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Is there any body who have some kind of a software to check where the noise is coming from?
I'm using channel bonding in onw area where i have a really bad network, but i still have a lot of noise on all frequencies. and had the customers down.

is there any possiblity to find something to locate the noise source? so the technicians find it quickly?


The best known solve is to

The best known solve is to send technicians into field/plant and using some kind of perl/bash script check eg. every 2-3 seconds the snr.
Then using this readings technician disconnects half of the line simply by removing upstream diplex or amp. Then again half pf line and so on... Believe mi there is no automatic way in any reasonable money - technician is fast enough (don't forget to give him mobile phone :).

you can use the cablelabs

you can use the cablelabs Proactive Network Maintenance Reference Implementation found at

download the and install it on a web server

you can then grab the preeq info and paste it in or if you have PHP 5.4.0 or greater you can use the following script saving it as equalization.php in the PreEqDemoWeb folder


header("Content-Type: text/plain");
$ip = $_REQUEST["ip"];
@$index = $_REQUEST["ifIndex"];
$session2 = new SNMP(SNMP::VERSION_2C, "$ip", "private");
//$session2->oid_output_format = SNMP_OID_OUTPUT_SUFFIX;
$session2->quick_print = 1;
//echo(trim(preg_replace("/\s|\"/", "", $session->get(""))));
$equalizationData = ($session2->walk(""));
$macAddress = ($session2->walk(""));
$ipAddress = ($session2->walk(""));
$ifIndex = ($session2->walk(""));
$x = 0;
foreach ($equalizationData as $key => $value) {
$macKey = preg_replace("/8(\.[0-9]+)$/", "2$1", $key);
$ipKey = preg_replace("/8(\.[0-9]+)$/", "3$1", $key);
$ifIndexKey = preg_replace("/8(\.[0-9]+)$/", "5$1", $key);
$eqdata = trim(preg_replace("/\s|\"/", "", $value));
if (!empty($eqdata)) {
if (isset($index)) {
if ($ifIndex[$ifIndexKey] === $index) {
echo $ipAddress[$ipKey] . "," . trim(preg_replace("/\s|\"/", "", $macAddress[$macKey])) . "," . $ifIndex[$ifIndexKey] . "," . getCMEqual($ipAddress[$ipKey]) . "," . $eqdata . "\r\n ";
} else {
echo $ipAddress[$ipKey] . "," . trim(preg_replace("/\s|\"/", "", $macAddress[$macKey])) . "," . $ifIndex[$ifIndexKey] . "," . getCMEqual($ipAddress[$ipKey]) . ",". $eqdata . "\r\n ";
function getCMEqual($ip) {
$session = new SNMP(SNMP::VERSION_2C, "$ip", "public", 100000);
//$session2->oid_output_format = SNMP_OID_OUTPUT_SUFFIX;
$session->quick_print = 1;
$eqdata = trim(preg_replace("/\s|\"/", "", @$session->get("")));
return (empty($eqdata)) ? "0": $eqdata ;
//$ifIndex CMTS Equalization data
//$modemIndex CMTS Equalization Data

first to the right of the datafile box select all the buttons except lat/lon (only preeq is selected by default) and then in the datafile field on the demo you enter equalization.php?ip= where is the cmts ip to get all the info from the modems, or equalization.php?ip= which will only get the modems on upstream interface with ifIndex of 105. after typing in the url press enter to start it.

The script can take a while to run (approx a min per 500 modems) and a beautiful popup box with nothing in it comes up when you run it but it does work.

once the data is loaded you can use the Red/orange and green balloons and the refresh button to the left of the balloons to filter the modems you want.

PNM versions etc

Ok, I ran down this road a ways, and this is some pretty cool stuff, I have the web demo up and running, but the php didn't work (5.3.x) and I need to upgrade that. But I ran the snmp queries and I receive some OID not found errors. Is this only for Docsis 3? We are running Cisco 7246VXR's and currently doing 1.1, didn't see the need for 2.x yet but equalization looks like a good idea. I enabled it but am not seeing anything happening.
So for this to work, what version of docsis has to be running, and what options need to be on?


I believe preeq works with 1

I believe preeq works with 1.x+ modems to varying degrees. the php script i posted requires php 5.4.0+ update to that version and youll be in business. I have ran the script on 7246 vxr and non vxr with no issues.

Can you guys elaborate PNM RI usage

Documentation available is not very clear for PNM RI to me. Followed equalization.php steps but all in vein.In Data File field I m entering cmts ip & ifindex of upstream.then press enter nothing happens.Tried with different servers,different browsers,different OS,CLI also.Not getting CLI syntax "java -jar Pre..jar" then i dont know how to specify cmts ip,ifindex community string etc..If you can find time to write pls. help.




I have preeqwebdemo working, it does work on 1.0/1.1 modems, just fewer data points. It looks like cablelabs took the download away or moved it. Occasionally it just doesn't work (something in their java doesn't error check). I can run the extract and put it in a data file and it works fine.. I was hoping they had updated.

Not able to download the Zip File

I am not able to download the Zip File.
Can you check the URL?


-- Silvano


Can anyone upload the zip file?

Thanks Barni

PNM Software

Check out what we have as a solution. One of the first hosted software to market called PreEqualization Analyzer. Check out details here:

We also have Upstream and Downstream Spectrum software available as well.

Does anyone still have a link

Does anyone still have a link to this download, or the zip file lingering around? If i could find it I'd pretty well be willing to put it up in a permanent location for everyone else to have access to.

new link

It appears that the link is still active on cable labs, but it is only reached from IPv6 now.

Try this link:

I was able to download it recently.

Hope it helps.


Thats not resolving

That link is dead. :/

No! - it´s alive

It is alive ... but it is IPv6 only.

Try reaching it using a proxy like




Well here we go, IPV6 Only...never thought i'd see the day.

Commercial implementations of

Commercial implementations of that PNM demo are available these days eg

* equalizer analysis tool, pretty obvious they took that demo and fixed / improved it. Not really going to help you locate noise, but I guess would help locate other plant defects.

* live upstream spectrum analyser, using data from the CMTS (no extra hardware needed). Could be handy for field techs to watch the SNR readouts on their phone/tablet why disconnecting coax legs in the field?

I believe other companies like zcorum are reselling the nimble-this tools.

Pre-eq decoder

I was trying to figure out how variations on TAP values impact the Pre-equalization frequency response, so I decided to code a small application to check that.

The app is quite simple. Paste the pre-eq data you captured from the modem and hit "Calc". After that, you can play with the Real and Imaginary TAP values to see how the graphs are affected.

It is available at

Hope you find it interesting.



File missing

Hi! Anyoane has ?

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