Rf survey


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A presentation on RF survey, showing how survey of a cell site is done, how a microwave link is established, and how to perform the LOS survey for clearing the obstacles in between the links

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Rf survey

  1. 1. session : 2011-12Guided By:- Prepared By:-Mr. virendra Verma Harish KumawatH.O.D. (E.C.)
  2. 2.  Sharing site survey New site surveyi) Sharing site survey:- -coverage capacityii) New site survey:- - GBT, RBT, RTP - Nominal point - Range (100-200m) - Site options
  3. 3.  Survey of land -size -tools compass, GPS, measuring tape, camera, binoculars, ultimeter, inclinometer, maps, 10 or 50 meter tape measure, Site survey document Deviation P1 r known as side shift. 0 P3 P2
  4. 4.  Coordinates latitude and longitude AMSL Complete Address of proposed site Accessibility - nearest city, highway, railway station, airport
  5. 5.  Tower height GSM height Orientation BTS (indoor/outdoor) Wiring distance Hop length Shelter Layout of proposed site
  6. 6.  GPS GSM Access photos Plot photos Para photos Sector photos Cluster photos
  7. 7.  GPS photo
  8. 8.  GSM photo
  9. 9.  Sector photos
  10. 10.  Cluster photos
  11. 11.  Access photos
  12. 12.  Para photos - 12 photos - at every 30 degrees 30º 270º 330º
  13. 13.  Line of sight survey Connectivity of two sites Clearing links carried out physically checking the terrain between the hop and selecting the sites for acquisition.
  14. 14.  Collect Nominals of proposed site and those of the nearest locations to which customer proposes the LOS connectivity & Verification Record latitude, longitude, building data, obstruction data and surrounding terrain data on the LOS Survey template. Generate LOS Path Profile for the proposed Link using Path Loss 4.0 Generate LOS report for the proposed Link using Path Loss 4.0.Conduct physical survey of the hop to identify any field obstructions and verify the LOS path profile
  15. 15. Microwave Links Basics The preferred media when building new access network links High capacity transmission links from 2x2Mbps to 16x2Mbps, 34MbpsPros: Cons: low operating costs  needs frequency license easy to install  environment dependant flexible link quality (e.g. rainfall) quick & reliable solution  LOS not always available Repeater station Terminal Terminal station A station B
  16. 16. Microwave Links Types of MW• Long Haul Radios: ~ 30 - 80 km 2 GHz, 7 GHz• Medium Haul Radios: ~ 25 - 45 km 10 GHz, 13 GHz, 15 GHz• Short Haul Radios: ~ 5 - 30 km 18 GHz, 23 GHz, 26 GHz, 38 GHz,• Nokia Metrohopper: < 1 km 57 GHz (uses oxygen absorption in air to limit range)
  17. 17. Microwave Links Radio Link Availability• Microwave outages – equipment failures • use protected equipment – caused by nature • temporary failures • self-recovery • use protected connections• Examples of natural outages: – heavy rainfall zones: • most severe in upper bands (2..3dB/km) • significant above 10 GHz – multipath fading • problem with lower bands
  18. 18. Microwave Links How to Avoid Interference• Use the highest available frequency band• Attenuate the Tx power to a minimum just to meet the required availability• Locate dishes as low as possible with maintaining the required LOS• Use big dishes• Use different polarisation• Select your channel(s) carefully• Maintain High-Low -rule on hub sites• Try to get similar received signal levels at hub sites
  19. 19. Microwave Links LOS CheckLOS Methods Balloon method Mirror reflection method Using binoculars Route track method
  20. 20. Microwave Links Fresnel Zone• Line-of-sight path needed between both nodes of a microwave link• Keep 1st Fresnel zone clear of obstacles• nth Fresnel zone: Ellipse around direct path, where path difference to direct line is n* /2. 1st Fresnel zone 2nd 3rd d b d [km] b 274 [ m] f [ MHz ] Radius for n-th zone = b * sqrt(n)
  21. 21.  Curvature of earth = (d1*d2)/(12.75* k) where k=(eff. Earth radius/true earth radius) RF effect of fresnel zone fresnel zone= 17.32*[√{(d1*d2)/(D*f)}] Path loss Transmitted and received power Transmission line losses Frequency of operation Antenna gain gain= {17.8+20log(D.f)}
  22. 22.  Earth bulgeAntenna Height = Earth Buldge + Maximum Obstacle Height+ Fresnel Zone
  23. 23.  To establish links Feasibility of studies Upgradation of existing links