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Press “space” to start !. Presents…. Page 0100 0100 Text-TV Your favourite Channel Monday 18. October 1999. Connecting and Return Path in CATV Networks. Page 0100 0100 Text-TV Your favourite Channel Monday 18. October 1999. You have probably seen this before.

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  1. Press “space” to start!

  2. Presents…

  3. Page 01000100 Text-TV Your favourite ChannelMonday 18. October 1999 Connecting and Return Path in CATV Networks

  4. Page 01000100 Text-TV Your favourite ChannelMonday 18. October 1999 You have probably seen this before...

  5. Page 01000100 Text-TV Your favourite ChannelMonday 18. October 1999 Your favourite TV Channel News.............. 110 Sport ............. 200 Latest ............ 130 Advertising ..... 700 TV today ........ 320 Cabelcon …..... 600

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  8. Page 01000100 Text-TV Your favourite ChannelMonday 18. October 1999 Your favourite TV Channel News.............. 110 Sport ............. 200 Latest ............ 130 Advertising .... 700 TV today ........ 320 Cabelcon …..... 600 - and you know why too! Right?

  9. Page 06050605 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Lacking system performance…!

  10. Page 06070607 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Safe signs of poor system performance with analogue TV signals: Ghost pictures

  11. Page 06100610 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Like this...

  12. Page 06120612 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Safe signs of poor system performance with digital downstream signals... Increased bit error rate. Typical “visible” results of this will be...

  13. Page 06150615 Text-TV Cabelcon ConnectorsMonday 18. October 1999 • TV-Text unreadable. • Noisy (or no) digital sound (NICAM).

  14. Page 06180618 Text-TV Cabelcon ConnectorsMonday 18. October 1999 - and at digital upstream signals?(using the return path band)

  15. Page 06200620 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Poor system performance in a CATV network could originate from… • Poor return loss values • Poor carrier to noise level • Insufficient screening followed by... • Ingress of noise and unwanted signals

  16. Page 06230623Text-TV Cabelcon ConnectorsMonday 18. October 1999 There can be many reasons for decreased performance. • Here we will concentrate on... • Poor or incorrect cable preparation and connector installation. • Unreliable connector quality.

  17. Page 06260626 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Most return path problems originate at the subscriber’s end of the network... • It’s a well-known fact, that 75-80 percent of service calls are related to drop installation. • -and that around half of those are caused by poor connections! • (Just one under-tightened connector can course serious trouble in your network!).

  18. Page 06290629 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Noise and unwanted signals will be added from all parts of the network. Noise from just one singlesubscriber can block the return path system completely! • Intrusion of “Man-made” noiseoriginates from • Computers • Refrigerators • Heaters • Thermostats • TV-sets • Cellular phones • - and from lots of other sources! Subscribers Node/ head-end Node/ head-end Upstream blocked Upstream

  19. Page 06310631 Text-TV Cabelcon ConnectorsMonday 18. October 1999 “No chain is stronger than the weakest link” - and the weakest links in a CATV network? Connections... - and there are thousands of them!

  20. Page 06350635 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Let’s take a look at the most frequent connection problems...

  21. Page 06370637 Text-TV Cabelcon ConnectorsMonday 18. October 1999 This is an example of a screw-on connector and a cable which have been exposed to salty moisture for just 300 hours: Metal in the cable is close to disappearing! Heavy corrosion

  22. Page 06390639Text-TV Cabelcon ConnectorsMonday 18. October 1999 • This will lead to.. • Signal egress & ingress • Intermodulation distortion • Ghost pictures • Loss of return path data • Loss of forward signals • Blocking at the node • System downtime • Expensive repair costs • - and the results of corrosion: • Poor screening • Poor return loss

  23. Page 06420642 Text-TV Cabelcon Connectors Monday 18. October 1999 Let’s take a look at PIM - Passive Intermodulation (CPID - Common Path Intermodulation Distortion) • Moisture creates a layer of oxide between two different layers of metal (like a sandwich: Metal- Oxide-Metal). • Oxidation creates a semiconductor effect (like rectifier diodes). • Diodes act naturally as frequency mixers and multipliers.

  24. Page 06450645 Text-TV Cabelcon ConnectorsMonday 18. October 1999 - and furthermore on PIM... • Carriers present in the network will be mixed and multiplied by the sum and difference. • All these “new” created and unwanted carriers (intermodulation) will appear at more or less unpredictable frequencies. • PIM will be more “visible” below the FM-radio band (return path range) due to lower cable attenuation!

  25. Page 06480648 Text-TV Cabelcon ConnectorsMonday 18. October 1999 PIM - Passive Intermodulation - schematic Two connector parts (or cable/connector parts) Mixing of carriers and frequency multiplication create many “new” carriers (PIM). Occurrence of diode effect through oxidation

  26. Page 06520652 Text-TV Cabelcon ConnectorsMonday 18. October 1999 PIM, return loss and ingress problems grow at low frequencies (in return path band)... • Cable attenuation is low (negligible). Almost no attenuation of reflected carriers caused by poor return loss. • Frequency difference products (PIM) - caused by corrosion, are typically generated at low frequencies. Disturbance occurs in the return band. • Considerable decrease in cable screening attenuation below 30 MHz. Extensive risk for ingress of unwanted signals and noise. Radiation will increase with poor return loss.

  27. Page 06550655 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Poor return Loss... Reflections andloss of wanted signals Increased radiation Forward signal Amplifierw/return path Amplifier Coaxial Cable Reflected signals + upstream (return path) Corroded or badly installed connection Increased bit error rateand loss of data or transmission speed! What happens?

  28. Page 06570657 Text-TV Cabelcon ConnectorsMonday 18. October 1999 How can we prevent or minimise problems in the return path band? • First of all through... • Use of quality connectors • Use of the right type of connector for your application. • Use of quality cables with a high degree of screening. • Proper installation practices. Let’s see some more examples...

  29. Page 06600660 Text-TV Cabelcon ConnectorsMonday 18. October 1999 The result after inspection... - while the cable installed with ourmoisture proof typeremains unaffected! Darkened copper foiland braid. A pre stageto corrosion - throughingress of moisture. Poor return loss &PIM will sooner or lateroccur after a certain time with corrosion - You can see the difference! This is a standardcrimp connector for indoor use - and this is a moisture proof type for outdoor use! Two different types of crimp connectors - both manu-factured by Cabelcon - are mounted on a piece of cable. Both have been exposed to salty moisture for 300 hours in a chamber.

  30. Page 06630663 Text-TV Cabelcon ConnectorsMonday 18. October 1999 - and the same result can be seen on an UltraSeal™compression connector No moisture ingrees!

  31. Page 06650665 Text-TV Cabelcon ConnectorsMonday 18. October 1999 - this applies to connections at all levels... - from the smallest drop connectors... - to the bigger trunk connectors.

  32. Page 06750675 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Precise installation is important! An example...

  33. Page 06760676 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Two cables - one prepared with a special tool, while the other one was stripped in the old fashion way, using a tube cutter. Special preparation tool Ordinary tube cutter Visible difference: The outer conductor was 2 mm too short on the “hand stripped” cable

  34. Page 06770677 Text-TV Cabelcon ConnectorsMonday 18. October 1999 The result after installation and test... Measured return loss was two dB worse on the “tube cutter” stripped cable/connector. “Just two dB? ” It could easily be more than two dB in each connector all the way from head-end to subscriber!

  35. Page 06780678 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Preparation tools • Preparation tools - especially designed for the combination ofyour cables and connectors - will ensure a precise installation and... • Prevent or minimise return path problems in your network.

  36. Page 06790679 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Finally some advise... • Do not use screw-on connectors for professional applications. • Choose the right type of connectors for your applications. • Use moisture proof types (or heathshrink tube) for outdoor installations. • Read and follow the manufacturers instructions for proper cable preparation and installation of your connectors. • Use appropriate preparation tools - when available - for your connectors/cables to ease installation and to ensure optimal performance of your network.

  37. Page 06800680 Text-TV Cabelcon ConnectorsMonday 18. October 1999 If you have any questions or require more information... - please visit our stand no. 438 This presentation can be downloaded fromwww.cabelcon.dk/ecc99.htm

  38. Page 06850685 Text-TV Cabelcon ConnectorsMonday 18. October 1999 Thank you for watching this presentation from A Cabelcon production Presented by Jeremy Stubbs Copyright 1999 by Cabel-Con A/S All Rights Reserved

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