Topic 'Splitter backwards?' in forum 'Canadian Broadband' - dslreports.com

Re: Splitter backwards?

Mon, 03 Apr 2017 13:15:08 EDT

anon posted : RG-59 is shielded the same way as RG-6 if you take the same shielding specs. Both have aluminum foil and metal braid. RG-6 is simply bigger than RG-59 for less high frequency losses. There's nothing wrong with RG-59 as long as the rated losses fall within your signal budget loss. RG-6 in a house is a waste of money unless the runs are very long. Hell you can even use exterior hardline if you want, it's not gonna do a thing more than having less high frequency losses. You will see T3 timeouts when the upstream signal path have ingress in it. It could be from your house (maybe the cheap splitter, usually a good splitter wil have 110 dB isolation from exterior aerial signals) or from the network. Only way to know for sure is check your upstream SNR and you won't have access to that since it can only be read from the UBR at the head-end.

Re: Splitter backwards?

Mon, 03 Apr 2017 10:29:44 EDT

heezus posted : The wiring is rg6. I have numerous wires in the house that run into the outdoor connection box. However, they're not terminated or connected to anything is this fine?

Re: Splitter backwards?

Mon, 03 Apr 2017 10:00:55 EDT

En Enfer posted :

said by heezus:

I currently have a cheap dollarmax splitter installed.

There's the problem. Cheap splitters are designed to use for OTA and satellite TV. Cable company here uses Regal splitters, which are designed for bidirectional communications.

Also, the cable quality. How old are these cables ? Look at what's written on it, you should spot RG-59 or RG-6. The RG-59 is "economic", while the RG-6 has an additional shield and that's what cable companies install now.

If there are other splitters used in the house with unused outputs, or if for each output the other end of any wire is not plugged to anything, these can act like an antenna and cause interference and radio frequencies can easily find its way into the wire and cause the modem's signal errors. RG-59 ain't shielded, so it can potentially cause problems.

About lenght, you'll lose much more dB with an RG-59.

Re: Splitter backwards?

Mon, 03 Apr 2017 08:35:17 EDT

anon posted : If your noise floor is already low, you won't be able to lower it. So if you have let's say a noise floor at -35 and the QAM total power is at +5 you should have 40 SNR. If you use a 3.5 dB attetunation, the noise floor won't decrease because it's already low (let's say you are at the bottom floor for the cable) but your QAM level will drop by 3.5 giving you 36.5 SNR. Most of the time, if no ingress is present in the network, low SNR mean badly tuned amplifiers cascades. I see no problem on your stats beside the uncorr blocks. Uncorr blocks means slow downs because data as to be re-sent. But I suspect that you disconnected the coax line from the modem while it was online and not network problems.

Re: Splitter backwards?

Mon, 03 Apr 2017 01:34:15 EDT

InvalidError posted :

said by mackey:

Not always true, a few years ago I had a modem who's input section got overloaded at around +16 dBmV, and adding an attenuator increased the SNR by about 3 dB.

The attenuator did not increase the SNR, it merely solved your front-end clipping issue. I wouldn't count distortion introduced by the modem's limited input dynamic range as SNR of the input signal itself.

Re: Splitter backwards?

Sun, 02 Apr 2017 13:45:44 EDT

heezus posted : Wouldn't the splitter be reducing the incoming signal by 3.5? If I remove it I thought it would improve as there would be more signal and most likely less noise too.

Re: Splitter backwards?

Sun, 02 Apr 2017 13:09:21 EDT

mackey posted :

said by Anondaf68 :

You won't get a better SN by reducing the signal because the lower the signal, the closer you get to the "natural" noise floor in the coax.

Not always true, a few years ago I had a modem who's input section got overloaded at around +16 dBmV, and adding an attenuator increased the SNR by about 3 dB. That said, the OP is not going to see that on his line as his +5 dBmV is way too low for "too hot" to be an issue.

Re: Splitter backwards?

Sun, 02 Apr 2017 09:43:01 EDT

anon posted : You have a lot of uncorr blocks on the downstream. It should be at zero. It's either network problems or you disconnected the rf line while it was on. Try connecting the modem directly to the coax line and see if your SN increase. If it dosen't, the splitter is fine. You won't get a better SN by reducing the signal because the lower the signal, the closer you get to the "natural" noise floor in the coax.

Re: Splitter backwards?

Sun, 02 Apr 2017 09:05:10 EDT

InvalidError posted : 36dB of SNR both downstream and upstream, nothing to fix there.

Cable companies usually disable diagnostic pages to prevent people from worrying about inconsequential stuff.

Since you got a non-approved modem activated, don't be surprised if a network audit finds out that the HMAC address doesn't match the manufacturer and the cable company ends up deactivating it. I'm surprised that such a lookup isn't part of the activation process in the first place.

Re: Splitter backwards?

Sun, 02 Apr 2017 04:47:20 EDT

heezus posted : I can send a picture later today, peeling the label reveals its expoxied not welded. I purchased it from a dollar store so I am not expecting it to be top notch.

Re: Splitter backwards?

Sun, 02 Apr 2017 04:42:53 EDT

mackey posted : No idea, I don't have enough information about your current splitter. If it's of a reasonable build quality and is not defective then a new splitter is unlikely to do anything. If it's cheaply built (and thus likely defective) or damaged then a new splitter would help.

Re: Splitter backwards?

Sun, 02 Apr 2017 04:30:57 EDT

heezus posted : Its a tpia, I highly dobut a tech would ever be sent even if my cable line was chopped. I really appreciate your help. As you're way smarter than me, do you think I could improve me snr by gettint a splitter from shaw?

Re: Splitter backwards?

Sun, 02 Apr 2017 04:28:39 EDT

heezus posted : I told the correct hfc mac and serial but I "accidently" said its a thompson. Its was 10 bucks and provides me with the same speeds. I wanted to move away from the gateway combo

Re: Splitter backwards?

Sun, 02 Apr 2017 04:26:22 EDT

jessegr posted : So how did you get Netgear CMD31T activated for TPIA in West. Did you lie about the serial and mac address. A few weeks ago you seemed to have been using a Hitron.

Re: Splitter backwards?

Sun, 02 Apr 2017 03:55:50 EDT

mackey posted : Splitters are bi-directional; there is no "in" or "out" on them, the manufactures just add those labels to try and help customers figure out the "correct" way of hooking it up for most situations. Most splitters provided by the cable co are rated to either 1 GHz or 1.2 GHz, so the 2 GHz on yours is probably not a typo; splitters designed for satellite systems go to 2.4 GHz or so.

A 2-way splitter will "lose" (reduce the signal strength by) 3.5 dB between the "in" and the 2 "out" ports. If a signal travels from one "out" port to the other "out" port it first needs to go through the "in" port resulting in a 7 dB loss. The actual direction of the signal doesn't matter.

That said, splitters will decrease downstream levels and increase upstream levels, the opposite of what you said in your original post. Furthermore, while they're great at reducing the downstream, trying to use them to increase your upstream will only make the levels *look* prettier; in reality it is unlikely to actually do anything.

I have no idea if those stats you posted are with the splitter or before you added it, but in them your downstream is fine though your upstream is actually borderline low. The good range is typically -10 to +10 dBmV downstream and +35 to +49 dBmV upstream; at +5 dBmV your downstream is fine, but your +35 dBmV upstream is right on the edge. Unfortunately there really isn't anything you can do about that. If it's causing you noticeable disconnects then you can bug your cable provider to fix it, but they're not going to do anything if the only symptom is a few log messages.

Re: Splitter backwards?

Sun, 02 Apr 2017 02:11:09 EDT

heezus posted : I am using a splitter for shaw digital cable, I tried using the splitter in numerous ways but I was wondering if anyone could inlighten me about the effects it could cause as I couldn't find it online.

1= in port. 2/3 = out port

I tried using the splitter how its used. Then plugging my modem into 1 while the main cable and tv are on 2/3. I then plugged tv into 1 while modem and main line were on 2/3. Sorry if I confused you, I am not very good at explaining

Re: Splitter backwards?

Sun, 02 Apr 2017 02:01:29 EDT

Dcite posted : Why do you need a splitter at all?
Assuming a normal splitter is going to be like In1(wall) to Out1(tv) & Out2(modem)

Are you trying to run In1(modem) to Out1(tv) & Out2(wall)? If this is what you are doing, the TV box will probably stop working.

Unless you are actually experiencing poor connection, don't worry too much about T3 timeouts?

Lastly, what is your Upstream dBmV? Something like -35? or more like -51?

(edit, welp I posted too slow, reading)

One T3 timeout a day isn't much.. unless it's actually kicking you offline or given you inconvenient disconnects, your signal levels look fine in my eyes. (Not a tech, just someone else with a cable modem)

Re: Splitter backwards?

Sun, 02 Apr 2017 01:58:43 EDT

heezus posted : Here are my stats and diag.

Splitter backwards?

Sun, 02 Apr 2017 01:52:54 EDT

heezus posted : Hey guys, its the young kiddo posting again! I have been messing around in my modems log and found I am having t3 timeouts daily. After browsing on DSLreports I realised most of these errors occur because of poor snr or high upstream levels. I currently have a cheap dollarmax splitter installed. It's rated to be capable of 2 ghz but I am sure that's a typo on the sticker. I was wondering by using a splitter in reverse would it decrease my upstream strength and increase my downstream? I am also trying to flag down a shaw tech to get a good quality tap or splitter. I have seen a shaw tech in my neighbour hood, hope he comes back around. My neighbour works for telus so I could ask him for a splitter but I am not sure if the frequency's would match. Telus is Adsl but they are known for using hpna or moca for their optik tv setups.