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High downstream & Upstream

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revisco
High downstream & Upstream

Hello

I checked my parameters at modem recently and noticed that both my downstream and upstream power were high.

Downstream : +10 db
Upstream : +52 db

What can cause this thing to happen and how can I fix it?

Thanks,

kwesibrunee
without knowing how many

without knowing how many downstreams/upstreams you are connected to it is hard to say if those values are out of the norm.

generally on downstreams anything between -15 dB and +15dB is ok and within spec.

on upstreams it depends very much on modulation used, the upper limit could be as low as 52 dB or as high as 61 dB, so hard to say if that value is out of range. We typically aim to have our customers have a 45-50 dB upstream. This allows the signal to fluctuate due to temperature and other factors.

per the spec here is the range for the upstream, based on modulation (assuming single upstream carrier)
+17 to +57 dBmV (32-QAM, 64-QAM)
+17 to +58 dBmV (8-QAM, 16-QAM)
+17 to +61 dBmV (QPSK)
S-CDMA: +17 to +56 dBmV

There is not the correlation between downstream and upstream I would expect to see (with a +10 dB downstream, I would expect a 35 dB upstream), but it would be impossible to tell if this is a problem or not without knowing how the plant is setup.

If your having difficulties, please post your modem logs and a screen shot of your signal page, may be better able to help you. Keep in mind though, without being able to see the other side, the CMTS, it will not be possible to definitively say there even is a problem. Ideally your provider, who has access to this information, would be best suited to help you.

for reference the relevant Docsis 3.0 spec is http://cablelabs.com/wp-content/uploads/specdocs/CM-SP-PHYv3.0-I12-15030...

mbowe
Are you an end user? If so,

Are you an end user? If so, you cannot fix this combination. You need to speak to your ISP.
The levels are high, but the modem should still be working fine.
It's just that there isn't much headroom to handle any other variations which can sometimes happen in the network.
If your levels are rock steady, it's actually a good combination to have !

If you are the ISP, then it sounds like you need to get this run / node rebalanced to bring both these levels down a bit.
They are probably 10dB too high.
Maybe first thing to check is if the correct value tap face is installed.

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