Gutermann Technology ZS820915AL2 Wireless Transceiver for data collection User Manual ZONESCAN NET Manual 2 1 Rev3 en

Gutermann Technology GmbH Wireless Transceiver for data collection ZONESCAN NET Manual 2 1 Rev3 en

Contents

user manual

 Manual                                               EN             –   Version 2.1
         2 I 72  Table of Contents 1 Indications for Use .......................................................................................................... 4  Symbols .................................................................................................................. 4 1.1 Safety ...................................................................................................................... 4 1.2 Warning ................................................................................................................... 5 1.3 Intended Use ........................................................................................................... 5 1.42 Introduction .................................................................................................................... 6  Main Features ......................................................................................................... 6 2.1 System Overview .................................................................................................... 6 2.23 Leak Detection View ....................................................................................................... 8  Leak Detection Map ................................................................................................ 8 3.13.1.1 Structure of the Screen .................................................................................... 8 3.1.2 Google Maps Area ..........................................................................................10 3.1.3 Correlations and Logger Layer ........................................................................16  Correlations Table ..................................................................................................18 3.23.2.1 Table Fields ....................................................................................................18 3.2.2 Entering Pipe Data Manually ...........................................................................20 3.2.3 Entering Pipe Data with the Pipe Wizard .........................................................21 3.2.4 Correlation Context Menu ...............................................................................24 3.2.5 Correlation Graph ............................................................................................26 3.2.6 Correlation Spectrum ......................................................................................27 3.2.7 Correlation Report ...........................................................................................28  Logger Noise Table ................................................................................................30 3.33.3.1 Table Fields ....................................................................................................30 3.3.2 Logger Noise Context Menu ............................................................................32 4 Print Menu .....................................................................................................................46 5 Maintenance View .........................................................................................................48  Logger Table ..........................................................................................................48 5.15.1.1 Table Fields ....................................................................................................49 5.1.2 Context Menu ..................................................................................................49  Alpha Table ............................................................................................................51 5.25.2.1 Table Fields ....................................................................................................52
      3 I 72   Repeater Table ...................................................................................................... 52 5.35.3.1 Table Fields .................................................................................................... 52 6 Administration View ....................................................................................................... 53  Current Project Settings ......................................................................................... 54 6.16.1.1 General Table ................................................................................................. 54 6.1.2 Alpha Table ..................................................................................................... 55 6.1.3 Repeater Table ............................................................................................... 56 6.1.4 Logger Table ................................................................................................... 57 6.1.5 Correlations Table ........................................................................................... 59 6.1.6 Leak Score Table ............................................................................................ 60 6.1.7 Calculation Table ............................................................................................ 60 6.1.8 Events Table ................................................................................................... 61 6.1.9 E-mail Settings Table ...................................................................................... 62 6.1.10 Administration Table ....................................................................................... 63  KML Overlays......................................................................................................... 64 6.2 Projects .................................................................................................................. 64 6.3 Users ..................................................................................................................... 65 6.4 System ................................................................................................................... 65 6.56.5.1 Messages ........................................................................................................ 66 7 Appendices ................................................................................................................... 67  Correction explained in detail ................................................................................. 67 7.1 Center Correction explained in detail ...................................................................... 69 7.27.2.1 Example .......................................................................................................... 70 8 Hardware Description .................................................................................................... 71  Overview ................................................................................................................ 71 8.1 Installation .............................................................................................................. 72 8.2 Conformity .............................................................................................................. 72 8.39 Disposal ........................................................................................................................ 72 10 Imprint ....................................................................................................................... 72
         4 I 72  1  Indications for Use It is essential to read the operating instructions carefully and completely before using the first time the equipment and software. They contain important information on safety, installation and use. Keep these instructions in a safe place.   Symbols 1.1                   Warning of dangerous situations that can cause injury and  damage to the devices.       Warning The  ZONESCAN  Correlating  Radio  Noise  Data  Logger contains  a  very  powerful  magnet.  The  operation  of cardiac  pacemakers  and  implanted  defibrillators  can  be influenced.  People  with  cardiac  pacemakers  and implanted  defibrillators  are  not  permitted  anywhere  near this product.   Important notes and tips. Follow these guidelines.       Never put in your household waste bin.    Safety 1.2The  operating  and  maintenance  personnel  must  read  carefully  the  instructions before  operating.  Knowing  all  the  information  contained  therein  -  in  particular  the warning  and  safety  instructions  -  is  needed  to  safely  operate  the  equipment.  To  protect yourself  and  others  against  possible  dangers.  Ignoring  the  warning,  safety  and  operating instructions can result to a considerable shortening  of the useful life of equipment.  Do not make  any  intervention,  changes  and  alterations  to  our  products.  Never  open  the  device, otherwise  any  warranty  and  conformity  expires.  For  questions  concerning  replacing  the
      5 I 72  battery, please contact your Gutermann distributor. If  you use  the software and  associated mobile equipment, pay the necessary attention particularly in traffic.   Warning 1.3The  ZONESCAN  Correlating  Radio  Noise  Data  Logger  contains  a  very  powerful magnet.  The operation of  cardiac  pacemakers  and  implanted  defibrillators  can  be influenced.  People  with  cardiac  pacemakers  and  implanted  defibrillators  are  not  permitted anywhere near this product. ZONESCAN S-Alpha does emit electromagnetic fields  in  operation. To protect your health, keep a distance of at least 8 inch (20cm) from the device and its antennas. Installation of the device has to be performed in such a way that this minimal distance is maintained under all circumstances.   Intended Use 1.4ZONESCAN  products,  hardware,  software  and  accessories,  are  exclusively  intended  for industrial use and exclusively intended for leak detection on water pipes of the public water supply.  In  particular,  these  products  are  not  intended  for  the  use  of  waste  water  and  gas lines.  Gutermann  Technology  GmbH  is  not  liable  for  any  damages  caused  by  misuse, improper operation, and as a result of non-compliance with safety instructions and warnings.
         6 I 72  2  Introduction Gutermann  Technology  has  developed the  ZONESCAN  NET  System  for  professional  leak detection in public drinking water pipelines. This unmanned, acoustic leak monitoring system with  noise  level  and  correlation  measurements  ensures  that  leak  detection  specialists  are deployed only at the actual leak locations.   Main Features 2.1Continuous leak monitoring of the entire water network Distributed  over  the  entire  water  network,  ZONESCAN  Loggers  continuously  monitor  and analyze the noise characteristics and can thereby detect the presence and location of leaks. Extensive leak database allows for a permanent reduction in water loss Each  data  Logger  stores  the  leak  analysis  results,  including  the  detailed  noise  level distributions which are transferred to the ZONESCAN NET via the Repeater and Alpha array. This measurement data is automatically stored in the powerful ZONESCAN NET database. This  is  used  to  produce  detailed  logs  for  the  maintenance  personnel  and,  ultimately,  a systematic analysis of historical data for optimizing future water network planning. Integration of GPS in the ZONESCAN NET System The  ZONESCAN  Net  System  offers  the  possibility  to  integrate  GPS  for  automatically importing noise level and correlation data.   System Overview 2.2The  ZONESCAN  Correlating  Radio  Noise  Data  Loggers  are  mounted  directly  in  the  water network  to  record  and  to  save  the  existing  noise  level  and  the  ambient  temperature.  The statistical analysis of the stored values indicates whether or not a leak is present. A number of  strategically  mounted  ZONESCAN  Correlating  Radio  Noise  Data  Loggers  allow  all segments with water losses to be identified.  The  data measured  by  the  logger is  collected  by the  repeaters, which are  mounted  above ground.  The  repeaters  then  transmit  the  data  via  radio  signal  to  the  alphas. The  collected data is then transmitted by means of GPRS (General Packet Radio Service) via the alpha to your ZONESCAN NET Program for further processing.  The software automatically evaluates the collected data daily. The more exact the pipe data entered  by  the  user,  the  better  the  results.  The results  calculated  in ZONESCAN NET  are numerically and graphically presented in the form of histograms and frequency distributions, interpretation of the statistical evaluation facilitating the identification of the leak locations. A numerical leak indicator simplifies the interpretation of the statistical evaluation.
      7 I 72               Figure 1: Functionality of logger, repeater and alpha  Interactive communication between ZONESCAN NET and the leak detector While  conventional  radio  loggers  are  equipped  with  a  simple  radio  transmitter,  the ZONESCAN  Correlating  Radio  Noise  Data  Loggers  feature  a  transceiver  (combined transmitter  and  receiver).  This  allows  for  interactive  communication  between  the  sensor located in the chamber and the leak detector. In addition to correlation and remote listening, programming of the ZONESCAN Correlating Radio Noise Data Loggers is also performed via radio signal directly from the vehicle (i.e., without physical contact with the logger). Thus, the factory settings can be easily adapted at any time by you to meet your specific measurement needs.
         8 I 72  3  Leak Detection View   Leak Detection Map 3.13.1.1  Structure of the Screen Note! If the alpha fails, no data can be collected by the repeater and the logger and transmitted Figure 2: Structure of the screen with numbers  to  for explanation   Map Area The Map Area contains a map by Google Maps with the area of the selected project. Use the buttons  located  above  the  map  to  execute  various  functions  which  vary  depending  on   "View" - Leak Detection or Maintenance. For an explanation of the individual functions, hold the cursor over the button. The buttons in the upper part of the map can be used to display and hide individual elements of the map. Depending on  "View" - Leak Detection or Maintenance - the correlations, leak values  and  custom  or  alpha,  repeater,  logger  and  custom  fields  are  displayed.  Changes made here affect the view in  "List Area". By default, a legend is displayed in the lower part of the map.  View In View, you can switch between Leak Detection, Maintenance and Administration. Use the printer drop-down menu to print the screen, the map, correlated leaks or the leak values.   Project In the Project menu bar, the user can select the desired project via the drop-down menu.  Measurement Period
      9 I 72  The measurement period can be changed  in  the drop-down menu.  Select from  5  days, 30 days or an entire month. The current setting is displayed at the right.  Selected Item Use  the  blue  arrow  buttons  to  change  between  the  individual  values  in  the  list  area.  The current selection is displayed in the upper area.   List Area In List area, the user finds all data relevant for the evaluation.   Logout Button The user logs out with the logout button.
         10 I 72  3.1.2  Google Maps Area The  Google  Maps  Area has  the  regular  Google  Maps  features  such  as  changing  the  map view to satellite and terrain (beneath the Map field)  Figure 3: Google Maps Display  Figure 4: Google Satellite Display
      11 I 72                            Figure 5: In the top left corner all four symbols are explained in speech bubbles    Zoom all items which adjusts the map by automatically to fit zooming in or out to fit all items in the window Shows or hides the map legends at the bottom of the screen Displays the logger numbers or not – next to the colored dots representing the loggers Displays the logger noise levels in dB (decibel) – on top of the colored dots
         12 I 72   Figure 6: Zoom In/Out The Google Maps Zoom Slider allows one to zoom in or out  Google Street View  This powerful function that Google Maps have introduced allows the user to view and walk through the photographed 3D streets. If there is an orange Pegman present above the zoom bar then Google Street View is available. Follow the link for further detail about using Google Street View: https://support.google.com/maps/?hl=en#topic=3092425 Figure 7: Google Street View This is location dependent as not all countries, cities or towns have street view available.
      13 I 72   Figure 8: Google Street View Pegman (red circle) •  Hover the cursor over the orange Pegman and he will lean forward as shown above  Figure 9: Google Street View moving the Pegman (red circle) •  Click and hold the cursor on the person then drag him to a chosen location on the street which  will  highlight  blue  to  show  which  streets  have  the  street  view  present.  Simply release the mouse button to drop him on the street
         14 I 72   Figure 10: Google Street View 1st person perspective •  The  map  changes  to  a  photographic  image  of  the  street  with  the  ZONESCAN  Logger plotted in in place. The street names are marked and the white arrows are used to track forward or back through the street
      15 I 72    Figure 11: Google Street View 1st person perspective – cont. •  The user is able to turn 360degrees on the spot by moving the cursor left or right until a rectangular  white  shadow  appears,  simply  click  the  mouse  to  move  in  the  chosen direction. The top left corner  has  the orientation wheel and  zoom function bar  similar  to the normal Google Maps   Figure 12: Google Street View Guidance
         16 I 72   Figure 13: Google Street View Correlation Point (red circle) An  orange  fuzzy  spot  plotted  on  the  road  represents  a  correlated  point  for  further investigation.  This  is  a  very  powerful  remote  tool  for  the  leakage  technician  to  further investigate. 3.1.3  Correlations and Logger Layer The user may choose their correlations and logger display preferences by ticking the relevant box within the drop-down menu as shown in the following screen shots:  Figure 14: Correlation Drop-Down Menu
      17 I 72  •  In  the  window  above  the  Probable,  Possible,  w/o  Pipe  and  Out  of  Bracket  correlations maybe ticked to show or unticked to hide the correlation icons   Figure 15: Logger Noise Drop-Down Menu •  Shows the Logger Noise options Probable, Possible and No Leak, tick to display all the Loggers on the map or untick to hide any of the options   Figure 16: Logger Custom Drop-Down Menu •  Allows  the user  to select  the  pipe  network  created  using  the correlation  wizard  or  KML (Keyhole Markup Language) layer provided by the water authority
         18 I 72    Correlations Table 3.2Figure 17: Correlated Leaks •  The sorting of the tables can be changed at any time. Click the small arrow in the title field of the value that you would like to change. In the selection box that opens, you can sort in either  alphabetical  or  reverse  alphabetical  orderThe  columns  can  also  be  displayed  or hidden from  the table. To  do  this,  click  the  small arrow in  the  title field.  In  the  selection menu that appears, move the cursor to the Columns item. In the list that is now displayed, you can set a check mark in the field that you would like to display or remove the check mark from a field that you would like to hideClick the Correlated Leaks table to display all values in the list area that you have displayed in the map       3.2.1  Table Fields
      19 I 72  Figure 18:  Correlation Table Fields A statement on the Quality of the  correlation graph is made. The assessment ranges from 0 - 100%. The settings for the display of a  possible  or  probable  leak  are  made  under  Administration  in Settings  Reference number of the first Logger that was correlated Reference number of the second Logger that was correlated Distance  L1  specifies  the  distance  between  Logger  1  and  the noise source. When the pipe material or a straight section of pipe is  between  L1  and  L2  then  a  numerical  value  will  be  shown.  If there is a bend in the pipe then a greater > sign will be given next to the value Distance  L2  specifies  the  distance  between  Logger  2  and  the noise source. When the pipe material or a straight section of pipe is  between  L1  and  L2  then  a  numerical  value  will  be  shown.  If there is a bend in the pipe then a greater > sign will be given next to the value If  there  is  a  correlation  with  no  pipe  data  it’s  not  possible  to calculate the leak location especially without the pipe length. Using the  sound  velocity  of  the  defined  pipe  material  enables  us  to calculate  the  Distance  of  the  leak  from  the  middle  of  the  pipe section between the 2 loggers. If  there is a negative value (e.g. -67.4m)  then  the  noise  source  is  left  of  center  in  the  direction  of Logger  1.  A  positive  value  means  the  noise  source  is  right  of center and in the direction of logger 2 Quality Logger 1 Logger 2 Distance L1 Distance L2 Center Distance
         20 I 72  This is the total Pipe Length between Logger 1 and Logger 2  Located in the Pipe Setup field are red, yellow or green indicators  Red indicators indicate that no pipe settings have been entered yet and the used data were taken over from the default values Yellow  images  appear  if  manual  settings  were  made  and  not  all details are known (pipe length, diameter and material are known). With manual  settings, the course  of the  pipe  cannot be  changed, unlike with the Pipe Wizard  Green  indicators  mean  that  all  details  are  known  for  the  settings and were taken over in full from the Pipe Wizard  To  enter  the  pipe  settings,  use  the  mouse  to  click  the  small triangles,  next  to  Comments,  in  the  field  that  you  would  like  to change. In the menu that appears, select “Manual Pipe Data Entry” if you would like to enter the data "manually" or “Start Pipe Wizard” if  the data are  to  be  determined  automatically.  To  delete  existing pipe data, select the “Delete Pipe Information” item   Figure 19: Entering pipe settings         3.2.2  Entering Pipe Data Manually Pipe Length Pipe Setup
      21 I 72         Figure 20:  Entering pipe settings – cont. •  Click the “Add Segment” button to enter a new pipe segment. Then complete the “Length, Material  and  Diameter”  fields.  The  sound  velocity  is  automatically  calculated  from  your values  and  entered  in  the  respective  field.  If  you  have  more  exact  information  on  the sound velocity in this pipe segment, you may enter it manually in this field •  To apply the settings, click the “Save” button •  An already stored entry can be removed by clicking “Remove Segment; confirm removal by clicking “Save” 3.2.3  Entering Pipe Data with the Pipe Wizard With  the  Pipe  Wizard,  data for  the  pipe  settings  are  determined automatically  via  the  pipe network and entered. •  First, you are requested – if necessary – to move the Logger to the correct position. To do this,  click  the  Logger  that  you  would  like  to  move  and  drag  it  to  the  desired  position. Repeat the process with both  Loggers until they are correctly positioned. Use “Undo” to undo your last change •  The Logger 1 and Logger 2 fields indicate the respective, current positions of the Loggers •  Once the Loggers are correctly positioned, click “Next”
         22 I 72   Figure 21:  Adjusting loggers •  In the next step, you have the option of changing the  course of the pipeline. To do this, click the small box in the middle of the pipe that you would like to move. With the mouse pressed down, drag the pipe to the desired position  •  You  can  now  repeat  this  with  the  individual  segments  until  the  pipeline  is  correctly positioned. Use “Undo” to undo your last change. Displayed in the Pipeline Properties box are the current number of segments and the current pipe length •  After adjusting the course of the pipeline, click “Next”
      23 I 72  Figure 22:  Adjusting the pipeline •  Next, you are prompted to edit the properties of the individual segments of the pipeline. Complete the “Length, Material and Diameter” fields  Note! If the data – Length, Material and Diameter – are contained in a displayed KML (Keyhole  Markup  Language)  layer,  it  can  be  displayed  in  the  map  by  clicking  the corresponding  pipeline. The  values can  be  taken over  1:1  from the  pop-up  window that opens •  The  Sound  Velocity  is  automatically  calculated  from  your  values  and  entered  in  the respective  field.  If  you  have  more  exact  information  on  the  Sound  Velocity  in  this  pipe segment, you may enter it manually in this field •  After  all  fields are  filled,  click  the “Finish”  button  to  start  the  calculation.  The calculated values are stored automatically
         24 I 72   Figure 23:  Adjusting the pipeline – Finish Note! It  is  possible  that  the  Pipe  Wizard  calculation  cannot  be  performed immediately. It depends on the complexity of the recalculations and the workload of the server  3.2.4  Correlation Context Menu •  A context  menu  can be displayed for  each individual, correlated leak. To  do  this, select the value in the table that you would like to visualize •  Right-click  to  open  the  context  menu.  Here,  you  can  select  the  type  of  graph  to  be displayed. In addition, you can insert a comment •  The same menu can be opened by right-clicking a Correlation on the map
      25 I 72   Figure 24:  Context menu for correlations The map will switch to Google Street View and automatically zoom in on the chosen correlated point. See previous section on Google Street View  Figure 25: Google Street View of correlated leaks    Show in Street View
         26 I 72  3.2.5  Correlation Graph  Figure 26: Correlation Graph Correlation is a mathematical method for comparing two time synchronized signals with one another. A leakage noise is simultaneously recorded by two sensors at different locations which are represented by the black lines at either side of the graph if the pipe data is known. The sound emitted  by  the  leak  spreads  in  the  water  pipe  at  a  defined  sound  velocity.  If  the  acoustic event were to be brief and occur only once, e.g., a blow with hammer, it would be simple to measure  the  arrival  at  both  receivers.  In  this  case,  one  would  only  need  to  compare  the arrival  times  at  the  two  receivers  with  one  another.  If  these  are  the  same,  the  sound  has traveled the same distance to the receivers, i.e., the sound source lies in the middle of the pipe between the receivers. If the  arrival times are different, it  is possible to calculate the distance to  the two receivers from the measured time difference. The sound arrives at the closer sensor before the more distant sensor. In  the  context  of  leakage  noises,  the  goal  of  the  correlation  measurement  is  primarily  to determine the propagation time difference of two signals.  Because  the  correlation  curve  also  includes  spectral  information,  it  is  often  of  interest  to define the character of the leakage noise,  particularly for distinguishing noises that  are not related  to  the  leak,  provided  this  can  be  detected by  means  of  a  frequency  analysis  (e.g., electrical noise). The correlation curve can also be mathematically filtered for the purpose of
      27 I 72  retroactively  separating  such  interfering  noise  to  better  identify  the  correlation  maximum caused by the leak. 3.2.6  Correlation Spectrum  Figure 27 Correlation Spectrum The correlation spectrum is a combination of the signal spectra of the two sensors, which is used for the correlation on the pipeline between the two sensors. In these common spectra, it may  be  possible  to  identify  the  influence  of  noises  not  related  to  the  leak  (e.g.,  electrical noise or pumps) on the correlation result (see also 3.2.4 Correlation Context Menu).
         28 I 72  3.2.7  Correlation Report Choose the required options by ticking the box opposite and then click open. A new window will  open  in  the  browser  with  the  relevant  maps  and  graphs  associated  with  the  chosen correlation. Figure 28: Correlation Report Options  Figure 29: Correlation Report – Part 1
      29 I 72   Figure 30: Correlation Report – Part 2
         30 I 72    Logger Noise Table 3.3Displayed in the Logger Noise Table are all values that are needed for an evaluation. Figure 31: Logger Noise Table 3.3.1  Table Fields The Leak Score is specified in a range from 0 to 100. The higher the  number,  the  greater  the  probability  that  measurements  will actually detect a leak. The  goal  of  the  noise  measurement  with  Loggers  is  to  obtain  as reliable a statement as possible regarding the presence of a leak at a specific point of the monitored water network. For the greatest reliability  with  respect  to  the  presence  of  even  small  leaks,  all information  that  is  indicative  of  a  leak  near  a  Logger  should  be included. Misinterpretations should be avoided in this process. The measurement values obtained from the histogram (see 3.2.4 Correlation  Context  Menu)  –  particularly  the  lowest  ascertained sound-level value dBmin – which are a strong general indicator of a leak, are included in the subsequent processing. In addition to the described histogram evaluation, the Leak Score includes,  above  all,  knowledge  from  the  frequency  response Leak Score
      31 I 72  (spectrum).  These  values  are  used,  in  particular,  for  removing background noise. The frequency spectrum data enables the algorithm to differentiate between leak noise and mechanical noises. In  addition,  if there  is  a correlation  at  the same  position  near the logger for more than one day, this will also increase the leak score. The result is  output  as  the Leak Score in a  range from  0  to 100. The  settings  for  the  display  of  a  possible  or  probable  leak  are made under Administration in Settings  Reference number of the displayed Logger The Location field is a text field in which the location of the Logger, e.g., the street and street number, can be entered The smallest dB value measured during the last measurement. Comments  is  a  text  field  with  entries  on,  e.g.,  permanent  noise sources    Logger Location Min. Noise Comments
         32 I 72  3.3.2  Logger Noise Context Menu A context menu can be displayed for each Logger. To do this, select the Logger in the table that you would like to visualize. Right-click to open the context menu. Here, you can select the type of menu that is displayed. In addition, you can insert a comment. The same menu can be opened by right-clicking a Logger on the map.  Figure 32:  Graphical choices for leak score The Map will switch to Google Street View and automatically zoom in on the chosen logger. See section 3.1.2 Google Maps Area  Figure 33: Google Street View shows chosen logger Show in Street View
      33 I 72  The histogram is the graphical display of a noise distribution of the measured sound level   Figure 34: Logger Histogram   Histogram
         34 I 72  During noise monitoring, the noise level is repeatedly measured in intervals  of  a  few  seconds.  During  a  one-hour  measurement period  (e.g.,  from  2  a.m.  to  3  a.m.),  several  hundred  individual measurement values are collected. The sound level is measured in dB. If, for example, the sound intensity of 15 dB is measured 120 times,  this  sound  intensity  has  a  frequency  value  of  120.  Other sound intensity values are measured with a different frequency. If all of these frequencies are plotted as y values against a scale of the various dB sound intensities (x axis), one obtains the so-called histogram as a frequency distribution. This  histogram  is  a  representation  of  the noise  distribution  in  the measured  period  of  time.  The  curve  has  a  maximum,  which represents the most frequently measured noise sound intensity. For  leakage  noise  monitoring,  the  quietest  noise  detected  in  the observed period is of particular interest. It is the smallest dB value for which a measurement value exists. Because a leakage noise is always  present,  one  assumes  that  this  value  most  likely characterizes  the  leakage  noise,  while  higher  dB  sound  intensity values  arise from the  addition  of  primarily  random  noise  sources (e.g., vehicle traffic).  The so-determined smallest sound intensity value, found at the left edge of the histogram curve, is referred to as the dBmin value and plays a key role in the evaluation of the leakage noise The  signal  spectrum  can  be  used  to  make  a  statement  about  a possible leak. Figure 36 shows a spectrum with electrical influence. If the curve has  this  appearance,  one  can  assume  that  no  leakage  noise  is present  Figure 35: Spectrum with electrical influence  Histogram cont. Signal spectrum
      35 I 72  In  figure  37,  you  see  a  typical  spectrum  of  a  leakage  noise.  It  is clearly  seen  that  the  curve  differs  from  that  of  a  spectrum  with electrical  influence.  If  the  graph  has  an  appearance  similar  to  that shown in figure 37, one can assume a leakage noise  Figure 36: Spectrum with leakage noise
         36 I 72  The Leak Score History visualizes the historical values from the last 30  days,  3  months,  6  months,  12  months,  2  years  or  full history  as long as the data is available for the time span. If the data available is less than a chosen period then the software will adjust the window to fit.  On  days  with  sound  signal,  the  leak  score  is  shown  in  blue, otherwise in green. In the example below, the leak score on days with sound  signal  is  lower  because  the  spectrum  calculated  from  the sound signal is not typical of a leak.  Figure 37: Logger Leak Score History The  dBmin  History  visualizes  the  historical  values  from  the  last  30 days, 3 months, 6 months, 12 Months, 2 years or full history if data is available Leak Score History Min Noise History
      37 I 72   Figure 38: Logger dBmin History The  actual  leak  noise  sample  can  be  played  through  the  PC speakers  or  headphones  to  help  identify  the  type  of  sound recorded  by  the  chosen  logger.  To  help  distinguish  between background sound and leak sound compare a logger which has a leak score of 0 (zero) and then listen to a logger with a high leak score  •  Depending  on  your  browser,  either  click  the  Signal  Spectrum and  choose  the  Download  Sound  File  or  press  the  “Play” button.  Figure 39: Download Sound File Play Noise

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