Which Location for Attenuator on Broadband Cable?

Status
Not open for further replies.
Joined
Jul 2, 2007
Messages
5,294
In reference to my thread last month about my broadband provider needing to fix our easement box, they came out and did whatever they did which improved but hasn't eliminated the correctable error count. Was getting 750,000 correctables in 24 hrs of uptime, now they're way down to about 25,000 a day. But the downstream power is unchanged @ +9 dBmv. Speeds are back within spec, tests on avg about 70 - 90 Mbps download, 10.9 Mbps upload (subscribed @ 100/10 Mbps), and internet route ping is between 31 - 44ns most of the time testing on the usual speed tests online and not hardwired to the cable modem (clients connected via 5Ghz wifi connection running from 175 - 433 Mbps client to router).

So my question is which is best location (or does it matter) to put a -6 dBmv attentuator ? It's a one way, downstream only ... does not attenuate the upstream power. I currently just have it screwed directly onto the cable modem's coax fitting, but would it be better to locate it in the outside wall box on house to attenuate the power before it enters the house's cable plant?

With the one way attenuator on the modem now, downstream power is holding at +3 dBmv.
 
It does not matter.

Are there any splits inside the house for TVs, or is the cable modem the only thing on the line? In general the fewer connections and splitters you have between the street and the modem, the better it will work.

Correctable errors don't hurt your speed, because the data is immediately corrected by the modem and sent to your network -- it doesn't need to be retransmitted. Uncorrectable errors are a problem.
 
Last edited:
Why do you need an attenuator? Why isn't the cable company giving you service that meets the specs? I would have them out and be there working with them until its right.

But until you get fiber there will always be come issues with coax.
 
You should have linked to that topic or better still, provided a concise summary.

Without that, it appears that you are following bad information. There is no need to attenuate a +9dBmV downstream signal. It is within spec and gives you extra margin should the line degrade or you later need to use a splitter for more devices. Take the attenuator off and see what happens. If the error rate goes up, odds are your modem is faulty.

What is your SNR? Is this an apartment building and there's a cable amp on the line? If so the attenuation should be before the amp, except I don't think YOU should have one at all, rather the amp is flaky, which would not be your property, or the SNR getting to it needs attention. Again this is only in a multi-dwelling apartment/etc where there's an amp to get to 9dBmV.
 
Last edited:
Single family home, no splitters on the line and incoming buried coax connects directly to the coax of the modem's wall drop via a male to male grounded union. Cable company diagnosed last month that the amp or something was faulty in their utility box in the neighborhood's shared easement back of property behind the house, said that box serves four houses (subdivision). SNR is in the 41's all 16 bonded downstream channels, and in the 43's on three bonded upstream channels.

Modem is a two year old Zoom 5370 Docsis 3.0, very stout unit, don't suspect it but will try what you suggested. Thanks for the help
smile.gif
 
The utility box probably just has splitters in it, that also attenuate the signal. I'm doubting the problem is on your end, probably they re-did the coax connectors to the splitters just enough to get it working to minimum standards but not quite perfect.

You may be stuck in a gray area of "it works, we delivered what we advertised" if all you're getting is the correctable error count. Realize that a correctable error count is just that, errors that were corrected. Uncorrectable errors are the bigger problem. Your SNR looks good.

I'm just saying that your setup may not be that far from typical if you're doing a fair amount of downloading, streaming video or P2P, etc. to result in 25K correctable errors.

Tell us again why you are chasing correctable errors if you're getting the throughput you're supposed to? Over wifi no less?
 
Last edited:
Originally Posted by mk378
It does not matter.

Are there any splits inside the house for TVs, or is the cable modem the only thing on the line? In general the fewer connections and splitters you have between the street and the modem, the better it will work.

Correctable errors don't hurt your speed, because the data is immediately corrected by the modem and sent to your network -- it doesn't need to be retransmitted. Uncorrectable errors are a problem.


+1

CEC's are not a problem no matter how high they get. Its CRC errors that cause problems, more specifically your internet would disconnect.
 
I've never had any luck with zoom.

I'd snag a sb6183 they are cheap now... easy to rule that out then.

but doesnt seem like you have concrete issues?
 
Reason I looked at modem page last month was because of pauses in streaming and speed test results well below subscribed limits even in off peak times of day. That prompted initial call, then they came out and diagnosed.

At my other house (been in this current one less than a year) the plant was crystal perfect. Text book signal quality with zero error count 24/7. So I guess I'm spoiled due to that, lol.
 
Originally Posted by Dave9
The utility box probably just has splitters in it, that also attenuate the signal. I'm doubting the problem is on your end, probably they re-did the coax connectors to the splitters just enough to get it working to minimum standards but not quite perfect.




Probably is the case. Six months into a two year contract for 100 Mbps down, 10Mbps up and bring my own modem. But, it's only $24.99 a month so maybe I should stop griping.
 
Status
Not open for further replies.
Back
Top