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Another power hour of cable with Brady Volpe and John Downey CMTS Technical Leader at Cisco, show real world examples of testing Coax, Taps and other passives.  The discussion is on all things DOCSIS.

NanoVNA (Vector Network Analyzer) testing:

  • General intro
  • Test equipment
  • RF basics
  • Test One
    • Diplex filter
      • explained
      • active equipment has a diplex filter
      • It enables the plant to be upstream and downstream capable
      • 75 Ohm world
    • Cross over
    • Cold solder joints, fingers touching surface mount components issues with diplex filters
    • The higher the split the more difficulty you run into
  • Test One
    • Diplex filter connected
    • in common – out low side
    • 42/54 split diplex filter
    • 42 MHz low pass side
    • blue line low pass
    • hello line high pass
    • crossover difficult to accomplish in RF
    • 40/52 split
    • chrominance to luminance delay
    • phase delay – impacts timing – group delay
    • legacy filters – cause issues due to 30 MHz low pass filter
    • PNM can detect diplex filter issues
    • Red modems in PNM – group delay – diplex filter issues
    • Remove terminator
    • None ideal load
    • Eagle comtronics
  • Test two
  • Test Three
    • Stump the chump
    • RG6 cable
    • Failed – due to evaporation
    • 6 dB pad film on center connector
  • Test Four
    • Two splitters and connect them together
    • 7 dB of loss
    • Equal length cable – phase match
    • Power Doubling – Quovo
    • Double the length of the cable
    • Testing on the fly
    • Out of Phase
    • Combining signals does not work
  • Test Five
    • Common filter used in headends etc
    • Quick way to verify filters
    • Full band capture in Nimble This PNM app can find subscribers that get channels they shouldn’t be
      • Find filters in plant
  • Water in Cable
    • This is way when it rains plants get worse
    • intermittent modems

End Podcast

John thank you for your time today. This was a great episode.  Our next Episode 72 in February 19th.

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Thank you so much for being here and we will see you next month. 

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