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Tom Sullivan July 14, 2011 PIM Fundamentals & Support.

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Presentation on theme: "Tom Sullivan July 14, 2011 PIM Fundamentals & Support."— Presentation transcript:

1 Tom Sullivan July 14, 2011 PIM Fundamentals & Support

2 2 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc Agenda – PIM Fundamentals & Support PIM Fundamentals (Passive Intermodulation) PIM Contributors & Measurements PIM Happens---Just Not On Our Watch Campaign Conclusions Questions & Answer Session

3 3 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc What, When, Where Base Station Antennas TMAs, Diplexers Cable Filters, Amplifiers Duplexer, Diplexers TMA Bias Tee Base Station Antennas Connectors HELIAX™, Feeder Cable Jumpers

4 4 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc What is PIM (Passive Intermodulation)? PIM is unwanted signals created by “nonlinearities” in the system, these sometimes interfering with the Base Receiver –3rd order PIM give the highest level of interference In the past, careful frequency assignments could be made to avoid worst case PIM interference Next Generation Network (NGN) broadband signal such as LTE, the probability of interference is greater New frequency bands increase this probability of interference. Potential PIM Components in band can be identified based upon frequencies in use. For Next Generations System: PIM is a challenging RF Path issue

5 5 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc PIM Fundamentals – 2A-B Component Understanding 2A-B 2A – B RX PIM = 844 MHz 3 rd order TX (F1) or A = 869 MHz TX (F2) or B = 894 MHz 2B – A RX PIM Low frequency side RX 3rd order = 2 x f1 (1738) – f2 (894) = 844 MHz RX 5th order = 3 x f1 (2607) – 2 x f2 (1788) = 819 MHz RX 7th order = 4 x f1 (3476) – 3 x f2 (2682) = 794 MHz RX = f2 (894) – f1 (869) = 25 MHz is carrier and IM product spacing

6 6 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc PIM Fundamentals – Contributors to PIM Site Guy Wires Steel Tower Other Sites IMD Lighting Installation Poorly torqued connectors Scratches Contamination on conducting surfaces Contamination left in dielectric material Components Poor quality of components Poor component durability Materials Hysteresis Rust Ferromagnetic materials Semi-Conductive Films Poor Quality Plating Test Equipment Poor Quality Loads Low Quality or Damaged Jumpers, Adapters, and Connectors Handling and usage causing deterioration Other Microphonics Welders Contact Pressure

7 7 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc On-Site Antenna Measurements with iQA2000 Portable PIM Clear sky RF field of view required to avoid any secondary PIM sources which could cause false PIM failures. Retest in other positions to confirm failure. Example: HBX-6516-R2M, Typical PIM Spec -107 dBm / -150 dBc PIM Measurements–Field Observations Clear sky -123 dBm (-166 dBc) Person nearby with phone, keys, adapters, and badge -94 dBm (-137 dBc) Pointed at fence -102 dBm (-145 dBc) Towards forklift -84 dBm (-127 dBc) Near shelter -102 dBm (-145 dBc) Near cabinet and test equipment -96 dBm (-139 dBc)

8 8 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc PIM Fundamentals PIM is measured as a ratio of interference signal to carrier signal, shown in: dBm or dBc Reference (carrier) power level is typically 20W (+43dBm) Convert from dBm to dBc by subtracting 43 Example: Specification of -107 dBm - 43dB = -150 dBc Measurement uses 2 carriers, each typically 20W Measurements can be 2 tone or swept mode. Order of PIM signal – Highest Level is for 3 rd Order Test frequencies defined mathematically – ie, 2a-b, 2a+b

9 9 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc PIM Fundamentals – dBm & dBc -173 dBc -163 dBc -143 dBc-100 dBm -130 dBm -120 dBm 0 dBc+43 dBm 0 dBm-43 dBc +37 dBm-6 dBc -50 dBm-93 dBc 173 dB PIM level is expressed in either dBm or dBc Absolute power relative to 1mW Power relative to the carrier level Relative dB 20 watts Not to scale +40 dBm-3 dBc10 watts 5 watts 2 watts+33 dBm-10 dBc

10 10 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc PIM Fundamentals – What we are trying to measure? Let’s visualize a typical required PIM level, -150 dBc, as a mechanical measurement, and suppose the carrier level (0 dBc) is a length of 500 miles In voltage terms (which relates to receiver sensitivity), a level of -150 dBc is one part in about 32 million, which is 1 inch in 500 miles.

11 11 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc PIM Measurement - Verify Equipment Performance Must first validate the test equipment Use of low IM of jumper cable, load and adapters is important Minimize number of adapters Connector faces must be undamaged Connectors must be tight There should be no mechanical strain on the connectors True verification of low IM requires swept frequency equipment

12 12 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc PIM Measurement - Do not use old or worn adapters All connections must be clean and tight at both inner and outer conductors A loose contact is an IM generator, especially at the inner conductor Minimize the number of adapters

13 13 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc De-burr both inner and outer conductors X Burrs, ragged edges, folds etc. in either inner or outer cause uneven contact and poor IM Make sure blades in prep tools are sharp

14 14 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc Correct Cable Preparation is Critical A clean, square, properly de-burred and debris-free cable preparation is needed for low IM performance Always use the correct cable preparation tools

15 15 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc PIM Fundamentals - Improperly Torqued Connections Hand-tightening of connectors can provide unstable and non- repeatable measurements. Use torque wrench with connector manufacturer recommended settings. Improper Torque Torque Wrench Note: Use 2 wrenches where necessary

16 16 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc PIM Fundamentals – Summary PIM is measured as a ratio of interference signal to carrier signal, shown in: dBm or dBc and typically 2 carriers x 20 watts per carrier. PIM distortion exists at some level in all passive systems. PIM contributions can come from the various components Random phase for a typical system level Can be calculated Favorable or unfavorable phase combinations Best Case/Worst Case

17 17 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc Why is PIM a HOT topic? What changed? Frequency Overlays – 700, 800, 900, 2000 Mhz Co-location Higher Traffic Level & Utilization of the Network Expanded usage of data and ever increasing data rates In-building coverage expansion & environment Where we were & where we are today regarding PIM

18 18 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc PIM, A Disruptive Problem that Continues to Grow!

19 19 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc Support & Solutions - Campaign Theme

20 20 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc PIM is an issue for everyone, from installers to those in purchasing and system design. The more knowledgeable each individual is regarding the root causes and effects of PIM, the better the chances of minimizing its effects. We’ve created an active PIM education and awareness program involving easy web access to: Technical Articles/White Papers PIM Expert Blogs Frequently Asked Questions Brochures PIM Calculator PIM Testing Guidelines Located in the “PIM Support” Section on

21 21 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc The best way to minimize the cost and problems created by PIM is to work to prevent it during field installation. The Andrew Institute, now offers PIM Fundamentals, a new curriculum designed around minimizing PIM and the best practices for site installation.PIM Fundamentals Course Outline: Causes of PIM Antenna testing Cable/Connector testing TMA testing Cross Band Coupler testing Test equipment overview Hands-on demos

22 22 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc Should unacceptable levels of PIM be detected in the RF path, it is critical that the source(s) be identified and located as quickly as possible using accurate test equipment. Andrew’s Field Engineering Services has the experienced personnel and field experience to provide site support to pinpoint the sources of PIM in your network quickly and precisely. With our core knowledge, and expanded PIM field testing capabilities, we’ll identify the offending component and recommend a solution.

23 23 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc Once a component is isolated and identified as lacking PIM compliance or exceeding system specified PIM performance level, it must be replaced as soon as possible. Andrew Solutions has a dedicated PIM-qualified Rapid Response Product Replacement Program for most components.Rapid Response Product Replacement Program The Rapid Response program will initially support delivery of SureFlex ™ Premium Cable Assemblies. Replacement parts are thoroughly tested prior to delivery to ensure they meet the customer’s specifications for PIM compliance.SureFlex ™ Premium Cable Assemblies

24 24 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc While 24-hour help through the Andrew Technical Support Center has always been a part of our customer service program, we have now added technical support for issues regarding PIM. The Andrew “Intermod Squad” consists of technical experts experienced in troubleshooting, diagnosing, and resolving PIM issues. You can access their expertise either on the phone, 24/7 toll-free , or via at

25 25 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc PIM Fundamentals Class Links Links to SureFlex Rapid Response Program Contact Info And contact Identifies 5 legs of program Andrew Website Landing Page: Under Support Section/PIM Support PIM Calculator Download Marketing Collateral Links to PIM Blogs

26 26 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc Largest inventory of CommScope factory built PIM jumpers in North America. Robust inventory of Hutton built CommScope PIM tested jumpers with industry leading prices. 1-2 day turn around on Hutton built CommScope PIM tested custom jumpers. Contact:

27 27 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc CommScope can help! Thank you! Questions?

28 28 PRIVATE AND CONFIDENTIAL © 2011 CommScope, Inc


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