UPC: Acceptable 'Power Levels'

Sir Oxman

Hi all UPC BB users,

Just a quick question regarding 'power levels' in your Cisco modem

What are acceptable levels for Receive power Level and Transmit power Level?

For some reason, UPC are sending another tech out to me this week to look at internal stuff whilst also admitting it's an area wide problem and that my power levels are all over the place.

I couldn't dissuade them to not waste their time and mine, so am playing the game with them

Mine were receive Power 16dbmv transmit 38dbmv

Now, receive 11dbmv, transmit 33dbmv

What I've read is that receive should be between -2 & 2 and transmit should be 42-44dbmv

Thanks

watty

it's only receive SNR that matters.
Transmit has really only an upper limit. Over 50dBm is sick

RX +11dBm to +16dBm might be a trifle high. What's the SNR?

TX 33dBm to 38dBm is fine

DOCSIS is very adaptive, but doesn't like sudden power level changes. If the signal is too high, then a 6dB or 12dB attenuator can be used on the coax to/from the Modem.

If it's varying by 5dB to 6dB there may be a loose connection or bad cable tap/splitter in the feed to you.

Those RX are not - ? Definately +?

I'd expect the TX power to go up when the RX level falls. I can't see why TX should go down as well as RX drop unless UPC has changed the Upstream level they want to see at their CMTS.

Anyway they can see the RX & TX level at your modem AND see the CMTS RX level from your TX and know of course what TX level is leaving them. Also they know their RX SNR from your signal and your SNR from their TX.

So they must want to check trunk taps at your house and cable from that to your modem. They will ave all the variations logged. I've done SQL and made pretty graphs of this sort of stuff.

Sir Oxman

Thanks watty.
The last tech out to the house put an attenuator on then took it back off saying the power levels were too erratic with it on.
I can't see SNR in the stats page of the modem, they have most pages disabled on this cisco

lucernarian

Roughly where in Dublin are you based?

Sir Oxman

Dublin 7, t b c

Sir Oxman

Well, no-one called out. Again.