Datalogger. functions. interface. Mechanical. Power

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1 bringing light to measurement FS 4500 PORTABLE BraggSCOPE DYNAMIC MEASUREMENT UNIT FOR FBG SENSORS BraggSCOPE : fast acquisition for dynamic measurements : up to 4 sensors per fiber : high-power broadband source : software with full data logger capability : intuitive user interface : FFT analysis : automatic configuration for FiberSensing sensors : battery power supply for field operation : robust design for 24/7 operation FiberSensing BraggSCOPE measurement unit for FBG sensors combines high-power broadband optical source with proven thinfilm optical filtering technology in an intelligent approach to perform dynamic measurement of the Bragg wavelength. BraggSCOPE The proprietary BraggSCOPE technology is based on wellestablished integrated add/drop WDM components that enable a cost-effective filtering solution for Bragg wavelength measurement within predefined bands. Up to four sensors can be connected in series, which in combination with embedded optical multiplexing makes this measurement unit suitable for medium scale dynamic sensing networks. Configuring sensors in the BraggSCOPE unit is very simple. Each FiberSensing sensor is provided with a barcode ID allowing its characteristics to be automatically configured, so measurements can start immediately after plugging the sensor. PORTABILITY Autonomous battery operation and high level of integration offer true portability over extended time. The Portable unit is supplied with a rugged carrying case optimized for field operation. DATALOGGER FiberSensing measurement units feature an intuitive and easy-touse software interface with built-in datalogger functions such as automated sampling, archiving and transmitting. A highperformance local database manages both multiple sensor network configurations and large datasets. Acquired data can also be exported to analysis tools through Excel compatible files. ORDERING INFORMATION FS 4500 Portable BraggSCOPE Single optical channel...p/n Embedded 1x4 optical multiplexer...p/n SPECIFICATIONS Wavelength Measurement operating range C band (1530 to 1570 nm) resolution 0.1 pm absolute accuracy ±20 pm repeatability ±10 pm sensors per fiber 4 (maximum) measurement range 3.2 nm per sensor sample rate 20 ks/s per sensor ASE Source optical output power 13 dbm optical flatness 5 db Inputs / Outputs optical connectors FC/APC Embedded Optical Multiplexer (optional) channels 4 switching time 1 s Datalogger functions interface data format Environmental operation temperature relative humidity Mechanical dimensions weight Power voltage power autonomy sampling archiving transmission touchscreen GUI ethernet, USB mysql database Excel compatible files 10 to 40º C < 90% at 40º C 295 x 240 x 55 (mm) 4 kg 9-18 VDC 90 W 2 hours Specifications may change without notice. measurement units FiberSensing Sistemas Avançados de Monitorização, S.A. T F info@fibersensing.com

2 PORTABLE BRAGGSCOPE QUICK USER GUIDE FS 4500 FiberSensing, Sistemas Avançados de Monitorização, S.A. T ; F

3 FS 4500 Portable BraggSCOPE Quick Guide SW version: A - v 1.9_k Quick-guide version: August.2007 Any questions or comments regarding this guide please report to: support@fibersensing.com FiberSensing BraggSCOPE bringing light to measurement are registered trademarks from FiberSensing, Sistemas Avançados de Monitorização, SA. August /28

4 Index Technical Details 5 General Information 5 System Components 5 Technical Data 5 Software 6 SOFTWARE VERSION 6 LICENCE 6 SOFTWARE UPDATE 7 HARD DISK IMAGE RECOVERY 7 Operation 9 Connectors 9 Setting Up 9 Switching On 10 Display 10 GENERAL AND MANAGEMENT CONTROLS 10 DISPLAY TAB 11 Graph and plot 11 Saving data 12 Battery status 12 DATA TAB 12 Displaying saved data sets 13 Copying saved data sets 13 Deleting saved data sets 13 SENSORS TAB 13 Creating a new sensor 14 Editing sensors on the Sensors Menu 15 Editing Sensors on the Main Table 19 Using previously defined sensor lists 20 Filtering 20 FFT (FAST FOURIER TRANSFORM) TAB 20 Zoom 21 FFT Options and Spectrum Representation 21 Save FFT Chart 23 ALARMS TAB 23 CONFIG TAB 24 Measuring Examples 27 Measuring in 5 steps 27 Typical Configuration 27 August /28

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6 1. TECHNICAL DETAILS GENERAL INFORMATION The FS 4500 Portable BraggSCOPE combines a high-power broadband optical source with proven thin-film optical filtering technology in an intelligent approach to perform dynamic measurement of the Bragg wavelength. By integrating proprietary add/drop WDM design, it allows the measurement of up to four sensors connected in series, operating within predefined wavelength bands. This, in combination with optical switching makes this measurement technology a cost effective solution for medium scale dynamic sensing networks. Acquisitions rates can go up to 20 ks/s with 0.1 pm resolution and +/-20 pm absolute accuracy. SYSTEM COMPONENTS The FS 4500 Portable BraggSCOPE set includes: Measurement Unit AC Adapter power supply Power cord Protection and carrying bag Connector protection caps Touch screen pen TECHNICAL DATA Wavelength Measurement operating range C band (1520 to 1570 nm) resolution 0.1 pm absolute accuracy +/-20 pm repeatability +/-10 pm sensors per fiber 4 (maximum) sample rate 1 to 20 ks/s per sensor ASE Source optical output power 13 dbm optical flatness 5 db Inputs / Outputs optical connectors FC/APC Embedded Optical Multiplexer (optional) channels 4 switching time 1 s Datalogger functions Sampling, archiving and transmission interface touchscreen GUI, ethernet, USB data format mysql database; Excel compatible files August /28

7 Environmental operation temperature relative humidity Mechanical dimensions weight Power voltage power autonomy 10 to 40º C < 90% at 40º C 295 x 240 x 55 (mm) 4 kg 9-18 VDC 90 W 2 hours SOFTWARE SOFTWARE VERSION This document refers to FiberSensing measurement unit model FS 4500 Portable BraggSCOPE running FiberSensing Measurement Unit software version A - v 1.9_k. LICENCE When running the FS 4500 Portable BraggSCOPE software for the first time, a licence box will prompt as shown in Figure 1. Figure 1 The purchase button should be pressed. The code number displayed on the monitor (Figure 2) should be sent to the local reseller so that later on the user can receive the «Lic.dat» file that will enable the measurement unit software (Figure 3). August /28

8 Figure 2 Figure 3 SOFTWARE UPDATE The FS 4500 Portable BraggSCOPE measurement unit software can be updated. Instructions will be supplied with the new software version. HARD DISK IMAGE RECOVERY The FS 4500 Portable BraggSCOPE has a functionality to replace default settings and original configurations of the measurement unit hard disk. On request, FiberSensing will deliver an application note on the recovery process. August /28

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10 2. OPERATION CONNECTORS Figure 4 Left view Right view The connectors and buttons on Figure 4 are: 1. ON/Off Button 2. VGA Connector 3. LAN Connector 4. USB Connector (2x) 5. Fan 6. Power Connector 7. Optical Channel Connector CH0 8. Optical Channel Connector CH1 9. Optical Channel Connector CH2 10. Optical Channel Connector CH3 SETTING UP Before turning on the FS 4500 Portable BraggSCOPE for the first time, the batteries should be fully charged. For charging, connect the measurement unit to 100~240 V power line using the provided 20 V AC adapter. Once the measurement unit starts charging, the left sided fan (see Figure 4) will August /28

11 start working. A full charge with the measurement unit turned off should take about one and a half hours. Attention! Battery with less than 30% of maximum charge will compromise the correct start up of the measurement unit. To connect fibre Bragg grating based sensors to the FS 4500 Portable BraggSCOPE FC/APC connectors must be used (see Figure 4 on section Connectors on page 9). Attention should be paid to the cleaning of the connector. A dirty connector can compromise the measurement and will degrade the measurement unit. It is advisable to frequently clean the connectors using appropriate tools. SWITCHING ON Pressing the ON/OFF button (see Figure 4 on section Connectors on page 9) will start the engine. The Measurement Unit software will automatically be launched. An information box on start up status and on software version will appear on the LCD touch screen. Once the measurement unit is turned on both fans (see Figure 4 on section Connectors on page 9) will start working. DISPLAY The LCD monitor is a touch screen so every action can be performed by simply touching the displayed button. This can be done with the finger or with the pen that is provided with the unit. Alternatively, an USB mouse can be used. The Front Panel of the FS 4500 Portable BraggSCOPE is divided in two functional areas. The top one contains the controls that are always available. The bottom one has several menus separated with tabs. GENERAL AND MANAGEMENT CONTROLS The controls always available are the following: Figure Windows Explorer Opens Windows Explorer 2. Windows Internet Explorer Opens Windows Internet Explorer 3. NI-MAX Opens Measurement and Automation Explorer from National Instruments 4. Task Manager Opens Windows Task Manager August /28

12 5. General Information Bar Displays information on the actual status or instructions 6. Run/Stop Starts and stops data acquisition 7. Exit Shuts down the FS 4500 Portable BraggSCOPE or exits the application (see section CONFIG Tab on page 24) DISPLAY TAB This is the main FS 4500 Portable BraggSCOPE tab. Within this tab real time measurements can be monitored Figure Data is both displayed in values format (Figure 6.1) and charts format (Figure 6.2). GRAPH AND PLOT Both vertical scales of the chart can be changed by touching the label near the edge and on the side of the scale to alter. The time scale is defined as one second. For acquisition rates lower than 50 S/s, the horizontal scale can be altered using the Graph Interval dropdown box (Figure 6.3). By touching or clicking on the graph area the plot will be presented in full screen mode. Touching it again will undo this option. The Zero button (Figure 6.4) memorizes the actual values of each active sensor when pressed on, subtracting it to the new values for graphical purposes. While this function is on the button is presented with a red border. Once it is pressed again, the graphical zero function is turned off and actual values are displayed. Attention! The saved values on the recorded data will be the original ones despite the graphical representation. August /28

13 Another tool to ease graphical interpretation is the Cursor (Figure 6.5). With this button the appearance of two horizontal dash-space lines can be configured. Every plot line colour can be customized by clicking on the coloured box that appears as a legend (Figure 6.6). The maximum number of sensors that can be plotted is 16. Sensor order of appearance is defined on the tab SENSORS (see section SENSORS Tab on page 13). SAVING DATA The first action to perform before starting an acquisition is defining sensors. This procedure is explained on section SENSORS Tab (page 13). The Run/Stop button (see Figure 5 on section General and Management controls on page 10) will start acquisition. Sampling rate is defined using the Sample Rate dropdown button (Figure 6.7). Several acquisition frequencies are available from 1 sample per second to samples per second. Data can be saved by pressing the Save button (Figure 6.8). Saved data consists on a table containing the timestamp for each measurement and corresponding values for the active sensors as displayed on Figure 6.1. Other relevant information relative to active sensors and unit configuration is also saved. To stop recording, acquisition must be stopped and then the save button should be pressed. A prompt window will ask for the name to assign to the recorded data. This data can be consulted and transferred under the tab DATA (further details are presented on section DATA Tab on page 12). BATTERY STATUS On the DISPLAY tab there is also the information on the battery status (Figure 6.9). This icon has three different states regarding the actual power situation: Charging, Battery OK or Battery Low. To obtain the percentage of battery left, leave the cursor on the battery icon for a few seconds. DATA TAB With several functionalities, this FS 4500 Portable BraggSCOPE tab is suitable for viewing data sets that were previously saved, getting additional information on the available database space and transferring data through an USB pen drive. August /28

14 Figure DISPLAYING SAVED DATA SETS Clicking on the Data Set dropdown box (Figure 7.1) the data on which commands are to be preformed can be selected. By default, Begin and End time stamp (Figure 7.2) values correspond to the beginning and to the end of the selected data sets. These time stamps can be altered using the calendar (Figure 7.3) or simply by writing time stamp on the right format (hh:mm:ss.mss DD-MM- YY). To display data select the Show Data Set button (Figure 7.4). While data is being loaded the Log Off button from the general information bar (see Figure 5.5 on section General and Management controls on page 10) is replaced by a Stop button (Figure 7.5) that can be used to stop data loading. In this case, the end time of the data set will be the one displayed on the graph. COPYING SAVED DATA SETS Data can be readily saved as a.txt file to an external USB Pen drive by pressing the Save button (Figure 7.6). The drive for transferring the data can be selected using the Drives Dropdown Box (Figure 7.7). To safely remove the USB Pen Drive press the Eject Pen button (Figure 7.8). DELETING SAVED DATA SETS The Available Database Space is displayed on a specific box (Figure 7.9). Pressing the Delete button (Figure 7.10) will remove the selected data set. Note that saving new data (see section Saving data on page 12) is impossible when Available Data Base Space is lower than 5%. SENSORS TAB Under the SENSORS tab it is possible to configure the sensors to be measured by the device. August /28

15 Figure CREATING A NEW SENSOR There are four different ways for creating a new sensor on the FS 4500 Portable BraggSCOPE: The New Sensor button (Figure 8.1) allows the definition of a new sensor from scratch. The Duplicate Sensor button (Figure 8.2) uses the definitions of an existent sensor to create a similar sensor. Reading the bar code sticker that is provided with every FS Sensor will automatically define sensor characteristics, searching for data on the measurement unit, on the USB pen drive and on the FiberSensing website. This can be preformed by clicking the Scanner button (Figure 8.3) while an USB Barcode Reader device is connected to the FS 4500 Portable BraggSCOPE. The Barcode reader menu (Figure 9) shows the available sensors on all three locations. Once read sensor files remain in a local folder. Note: An USB Barcode Reader device that is capable of reading Code 39 barcode sticker s type should be used. August /28

16 Figure 9 The AutoScan button (Figure 8.4) automatically searches for Fibre Bragg Sensors on the selected optical channels filling in the main sensor characteristics. EDITING SENSORS ON THE SENSORS MENU The editing menu will automatically appear every time a new sensor is created using the New Sensor or the Duplicate Sensor button (see section Creating a new sensor on page 14). For editing an existent sensor on the sensor list, first select it with a tick on the Selection box (Figure 8.5), and then click the Edit Sensor Button (Figure 8.6). Figure 10 Sensor Category (Figure 10) defines whether the sensor is a FS Standard Fibre Bragg Sensor, a Custom Designed Fibre Bragg Sensor, an Electrical Sensor or a Virtual Sensor. August /28

17 FS Standard Sensors Figure 11 2 For all sensors the Name (Figure 11.1) is a compulsory field. To write on this field click on it so that the writing cursor will start blinking. This way the Virtual Keyboard button (Figure 11.2) will become active. Filling in the Serial Number (Figure 11.3) the sensor definitions will be automatically updated in a similar way to the Bar Code Reader sensor creation (see section Creating a new sensor on page 14). If the serial number is not available, the other fields can also be edited by hand. Standard sensors are defined in FS wavelength bands (Figure 11.4) that can be consulted clicking on the Band button (Figure 11.5). ). The FS Bands are also available on section Typical Configuration on page 27. The Formula box (Figure 11.6) allows the definition of the calculations to be performed on the measured value of WaveLengthShift (x). Type (Figure 11.7) and Unit (Figure 11.8) dropdown boxes are to be changed accordingly to the sensor output unit. Offset (Figure 11.9) creates an offset to be applied on Central WaveLength. The Plot box (Figure 11.10) defines the position of the sensor on the legend (see section Graph and plot on page 11). The Scale option (Figure 11.11) defines if the graphical representation is to be referred to the left (0) or to the right (1) scales. On the Channel Info menu the Optical Channel (Figure 11.12) of the sensor is selected. When a sensor is being defined for the first time, the Active check box (Figure 11.13) must be ticked. If the operation that is being preformed is editing an existing sensor, then the user can choose whether the sensor is to be active or not. A sensor that is not active will not be plotted nor saved on the data set. Sensors can be automatically compensated for temperature effects (Figure 11.14). This can be done using a preset and constant temperature (Figure 11.15) or by collecting temperature data from a temperature sensor in runtime (Figure 11.16). The corrected value to be displayed and saved can be TIP: Connect an USB keyboard and mouse to the FS 4500 Portable BraggSCOPE August /28

18 defined with a customized temperature sensitivity (Figure 11.17) or using a NI-MAX defined scale (Figure 11.18). The Temperature Compensated Value will be calculated using the Sensor measurement minus the influence of a temperature change in the sensor s output: TIP: Start acquisition for the temperature sensor to define T REF. [ ] [ ( ) ] FMLAS 1 WLS 1 offset S 1 CWLS 1 TS FMLAS 2 WLS 2 offset S 2 CWLS 2 TREF Equation 1 Where: S1 is the sensor to be compensated; S2 is the temperature sensor to be used as a reference; FMLA Sk is the formula defined for the sensor Sk (see Figure 11.6); WL Sk is the measured WaveLength for sensor Sk; offset Sk is the defined offset for sensor Sk (see Figure 11.9); CWL Sk is the Central WaveLength defined for sensor Sk; TS is the sensor s Temperature Sensitivity (see Figure 11.17), for example, µε/ºc for an optical strain gauge; T REF is the user defined temperature (Figure 11.19) that should correspond to the temperature sensor measurement on the instant the user wishes to define as zero. Attention! The FS 4500 Portable BraggSCOPE temperature compensation does not consider the effect of the temperature gradient on the structure. Custom Sensors 1 2 Figure 12 Custom Sensors are to be defined by hand. Most of the sensor characteristics that need to be filled have been described above (see section FS Standard Sensors on page 16). Central WaveLenght August /28

19 (Figure 12.1) is the wavelength value to which WavelengthShift is calculated. It should coincide as much as possible with the center of the pre-defined bands (FS bands and its Central WaveLengths can be checked in section Typical Configuration on page 27). The Ranges (Figure 12.2) are defined by the used optical filters. This means that WaveLength Shifts larger than 1.6 nm from the bands Central WaveLengths will not be measured. Electrical sensors Not an available feature on FS 4500 Portable BraggSCOPE. Virtual sensors The Virtual Sensor is a sensor that is defined as a function of two or more Real Sensors. 1 Figure 13 To set the Virtual Sensor formula click the Formula button (Figure 13.1) Figure 14 The formula can be entered on the Formula box (Figure 14.1) using the Sensor List dropdown (Figure 14.2) followed by a click on the Insert button (Figure 14.3) or using the Virtual Keyboard and the August /28

20 basic operations that are available (Figure 14.4). To delete the last entered value press the Delete button (Figure 14.5). To erase the whole formula press the Clear All button (Figure 14.6). P&T Sensors P&T sensors are a particular example of virtual sensors. The Pressure and Temperature sensor is a FS standard sensor that simultaneously measures water pressure and temperature using two FBG. For each Pressure and Temperature sensors three NI-Max Scales should be defined accordingly to the parameters given in the sensor datasheet. 1 2 Figure 15 The P&T sensor has two FBG, one to measure pressure and the other to measure temperature. Both these sensors should be defined in the sensors menu accordingly to their function. To edit a P&T sensor use these real sensors (Figure 15.1). The coefficient scales are to be selected in Figure 15.2). EDITING SENSORS ON THE MAIN TABLE Some of the characteristics explained on the previous section (see section Editing sensors on the Sensors Menu on page 15) can be edited in a simpler and faster way directly on the Sensors Tab. The editable characteristics appear as a dropdown box (Figure 8.7). The Offset can be directly updated on the main table by pressing the Zero button (Figure 8.8). On the instant the Zero button is pressed the Measurement Unit performs a Scan on the Optical Channels of the selected Sensors finding the corresponding WaveLength peaks and calculating the necessary offset to zero all values. August /28

21 Attention! Finding the sensor s offset to create a new zero may alter some of the calibration formulas. Example: Measuring absolute temperatures with a FS 6300 Surface Temperature Sensor with a calibration formula of : 99.8*x+30 And a CWL of : Selecting this sensor to zero with a room temperature of 24ºC, an offset of will be created, meaning that the correct calibration formula should be :99.8*x+24 Because x = (WL-offset-CWL) Pressing the Delete button (Figure 8.9) the selected sensors will be removed from the list. The fields Related Sensors (Figure 8.10) and Errors (Figure 8.11) are status that will be automatically filled. USING PREVIOUSLY DEFINED SENSOR LISTS Any sensor configuration can be saved in a.srs file format by clicking on the Save.srs button (Figure 8.12). Once there are saved sensor lists, they can be open with the Open.srs button (Figure 8.13). There is also the possibility to create a.csv file on a different computer and then open it on the FS 4500 Portable BraggSCOPE with the Open.csv button (Figure 8.14). A template.csv file can be generated for guidance. Note that the.csv file will only be readable if data is written in accordance to the generated template. FILTERING To ease visualization and editing, the Sensors tab is presented with a Filter (Figure 8.15) to be applied to the table. The possibilities are: seeing All sensors, sensors belonging to a specified Optical Channel and sensors that are Active. FFT (FAST FOURIER TRANSFORM) TAB The FS 4500 Portable BraggSCOPE also provides real time Fourier Transform results. August /28

22 Figure On the FFT tab, sensors response is graphically displayed on the frequency domain (Figure 16.1). ZOOM The FFT chart can be zoomed in or out. The Zoom In tool is ready every time the cursor is on the chart area. Zooming In is only possible on the horizontal axis. By pressing the Auto Scale button (Figure 16.2) the chart will zoom out to display the entire FS 4500 Portable BraggSCOPE frequency range, accordingly to the selected sampling rate. FFT OPTIONS AND SPECTRUM REPRESENTATION On the Spectral measurement dropdown box (Figure 16.3) the type of spectrum representation can be selected. The available options are: Magnitude RMS - Measures the spectrum and displays the results in terms of root-mean-square (RMS). Magnitude Peak - Measures the spectrum and displays the results in terms of peak amplitude. Power - Measures the spectrum and displays the results in terms of power. Power density - Measures the spectrum and displays the results in terms of power spectral density (PSD). Power spectral density is a scaled version of Power spectrum, where the power present within each spectral bin is normalized by the frequency bin width. The windowing methods minimize spectral leakage associated with truncated waveforms. Spectral leakage is a phenomenon whereby the measured spectral energy appears to leak from one frequency into other frequencies. It occurs when a sampled waveform does not contain an integral number of cycles over the time period during which it was sampled. The technique used to reduce spectral leakage is to multiply the time-domain waveform by a window function. The used function can be selected on the Window dropdown box (Figure 16.4). The available windowing methods are: August /28

23 None Applies a rectangular window to Signals. Applying a rectangular window is equivalent to not using any window because the rectangular function just truncates the signal to within a finite time interval. The rectangular window has the highest amount of spectral leakage. Hanning - Applies a Hanning window to Signals. The Hanning window has a shape similar to that of half a cycle of a cosine wave. Hamming - Applies a Hamming window to Signals. The Hamming window is a modified version of the Hanning window. The shape of the Hamming window is similar to that of a cosine wave. Blackman-Harris - Applies a Blackman-Harris window to Signals. The Blackman- Harris window is a modified version of the Exact Blackman window. The Blackman-Harris window is useful for single tone measurement. The Blackman- Harris window has a wider main lobe and a lower maximum side lobe level than the Exact Blackman window. Exact Blackman - Applies an exact Blackman window to Signals. Blackman - Applies a Blackman window to Signals. The Blackman window is a modified version of the Exact Blackman window. The Exact Blackman window has a lower main lobe width and a lower maximum side lobe level than the Blackman window. However, the Blackman window has a higher side lobe roll-off rate than the Exact Blackman window. Flat Top - Applies a Flat Top window to Signals. The flat top window has the best amplitude accuracy of all the smoothing windows at ±0.02 db for signals exactly between integral cycles. Because the flat top window has a wide main lobe, it has poor frequency resolution. 4 Term B-Harris - Applies a Four Term Blackman-Harris window to Signals. 7 Term B-Harris - Applies a Seven Term Blackman-Harris window to Signals. Low Sidelobe - Applies a Low Sidelobe window to Signals. The displayed spectrum can be averaged. Averaging successive measurements usually improves accuracy. The averaging mode can be selected on the Averaging dropdown box (Figure 16.5): The available modes for averaging are: No averaging Does not average consecutive measurements. Vector averaging - Eliminates noise from synchronous signals. Vector averaging computes the average of complex quantities directly. The real and imaginary parts are averaged separately, reducing noise but usually requiring a trigger. RMS averaging - Reduces signal fluctuations but not the noise floor. The noise floor is not reduced because RMS averaging averages the energy, or power, of the signal. Peak hold - Retains the peak levels of the averaged quantities. Peak hold averaging is performed at each frequency line separately, retaining peak levels from one FFT record to the next. August /28

24 When performing RMS or vector averaging, each new spectral record can be weighted using either linear or exponential weighting (Figure 16.6). Linear weighting combines N spectral records, or number of averages (Figure 16.7), with equal weighting. When the number of averages is completed, the analyzer stops averaging and presents the averaged results. To restart averaging the Restart Averaging button (Figure 16.8) should be pressed. Exponential weighting emphasizes new spectral data more than old and is a continuous process. The frequency on which the Spectrum is updated on the graph area can be chosen on the Produce Spectrum dropdown box (Figure 16.9). The spectrum result can be represented both in Linear scale using the sensor output scale, or in DB (Figure 16.10). SAVE FFT CHART The FFT chart can be saved as a Bitmap file selecting the Save Graph button (Figure 16.11) or as a spreadsheet using the Save Table button (Figure 16.12). These files will be saved in the external USB driver that is selected under the tab DATA (see section Copying saved data sets on page 13). Naming is automatic: OSA_DD-MM-YYYY_hh_mm_ss.bmp for picture format and OSA_DD-MM- YYYY_hh_mm_ss.xls for table format. Pressing the Remove Pen button (Figure 16.13) the USB driver can be safely removed. ALARMS TAB This tab is mainly used for gathering information on the generated alarms Figure All alarm messages are displayed as a table (Figure 17.1) and the Alarm Rates box (Figure 17.2) shows statistics on alarms. The only actions that can be preformed under this tab are: configure table size using the Alarms Table Size dropdown box (Figure 17.3) configure alarms file size using the Alarms File Size dropdown box (Figure 17.4) August /28

25 deleting the table by pressing the Clear button (Figure 17.5) CONFIG TAB The Configuration tab is aimed to group up generic properties and rules on the normal working progress of the FS 4500 Portable BraggSCOPE Figure Acquisition - If the button is on, the FS 4500 Portable BraggSCOPE will automatically start data acquisition with the defined sampling rate when switched on. 2. Shut Down on Exit If the button is on, the FS 4500 Portable BraggSCOPE will automatically shut down on exiting the MU application. 3. Alarms If the button is on, alarms will be saved and displayed on the Alarms tab. 4. Continuous auto gain If the button is on, gains will be adjusted on each iteration. Note: When measuring high frequency signals, continuous auto-gain may not work properly. In this case, disable this functionality. 5. Logging If the button is on, the FS 4500 Portable BraggSCOPE will automatically start saving acquired data when switched on. 6. Automatic Log Off If the button is on, the FS 4500 Portable BraggSCOPE will log off if there is no user activity for the customized time in seconds. This operation does not interfere with the unit acquisition state and is only available to prevent unauthorized access to application controls. This function will only work if there is a defined user password (see number 9). August /28

26 TIP: Disable Power Up Messages if the FS 4500 Portable BraggSCOPE is being remotely used. 7. Power Up Error Messages If the button is on, every time an error box is displayed during power on, there will be the need to acknowledge the error in order to proceed with power up. 8. Switching If the button is on, switching between optical channels is authorised and data acquired accordingly to the configured number of samples per channel. 9. User password The inserted password will be the one that will unlock the measurement unit when logging in. If the password box is empty, the Log In or Log Off function will not be available (see number 6). 10. Alarms transmission Allows the user to define if the alarm transmission is active and which is the communication way to use. 11. Information Pressing this button a complete information box on the software version will appear for a few seconds. 12. Save By clicking the save button, all alterations to the configurations become active. Note: If the save button is not clicked, FS 4500 Portable BraggSCOPE will consider the last configuration and will not update alterations. 13. Cancel Pressing the cancel button you will close the window. August /28

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28 3. MEASURING EXAMPLES MEASURING IN 5 STEPS To start making an acquisition it takes no more than five easy steps. 1. Charge batteries; 2. Turn on the FS 4500 Portable BraggSCOPE Measurement Unit; 3. Connect one sensor to an Optical Channel; 4. Click Auto Scan Button on the SENSORS Tab; 5. Hit the Run Button on the DISPLAY Tab or OSA Tab. TYPICAL CONFIGURATION Typically, a FBG s Sensing Network is divided into branches of sensors connected in series. On Figure 19 there is a scheme of a usual FBG sensing branch. OC3 OC2 OC1 Figure 19 OC0 Acceleration FBG Strain FBG Strain FBG Displacement FBG Each branch can reach 4 sensing gratings in series, one in each FiberSensing Band. The FiberSensing Bands are: TIP: Check the FS Bands on the Band Button on the FS Standard Sensors menu (Figure 11.5 on page 13). FiberSensing Bands WaveLength (nm) Minimum Central Maximum C D E F The employed technology allows a multi-functionality meaning that on the same branch it is possible to combine measurements of Strain, Temperature, Displacement, Acceleration, etc The sensing network can be up to 20 km away from the Measurement Unit for there are no EM/RF interferences or significant losses to the optical fibre. Each FBG sensor has a characteristic Central WaveLength that depends only on the measurand. This means that with this technology there is no need for recalibrations every time the system is shut down. The FS 4500 Portable BraggSCOPE is a portable measurement unit designed to be August /28

29 autonomous (uses battery) and easy to carry (small size and reduced weight) to be plainly used in different projects. August /28