Sunday, February 3, 2008

Howto Check your Cableone or Comcast Signal Strength for your DCT Digital Box

Got no signal with your DCT? Added a splitter or amplifier and want to check your signal? No problem... Follow these instructions...

  • Set both of the STB tuners to channels you have seen exhibit problems. Use the tuner swap button.
  • Turn the STB to Standby/Off and press OK/SELECT on the remote within 2 seconds to enter the Diagnostic Main Menu.
  • Use DOWN ARROW and then OK/SELECT to select the "d03 OOB STATUS" option.
    • The SNR (Signal-to-Noise Ratio) and AGC (Automatic Gain Control) values are of interest. Any value stated less than "GOOD" (i.e., "FAIR" or "POOR") could indicate a problem.
  • Press OK/SELECT to go back to the Diagnostic Main Menu.
  • Now select the "d04 INBAND STATUS" option.
    • The SNR and AGC values are of interest. Any value stated less than "GOOD" (i.e., "FAIR" or "POOR") could indicate a problem. Be sure to look at values for both Tuner 1 and Tuner 2.
  • Press OK/SELECT to go back to the Diagnostic Main Menu.
  • Now select the "d06 CURRENT CHANNEL STATUS" option.
    • On a digital/HD channel the MPEG VIDEO & AUDIO LOCK values are of interest for both tuners. (Use the UP/DOWN ARROWS to see info for both Tuner 1 and Tuner 2.)
  • Press OK/SELECT to go back to the Diagnostic Main Menu.
  • Press Power to exit the Diagnostic Main Menu and Power again to turn the STB back on.

What the values tell you

  • If your AGC levels are FAIR or POOR and the percentage is high (over 50%), then a stronger signal may help. If possible, try to minimize the number of splitters, connections, and poor quality RG-59 cable. Try to use RG-6 whenever possible. If you have simplified as much as possible, consider a broadband compatible RF amplifier. Ideally, it should be placed as close to where the cable comes into your home as possible.
  • If your AGC levels are FAIR or POOR and the percentage is low (under 50%), then you may have too strong of a signal, which can overload the tuner. Consider using an RF attenuator, or even a splitter or two to reduce the signal (a 1:2 splitter will reduce the signal strength by a little more than 50%). Any unused outputs on a splitter should have a terminator screwed onto it. (A terminator is a 75-ohm resistor inside a little cap to prevent noise from getting into the lines.)
  • If your SNR levels are FAIR or POOR (typically below 31dB or so), then check all connections. If possible, try to minimize the number of splitters, connections, and poor quality RG-59 cable. Try to use RG-6 whenever possible. A stronger signal MAY help, but not always. An amplifier also increases noise a bit, and could make things worse. If you only have problems with a few channels, it could be interference at a particular frequency leaking into the cable from someplace.

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