Microrad NHT-3D User manual

NHT-3D
Complex signal analyzer
User Manual

Version 2.4 – May 2017
Design development and manufacturing
MICRORAD
Piazza delle Azalee 13/14
05019 Orvieto (TR) – ITALIA
Tel [phone]
Fax [phone]
email [email protected]
web www.microrad.it

INDEX
1GENERAL INFORMATION.................................................................................1
1.1 Application..........................................................................................................1
1.2 About the instrument...........................................................................................1
1.3 Operating modes................................................................................................ 1
1.3.1 Frequency selective mode.......................................................................... 1
1.3.2 Wide band mode.........................................................................................2
1.3.3 Single EMF measurement.......................................................................... 2
1.3.4 NHT-3D remote control using Waves software........................................... 2
1.3.5 Downloading data to PC / Tablet................................................................ 3
1.4 Measurement probes.......................................................................................... 3
1.4.1 Low frequency electric field probes............................................................. 3
1.4.2 Low frequency magnetic field probes ......................................................... 3
1.4.3 Magneto-static field probes......................................................................... 3
1.4.4 Electromagnetic static and low frequency field probes............................... 4
1.4.5 Radio-frequency electric field probes.......................................................... 4
1.4.6 Radio-frequency magnetic field probes ...................................................... 4
1.5 Exposure limits ...................................................................................................4
1.5.1 Exposure limits for the population............................................................... 5
1.5.2 Occupational exposure lower limits ............................................................ 5
1.5.3 Occupational exposure upper limits............................................................ 6
1.5.4 Occupational exposure localized limits....................................................... 6
1.6 Values and measurement indexes description ...................................................7
1.6.1 Indexes displayed on the instrument .......................................................... 7
1.6.2 Indexes displayed through Waves software ............................................... 8
1.7 Filters.................................................................................................................. 9
1.7.1 1K span .................................................................................................... 10
1.7.2 20K span .................................................................................................. 10
1.7.3 400K span ................................................................................................ 10
1.7.4 50 Hz notch filter....................................................................................... 10
1.7.5 50 Hz interference notch filter................................................................... 11
1.7.6 DC filter..................................................................................................... 11
1.8 Acoustic alarm.................................................................................................. 11
1.9 GPS module .....................................................................................................11
1.10 Temperature Sensor......................................................................................... 12
1.11 Clock.................................................................................................................12
1.12 Equipment configuration................................................................................... 12
1.13 NHT-3D Technical Specifications..................................................................... 13
1.14 Normative references ....................................................................................... 14
1.15 Standard compliance........................................................................................14
2SAFETY INSTRUCTIONS................................................................................ 15
2.1 Foreword...........................................................................................................15
2.2 Correct Use....................................................................................................... 15
3CERTIFICATION AND WARRANTY................................................................ 16
3.1 Certification.......................................................................................................16
3.2 Warranty........................................................................................................... 16
3.3 Limitation of warranty........................................................................................16

4UNIT DESCRIPTION........................................................................................ 17
4.1 Front panel legend............................................................................................17
4.2 Connectors and interfaces legend.................................................................... 20
5PREPARATION FOR USE...............................................................................21
5.1 Unpacking......................................................................................................... 21
5.2 Storage.............................................................................................................21
5.3 Connecting the probes......................................................................................21
5.4 Power supply and autonomy............................................................................. 22
6OPERATION..................................................................................................... 23
6.1 Base unit switching on...................................................................................... 23
6.2 Main measuring screen .................................................................................... 25
6.3 Recording measured values............................................................................. 28
6.3.1 Single storing............................................................................................ 28
6.3.2 Monitoring................................................................................................. 29
6.4 Measurement download and display ................................................................31
6.5 Alert levels........................................................................................................31
6.6 Factory reset.....................................................................................................32
7WAVES SOFTWARE ....................................................................................... 33
7.1 Introduction.......................................................................................................33
7.2 Software installation..........................................................................................33
7.3 Upper toolbar description..................................................................................34
7.4 Description of side panel controls.....................................................................37
7.5 Chart diagram operation...................................................................................39
7.5.1 Diagrams zoom and pan........................................................................... 39
7.5.2 Diagrams pointers..................................................................................... 39
7.5.3 Diagrams Markers .................................................................................... 40
7.6 Snapshot panel.................................................................................................41
7.7 Monitoring panel............................................................................................... 42
7.7.1 Monitoring data numeric format................................................................ 42
7.7.2 Monitoring data graphic format................................................................. 44
7.8 GPS and Google maps..................................................................................... 45
7.9 NHT-3D firmware update.................................................................................. 46
ANNEX A COMMUNICATION PROTOCOL.......................................................... 47

1
1 GENERAL INFORMATION
1.1 Application
Human exposure to electromagnetic fields (not ionizing radiation) is nowadays
a very critical subject almost all countries in the world are dealing with.
Technical and normative bodies work alongside government institutions to
enact new guidelines and decrees regarding maximum permitted exposure
levels for populations and workers.
The measurement equipment for this type of analysis must suit the technical
requirements from the guidelines and must provide the user with qualified
physical parameters for compliance with legally required thresholds.
1.2 About the instrument
The NHT-3D is the new Microrad solution for the measurement and analysis of
complex signals in the electromagnetic safety applications.
Besides being handy and compact, the instrument operates in selective mode
in the frequency band DC÷400 kHz, and in wide band mode up to 40 GHz.
It is user-friendly and provides extremely reliable measurements; it also
provides the operator with local temperature and GPS coordinates of the site
being measured for inclusion in a final report.
1.3 Operating modes
The instrument performs measurements in two different modes, depending on
the type of probe: selective frequency mode and wide band mode.
In both modes, acquisition and display of measurement data is continuous and
real time.
It is also possible to store individual measuring points (snapshots) or
continuous sequences (monitoring) that can then be downloaded to a PC /
Tablet and analyzed using Waves application.
Waves application software also allows the device to be remotely controlled
thus providing the operator with access to measured signal portions for in
depth analysis both in the time domain and in the frequency domain.
1.3.1 Frequency selective mode
In frequency selective mode, the signal is sampled very quickly, allowing its
exact reconstruction in the time domain, and a subsequent spectral analysis,
its comparison with normative masks, and calculation of weighted indexes
linked to frequency performance and exposure limits.
In this mode signals in the frequency band from DC to 400 kHz are measured.
The probes used in selective mode are the so-called low frequency probes
(probes for the electric field and the magnetic induction field) and probes for
the magneto-static field.

NHT-3D 1. General information
2
1.3.2 Wide band mode
Wide band mode is typical of radio frequency probes for electric or magnetic
field, that are capable of measuring signals from approximately 100 kHz up to
40 GHz and over. These types of probes sample the signal after it has been
rectified within the probe. The probe provides the r.m.s. value (root mean
square), and it is no longer possible to discriminate the frequency information.
However, fast sampling allows to trace, with Waves application, a timeline of
the r.m.s. value, capable of representing impulsive signals with a width of few
microseconds.
1.3.3 Single EMF measurement
The main application of NHT-3D is to perform electromagnetic field
measurements allowing the user to make evaluations in relation to established
protective safeguards. The system uses a variety of probes to measure
specific physical parameters (magnetic induction, magnetic field and electric
field) according to the frequency band of interest.
On the instrument LCD display, are always displayed:
Instantaneous isotropic value ISO of measured field.
Instantaneous value on the three Cartesian axes X, Y, Z.
Maximum value MAX of measured field.
Moving average value r.m.s. in time domain AVG.
Spatial average value SPT.
Filter insertion status.
Frequency Span on ( only in selective mode ).
Regulation limit selected ( only in selective mode ).
WP or Ib index ( only in selective mode ).
Alarm threshold ALM.
Measurement unit.
GPS on/off.
Temperature.
Date and time clock.
Battery charging level.
The instrument can be used in direct operating mode via the front keyboard
panel and the measurements can be viewed on the LCD display. The
instrument can also be remotely controlled by connecting it to a PC/Tablet via
fiber-optic, and using the Waves software.
1.3.4 NHT-3D remote control using Waves software
This operation mode is recommended in order to avoid where possible the
influence of the user's presence on the environment being measured (mainly
for electric field analysis) or when there is a requirement to install the
measurement system in a screened and controlled space (anechoic chamber

NHT-3D 1. General information
3
for EMC testing). In such a situation it is strongly recommended that a wooden
tripod with variable height (optional) is used.
NHT-3D can be remotely managed through a fiber optic connection to an
external PC/Tablet. The Waves software allows the total remote control of the
NHT-3D unit displaying measured values, indexes and masks relating to
occupational or population regulations. Simultaneously it displays the graphic
curves in the time domain and in the frequency domain, with high resolution
diagrams.
Additionally, Waves software can perform in-depth analysis of the signal,
computing additional evaluation indexes and allowing data and images to be
exported for post-analysis, reporting, and recording.
The display of the normative limits mask and the diagram in the frequency
domain is only possible in selective mode, using low frequency or magneto-
static probes.
1.3.5 Downloading data to PC / Tablet
All measured values, recorded both as single acquisition or continuous
monitoring, can be downloaded to an external PC/Tablet through the fiber optic
cable using an optical/USB adapter.
Once the values have been transferred, they can be viewed and analyzed
within Waves software and saved on a hard disk or other mass storage units
for later reference. Data export in tabular format (Excel compatible) and
graphics, such as images, is also possible.
1.4 Measurement probes
Measurement probes available for use in conjunction with NHT-3D, are listed
below, according to the type of probe and field being measured:
1.4.1 Low frequency electric field probes
•11E : for measurements of electric field (E) in the frequency range from
1Hz to 400kHz; measurement range from 20 V/m to 20 kV/m.
1.4.2 Low frequency magnetic field probes
•10B : for measurements of magnetic induction (B) in the frequency
range from 1Hz to 400kHz; measurement range from 100 nT to 1 mT.
•20B : for measurements of magnetic induction (B) in the frequency
range from 1Hz to 20kHz; measurement range from 300 nT to 16 mT.
•30B : for measurements of magnetic induction (B) in the frequency
range from 1Hz to 400kHz; measurement range from 300 nT to 16 mT.
1.4.3 Magneto-static field probes
•10H : for measurements of magnetic induction (B), static field only;
measurement range from 150 nT to 2.5 mT.

NHT-3D 1. General information
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•20H : for measurements of magnetic induction (B) from static field up
to 1 kHz; measurement range from 1 mT to 15 T.
•30H : for measurements of magnetic induction (B) from static field up
to 1 kHz; measurement range from 200uT to 600mT.
1.4.4 Electromagnetic static and low frequency field probes
•33P : for measurements of electric field (33E) in the frequency range
from 1Hz to 400kHz, measurement range from 20 V/m to 20 kV/m, of
magnetic induction (33B) in the frequency range from 1Hz to 400kHz,
measurement range from 300 nT to 16 mT, and of magnetic induction
(33H), static field only, measurement range from 150 nT to 2.5 mT. The
3 measurements are combined in the same device, each of them can
be selected through a manual selector.
1.4.5 Radio-frequency electric field probes
•01E : for measurements of electric field (E) in the frequency range
from 100 kHz to 6.5 GHz; measurement range from 0.2 V/m to 350
V/m.
•02E : for measurements of electric field (E) in the frequency range
from 400 kHz to 40 MHz; measurement range from 2 V/m to 1’200
V/m.
•03E : for measurements of electric field (E) in the frequency range
from 100 kHz to 18 GHz; measurement range from 0.8 V/m to 650
V/m.
•04E : for measurements of electric field (E) in the frequency range
from 3 MHz to 40 GHz; measurement range from 0.5 V/m to 350 V/m.
1.4.6 Radio-frequency magnetic field probes
•02H : for measurements of magnetic induction (B) in the frequency
range from 300 kHz to 30 MHz; measurement range from 0.016 A/m to
16 A/m.
Each probe is automatically recognized by the NHT-3D when inserted.
Please refer to our website for additional technical details on probes and for
availability of new products (www.microrad.it).
1.5 Exposure limits
The limit of the electric or magnetic field levels at a specific frequency value
represents the r.m.s. value of a sinusoidal field tone at that frequency, beyond
which health security is no longer guaranteed.
Different regulatory limits are implemented: population and working
environments. The latter, as defined by law [4], is generally subdivided into
lower, upper and localized levels, both for electric field and magnetic field;
localized levels are defined only for magnetic fields.

NHT-3D 1. General information
5
The instrument performs an automatic analysis of compliance with exposure
limits only when it is working in selective frequency mode, even in the
presence of complex signals with bands up to 400 kHz, using low frequency
and magneto-static probes.
Exposure limits are in fact considered by the instrument in the calculation of
WP and Ib weighted indexes; these dimensionless indexes ensure that limits
are not exceeded when they have a value below 1.
Additionally, Waves software graphically represents the selected mask for the
limits within the signal diagram in the frequency domain, and uses them in the
calculation of the II98 and IRSS indexes.
1.5.1 Exposure limits for the population
For the population exposure mask, the reference levels contained in document
[1] paragraph 1.14 are adopted. The tables below show exposure limits for the
electric field and magnetic induction, up to 400 kHz.
Frequency E (V/m)
< 25 Hz 10’000
0.025 – 3 kHz 250/f
3 – 400 kHz 87
Tab. 1.1 – Electrical field limits for the population
Frequency B (uT)
< 1 Hz 40’000
1 – 8 Hz 40’000/f
2
8 – 800 Hz 5’000/f
0.8 – 150 kHz 6.25
150 – 400 kHz 920/f
Tab. 1.2 – Magnetic field limits for the population
1.5.2 Occupational exposure lower limits
For the workplace mask, lower levels, the exposure limits are defined in
document [2] paragraph 1.14 and in document [4] Annex II paragraph B. The
tables below show the exposure limits for the electric field and magnetic
induction, up to 400 kHz.

NHT-3D 1. General information
6
Frequency E (V/m)
< 25 Hz 20’000
0.025 – 3 kHz 500/f
3 – 400 kHz 170
Tab. 1.3 – Electrical field limits for professional environments, lower levels
Frequency B (uT)
< 1 Hz 200’000
1 – 8 Hz 200’000/f
2
8 – 25 Hz 25’000/f
25 – 300 Hz 1’000
0.3 – 3 kHz 300/f
3 – 400 kHz 100
Tab. 1.4 – Magnetic field limits for professional environments, lower levels
1.5.3 Occupational exposure upper limits
For the workplace mask, upper levels, the exposure limits are defined in
document [4] Annex II paragraph B. The tables below show the exposure limits
for the electric field and magnetic induction, up to 400 kHz.
Frequency E (V/m)
< 50 Hz 20’000
0.050 – 1.64 kHz 1000/f
1.64 – 400 kHz 610
Tab. 1.5 – Electrical field limits for professional environments, upper levels
Frequency B (uT)
< 1 Hz 300’000
0.001 – 3 kHz 300/f
3 – 400 kHz 100
Tab. 1.6 – Magnetic field limits for professional environments, upper levels
1.5.4 Occupational exposure localized limits
For the workplace mask, localized levels, the exposure limits are defined in
document [4] Annex II paragraph B. The tables below show the exposure limits
for the magnetic induction, up to 400 kHz. Localized levels are not defined for
the electric field.