Acceptable Signal Levels for Cable Modem

[TheTechGuru]

It's been a while since I've had cable internet, usually always go with DSL but not available here.

Are these numbers good?

Downstream Receive Power Level : -4.5 dBmV
Downstream SNR : 37.9 dB
Upstream transmit Power Level : 48.7 dBmV

Just wondering because there are 5 splices between me and the pole and 1 3.5db loss split.

 

[SatinKzo]

It's been a while since I've had cable internet, usually always go with DSL but not available here.

Are these numbers good?

Downstream Receive Power Level : -4.5 dBmV
Downstream SNR : 37.9 dB
Upstream transmit Power Level : 48.7 dBmV

Basic guidelines I work off for DOCSIS 2 when I worked with clients on their connections
Downstream power between -8 and 8
SNR above 30 is better
Upstream lower than 55db

DOCSIS 3.0 is pickier
SNR: 32dB-50dB
Down stream Power Level: -5 to 5
Upstream Power: 32dBmV-50dBmV

These are not hard fast rules that I know of, but maybe someone working on the engineering side of DOCSIS standards could chime in if here. Possibly some values are set by the ISP themself as what is acceptable on their system.
I am sure DSLreports or similar have specs for your ISP listed somewhere.

 

[TheTechGuru]

What a mess!!!

Looks like a trap, then a pigtail, then another trap, then the line.

I happen to know, internet only service should only require ONE trap that covers like 2-88 or something.

Sorry about the pic quality, didn't want to walk down to it so took it with a telephoto lens then did some digital zoom on top.

 

[TheTechGuru]

Just got all new RG11 installed from tap to house via aerial. Now there are only 2 splices and a 3.5db loss split. (There would be only 1 splice but it seems Charter now REQUIRES the use of a pigtail on the tap when using a trap!)

Downstream Receive Power Level : -1.3 dBmV
Downstream SNR : 38.2 dB
Upstream transmit Power Level : 44.7 dBmV

 

[digiblur]

Just got all new RG11 installed from tap to house via aerial. Now there are only 2 splices and a 3.5db loss split. (There would be only 1 splice but it seems Charter now REQUIRES the use of a pigtail on the tap when using a trap!)

Downstream Receive Power Level : -1.3 dBmV
Downstream SNR : 38.2 dB
Upstream transmit Power Level : 44.7 dBmV

Can't complain much about those. Well within the 15 to -15 spec for docsis 2.

 

[TheTechGuru]

Can't complain much about those. Well within the 15 to -15 spec for docsis 2.

But I do intend on upgrading to DOCSIS 3.0 so I can get the next fastest plan.

 

[digiblur]

But I do intend on upgrading to DOCSIS 3.0 so I can get the next fastest plan.

You should be fine. Although it isn't just about one signal after that. If I remember correctly, each of the 4 bonded channels have to be within 1 dbmv of each other or the bonding can drop.

 

[markbone100]

I dont like to use splices in drops. Only time is when its a ped for underground and then drop requires a trap. Then in that case its a 12" jumper to the trap then to the drop. Aerial I absolutely hate splices. if it needs spliced, I run a complete new drop to the house.

And for the traps at the aerial tap, I screw the trap into the tap itself, then the drop goes at the bottom of the trap. I will not make an aerial jumper for a trap. If its too short without it, a new drop is ran.

For the modem signals, DOCSIS standards here are:

Forward = +12 to -12
Return = 35 to 50
Forward SNR = 33 or higher
Return SNR = 22 and higher


If anything is out of range, modem is red-flagged as failing until levels are adjusted and another test is ran to show its in spec. These numbers are the same for Doc2, Doc3, and MTA's (Any DOCSIS equipment for the fact)

 

[TheTechGuru]

Just blogging my current signals for the record.

Downstream Receive Power Level : -4.7 dBmV
Downstream SNR : 37.2 dB
Upstream transmit Power Level : 41.2 dBmV

1 splice barrel at trap, another splice barrel at ground block, and a 2 way splitter inside.

All RG6 direct burial.

 

[The Insider]

What a mess!!!



Looks like a trap, then a pigtail, then another trap, then the line.

I happen to know, internet only service should only require ONE trap that covers like 2-88 or something.

Sorry about the pic quality, didn't want to walk down to it so took it with a telephoto lens then did some digital zoom on top.

That first item is not a trap but rather a security shield. To prevent theft of service.

 

[The Insider]

Just got all new RG11 installed from tap to house via aerial. Now there are only 2 splices and a 3.5db loss split. (There would be only 1 splice but it seems Charter now REQUIRES the use of a pigtail on the tap when using a trap!)

Downstream Receive Power Level : -1.3 dBmV
Downstream SNR : 38.2 dB
Upstream transmit Power Level : 44.7 dBmV

A "splice" has very little to any signal loss. Its unnoticeable in the grand scheme of things. That lil pigtail on or off you would need very good signal meter to tell the difference.

The pigtail requirement is usually only for underground installations, (because the pedestal lid can cause a big bend in the cable if the connector is pushed away using a trap). But overhead/underground you will not notice or get any improvement but adding or removing said pig tail.

You notice your signal only went up roughly 3db, and id bet the change from RG11 to RG 6 which in the higher freqs that broadband internet usually runs on has about half the loss as rg6 per 100ft.

Judging by your numbers id have to assume you have a pretty far travel distance from the tap to your house (150' plus) and at least 100' plus homerun to your modem. Even then it seems the levels maybe a bit low at the tap, but it could just be how they run there system. Either way you are WELL within the specs and any increase in signal will not change your service quality. You also appear to be at the end of the line which could also tell us why your signal might be a tad lower then usual.

 

[TheTechGuru]

Please note that I've moved since this thread was started, the earlier posts no longer apply. Post 9 is the current setup.

 

[TheTechGuru]

Downstream Channels
		Power Level: Signal to Noise Ratio: Channel 1: -2.1 dBmV 38.8 dB Channel 2: -1.9 dBmV 39.0 dB Channel 3: -1.7 dBmV 39.2 dB Channel 4: -1.2 dBmV 39.6 dB Channel 5: 0.0 dBmV 0.0 dB Channel 6: 0.0 dBmV 0.0 dB Channel 7: 0.0 dBmV 0.0 dB Channel 8: 0.0 dBmV 0.0 dB

Upstream Channels
		Power Level: Channel 1: 42.3 dBmV Channel 2: 0.0 dBmV Channel 3: 0.0 dBmV Channel 4: 0.0 dBmV

Just for my records.

 

[TheTechGuru]

Interesting, they must have turned an amp up.

Downstream Channels
		Power Level: Signal to Noise Ratio: Channel 1 : 2.1 dBmV 40.7 dB Channel 2 : 2.0 dBmV 40.5 dB Channel 3 : 2.0 dBmV 40.7 dB Channel 4 : 2.7 dBmV 41.4 dB Channel 5 : 0.0 dBmV 0.0 dB Channel 6 : 0.0 dBmV 0.0 dB Channel 7 : 0.0 dBmV 0.0 dB Channel 8 : 0.0 dBmV 0.0 dB

Upstream Channels
		Power Level: Channel 1 : 42.3 dBmV Channel 2 : 0.0 dBmV Channel 3 : 0.0 dBmV Channel 4 : 0.0 dBmV

 

[markbone100]

Probabally swept and adjusted the amp

 

[TheTechGuru]

For my log here:

Downstream Channels
		Power Level: Signal to Noise Ratio: Channel 1 : 3.2 dBmV 42.4 dB Channel 2 : 3.5 dBmV 42.5 dB Channel 3 : 3.5 dBmV 42.4 dB Channel 4 : 3.6 dBmV 42.5 dB Channel 5 : 3.6 dBmV 42.3 dB Channel 6 : 3.5 dBmV 42.2 dB Channel 7 : 3.5 dBmV 42.3 dB Channel 8 : 3.4 dBmV 41.9 dB

Upstream Channels
		Power Level: Channel 1 : 39.0 dBmV Channel 2 : 0.0 dBmV Channel 3 : 0.0 dBmV Channel 4 : 0.0 dBmV

Damn near perfect!