Interference identification?

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13dka
Posts: 136
Joined: Sun Feb 14, 2016 8:40 am

Re: Interference identification?

Postby 13dka » Tue Mar 21, 2017 12:09 pm

I always thought that VHF/UHF will be a last resort to enjoy the hobby if things go really bad on shortwave. Of course I was wrong. Until now, analog cable "only" caused interference on single channels, like these nice TV FM audio carriers in the 2m band coming from my neighbor's extremely crappy cable installation:

Cable_Interference.jpg
Cable_Interference.jpg (222.9 KiB) Viewed 1930 times


But analog cable TV is about to be turned off here, and the frequencies will be re-used for 7MHz wide DVB-C signals. It doesn't stop there, the cable companies want to implement a new internet technology (DOCSIS 3.1.) nation-wide on the cable nets until 2018, for frequencies up to 204MHz. If you consider the enormous level of this interference, this will be more or less the end of VHF reception in this neighborhood. My neighbor is almost 80 years old and will not be able to pay thousands of Eurobucks to repair his cable installation, or to sue the company that installed it some 30 years ago.

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DanubeBCL
Posts: 180
Joined: Sat Jul 02, 2016 12:39 pm

Re: Interference identification?

Postby DanubeBCL » Tue Mar 21, 2017 1:04 pm

For unwanted emissions from cable TV there are tight noise limits in Germany (likewise for FM transmitters for mp3 players or similar, opposite to PLC where the regulations are very loose). When informing the authorities there is more chance to stop such RFI than stopping PLC. This is what the staff members of the spectrum supervisor also told me.
But I know: Who wants to blame an 80 year old neighbour and force him to repair his cable including paying a fine?

73, Heinrich

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PG3
Posts: 29
Joined: Mon Nov 14, 2016 6:04 am

Re: Interference identification?

Postby PG3 » Fri Mar 31, 2017 7:55 am


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DanubeBCL
Posts: 180
Joined: Sat Jul 02, 2016 12:39 pm

Re: Interference identification?

Postby DanubeBCL » Fri Mar 31, 2017 8:17 am

PG3 wrote:Interesting read on the subject...
http://www.homegridforum.org/uploads/re ... A/4oMq.pdf

Yes, the members of the PLC interests group have noticed in the meantime that many PLC devices in a building interfere with each other: PLC networking with LAN or WLAN extenders, "smart home" grids, distribution of video streams from rooftop satellite TV headers, "smart" power meters, all this is done by PLC technology nowadays.
That they are interfering our shortwave reception is not so important. Important is that their technology fails in such houses. Now they are offering PLC filters to be added to the electric installation for separating rooms or apartments from each other. These "filters" of course do not clean our shortwave reception, they just confine the various PLC signals in the houses to certain rooms or apartments. The noise still is transmitted from the power lines. Maybe in certain cases such filters could reduce the noise in our receivers by a few dB. But nobody can force a neighbour to build in such a filter when not necessary from his point of view.
A complete nonsense technology ...

73, Heinrich

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PG3
Posts: 29
Joined: Mon Nov 14, 2016 6:04 am

Re: Interference identification?

Postby PG3 » Wed Apr 12, 2017 2:16 pm

FCC caught with their pants down on the issue...
https://smartmeterharm.org/2016/04/23/f ... on-limits/

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DanubeBCL
Posts: 180
Joined: Sat Jul 02, 2016 12:39 pm

Re: Interference identification?

Postby DanubeBCL » Wed Apr 12, 2017 3:51 pm

After reading this interesting web page I could not believe the sentence "The FCC limits are much higher than those in Europe and Japan." In Europe PLCs are allowed to put 105 dBµV onto the power line. I thought this huge limit could not be topped.
The electric field strength measured at 3 m distance does not play a role any more since the European regulations have superseded the former local regulations (which were more strict). After the new law about electromagnetic compliance has been passed last September in Germany the authorities even no longer measure the PLC voltage on the power lines. They (and the lawmakers) have capitulated to the lobby. But the authorities also did not do much before this deadline.

73, Heinrich

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g1hbe
Posts: 242
Joined: Sat Jan 17, 2015 3:28 pm
Location: Cheshire

Re: Interference identification?

Postby g1hbe » Wed Apr 12, 2017 6:40 pm

PG3 wrote:FCC caught with their pants down on the issue...
https://smartmeterharm.org/2016/04/23/f ... on-limits/


That's appalling, but any knowledgable SWL or Ham could have told these 'experts' that if you apply a significant amount of RF to a piece of wire it will travel along it and radiate from it. Sadly, there is no way back. PLT is here to stay, along with Chinese SMPU's, cheapjack LED lights and supermarket TV's.

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Andy

DanubeBCL
Posts: 180
Joined: Sat Jul 02, 2016 12:39 pm

Re: Interference identification?

Postby DanubeBCL » Thu Apr 13, 2017 7:00 am

g1hbe wrote:That's appalling, but any knowledgable SWL or Ham could have told these 'experts' that if you apply a significant amount of RF to a piece of wire it will travel along it and radiate from it.
The website of the well known German manufacturer of Fritzbox says, PLC does not interfere with radio reception at all. Some sentences down the text they say, to avoid radio interference they have notched the ham radio bands. They could not have expressed this more dumb.
g1hbe wrote:Sadly, there is no way back. PLT is here to stay, along with Chinese SMPU's, cheapjack LED lights and supermarket TV's.
This is the sad truth. And it will not only stay, it will become more and more.
73, Heinrich

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