Please read the posts in the Announcements section about the current status of Cumulus development now that I have retired

Please read this post before posting

Latest Cumulus release v1.9.4 (build 1099) - Nov 28 2014
Latest Cumulus MX release - v3.0.0 build 3043 Jan 20 2017. See this post for download

Lost Sensor Contact!!

Discussion specific to Fine Offset and similar rebadged weather stations
Charlie
Posts: 363
Joined: Thu Feb 04, 2010 12:22 pm
Weather Station: 1wire-Cumulus & Fine Offset
Operating System: Windows 7
Location: Whitehorse, Yukon Territory, Canada

Re: Lost Sensor Contact!!

Postby Charlie » Fri Apr 23, 2010 11:47 am

Great troubleshooting, Gina!
I extended my (already extended) cable by about 1.5 m (to about 10 m total) yesterday, and I am now seeing spikes. They are only about 0.5 to 1 degree so I may just live with them. At least I now know how to fix them if I choose to, thanks to your efforts.
Perhaps I should stop following your posts. I never seem to see the problems until you point them out! :lol:

Gina
Posts: 1885
Joined: Sat Feb 21, 2009 12:41 pm
Weather Station: Nothing working ATM - making one
Operating System: OS X, Linux Mint, Win7 & XP
Location: Devon UK

Re: Lost Sensor Contact!!

Postby Gina » Fri Apr 23, 2010 3:35 pm

Charlie wrote:Great troubleshooting, Gina!
Thank you :)
I extended my (already extended) cable by about 1.5 m (to about 10 m total) yesterday, and I am now seeing spikes. They are only about 0.5 to 1 degree so I may just live with them. At least I now know how to fix them if I choose to, thanks to your efforts.
Perhaps I should stop following your posts. I never seem to see the problems until you point them out! :lol:
If there's anything wrong you can be sure I'll find it :lol: I'm a "nit picker" :lol:
Gina

Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.

Gina
Posts: 1885
Joined: Sat Feb 21, 2009 12:41 pm
Weather Station: Nothing working ATM - making one
Operating System: OS X, Linux Mint, Win7 & XP
Location: Devon UK

Re: Lost Sensor Contact!!

Postby Gina » Fri Apr 23, 2010 4:53 pm

EvilV wrote:Conrgatulations Gina. You have certainly identified the cause and solved the problem. I see a tiny blip on your temperature graph at around 0830 this morning. Without the screened cable, I have little doubt that would have been another big spike.
Thank you :)
The next question is where is the interference coming from?

Can you record it any way? I'm wondering if your digital oscilloscope can preserve the spikes. If so, maybe you could make a directional antenna and gradually track it down by rotating the antenna over time and preserving the spike traces. If all else fails in the detection and recording business, you have a pretty effective ready made unit in your Fine Offset broadband interference detector. :)

Some kind of coupling transformer and a directional antenna fed into the socket of the F.O. wind input, and you'd be there, I think. The only hard part would be to work out how to make an effective directional antenna without having any idea what frequency you are dealing with. It is probably low frequency sparking or something, so research into the kind of antennas used for lightening detection might be useful. I once made a Direction Finding set up which worked very well, and it was just a high Q loop antenna with a variable capacitor in parallel with it. On the other hand, you can get a pretty good null with a ferrite rod antenna, so, you could wind a coil onto a ferrite rod, couple that into your detector / recorder (F.O.) and rotate the ferrite over time to identify the line that goes through the signal interference source. Unfortunately, it could be in either direction of the bearing you finally get, but nonetheless, it would give you an idea.

http://www.homingin.com/joemoell/80intro.html
I've been thinking about this. My hand-held scope won't run for for the several hours required to record the (rather infrequent) bursts of interference. A simple crystal set type of receiver would convert the rf bursts to something I could record. Either with an ADC or maybe even as audio. If it's sparking it will be wide band and anything will pick it up. Anyway a wide-band receiver should give an idea of what it is. I could record on the computer then look at the result. One thing I will say - my AWS is for measuring weather, not interference :lol:

I know a bit about RDF and may have a play with that later. It would be nice to know the what and where of the interference.
Gina

Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.

EvilV
Posts: 127
Joined: Wed Jan 27, 2010 11:28 am
Weather Station: Watson W-8261
Operating System: XP
Location: NE7 7QE Newcastle upon Tyne UK

Re: Lost Sensor Contact!!

Postby EvilV » Fri Apr 23, 2010 5:32 pm

If the amplitude of the interference is enough, I reckon a rotatable ferrite rod with a coil on it, fed into a simple transistor amplifier, might supply enough signal for you to record on the computer, though I have no idea where you would feed it in Gina. My mention of your PWS was simply because you already have ALL of the components for detecting and storing the pulses on there now, ready and working. Supply the signal from the ferrite rod antenna, rotate it a few degrees every twelve hours, keep a record of the times and bearings of the ends of the rods and then spot the nulls in lower amplitude pulses when they happen. Then you would know where the bearing of the interference source. My bet is some switching of a heavy current, or breakdowns on a power line insulator.

It would be interesting to finally solve the cause wouldn't it?

Gina
Posts: 1885
Joined: Sat Feb 21, 2009 12:41 pm
Weather Station: Nothing working ATM - making one
Operating System: OS X, Linux Mint, Win7 & XP
Location: Devon UK

Re: Lost Sensor Contact!!

Postby Gina » Fri Apr 23, 2010 8:30 pm

EvilV wrote:If the amplitude of the interference is enough, I reckon a rotatable ferrite rod with a coil on it, fed into a simple transistor amplifier, might supply enough signal for you to record on the computer, though I have no idea where you would feed it in Gina. My mention of your PWS was simply because you already have ALL of the components for detecting and storing the pulses on there now, ready and working. Supply the signal from the ferrite rod antenna, rotate it a few degrees every twelve hours, keep a record of the times and bearings of the ends of the rods and then spot the nulls in lower amplitude pulses when they happen. Then you would know where the bearing of the interference source. My bet is some switching of a heavy current, or breakdowns on a power line insulator.

It would be interesting to finally solve the cause wouldn't it?
It certainly would be interesting, I agree.

There are a couple of possibilities for feeding signals into the computer. I have a USB interface board with dual analogue to digital converters plus TTL digital inputs (also outputs). OR the detected signal could be fed into the line or microphone input. I think the latter would be quite adequate and would require a lower signal level.

Here is one idea for a wide-band receiver using components I already have. The 702 is an rf amplifiers (eg. uA702). The 741 is an audio/DC amplifier. The "long wire" aerial and coil could be replaced by either a ferrite rod aerial or a loop. I have both available as LW/MW radio aerials. I was thinking of a germanium point-contact diode for greater sensitivity.
Rx-1.png
You do not have the required permissions to view the files attached to this post.
Gina

Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.

Gina
Posts: 1885
Joined: Sat Feb 21, 2009 12:41 pm
Weather Station: Nothing working ATM - making one
Operating System: OS X, Linux Mint, Win7 & XP
Location: Devon UK

Re: Lost Sensor Contact!!

Postby Gina » Fri Apr 23, 2010 9:15 pm

EvilV wrote:I see a tiny blip on your temperature graph at around 0830 this morning. Without the screened cable, I have little doubt that would have been another big spike.
Yes, I agree. Another small spike has occurred around 1800 and now an even bigger (though still much smaller than before) spike at about 2050. This last spike has become of significant size IMO. Tomorrow I'll check that the screen connection is still intact and have a general check. I may then add the LC filters on the input lines though I am puzzled by this last spike.
24hrs-Temperature-only-k.png

To put things into perspective, I'm posting a 48 hour plot which includes the "standard" spikes when the screen was disconnected.
48hrs-Temperature.png
You do not have the required permissions to view the files attached to this post.
Last edited by Gina on Fri Apr 23, 2010 9:42 pm, edited 2 times in total.
Gina

Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.

EvilV
Posts: 127
Joined: Wed Jan 27, 2010 11:28 am
Weather Station: Watson W-8261
Operating System: XP
Location: NE7 7QE Newcastle upon Tyne UK

Re: Lost Sensor Contact!!

Postby EvilV » Fri Apr 23, 2010 9:32 pm

I'm sure that would work fine BUT don't forget you would have a lot of strong broadcast signals. The circuit would feed i the whole of the long wave and medium wave broadcast band signals, so I suspect you wouldn't want too much amplification. Of course whatever it is that is causing the interference is much stronger than that. You might need to put in some kind of attenuator, unless you just used the ferrite rod.

EDIT:

Sorry - you covered the use of just the ferrite rod antenna in your post.

Gina
Posts: 1885
Joined: Sat Feb 21, 2009 12:41 pm
Weather Station: Nothing working ATM - making one
Operating System: OS X, Linux Mint, Win7 & XP
Location: Devon UK

Re: Lost Sensor Contact!!

Postby Gina » Fri Apr 23, 2010 9:51 pm

EvilV wrote:I'm sure that would work fine BUT don't forget you would have a lot of strong broadcast signals. The circuit would feed i the whole of the long wave and medium wave broadcast band signals, so I suspect you wouldn't want too much amplification. Of course whatever it is that is causing the interference is much stronger than that. You might need to put in some kind of attenuator, unless you just used the ferrite rod.

EDIT:

Sorry - you covered the use of just the ferrite rod antenna in your post.
I had forgotten all the broadcast signals. Yes, I'll have to watch they don't overload the circuit. And yes, the interference must be pretty strong. Think I'll try without rf amplification first and I could cut out the audio amp if I use the microphone input.
RX-2.png

Now that's a lot simpler :lol: Add a variable C across the coil and we have the jolly old crystal set :)
You do not have the required permissions to view the files attached to this post.
Gina

Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.

EvilV
Posts: 127
Joined: Wed Jan 27, 2010 11:28 am
Weather Station: Watson W-8261
Operating System: XP
Location: NE7 7QE Newcastle upon Tyne UK

Re: Lost Sensor Contact!!

Postby EvilV » Sat Apr 24, 2010 8:27 am

Gina wrote:
EvilV wrote:I'm sure that would work fine BUT don't forget you would have a lot of strong broadcast signals. The circuit would feed i the whole of the long wave and medium wave broadcast band signals, so I suspect you wouldn't want too much amplification. Of course whatever it is that is causing the interference is much stronger than that. You might need to put in some kind of attenuator, unless you just used the ferrite rod.

EDIT:

Sorry - you covered the use of just the ferrite rod antenna in your post.
I had forgotten all the broadcast signals. Yes, I'll have to watch they don't overload the circuit. And yes, the interference must be pretty strong. Think I'll try without rf amplification first and I could cut out the audio amp if I use the microphone input.
RX-2.png

Now that's a lot simpler :lol: Add a variable C across the coil and we have the jolly old crystal set :)


Yes - that's what it is. I think it would also work if you just connected the coil across the mic input signal and ground. The diode in the crystal set is there to demodulate the audio signal on the Amplitude Modulated RF signal to produce a varying dc voltage that represents the audio signal. If you think of the long signal cable of your FO PWS as the coil in your circuit above, it is quite clear that the PWS didn't need any additional components to pick up the interference pulse and register its amplitude.

I'd still be using the old weather station to do this job :) but you are obviously a purist engineer, whilst I am back yard bodger....... :twisted:

Gina
Posts: 1885
Joined: Sat Feb 21, 2009 12:41 pm
Weather Station: Nothing working ATM - making one
Operating System: OS X, Linux Mint, Win7 & XP
Location: Devon UK

Re: Lost Sensor Contact!!

Postby Gina » Sat Apr 24, 2010 9:07 am

Now that I can actually see where the spikes occur, I can use the WS to show that info while I record the actual interference bursts separately. It'll show where to look time-wise in the recording. With that in mind I'll leave the WS as it is for now.
Gina

Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.

Gina
Posts: 1885
Joined: Sat Feb 21, 2009 12:41 pm
Weather Station: Nothing working ATM - making one
Operating System: OS X, Linux Mint, Win7 & XP
Location: Devon UK

Re: Lost Sensor Contact!!

Postby Gina » Sat Apr 24, 2010 11:59 am

Rx circuit built. Aerial is the cable that goes out of the house from the eaves and across to a post, down along the fence and was originally used to connect the fan. The audio is fed into the front mic input on my HP P4 machine and I'm using Audacity to record the signal. There is certainly plenty of it and the input gain is set quite low. It is currently picking up the pulses from the electric fence plus other noises. The fence pulses are not sufficient to cause trouble with the WS.

Choke is 1mH, diode OA47, load resistor 330K. The audio cable provides the capacitance.

Currently recording and listening on my PC speakers. Now waiting for interference sufficient to cause a spike in the temperature plot...
Gina

Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.

EvilV
Posts: 127
Joined: Wed Jan 27, 2010 11:28 am
Weather Station: Watson W-8261
Operating System: XP
Location: NE7 7QE Newcastle upon Tyne UK

Re: Lost Sensor Contact!!

Postby EvilV » Sat Apr 24, 2010 5:49 pm

But if you don't use a directional ferrite rod antenna, how will you be able to work out where it is coming from? Maybe I've misunderstood, and you are just proving the receiving system first.

I thought you would be gradually rotating a ferrite antenna, say 15 degrees every 24 hours and keeping a record of the bearing along the ferrite. That way, you would be able to see when the real nulls were happening and could correlate them with the rod positions. The signal will have a significant drop when the ends of the rod are pointing at the source as opposed to the side on position, and you should be able to pick that up on your data record. The side on will show higher signal strength, but you will get a much sharper null on the ends.

I expect about 60 turns of something around 28 swg wire on a decent ferrite rod (about 4" long would be a good size) will give good coverage of low frequency bands. It is almost certain to be pretty low I think, because it is likely to be sparking of some sort.

Gina
Posts: 1885
Joined: Sat Feb 21, 2009 12:41 pm
Weather Station: Nothing working ATM - making one
Operating System: OS X, Linux Mint, Win7 & XP
Location: Devon UK

Re: Lost Sensor Contact!!

Postby Gina » Sat Apr 24, 2010 6:24 pm

EvilV wrote:But if you don't use a directional ferrite rod antenna, how will you be able to work out where it is coming from? Maybe I've misunderstood, and you are just proving the receiving system first.
Yes, I'm just testing out the rx and recording setup.
I thought you would be gradually rotating a ferrite antenna, say 15 degrees every 24 hours and keeping a record of the bearing along the ferrite. That way, you would be able to see when the real nulls were happening and could correlate them with the rod positions. The signal will have a significant drop when the ends of the rod are pointing at the source as opposed to the side on position, and you should be able to pick that up on your data record. The side on will show higher signal strength, but you will get a much sharper null on the ends.

I expect about 60 turns of something around 28 swg wire on a decent ferrite rod (about 4" long would be a good size) will give good coverage of low frequency bands. It is almost certain to be pretty low I think, because it is likely to be sparking of some sort.
Yes, I'll do that next. I had a ferrite rod with coils already on it but I dropped it (only on the lawn) and it broke into 3 pieces :oops: I don't think that's the only one I've got - I'll have to have a hunt :lol: As I recall, if a ferrite rod gets broken it's no good fixing it back together again.

Depending on what I can find, I could have two ferrite rod aerials at right angles with 2 diodes and resistors and feed one into each stereo channel - two reading at a time that way.
Gina

Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.

EvilV
Posts: 127
Joined: Wed Jan 27, 2010 11:28 am
Weather Station: Watson W-8261
Operating System: XP
Location: NE7 7QE Newcastle upon Tyne UK

Re: Lost Sensor Contact!!

Postby EvilV » Sat Apr 24, 2010 7:00 pm

Ohhh - sophisticated trick that.


:bash:

Gina
Posts: 1885
Joined: Sat Feb 21, 2009 12:41 pm
Weather Station: Nothing working ATM - making one
Operating System: OS X, Linux Mint, Win7 & XP
Location: Devon UK

Re: Lost Sensor Contact!!

Postby Gina » Sat Apr 24, 2010 10:07 pm

I'm having a problem with Audacity - keeps stopping. Will investigate further tomorrow. Meanwhile, I'm using sound recorder and keeping fingers crossed.
Gina

Sorry, no banner - weather station out of action. Hoping to be up and running with a new home-made one soon.


Return to “Fine Offset/EasyWeather”

Who is online

Users browsing this forum: Bing [Bot] and 4 guests