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Microrad NHT-3D User Manual

Complex signal analyzer
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NHT-3D
Complex signal analyzer
User Manual

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Summary of Contents for Microrad NHT-3D

  • Page 1 NHT-3D Complex signal analyzer User Manual...
  • Page 2 Design development and manufacturing MICRORAD Piazza delle Azalee 13/14 05019 Orvieto (TR) – ITALIA Tel +39 0763393291 Fax +39 0763394423 email info@microrad.it www.microrad.it Version 2.4 – May 2017...

  • Page 3: Table Of Contents

    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.............
  • Page 4 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...

  • Page 5: General Information

    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.

  • Page 6: Wide Band Mode

    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.

  • Page 7: Downloading Data To Pc / Tablet

    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.

  • Page 8: Electromagnetic Static And Low Frequency Field Probes

    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).

  • Page 9: Exposure Limits For The Population

    NHT-3D 1. General information 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.

  • Page 10: Occupational Exposure Upper Limits

    NHT-3D 1. General information Frequency E (V/m) < 25 Hz 20’000 0.025 – 3 kHz 500/f 3 – 400 kHz Tab. 1.3 – Electrical field limits for professional environments, lower levels Frequency B (uT) < 1 Hz 200’000 1 – 8 Hz 200’000/f...

  • Page 11: Values And Measurement Indexes Description

    1.6 Values and measurement indexes description 1.6.1 Indexes displayed on the instrument The NHT-3D device calculates and displays on its screen the following values and measurement indexes: ISO: instantaneous isotropic value of the field, and corresponds to the value displayed in large digits on the instrument screen; even if it is called instantaneous, in reality it is an r.m.s.

  • Page 12: Indexes Displayed Through Waves Software

    NHT-3D 1. General information exceeded when its value is less than 1. It is calculated from the instrument using a weighted digital filter, whose parameters vary according to the type of probe (electrical or magnetic) and to selected exposure limits (population, lower higher, and localized occupational) for a total of 7 different configurations (localized is defined only for magnetic probes).

  • Page 13: Filters

    1. IRMS index is available only in frequency selective mode. 1.7 Filters The NHT-3D instrument is internally equipped with selectable digital filters, that can facilitate measurement by cutting off negligible bandwidths or selecting the frequencies that originate the captured signal.

  • Page 14: Span

    NHT-3D 1. General information 1.7.1 1K span The 1K span is selectable for all types of low frequency probe or for magneto- static probes. The filter function is to cut all spectral components above 1 kHz, leaving undisturbed those up to 1 kHz (low pass filter). Specifically, above 2.5 kHz an attenuation of more than 100 dB is achieved.

  • Page 15: 50 Hz Interference Notch Filter

    1.9 GPS module NHT-3D integrates a GPS module to acquire geographic coordinates as reference to the area in which the measurements were carried out. In case of outdoor activities, it is always recommended to add the GPS data related to the measurement site in order to mention them in the final report.

  • Page 16: Temperature Sensor

    USB A/B adapter cable Battery charger Waves software and user manual (available on website www.microrad.it) ISO 9001:2008 calibration certificates In order to proper work the NHT-3D meter must be connected to a measurement probe to be chosen among the available ones.

  • Page 17: Nht-3D Technical Specifications

    NHT-3D 1. General information 1.13 NHT-3D Technical Specifications PROBE TYPES Selective mode: DC – 400 kHz Frequency range Wide band mode: 100 kHz – 40GHz DISPLAY Type Transflective LCD monochrome Size 2,8” , 128x64 dots Backlight LED orange switchable 10s/continuous...

  • Page 18: Normative References

    NHT-3D 1. General information 1.14 Normative references [1] ICNIRP, Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields (up to 300 Ghz) – Health Physics Vol 74 Nr 4 pp 494-522 April 1998. [2] ICNIRP, Guidelines for limiting exposure to time-varying electric, magnetic fields (1 Hz to 100 kHz) –...

  • Page 19: Safety Instructions

    To avoid the danger of introducing additional hazards, do not install substitute parts or perform unauthorized modifications to the instrument. Return the instrument to Microrad Service Center for service and repair to ensure that safety features are maintained in operational condition.

  • Page 20: Certification And Warranty

    3.1 Certification Microrad certifies that this product met its published specifications at the time of shipment from the factory. Microrad also certifies that each probe for the NHT-3D instrument has been calibrated according to DIN EN ISO 9001: 2008. On request, SIT certification is available, covering magnetic and electric field strength and high frequency electromagnetic power density, and OKD certification for magnetic induction intensity and low frequency electric field.

  • Page 21: Unit Description

    4.1 Front panel legend The following table refers to Figure 4.1 which shows the keyboard and the main parts on the NHT-3D base unit front panel. Some keys have a second function, indicated in orange, which can be enabled by pushing the middle button SHIFT in advance.
  • Page 22 NHT-3D 4. Unit description Item Function Temperature sensor Blue LED indicating battery charging status. Led on (bright light): battery recharge. Led on (weak light): battery in maintenance charge (battery level> 90%). Led off: charger unplugged or charging timeout (about 9 hours).
  • Page 23 NHT-3D 4. Unit description ENABLE key GPS: enables / disables the GPS receiver. ALARM: enables / disables the acoustic alarm. When enabled, even if the ALM field is not displayed, it appears for few seconds at the right bottom to remember the value of the default value, when disabled, the message "ALM: Off"...

  • Page 24: Connectors And Interfaces Legend

    NHT-3D 4. Unit description The orange backlit screen (12) and the ¼-inch threaded hole for tripods or brackets mounts (13) are also indicated in the figure. 4.2 Connectors and interfaces legend The tables below refer to connectors and interfaces available on the back and at the top of the base unit.

  • Page 25: Preparation For Use

    The probe is equipped with a LEMO “Push/Pull” connector. To connect it to the NHT-3D unit, push the probe plug straight down into the probe socket until it clicks into place (the red mark on the probe plug must point towards the red mark on the unit socket).

  • Page 26: Power Supply And Autonomy

    When the instrument is on, an indication of the charge level is displayed, and within a few seconds the NHT-3D is automatically reset and continues the battery charge. During the batteries charging cycle, the blue LED (figure 4.1, item 2) lights up with the following meanings: Led on (bright light): battery recharge.

  • Page 27: Operation

    OPERATION 6.1 Base unit switching on Press POWER ON KEY (item 7, fig. 4.1). The instrument starts an auto test tool, emits a beep sound three times and simultaneously displays instrument information (identification data, configuration parameters, memory used). Fig. 6.1 shows the first screen displayed at power up and reports the identification data of the instrument for a few seconds.
  • Page 28 NHT-3D 6. Operation 22 – Snaps: number of single measurements stored in the NHT-3D memory. 23 – Monit: number of monitoring sequences stored in the memory and indication of total memory occupation. 24 – Tsamp: sampling interval used during monitoring.

  • Page 29: Main Measuring Screen

    If this type of problem systematically or frequently occurs, then it is necessary to send the probe and / or the instrument for repair to Microrad. If no probe is connected to the instrument, then the screen in Figure 6.5 will appear with the text "NO PROBE"...
  • Page 30 NHT-3D 6. Operation Fig. 6.6 – Main measurement screen 31 – Measurement unit; depending on the probe used and on selection made it can assume one of the following values: V/m, A/m, W/m , mW/cm uT, mT. Refer to item 10 of table 4.1 for more details.
  • Page 31 NHT-3D 6. Operation Latitude / Longitude = DDMM.FFC Where the 2 digits DD are used for degrees (digits can be 3 for longitude), the 2 digits MM for minutes, and the 2 digits FF for cents of minute. C is the cardinal direction: N (North) or S (South) for latitude, E (East) or W (West) for longitude.

  • Page 32: Recording Measured Values

    NHT-3D 6. Operation 6.3 Recording measured values The user can record the measured values using two different methods: • Manual storing of the single measured value (single storing) • Automatic storing of a measurement sequence (monitoring). The instrument reserves two different memory spaces for the two recording modes.

  • Page 33: Monitoring

    NHT-3D 6. Operation Fig. 6.8 –Single storing When the memory is full, the message "MEMORY FULL" will be displayed and it will no longer be possible to store data until the memory is erased using the Waves software or with a factory reset.
  • Page 34 NHT-3D 6. Operation remain in the same position and the GPS sensor is switched off to increase the autonomy. The backlight is also turned off for the same reason. The probe information is also saved only once, since it is not possible to change the probe during the monitoring;...

  • Page 35: Measurement Download And Display

    Waves software. 6.5 Alert levels The NHT-3D features a function which alerts the user by means of an acoustic signal which indicates that the measured field exceeds a user configurable threshold inserted via the Waves application; this function is enabled by pressing the ALARM key.

  • Page 36: Factory Reset

    Fig. 6.12 – Surpassing the probe range 6.6 Factory reset To perform a reset on NHT-3D unit, press the [RESET] key and hold it for 10 seconds. The system restarts by performing a general reset. This action will erase all measurement data and will restore all NHT-3D...

  • Page 37: Waves Software

    7.1 Introduction Waves is a PC/Tablet based software package which allows the user to interact with the NHT-3D device. By launching the Waves application with the NHT-3D instrument switched on and connected to the PC, the real-time signal acquisition is already active, in continuous mode. The application displays the...

  • Page 38: Upper Toolbar Description

    Set Avg Window – Allows the user to set the width of the moving window that NHT-3D uses for moving r.m.s. calculation (AVG). Set Monitoring – Setting monitoring parameters: sampling step, start delay, start and stop time programming.
  • Page 39 Snapshot Menu Download Snapshots – Transfers single snapshot taken by the NHT-3D device to the PC for further analysis and post processing; in particular, acquisitions can be stored on a PC's mass unit and visualized on the snapshot display panel.
  • Page 40 Waves software. Note that the measurement unit selected in the remote software is not synchronized with the unit in the NHT-3D instrument, For example, it is possible to use different units simultaneously on the instrument and on the software.

  • Page 41: Description Of Side Panel Controls

    7. Waves software 7.4 Description of side panel controls Fig. 7.2 – Side panel controls 50 – It starts and stops the transfer of real-time acquisition of the NHT-3D instrument. The STOP key blocks the screen at the last acquisition performed.
  • Page 42 NHT-3D 7. Waves software Window Time Frequency Acquisition Span length (ms) resolution (us) resolution (Hz) note 400K 32,768 0,5 us 30,52 Hz continuous 655,36 10 us 1,53 Hz window 13'107,2 200 us 0,076 Hz window Tab. 7.1 – Acquisition characteristics based on span selection 52 –...

  • Page 43: Chart Diagram Operation

    NHT-3D 7. Waves software remain unchanged since they are processed by the NHT-3D instrument and transferred to the application without any variation. 59 – Measured values and indices, related to the isotropic signal window and displayed in time and frequency domain diagrams. The first is a selectable index between WP, II98, Ib, IRSS, Irms.

  • Page 44: Diagrams Markers

    NHT-3D 7. Waves software Fig. 7.3 – Pointer 7.5.3 Diagrams Markers Each diagram, both in time domain and frequency domain, has 2 markers (displayed as 2 small triangles, one yellow and the other blue, in the upper left corner of the diagrams) that can be placed above points of interest.

  • Page 45: Snapshot Panel

    NHT-3D 7. Waves software 7.6 Snapshot panel User access the Snapshot Panel each time data from the instrument are downloaded (Snapshot → Download Snapshots menu) or when they are loaded by files (Snapshot → Load Snapshots menu). Each single measurement (snapshot) is represented by a line in a table which contains the following information: Fig.

  • Page 46: Monitoring Panel

    NHT-3D 7. Waves software Using the keys above the table, operator can load data from files (Load), save data (Save), export data in Excel format (Export), print data (Print) and exit from the Snapshot panel (Exit). 7.7 Monitoring panel User access the Monitoring Panel each time data from the instrument are downloaded (Monitoring →...
  • Page 47 NHT-3D 7. Waves software • Date and time. • X, Y, Z instantaneous component values for the field. • Instantaneous isotropic values of the field (ISO). • r.m.s. moving average value (AVG) calculated using the Tavg parameter that was selected at the time of the monitoring start, or calculated on 24h when the function Avg24h is selected.

  • Page 48: Monitoring Data Graphic Format

    NHT-3D 7. Waves software 7.7.2 Monitoring data graphic format In this section, operator accesses the time diagram (Fig. 7.11) of the monitoring sequence selected in the numerical display panel pressing the control #Monitoring. By highlighting (dragging the mouse with the left key depressed) parts of the table, the corresponding portions of the diagram automatically highlight and vice versa.

  • Page 49: Gps And Google Maps

    NHT-3D 7. Waves software • Tools : functions to zoom time dimension and to export the diagram to bitmap or jpeg files. 7.8 GPS and Google maps Localization information (latitude and longitude) from the GPS sensor are always displayed on the instrument screen, even inside the bar at the top right of the Waves main screen.

  • Page 50: Nht-3D Firmware Update

    • A message to switch on the instrument in firmware update mode appears on the screen; proceed as described in the following points. • Press the RESET key on NHT-3D keyboard and, keeping this key pressed, contemporarily press the instrument POWER ON.

  • Page 51: Annex Acommunication Protocol

    FTDIChip; the driver allows the software to see the USB line as a normal serial port and establish communication with UART protocol. Driver installation is not required if a PC where Microrad Waves software is already present is used. In any case, operator should verify that the VCP option is enabled: Device Manager (Gestione dispositivi) →...
  • Page 52 NHT-3D ANNEX A. Communication protocol software application, data serial communication mode and VCP option of the driver must be disabled. WARNING! In serial communication mode, the instrument optical transmitter (Class I LED) remains active even if the fiber optic cable is not inserted;...

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