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[JamesK]

Hi All,
For the past 9 months my line has started showing significant dips in the SNRM DS. There seems to be no pattern to when it happens. The dips constantly last for approximately 5 minutes, and they seem to come in groups of 4/5 occurrences with a period of 35ish minutes between them. This is the only observable pattern I can see forming, but I can't relate to this to any external source that could be causing problems.

My DS SNRM is currently 7.6, and when a drop occurs it takes it down to between 3.5 and 4.5.  When I look at the SNRM/Band DS, I notice that D3 gets hit the hardest, D2 less so, and D1 even less - which is to be expected I suppose.

The BT line into the property is underground all the way from the cabinet. I'm using the master socket which is less than 2 metres from the line enters the property with no extensions and no phones connected. If i connect a handset to the socket there's no crackling or other background noises to be heard. The HG612 is connected via the shortest cable I have to the socket. There's then a long ethernet run from the HG612 to the router.

I've attached a few pics of my MDWS stats. Username is JamesK on MDWS.

Any advice or analysis of my line would be much appreciated.

Many Thanks...

[JamesK]

Attached pic of BT socket

[johnson]

This is the only observable pattern I can see forming, but I can't relate to this to any external source that could be causing problems.

Going to be pretty hard for people to do better then I guess .

I'm no expert and others might have much better suggestions, but I found using an AM radio tuned to 600KHz or so during intermittent noise bursts helped no end to find the source. Was a neighbours SMPS for a monitor, and walking up and down to the road with the radio in hand narrowed it down to either our house or theirs, after flipping the breakers in mine it meant their place could be the only source.

This may be useless advice as you say it affects the higher bands much more and that is definitely above an AM radios range, but its worth a go given how obvious the noise is you can be certain of when its happening.


Edit: Also could you share the SNR vs freq graphs for during and normal?

[JamesK]

I've attached the SNR/tone graph for normal. I can't supply one for during 'abnormal' because it seems to happen at random times. You'll see from the 2nd attachment that it happened from around 22:30 to 05:30. It's the same pattern, a 5 minute drop in SNRM, followed by a 40/50min gap. I'm just not sure what kind of device would operate on that time frequency, and cause that much interference. Something that operates for 5 minutes and then stops for 45 mins.

[NewtronStar]

My thoughts are going in the direction of a residential sewage pump, most homes are based on gravity were the sewage flows downhill to septic tank but if the premises is below septic tank level it needs a electric pump.

[johnson]

My thoughts are going in the direction of a residential sewage pump, most homes are based on gravity were the sewage flows downhill to septic tank but if the premises is below septic tank level it needs a electric pump.

You mean like for basements and such?

Do you have experience with these, do they run in these 5 minute bursts every hour or so? I would have though they would be linked to toilet usage and so show a very different type of pattern.

[JamesK]

The estate where I live is about 15/16 years old, and built on the site of the old Hatfield airport. The whole area is pretty flat, and has been built as an extension to the existing area called Hatfield Garden Village, which must be around 80/90 years old.
That’s not to say there isn’t sewage pumps, but I’ve not seen anything around the estate to suggest there are.


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[NewtronStar]

Are there any fridge freezers near the modem

[JamesK]

Yes, there’s a 5 year old fridge freezer about 7/8 metres away from the modem.


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[NewtronStar]

Again another shot in the dark to find were this REIN event lasting 5 mins comes from, I am sure you know there is a pump in the fridge freezer which switches on for X amount of minutes and then off again for a longer amount of X minutes.

So with some patience and a stopwatch see if it matches what you see in your graphs.

[JamesK]

That’s a really good point. I hadn’t even considered that.


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[Westie]

Another shot in the dark...
How close are you to the large chilled distribution depot near Hatfield Ave? Maybe they have a large number of refrigerated trailers parked overnight for loading, with the chiller units somehow cycled in unison??? 

[JamesK]

Another shot in the dark...
How close are you to the large chilled distribution depot near Hatfield Ave? Maybe they have a large number of refrigerated trailers parked overnight for loading, with the chiller units somehow cycled in unison??? 

I live at the opposite end of Campion Road to the Arla distribution depot, thankfully. Most of the estate are connected to a cabinet near there that’s never been fibre enabled. 4mbps ADSL for all of them.

The fridge freezer is probably more likely. We had smart meters installed last year during a mini heatwave. The fridge freezer happened to be doing a defrost cycle when the power was cut. An hour later when the power came back the freezer wasn’t happy. Essentially a load of ice partially melted and then refroze jamming the fan. While the unit was repaired, mainly by an engineer using a hairdryer and me fully defrosting it. However the motor wasn’t changed, melting the ice freed the fan. It is since that smart meter change that I’ve been having issues with the line. I wonder if the motor was damaged.


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