Forum Discussion

iconoclast's avatar
iconoclast
New Contributor II
5 years ago

Cisco DPQ3212 Modem Power levels & S/N level

What should the range of these values be?

I was told earlier this year:
Power level s/b -12 to +15 dBmV
In 2017 I was told s/b -6 to +6
I read online it S/B -8 to +8

In 2016 I was told Downstream S/N best 36-41 dB

I don’t know what Upstream Power level s/b.

I have been experiencing internet outages or slowdowns that last 30 seconds to a couple minutes a few times each day or night.

I reset modem online. (Easier vs. manually doing it by pulling battery & unplugging)

I have preferred 150 Internet package.
I tested with speedtest app & looks good now:
146 Mbps D/L, 9.93 Mbps U/L, ping 7 ms, loss — %, Jitter 1.8 ms.

Modem Dx:
UPL 42.0-45.2 dBmV for my 4 channels

DPL -8.8 to -10.2 dBmV for my 8 channels

S/N 36.1 to 37.1 dB for 8 channels

  • ChrisL's avatar
    ChrisL
    Former Moderator
    5 years ago
    -15 to +15 is what we go by in terms of the window of acceptable downstream signal levels.

    -Chris
  • Bruce's avatar
    Bruce
    Honored Contributor III
    5 years ago

    Service providers provide the acceptable range of signal strengths for your particular plan and device.  Within those ranges are levels of quality.  For example, -8/+8 would be a great signal while -15/+15 would be a good signal with -20/+20 being operational.  These aren't accurate ranges but give you an idea of what's acceptable.

  • iconoclast's avatar
    iconoclast
    New Contributor II
    5 years ago

    Thanks ChrisL & Bruce for replying. I tried to  "Thank" but all I saw was Up or Down vote. I clicked "Up" & it appears to have just double posted your replies?  Under a new heading "Top Replies."

    It seems you both think my DPLs are fine.

    Any thoughts on acceptable & good range for UPL & also for downstream S/N ratio?

    • Bruce's avatar
      Bruce
      Honored Contributor III
      5 years ago

      As I said, only a Network Engineer can determine an in-spec signal level based on your plan and modem.  What may be acceptable on one plan may be out-of-spec on another plan.  The +/- 8's and 15's were probably just layman's rules-of-thumb at some point in time and may or may not still be true today.  I've read an overly strong signal can be just as problematic as a weak signal.

      Based on those rules-of-thumb, a great UPSTREAM POWER signal could be +42 to +50 dBmV with a good signal a little looser at +37 to +55.  As long as your SNR is over 30 dB, it's good but under 25 would be problematic.

      The results of your speed test look good considering you'd automatically lose 10% of your throughput due to network overhead.  If you're experiencing internet outages or slowdowns, what makes you believe it's your modem?  What router do you have?