NBN interference

[VK3RX]

We have FTTN and no issues, but will be FTTC at some point.

Anyone experienced noise related to this technology?

[VK2CSW]

Yup, noise aplenty.

It's the reason I am no longer active.


   

[VK3RX]

Interesting.

Did you determine e.g. with a portable receiver what actual component was causing it - DPU, NCD or something else?

[VK2CSW]

Eventually the guru's from NBN turned up with a bunch of VDSL test gear - specan like equipment.

The interference was the signal between the NCD (in the house) and the DPU (in the street). As we have an aerial lead in and VDSL operates in a a band of 10 to 150 MHz (or thereabouts, I can't remember the exact numbers) the lead in is in effect a very large antenna.

I had already replaced the Telecom Australia installed 2 pair with Cat 5, NBN replaced the 40+ year old 1 pair IBC lead in with a screen bearer Cat 5 equivalent. This reduced the RFI a fair bit but it is still there.

In the image you can see where I triggered the NCD/DPU to start interfering (2 or 3 watts at 14 MHz using FT8 triggers it each and every time) - the interference continues until the NCD/DPU is powered down and restarts. By the by, the NCD powers the DPU so not only are you paying for the service you are also paying to power it too.

The NBN engineer believes that as the VDSL is broadband and the RF from my station is in it's bandwidth then the NCD sees it as interference and turns the wick up and that's where the interference appears in the waterfall. Although he could see the interference in his equipment and in my equipment and saw that powering down the NCD and/or DPU stopped the interference there was nothing else they could do.

ACMA weren't interested as they can only refer it to NBN and as I had already had contact with NBN they couldn't help.

I have tried numerous other things like rerouting antenna cables, moving antennas, different antennas, turning the xmitter power right down (and right up), etc.

So after many tens of hours of frustrating phone calls, live chats, days off work, running cables and much frustration I've cut my losses. HF voice simply isn't viable here due to too much QRM from railways, high voltage transmission lines and many other spot sources, so digital modes (FT8 mostly) allowed me to get back on air, now that is too difficult and frustrating which has killed any fun.

The upside is I have much more room on my workbench now.

Cheers.

[VK3RX]

Is the whole overhead cable radiating (likely I guess)? And is the interference originating from the DPU or NCD?

I'm just thinking if it is one device then some clip-on ferrites at one end might do something, though not possible at the DPU end of course.

One might think you could temporarily fix the issue so you can operate by switching off your NCD, but that may not do anything because I believe power to the DPU is provided by all the premises that are connected to it, not just you.

It is a wider issue than just you of course i.e. an amateur or SWL whose neighbor gets FTTC with an overhead line and cops interference. And if the whole street gets FTTC ....

Something the WIA should investigate I think, because the problem is only going to get worse.

I've read that if a pit to premises cable is sus, NBN Co. may where possible install an overhead line replacement rather than run a new trench. Also that in time areas currently FTTN may have FTTC rolled out to serve the users too far from a node to get acceptable speeds.

Edit: a friend has had good results with an MFJ-1026 unit for solar panel and what he assumes is NBN interference in his suburban area.

[VK2CSW]

It's hard to differentiate whether it's NCD or DPU. If you disconnect the lead in to the NCD this poers down the DPU, but the NCD loses sync with the DPU so stops transmitting. Same if it is disconnected at the DPU end.

I tried ferrites of many types and configurations with no joy.

Unfortunately when using digital modes it is useful to have the internet connection working for logging and the like.

I even set up an antenna in the back corner of the yard and ran coax to it, away from the lead in path. Made exactly zero difference.

The replacement of the aerial lead in did improve things, but once we reduced the interference from my lead in we could then start to see interference from other installations.

[VK2VRC]

I have had FTTC for about 12 months or so ,without any problems, then last month, during the big rain event we had, suddenly I have S9 noise on 40m and 80m and S8 noise on 20M , but when I transmit on 20M I get a noise signal that appears to attach itself to my transmit frequency . I would understand if it appeared when they installed the NBN,but this is nearly a year later.

   

This happens as soon as I key up and the noise is very loud.
What should I tell NBN Co when I call them,I am sure they will be very helpful if I say that I have interference on my Amateur radio equipment ?

Regards

Wayne 
VK2VRC

[VK5TM]

What should I tell NBN Co when I call them,I am sure they will be very helpful if I say that I have interference on my Amateur radio equipment ?

Regards

Wayne 
VK2VRC

Don't hold your breath, the NBN bunch can be a very ignorant mob most of the time and it wont matter what you tell them.

Now, if you could prove you had a loss of internet service, ie slow speed, drop outs etc, you would probably get more interest.

[VK5PJ]

I have had FTTC for about 12 months or so ,without any problems, then last month, during the big rain event we had, suddenly I have S9 noise on 40m and 80m and S8 noise on 20M , but when I transmit on 20M I get a noise signal that appears to attach itself to my transmit frequency . I would understand if it appeared when they installed the NBN,but this is nearly a year later.



This happens as soon as I key up and the noise is very loud.
What should I tell NBN Co when I call them,I am sure they will be very helpful if I say that I have interference on my Amateur radio equipment ?

Regards

Wayne 
VK2VRC

Hello Wayne,
check the AM radio band for interference, they are obliged to fix any interference to AM broadcast and it is something they will understand about when the fault is reported.I had problems with fixed wireless early on as it killed 160 / 80 /40 here and also killed AM broadcast....  they did not give two hoots about HAM but they understood they had to fix AM broadcast   
My roof top unit was replaced and problem had not appeared again.
Regards,
Peter, vk5pj

[VK2CSW]

In my case it took much persistence.

You need to accept that in the first instances you will need to deal with your ISP as they are the first port of call. This will lead to much frustration.

In the end I was lucky that it got escalated and once the NBN tech's got involved there was progress but no fix.

One thing that did make a small difference is that the lead-in was recabled with a tight twist Cat6 type cable from DPU to NCD. We have a aerial lead-in which acts like a big old antenna, the Cat6 reduced some of that.

I was told by the NBN network engineer who came to visit that the VDSL modulates between 10 and 140 MHz. When RF enters the system in that range the NCD senses the change in conditions and turns up the power to overcome the 'interference'. For me this resulted in broad-band interference.

I wonder if this was caused by water ingress and the cable (either underground or in infrastructure) that is causing some kind of earth load and the NCD is trying to overcome it by turning up its output?

Your ISP should be able to detect line issues such as this with their tests.

[VK3RX]

<snip>
the VDSL modulates between 10 and 140 MHz.
<snip>

I've read that other countries e.g. the U.K. have the range notched to exclude amateur, aviation and other bands.

Does this not happen here?

As regards specific problems, if there has been a service bulletin or similar issued to tech staff by the NBN, it would be useful to quote it's ID when reporting, so at least someone is pointed in the right direction.

[VK2VRC]

I have an aerial lead in , from the telegraph pole on the street to the box on the house , it is an old copper lead fitted in the very early 70's ,when I first moved here .

I asked the technician when they were installing the NBN ,if he was going to replace it, and he said it was still ok .I had a feeling he was on commission for how many installs he did per day ,and was not really interested.
I have broadband interference , since this problem popped up about a month ago ,59+ on 40m and 80m , but my dipole on these bands doesn't seem to cause the same increase in the noise around my transmitted signal.But on 20m with the Yagi,it only takes a couple of watts to cause the problem, which sounds a bit like the woodpecker ,but at a higher and faster rate.
have been wondering if it was caused by water ingress ,either from a flooded pit, or from one of those black connectors on the telegraph poles.As it is strange that I have never previously had any noise, and then during all that very heavy days of rain, the noise suddenly appeared.I was listening the moment that it started,I initially thought I had a problem with the software on my SDR.But changing radios,quickly showed it wasn't radio induced.

I have to call my ISP anyway, because I now have a problem with my home phone, which now runs through the NBN ,I call some phone numbers here in Sydney ,and get a message that " my call can't be completed with the long distance company that I have selected .Please dial your call within access code" whatever that is supposed to means it is a local call within Sydney. It is a reason to get a technician involved, and hopefully the 2 problems are related .


In my case it took much persistence.

You need to accept that in the first instances you will need to deal with your ISP as they are the first port of call.  This will lead to much frustration.

In the end I was lucky that it got escalated and once the NBN tech's got involved there was progress but no fix.

One thing that did make a small difference is that the lead-in was recabled with a tight twist Cat6 type cable from DPU to NCD.  We have a aerial lead-in which acts like a big old antenna, the Cat6 reduced some of that.

I was told by the NBN network engineer who came to visit that the VDSL modulates between 10 and 140 MHz.  When RF enters the system in that range the NCD senses the change in conditions and turns up the power to overcome the 'interference'.  For me this resulted in broad-band interference. 

I wonder if this was caused by water ingress and the cable (either underground or in infrastructure) that is causing some kind of earth load and the NCD is trying to overcome it by turning up its output?

Your ISP should be able to detect line issues such as this with their tests.

---

I have had FTTC for about 12 months or so ,without any problems, then last month, during the big rain event we had, suddenly I have S9 noise on 40m and 80m and S8 noise on 20M , but when I transmit on 20M I get a noise signal that appears to attach itself to my transmit frequency . I would understand if it appeared when they installed the NBN,but this is nearly a year later.



This happens as soon as I key up and the noise is very loud.
What should I tell NBN Co when I call them,I am sure they will be very helpful if I say that I have interference on my Amateur radio equipment ?

Regards

Wayne 
VK2VRC

Hello Wayne,
check the AM radio band for interference, they are obliged to fix any interference to AM broadcast and it is something they will understand about when the fault is reported.I had problems with fixed wireless early on as it killed 160 / 80 /40 here and also killed AM broadcast....  they did not give two hoots about HAM but they understood they had to fix AM broadcast   
My roof top unit was replaced and problem had not appeared again.
Regards,
Peter, vk5pj

Hi Peter

Checking the broadcast bands is one of the first things I did , as I know that ACMA are not interested in helping Amateurs , but if I had interference on the broadcast bands ,then as a member of the public ,they would be compelled to look into it . But the broadcast stations are so strong here ,the signal would need to be extremely strong to cause any problems.

Wayne 
VK2VRC

[VK2CSW]

Any improvement as things have dried out a little?

[VK2VRC]

No improvement at all ,I was hoping that this rain might cause something else to happen ,but still just the same noise .It is OK if I point LP North America or Short Path South Africa , but anywhere else ,signals need to be S9 or above , and even then ,the noise is so grating ,that you can't spend much time listening. If I just want to listen , I normally just transmit a quick carrier at the bottom of the band ,and the noise will stay there ,and I can at least listen with some normality further up the band ,at least until I key up.

[VK2CSW]

Out of idle curiosity does is stop if you power down the NBN NCD?

[VK2VRC]

I just did a new check, just in case..... Noise is still there with NBN NCD powered down and all cables removed ,also router off and all cables removed.

[VK2CSW]

That makes it hard to pin it on the NBN - they will do that test.

Now there is a grey area though. I was lucky here as initially I was the only one who was yet connected to the DPU, so when I powered down the NCD I also powered down the DPU. (The consumer powers the NBN FTTC gear from the NCD). Once others were connected they kept supply to the DPU when I pulled the power off.

Just something to keep in mind when designing test scenarios and tracing the noise.

[VK3RX]

I just did a new check, just in case..... Noise is still there with NBN NCD powered down and all cables removed ,also router off and all cables removed.

A wander around the neighborhood with a portable radio might narrow down the source.

AM broadcast band may suffice if you don't have a shortwave.

[VK2VRC]

Any improvement as things have dried out a little?

I just did a new check, just in case..... Noise is still there with NBN NCD powered down and all cables removed ,also router off and all cables removed.

A wander around the neighborhood with a portable radio might narrow down the source.

AM broadcast band may suffice if you don't have a shortwave.

I have been for a walk around the neighbourhood with my portable short wave receiver ,and even tried it connected to an active loop .I must admit that there was nothing really definitive found , can hear the noise but not very strong like I would expect.Can't hear anything on the AM broadcast band unfortunately, or I would have called ACMA .
The noise is directly in the direction of a power pole out the front of my neighbours place, when I point my 20m Yagi .Borrowing a mobile transceiver later , and will check out the neighbourhood for the noise .

---

Any improvement as things have dried out a little?

That makes it hard to pin it on the NBN - they will do that test.

Now there is a grey area though.  I was lucky here as initially I was the only one who was yet connected to the DPU, so when I powered down the NCD I also powered down the DPU.  (The consumer powers the NBN FTTC gear from the NCD). Once others were connected they kept supply to the DPU when I pulled the power off.

Just something to keep in mind when designing test scenarios and tracing the noise.

I am hoping that by using a mobile radio and resonant antenna, that I will be able to pinpoint the noise .Once I know for sure where it is coming from ,I will be able to form a plan of action.
I must admit that I know nothing about the NBN ,and am relying on other peoples knowledge and experience .We can think of nothing else that can cause this sort of localised interference , and appears to ramp up when it sees an RF signal.

[VK2VRC]

Checked with a mobile and a portable receiver ,the noise appears to be coming from a telegraph pole and an NBN pit outside my next door neighbours house.Noise was 59+10 on the mobile directly outside my property . The only saving grace is that propagation is quite good at the moment, and there are a few very strong signals that I can work, beaming into the direction of the noise.Luckily I have an Apache Labs Anan SDR transceiver with dual NR ,which allows me to work stations I wouldn't normally be able to work .Not sure where to from here !