U72 cable, signal-to-noise ratio and speed

Hello zämä

I’ve had constant internet interruptions since Easter.

I then summoned a Swisscom technician. He measured that only a very weak signal was arriving at the UP on my Anschluss.

The technician then called up the Cablex. They discovered that a cable on the DSLAM was not plugged in correctly.

Afterwards, all of the old copper cables in the house were replaced with U72M 1×4×0.5. Everything connected directly without bridge taps.

With the old copper cables I always had a signal-to-noise ratio of around 6 dB and the router synchronized at around 310,000 kb/s. Yesterday the signal-to-noise ratio increased to around 9 dB and the synchronization speed fell to 260,000 kb/s. As of midday today, the signal-to-noise ratio is approximately 12 dB and the synchronization speed has fallen to 126,000 kb/s.

I’m a bit afraid that in a few days the speed will drop to 0 kb/s if it continues like this 😀

I asked the two other parties in the house. The synchronization speed has also fallen for them, although according to Checker we should have 300,000 kb/s and still had it until a few weeks ago.

I actually expected everything to be better with the U72 cables. What could be going on?

Greetings Tom

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Hi @Heinekentom

There will probably be some other interference (powerlines in use?). Since the in-house installation was carried out professionally, it is reasonable to assume that something is wrong outside.

But @Roger G can certainly tell you more.

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Good evening,

In Kundencenter I have a speed of 200 / 40

Synchronized speed until yesterday Saturday about 220 / 47, measured with cnlab 202 / 46

this Sunday about 131 / 47 with cnlab 122 / 47

Signal-to-noise ratio yesterday and today 6.1 / 6.1 each

Did Swisscom change anything over the weekend?

PK39 wishes you a nice evening

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  • WalterB has responded to this post.

    PK39

    What does it show you when you enter 192.168.1.1 in the browser and then at the first green dot

    the mouse clicks?

    See pattern below.

    System-Daten.jpg

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    Installationen, Netzwerk, Internet, Computertechnik, OS Windows, Apple und Linux.

    Hi

    Based on your speed, I assume a g.fast Anschluss.

    The so-called microCAN detects when your line is running unstable and uses the NoiseMargin to correct the line until it works stably. The higher the NM, the lower the Att. bit rate - you’ve already noticed that.

    We had some very exciting disruptive factors with g.fast connections. These can be PowerLines, transformers for standard lamps or similar, a newly purchased electrical device, amateur radio operators, etc.

    The mean thing is that we already had a case in which the neighbor’s PLC (PowerLine) had a negative impact. This is particularly the case with multi-family homes.

    In one case, the neighbor’s PowerLine interfered all the way to the district distribution column, as the modern PLC also uses the potential earth to transmit the signal. Since the telephone cables or their incoming earth are usually connected to the potential earth on the house connection box. So there was an antenna effect and it was so strong that the neighbor’s single-family home negatively influenced the neighbor’s g.fast signal. I would say that this is an extreme example that actually rarely occurs. And despite everything, it happened. When the neighbor took the PLC out of operation as a test based on Swisscom’s analyses, our customer ran without any problems from then on.

    Do you have an overhead line?

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      PatrickS

      Yes, it is a g.Fast Anschluss. No overhead line and the DLSAM is about 50m away from me across the street.

      But now you’re talking about something that I’ve already thought about.

      In the neighboring house (approx. 5m as the crow flies from my apartment) a tenant has been installing a 4 meter long CB radio antenna for about 4 weeks. I was also wondering whether this had an influence. When the Swisscom technician was with me, I asked him and he said the antenna had no influence. But it’s just a coincidence that I always have problems on weekends when the tenant is at home.

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      Thanks for the reactions,

      Now the values ​​are rising again from this evening, currently at 162. I will announce the latest values ​​tomorrow, Monday.

      Urban conditions without overhead lines. I don’t use dLan. Ib3 and UHD TV box connected to Lan over a distance of 25m.

      It’s a surprise to me that the speed drops so much during the night. Hence the question of whether Swisscom has changed anything.

      Have a nice evening again and thank you

      PK39

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      @PK39

      It would be good if you could put the data here as shown in the picture above, then you would see a lot of things that are not good.

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      Installationen, Netzwerk, Internet, Computertechnik, OS Windows, Apple und Linux.

      Hi @PK39

      In general, I would neither rule out radio nor classify it as the cause.

      First and foremost, it would be good to know what type of radio your neighbor uses. CB radio is somewhere between 26/27 MHz. This is license-free.

      Then there is amateur radio, which requires a test. This radio is transmitted in different bands - these in turn use different frequencies.

      VDSL2 moves between 8 and 17 MHz, depending on the spectrum profile.

      Super vectoring (not used in Switzerland) is at 35 MHz.

      G.fast uses frequencies up to 212 MHz.

      Unfortunately, I cannot answer you in detail which frequencies are used by your Anschluss or by g.fast in the Swisscom network.

      In my opinion, in the g.fast range, at most the 2 m band would be an option. This is around 144 MHz. I would have to look up the exact frequency first. But other bands could also be responsible for interference.

      Notching technology would be used to defuse interference from radio systems. Since this solution could also have a negative impact on the Att. bit rate, it is not active by default. However, in your case it may have to be activated if there is actually a disruption due to the radio.

      Before you attack your neighbor and condemn him as a scapegoat, this theory should be clearly proven.

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      @PatrickS

      A small addition to the frequency question.

      As far as I know, the g.Fast used by Swisscom only uses frequencies up to 106 MHz.

      The part above that, up to 212 MHz, belongs to the so-called “Super g,Fast” with transmission rates of up to a good 1 GB, which is neither used by Swisscom now nor in the future (Swisscom’s strategic growth path is from g.Fast directly to XPON technologies).

      The Internet boxes currently in use would not support frequencies up to 212 MHz.

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      Hobby-Nerd ohne wirtschaftliche Abhängigkeiten zur Swisscom

      @Heinekentom: The antenna has to go, or at least on the roof. We don’t know what power it uses to transmit, but placing the antenna between the houses is a no-go. In my youth, I boosted my performance beyond what was allowed - you try everything 🙂 I don’t know the current legal situation, but I would like to inform OFCOM that there are radio interference there. You can speak to him and warn him that he will then have to pay the costs for the measurement by OFCOM and if the performance is above the permitted value, he will be reported, which will also result in a fine.

      We can’t say yet whether the problem will go away because I’m still analyzing in a different direction. A measurement that someone of us took today still shows at least a BridgeTap in the apartment/house. But if you can rule out with 120% certainty that after the terminals in the apartment the line does not continue to the socket of the DSL cable, then we have to look further. Please check there first to make sure everything is OK. Please give some quick feedback, thank you.

      The noise margin increases when we measure too many disturbances. The increase automatically reduces the speed and the line becomes less susceptible to faults. But the speed in the DS is still above that of your subscription.

      @All: just a few more facts:

      • g.Fast is from 19.6-106MHz. With Huawei network elements, two ports per customer would be needed for 212 MHz.
      • The DSLAM cannot adjust the noise margin itself (actually it can, but only temporarily and dynamically on a small scale). Here it is our background systems that measure the disruptions and set the new margins above certain threshold values.
      • Amateur radio operators mainly use the VDSL2 range (2.2-17MHz). The equipment is also quite expensive. If the DSL signal over an overhead line interferes, then we have to “notch” certain areas, but not the other way around. The radio operators must adhere to the distances, installation locations and lengths of their antennas to the lines and the transmission power.
      • For CB radio operators who use 40W (I don’t mean allowed, but common), you can easily identify the disruptors by their harmonics. Fortunately, this is not a niche that is not growing and we rarely have problems there.

      Best regards

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      Roger G.
      Swisscom (Schweiz) AG, Product Manager Wireline Access

      • foobar has responded to this post.

        Roger G wrote:

        @Heinekentom: The antenna has to go, or at least on the roof. We don’t know what power it uses to transmit, but placing the antenna between the houses is a no-go.


        With the 4W, he can place his antenna wherever he wants, as long as it doesn’t violate building regulations or the rental agreement. He has little to fear from NISV (the safety distance is a few cm).

        • Amateur radio operators mainly use the VDSL2 range (2.2-17MHz).

        This has been the case in recent years because of the sunspot minimum; As solar activity increases, the higher frequencies become usable again. In the coming years, activity on the 21-52 MHz frequencies will increase significantly.

        ises-solar-cycle-sunspot.png

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        • hed likes that.

        @Roger G

        Thank you very much for your answers.

        I’m going to check the house plumbing tonight to see if I can find the Bridge Tap. As far as I can vaguely remember, a cable runs from the DSL socket in one apartment to another room. But nothing is connected there.

        About the antenna, I will ask my neighbor about it at the weekend when he is at home.

        Greetings Tom

        @All

        Thanks for your answers

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        @Heinekentom

        It doesn’t necessarily have to be connected to an outgoing line, as the line itself can cause interference.

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        Installationen, Netzwerk, Internet, Computertechnik, OS Windows, Apple und Linux.


        @WalterB wrote:

        @Heinekentom

        It doesn’t necessarily have to be connected to an outgoing line, as the line itself can cause interference.


        That’s right, because such lines create reflections that have a strong influence on the original signal. This depends on the length, which then determines the frequency where the disturbance occurs. With the switch from analog to digital (All-IP), it became necessary for only one line to lead to the router without a branch. Unfortunately, this was rarely cleaned and we still come across locations like this every day.

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        Roger G.
        Swisscom (Schweiz) AG, Product Manager Wireline Access

        @Heinekentom

        Here are the conditions for the line between UP (transfer point) and IB:

        Direct point-point connection with cable U72m WITHOUT sub-clamps, parallel boxes, branches, bridge taps, filters, splitters, terminating resistors.

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