to be measured and recorded.
A Windows user interface (V-NRT, supplied with the sensors) is available for all
these applications. This program allows
setting of all the available measurement
functions as well as display and storage
both of individual results and of whole
measurement series.
Interface Converter NRT-Z4
Windows User Interface V-NRT
Directional Power Sensors NAP-Z
The power sensors of the predecessor
model NAP cover all the main frequency
bands, from the maritime radio frequencies at 200 kHz via the shortwave range
and the aeronautical radio bands through
to the GSM 900 network at 900 MHz. The
power measurement range extends from
0.3 mW to 2 kW.
Like Power Sensors NRT-Z43 and
NRT-Z44, all sensors of the NAP-Z series
are able to measure the average power
irrespective of the modulation mode and
some of them even the peak envelope
power (PEP). All NAP-Z sensors up to
1 GHz have a directivity of at least 30 dB
and thus allow very precise reflection and
power measurements.
ward and reflected wave and influences
the accuracy both of the reflection and
the power measurement.
Directivity defines the absolute maximum
for the measurable return loss. The return
loss of a load featuring good matching
can only be measured with low measurement uncertainty if the directivity is sufficiently high, as for instance with Power
Sensors NRT-Z and NAP-Z.
High directivity is also required for accurate power measurements on mismatched loads. The use of low-cost
instruments may lead to a considerable
measurement uncertainty, with too high
or too low val ues be ing in dicat ed d epend ing on the phase of the load reflection
coefficient.
Win dows is a r egis tered trad emar k of M icro soft Corp .
High directivity means high
measurement accuracy
The two main parameters for specifying
the accuracy of a directional power meter
are the power measurement uncertainty
with matched load and the directivity. The
directivity is a measure of the selectivity
of the directional coupler between for-
Power Reflection Meter NRT 5
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