Noise measurement ethernet port
Contents
Isolation Spectrum analyzer
How well does a switch isolate between ports? After all, if a device emits a lot of noise, it can leak noise to other ports.
For this test, we inject white noise into the switch and see how well the switch manages to keep it away from other ports.
Again, we see big differences between the various models. Each model filters differently. The new Dlink 108 V4 filters much better than the old 108 V3. The Dlink 1100 is clearly based on the older 108. The Dlink 108V4 scores very well in this test.
The Netgear 108 and 108E differ from each other. The 108T is similar to the 108E. Both filter better than the regular 108. Netgear scores very well here with the 108E and 108T.
The Zyxel 1200-08 does not seem to filter very well. The 2200 does much better, we know from other / older surveys.
What we clearly see with all switches is that it is crucial to ground things properly: that significantly reduces the noise floor. We have also tested and heard this before: focus improves and there is more calmness in the soundstage and presentation.
Noise from LAN port – Picoscope
We also measured the noise from the lan port. This is done through a so-called CDN – Coupling / Decoupling Network. We capture the noise from the port and send it through a splitter for differential and common mode noise.
What is noticeable is that the Netgear measures the quietest. And then the GS108E version. The Dlink 108 V4 is close to that. That also comes from the previous measurement where we measure port isolation.
The power supply – as you can see – is crucial to the noise level. Both linear power supplies and filtered versions perform significantly better than standard adapters. We see this later also in the jitter measurement.
100 Mbit?
However, what is also noticeable is that the 100 Mbit ports show much more spikes / noise. Now this could be due to two things: the noise is just higher, or we are looking at data. Now it is true that the absolute noise floor is lower. But so there are also a lot of spikes. We are looking into this further.
Sir,
Thank you!
Sean
Sirs,
Trying to follow your D-Link advice but cannot distinguish DGS-108 Version 3 from 4.
D-link does not assist and email to D-Link not returned.
Mine also says on Box: 8 port Gigabit desktop switch. One light on each port.
On bottom says: H/W Ver.:E1.
Very much enjoy your testing!
Best!
Sean
Hi Sean. Version E1 is version 4. Version 3 is indicated as C6.
I’ve used an iFi SupaNova (included filter) power cable in the network box + an IEC C14 to Schucko female before the distributor for switches. This way all the equipment (router, switches, media converters) benefit from the power filtering.
For grounding the switches (better said, EMI/RFI draining) one can also use the ToughCable Connector Ground from Ubiquiti which can be plugged in one free Ethernet port. I prefer padding the interior of metal casing of the switch with copper adhesive foil and insert a drain copper wire or screw and then plug it (with a regular banana connector) to the special jack in the iFi / SilentPower AC iPurifier (that can be plugged in a free Schucko outlet).
a question: what kind of filters did you use?
It is a filter between the power supply and the switch.
the question was more related to brand and model
Can you elaborate bit more on this?
“What we clearly see with all switches is that it is crucial to ground things properly: that significantly reduces the noise floor. “
What else do you need to know? Grounding the switch – for example the casing – lowers noise.
There’s no ground connectors on normal switches so I o wondering how you go about this. Entreq for example have ground RJ45 connectors connected to ground boxes. But as I understand you you mean adding a cable to the chassis somewhere and connect to mains ground or?
The D-Link switch has a grounding screw on the case, for instance. Connect a wire from the case, with the D-Link from the screw, to the earth connection of an earthed plug and put that plug into an earthed socket. We tested it like that a few times, and it is clearly audible.
Only do so when you know what you are doing.