Temperature Spikes and Spike Removal

[Tau Bootis]

Yes I was slightly uncomfortable in using the word ‘spikes’ that’s why I also used the word interference, the thing that’s bugging me is that it was perfect before I started messing with it.
I think I will get up there tomorrow and unclip the cable from the mast to see what happens. I just ordered some RJ11 plugs but I won’t see them until next weekend.
Here is a trend showing the point in time when the interference started.

[mcrossley]

That looks like Cumulus has been restarted, the 'smooth' data being the 'sparse' values from the log files, and the 'noisy' data the live feed. http://wiki.sandaysoft.com/a/FAQ#My_gra ... _starts_up

[Tau Bootis]

That looks like Cumulus has been restarted, the 'smooth' data being the 'sparse' values from the log files, and the 'noisy' data the live feed.

The graph was taken from Select-A-Graph which only uses the log data... I think.

Its a bit too windy at the moment, so am holding off doing my test of unclipping the cable to rule out the interference question I am still convinced its a poor connection as things seem to be slowly improving over time, at first there was a change in temp every 48 seconds but now there can be a few minutes in between.

Just going back to Skyline,s question, yes it is possible to have one of these stations 'with extended cables' to operate without spiking, this station has two extentions, one home made one, from wind sensor down to a JB, and an 'off the shelf one' from the JB to the sender unit, also none of it is Cat5, just basic phone wire.

[ScottVan]

I ran CAT6 up to my antenna mast and terminated the two connections in an waterproof outdoor electrical box. I located my sender unit in a home made Stevenson-like box in the shady side of the house. The antennas are well grounded per generally accepted grounding schemes. Since the CAT6 has an extra pair I used those to connect directly to ground as well as add two torrids, up top and down by the sender.

Good results although it was a lot of tinkering.

Here's the thread. I've permanently mounted the sender unit now.

https://cumulus.hosiene.co.uk/viewtopic.php?f=16&t=6069

Just thought people might be interested in progress on this one.

I have now fitted aluminium shielded Cat5e cabling from the wind direction sensor all the way to the transmitter. I decided not to risk keeping the old cables so I removed them altogether and soldered the Cat5e directly into the direction sensor circuit board. At the transmitter end I fitted an RJ11 directly onto the Cat5e and plugged into the transmitter. The total run is about 6m.

I am disappointed to report this does not seem to have helped eliminate the outdoor temperature spikes. I am stuggling to claim even a marginal improvement and given the fact that the weather has fallen relatively calm since the New Year gales I think I'm heading up the wrong track but at least its eliminated the cable. What I have proved is that there is no such problem when the wind sensor is disconnected from the transmitter. So this implies that either there is a strong source of interference which only affects the wind section/cable or that the signals entering the transmitter affect the temperature data. Given that the transmitter only transmits a signal every 48s or so, presumably whatever causes this problem would have to coincide with the transmission time unless it related to the wind equipment. I'm guessing upon transmission a simple snapshot is taken of wind direction and speed as well as temperature. By overlaying the wind and temperature graphs you can also see that the temperature spikes sometimes, but not always coincide with high wind gusts.

So it remains a mystery but if I discover anything new I will let you know.

Skyline

[Skyline]

Well Mark if your station is working OK its good to hear there is at least a possibility that one day I can get rid of these spikes. I dont have extended cables anymore, no more than 2m max from the wind and rain sensors down to the transmitter, so its not that. I've checked all the connections moved the cables around, separated them and am still using Cat5e on the main wind connection down to the transmitter. I even tried a modified ADSL filter but it made the problem even worse.

To be honest I find it difficult to believe that this is being caused by poor connections or even external interference. The fact that the problem is 10 times worse when the wind blows and is only associated with the anemometer being connected rules out external interference sources for me. I cannot get the transmitter any closer to the logger or it may as well be mounted on my head, so its not that either. It has to be down to the additional signals that the cable is carrying or that the transmitter is receiving when the anemometer is connected. I dont know enough about electronics or the way the transmitter works to comment but my money is on this issue being down to the way the unit is designed and ultimately its capability. You usually get what you pay for and you might get lucky and you might not.

PS - my units history is not great. The first one I had had gave faulty pressure readings so the logger was exchanged by Maplin - twice. The first time they also replaced the transmitter because they thought that was faulty too. Then the rain gauge started reporting rainfall of around 5000 mm a day and after protracted discussion with Tech Support the rain gauge was replaced as well.

Skyline

[Tau Bootis]

Yes I think you are right there with what you say, its pot luck whether you get a good unit or not, you seem to have had more than your fair share of bad ones!
I too am no expert in this field but it does seem like there could be somethig up with the circuitry, have you opened up the sender unit yet to see if there is anything that looks out of place, dry joint, bad soldering etc.

[Skyline]

I have a snippet of information for everyone using fine offset stations like the WH1081 from Maplins and who are experiencing temperature spike issues.

I went via Maplin Tech Support on another issue and ended up being directly in touch with the Engineers who design these units at the manufacturers in China. I explained the problem regarding temperatures spikes and the relationship with the anemometer.

The Chinese Engineer wrote back and said they were aware of this issue and it is associated with the firmware design. They have a solution to the problem i.e. updated firmware and this is going to be fitted to new units. There is no solution for those already on the market.

I'm guessing it will be impossible to know if and when those new units get to the market and if they will get rebadged as a different model.

So knowing this might save you some time if you are trying to find the cause of this problem. I will keep my anemometer plugged in but in a fixed position so it cannot rotate. That way I get wind direction data and only lose the wind speed info. And NO spikes!

Skyline

[MickinMoulden]

The Chinese Engineer wrote back and said they were aware of this issue and it is associated with the firmware design. They have a solution to the problem i.e. updated firmware and this is going to be fitted to new units. There is no solution for those already on the market.

That's good, but I believe there is still an issue that happens that isn't related to firmware. I get spikes, but they do increase when the conections are bad, like when I get moisture in the conection from the wind instruments to the extension conector. And my normal spikes only happened after moving/extending the unit. I haven't tried extending the USB so the indoor unit is closer. May be one day.

[Tau Bootis]

OK I said I was going to replace the rj11 connector on the anemometer as its seen better days, so first I thought I would just unplug the wind sensor cable from the sender unit to observe a nice smooth temperature trend, guess what.. it made no difference.
The upshot of that was I haven't bothered replacing the plug; at the moment it is only bouncing by 0.1 C when the temperature is fairly level and is generally OK when rising or falling. If it starts to play up again in the future Ill put a new plug on.

Skyline that's interesting info, and a bit of a coup being able to contact the Chinese engineers and getting a sensible response