CRC Errors

ichigo

ichigo

Executive Member
Joined
Aug 1, 2006
Messages
9,251
Reaction score
36
Location
Pietermaritzburg
My internet seems fine but i get upstream CRC errors

DSP Firmware Version E.25.41.55 A
Connected true
Operational Mode G.Dmt
Annex Type AnnexA
Upstream 512000
Downstream 4096000
SNR Margin(Upstream) 28 dB
SNR Margin(Downstream) 27.0 dB
Line Attenuation(Upstream) 5.0 dB
Line Attenuation(Downstream) 8.0 dB
CRC Errors(Upstream) 3622
CRC Errors(Downstream) 0
Latency(Upstream) Fast
Latency(Downstream) Fast

Not sure but seems to happen when someone calls the house an chats
 
Are you running a POTS filter on your telephone line?

If you're not, it could explain why you're picking up CRC errors when the phone rings as the POTS filter helps keep the ADSL and Analogue frequencies seperate.
 
so need to replace a filter right?

got 2 port pots filter for phones, ones for a fax machine other is normal phone

edit: btw how long do filters last? can it also cause internet to not connect if i restart router without using phone?
 
Last edited:
any answer to my last question?

edit: seems when i unplug both phones and pot filters my internet disconnects
 
Last edited:
You just need a splitter filter (1x RJ11 socket for ADSL and another RJ11 socket for telephone/fax) that you can get from Telkom shops.
If you have a dual filter (2x RJ11 sockets for 2 telephones/fax machines), then you'll still need a splitter filter for the ADSL modem, otherwise you'll have noise on your telephone.
For the best signal quality, connect the splitter filter to the incoming telephone line and then run a cable to the ADSL modem, and run a second cable from the splitter to the fax & telephone.
If you split the cable before the splitter filter, you'll need a second filter.

Your ADSL modem should be able to sync if you have no filters plugged in too.

Here's a complex example:
Code: 
Telkom <─┬─[ <──Dual filter=╦=Tel socket[ <──Telephone
         │                  ╚=Tel socket[ <──Fax
         └─[ <──Splitter filter=╦=ADSL socket[ <──ADSL modem
                                ╚=Tel socket[ <─┬─Telephone
                                                └─Alarm

The filters should last a couple of years, depending on the quality of capacitors they use.
A broken filter can prevent your ADSL from synchronizing (and thus preventing it from establishing a PPPoE connection).
 
my routers on different port on splitter to phones with filter

Code: 
Telkom [ <──Splitter filter=╦=ADSL socket[ <──ADSL modem
                            ╚= Dual Pots Filter <---- Tel socket[ <─┬─Telephone
                                                <---- Tel socket[ <─┬─Fax


thats how mines setup
 
Last edited:
If you meant a setup like this:
Code: 
Telkom [ <──Splitter filter=╦=ADSL socket[ <──ADSL modem
                            ╚= Dual Pots Filter <---- Tel socket[ <─┬─Telephone
                                                <---- Tel socket[ <─┬─Fax
Then it should be fine. I would rather get a splitter cable to use instead of the dual POTS filter, because its pointless to filter something that has already been filtered.
 
tried a new pots filter and seems to do same :P

dont think box which telkom supplied when they installed everything filters the signal since i tried plugging phone in it without pots filter and gives noise
 
Merenwenrago said:
my routers on different port on splitter to phones with filter

Code: 
Telkom [ <──Splitter filter=╦=ADSL socket[ <──ADSL modem
                            ╚= Dual Pots Filter <---- Tel socket[ <─┬─Telephone
                                                <---- Tel socket[ <─┬─Fax


thats how mines setup
Click to expand...

BAD.
Try removing the splitter. Does your adsl modem not have its own splitter+ filter (i.e. modem on one, phone on other), if it does, plug that in straight to the line, then for the phone output just put the splitter and then connect the phone and fax straight to it. no need for the dual POTS filter.

Edit: Ooops, noticed that's what you meant by splitter filter. Remove that dual pots filter, you dont need it, try with just telephone. If it doesnt cause crap, it's the POTS filter.
 
Last edited:
the ADSL modem is supposed to work without the POTS filter! The ADSL modem would lose sync every time you get a call on the telephone line if the ADSL modem isn't connected via a filter.
 
When you make a phone call, is it noisy?! Also, have you tried isolating it by just having the adsl modem in and nothing else? Need some intense testing. Could be anything from bad router to some weird emissions in the UL band.

P.S. You said that without the dual-pots filter, it dropped. Are you sure your 'splitter filter' is a filter as well and not just a standard splitter?
 
Last edited:
its standard splitter

and ye dropped without phones on line and the pots filter

i actually got two outlets with standard splitter in different rooms
 
Last edited:
Aaaah, that explains. Well, first of all, to test your modem, make sure to plug EVERYTHING out, the modem should be the only thing connected to a phone line in your house. If that doesn't work (i.e. lots of CRC errors) then your problem isnt with the splitters at all, its the line and/or modem. If it does work, then your ADSL modem should've come with a splitter? use that instead of the splitter you are using now.
 
UnUnOctium said:
Aaaah, that explains. Well, first of all, to test your modem, make sure to plug EVERYTHING out, the modem should be the only thing connected to a phone line in your house. If that doesn't work (i.e. lots of CRC errors) then your problem isnt with the splitters at all, its the line and/or modem. If it does work, then your ADSL modem should've come with a splitter? use that instead of the splitter you are using now.
Click to expand...

ok going to try it

and ye think i got a splitter with my router
 
hmm without anything on the line, the router connected fine but still gave CRC errors 200 more than normal (normally doesnt connect at all without a phone call)

DSP Firmware Version E.25.41.55 A
Connected true
Operational Mode G.Dmt
Annex Type AnnexA
Upstream 512000
Downstream 4096000
SNR Margin(Upstream) 28 dB
SNR Margin(Downstream) 26.5 dB
Line Attenuation(Upstream) 5.0 dB
Line Attenuation(Downstream) 7.0 dB
CRC Errors(Upstream) 1191
CRC Errors(Downstream) 0
Latency(Upstream) Fast
Latency(Downstream) Fast
 
First of all, unplug everything. Is your wall socket a single or dual socket?
If necessary, blow out the sockets to clear dust.

Plug in your phone into the wall, and lift the handset so you can hear dial tone. If necessary press a digit to get a clear line. Do you hear noise? It should be silent, no crackling or any kind of noise.
If you're getting noise, there's a problem with your line, and you should log a ticket with telkom.
Do the same procedure with the other socket.

I suggest jiggling the cable near the plug at either end to hear if you get crackling on the line. If you do, replace the cable, as it has a loose connection.

If you only have a single socket, plug in your splitter, and then do the same procedure to listen for clear line. If your splitter doesn't make a secure connection, you could end up with crackling on your line. Jiggle the splitter in the socket to hear if it makes any noise. If necessary, replace your splitter.

Unplug the phone cable from your modem, and test it with your handset to check that the cable doesn't have any issues (ie, jiggle the cable to check for loose connections).

If everything is clear so far, plug your modem into one of the sockets (either on the splitter, or the dual socket box), with the cable you just tested. Then, get your filter, blow out the socket to remove any dust, and connect your handset to it. Check that a) it works, and b) there's no noise.

If you're using a surge protector somewhere in your circuit, be sure to test with and without it to see if it's not that that is causing your problem.

I was getting terrible crackling on my line until I got around to unplugging and checking all the connections. Turns out that the connection from the wall socket to the surge protection unit was not secure, AND the cable from the splitter to the modem was dodgy which was causing my modem to lose sync from time to time.

[Dual Wall Socket] (Only using one socket)
|
[Surge Protection]
|
[Splitter]--[Filter]--[Phone]
|
[Modem]
 
thisgeek said:
First of all, unplug everything. Is your wall socket a single or dual socket?
If necessary, blow out the sockets to clear dust.

Plug in your phone into the wall, and lift the handset so you can hear dial tone. If necessary press a digit to get a clear line. Do you hear noise? It should be silent, no crackling or any kind of noise.
If you're getting noise, there's a problem with your line, and you should log a ticket with telkom.
Do the same procedure with the other socket.

I suggest jiggling the cable near the plug at either end to hear if you get crackling on the line. If you do, replace the cable, as it has a loose connection.

If you only have a single socket, plug in your splitter, and then do the same procedure to listen for clear line. If your splitter doesn't make a secure connection, you could end up with crackling on your line. Jiggle the splitter in the socket to hear if it makes any noise. If necessary, replace your splitter.

Unplug the phone cable from your modem, and test it with your handset to check that the cable doesn't have any issues (ie, jiggle the cable to check for loose connections).

If everything is clear so far, plug your modem into one of the sockets (either on the splitter, or the dual socket box), with the cable you just tested. Then, get your filter, blow out the socket to remove any dust, and connect your handset to it. Check that a) it works, and b) there's no noise.

If you're using a surge protector somewhere in your circuit, be sure to test with and without it to see if it's not that that is causing your problem.

I was getting terrible crackling on my line until I got around to unplugging and checking all the connections. Turns out that the connection from the wall socket to the surge protection unit was not secure, AND the cable from the splitter to the modem was dodgy which was causing my modem to lose sync from time to time.

[Dual Wall Socket] (Only using one socket)
|
[Surge Protection]
|
[Splitter]--[Filter]--[Phone]
|
[Modem]
Click to expand...

Went through most of that. Seems he still gets the high amount of CRC errors with modem only.

@OP, have you tried borrowing a different modem from a friend? Possibility is that it's the modem. That is an easily testable one. The second test (if the first one works) is to check for some spurious emissions on the line in the UL band. Do this by taking some telephone wire, cut it and separate the two cables (DON'T LET THEM TOUCH, do this by cutting one closer to the jack than the other one) then take a multimeter, switch it onto AC voltage (units) and measure the terminals. The reading should be very low and almost zero. If it isn't, you have something on the line. (Make sure everything is plugged out while doing). This does depend on how good your multimeter is though, ideally you'd want a spectrum analyser for this, but $$$.
 
You must log in or register to reply here.
Back
Top
Sign up to the MyBroadband newsletter
X