News items for tag weatherstation - Koos van den Hout

2013-12-27 (#) 3 years ago
When I get around to wardriving lately I use the wigle app for android, so I decided to repurpose the wardrive box as shednet computer. This will also mean I can stop using PLC network to link the shed computer to the rest of the network, replacing it with wifi. Using PLC offends the radio amateur in me and people at the radio club now ask me whether I dumped it already. So, time for different hardware which as a plus will also use less power.

I already built in a laptop harddisk in the wardrive box and removed the compact flash holding the wardriving box image (I'll save it so I can restart using the wardriving box if needed). The alix 1c can work nicely with an IDE laptop harddisk.
2.5 inch laptop harddisk in ritchie
The laptop harddisk built into the ritchie mini-itx case

The installation will probably be done with a recent debian jessie distribution.

Plans for the new shednet computer include an ntp server, but since the current gps unit (gpskit) seems to fail after running for a few days in the test setup that may have to wait.

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2012-08-23 (#) 4 years ago
I used the wardriving box at home after I noticed I hadn't used it at all in over two months. It hung after a while, not responding to network or keypresses but still reporting on ethernet link state changes. I thought the temperature might have something to do with it since the box does get a bit warm and it was in the direct sun.

So I loaded the internal sensor driver w83627hf which is mentioned in the voyage linux getting started page and had a check:
ritchie:/sys/devices/platform/w83627hf.656# cat temp?_input
72000
56500
51000
72 ⁰C seems a bit high, but other reports of measured temperatures list the same values, like this openbsd on the alix1c for www.stare.cz dmesg shows.

Later during the day with the wardriving box out of the direct sun it keeps running fine.

With the probable hardware for the weather station computer also being an alix1.d the ideas now include measuring and graphing of all available temperatures, if only to keep an eye on possible stability issues.

Update: 47 new wi-fi networks found without moving the wardrivebox 1 centimetre...

Update 2012-08-24: I wanted to bring the wardriving box on my bike but .. the carrier on the back is slightly broken from earlier wardriving, and there is no place to stick the gps to at the moment.

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2012-05-02 (#) 5 years ago
Another improvement to the homepage: the weather projects get a bit more attention, with the latest weathermap for the Netherlands and the current weather readings in the right-hand sidebar. This costs about 0.02 second so it may need some optimization. In the optimization process I could even make the weather data publicly available in some portable format.

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2012-04-30 (#) 5 years ago
I moved the weatherstation website to (I hope) better URLs so they will be easier to find.

http://weatherstation.idefix.net/: Weather station Utrecht Overvecht the Netherlands
http://weerstation.idefix.net/: Weerstation Utrecht Overvecht.

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2012-02-07 (#) 5 years ago
Het Weerstation Utrecht Overvecht heeft nu ook Nederlands geleerd. Voorlopig voor de waarnemingen en de webpagina, misschien in een later stadium ook voor de teksten rond de gegenereerde grafieken.

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2012-02-07 (#) 5 years ago
Low temperatures in the Netherlands: the Weather station Utrecht Overvecht is measuring temperatures below zero at the moment. Which all goes fine, the software deals with it nicely.

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2011-10-06 (#) 5 years ago
Updated the Weather station Utrecht Overvecht page to give the latest measurements. In the background it changed from an rrdcgi page to a perl page so I could easily add those measurements.

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2011-09-28 (#) 5 years ago
On Monday I got around to working on the weatherstation project again and I assembled the 'weather shed' I built and fixed it to the shed. It's painted white, it faces north, it is 1.5 meters above the ground level and it ventilates outside air. It's just not in a grassy field with lots of space in all directions, it's in our back yard.

The result: the Weather station Utrecht Overvecht now has 'real' numbers for the temperature and humidity (air pressure inside and outside the shed is the same). Comparing it to measurements inside the shed shows that there was quite some dampening of changes and a delay.

It's good to have something I've been working on for ages 'done'. It is partially done because I still need to develop the (low-power) computer for inside the shed.

Update: Pictures! Weatherstation set on Flickr by kvdhout.

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2011-05-05 (#) 6 years ago
In between fatherhood today I found some time to do adjustments on the barometric pressure sensor for the weather station project which had a notable difference with the two nearest weather stations. Simply by adjusting the offset until the readout was near to the current values for De Bilt from actuele waarnemingen KNMI. Which gets interesting because the KNMI website has a 15-30 minute delay. The current offset is somewhat less than 1 millibar/hectoPascal but the pressure was dropping today. Maybe I should try to get that last bit on a day with more constant air pressure. For now it is a good approach.

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2011-05-01 (#) 6 years ago
Just did an interesting adjustment: moved the solar sensor from the shade to the full sun. The readouts are interesting:
2011-05-01T14:02:00+0200 Solar 8.299400 mV
2011-05-01T14:04:00+0200 Solar 119.853104 mV
According to the w1retap documentation this means the sun power is 24.63 Watt/m^2 in the shade and 355.75 Watt/m^2 in the sun at the moment.
Update 2011-05-02: Mounting the solar sensor outside is a bit more 'interesting' as it has to look up at the sky (logically) but at the same time I want the other two sensors in that housing to be in the shade in the future 'weather hut'. I found a description of mounting a 1-wire hobby-board solar sensor which has a good suggestion. Downside is that I will need more space in our backyard for the 'weather experiments'.

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2011-05-01 (#) 6 years ago
Interesting bit with the pressure measurements at the moment. I now have two running sensors, the old one from the Conrad weather station and the new one from Hobby-Boards. The new one is calibrated for 2 meter above sea level which matches the height reported for our street and backyard at Actueel Hoogtebestand Nederland. And as a reference there is the measurement from De Bilt and Cabauw at the actuele waarnemeningen Nederland knmi. And there is a big disagreement between our shed and the officials. For today 12:00:
  • The 'old' sensor (Conrad) in the shed: 960 hPa
  • The 'new' sensor (Hobby-Boards) in the shed: 988.8 hPa
  • KNMI measurement De Bilt: 1012.8 hPa
  • KNMI measurement Cabauw: 1012.5 hPa
I've been mapping the difference between the old sensor and the measurement from De Bilt at the weather station page and it seems to be nearly constant. I first thought the age of the old sensor was showing. But with two sensors here showing about the same difference with official sensors I'm not sure what the cause is.

First thought after I finished typing: move the sensor outside. But that does not 'fix' the problem.
Update 2011-05-02: More thinking and reading made me wonder if 'above sea level' has different meanings between the US (where hobby-boards calculated the offset for me) and the Netherlands, but that doesn't seem to be the right way. If I try to follow the calculations at Air Pressure and Altitude above Sea Level - The Engineering Toolbox it seems I miss 19 meter height above sea level.

Difference: 21 hPa, using the formula above I can get the closest to that difference with a height of 19 meters in that formula:
101325 * (1 -2.25577*(19/10000))^5.25588
Runtime warning (func=(main), adr=42): non-zero scale in exponent
99172.15726627368573690675

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2011-04-30 (#) 6 years ago
The ordered weather sensors arrived so I want to test them using w1retap. Time for rounds of configure / fix missing stuff. The resulting logging will be to postgres / rrdtool but I want to test with filebased logging first just to make sure the sensors work.

The configure script of w1retap insists on libxml2-dev and I don't see an easy way to disable this test. On the planned low-power, running from ramdisk weather station computer I won't allow for unused libraries, but for now the easy solution is just installing that library. Even ./configure --without-applet --disable-xml or ./configure --without-applet --disable-xml2 or other variants show:
checking for xml2-config... no
configure: error: missing program 'xml2-config'; is 'libxml2' or
'libxml2-devel' installed?
Fixed by installing libxml2-dev. The next thing it insists on is pkg-config and gmodule-2.0. The gmodule library is needed for dynamic loading of modules. This comes from ubuntu package libglib2.0-dev. The last bit is libusb-dev. Now I can build the package. First everything needs to run as root, but I fixed that later with
# chmod 666 /dev/bus/usb/001/002
Later improvement will be to find an udev rule which does this automatically for device:
Bus 001 Device 002: ID 04fa:2490 Dallas Semiconductor DS1490F 2-in-1 Fob, 1-Wire adapter
With the humidity, temperature, solar sensor and the barometer I see:
# w1find DS2490-1
(1) 108FB1130208003E    18S20:high precision digital thermometer
(2) 26C1E0F1000000ED    2438:smart battery monitor
(3) 26BD60B50000002D    2438:smart battery monitor
(4) 81AF632F00000067    :Serial ID Button
With just the barometer:
# w1find DS2490-1
(1) 26BD60B50000002D    2438:smart battery monitor
(2) 81AF632F00000067    :Serial ID Button
The general config is by default in ~/.config/w1retap/rc, where I have:
init = w1file
log = w1file=/tmp/w1log
altitude = 2
device = DS2490-1
It took a bit of browsing in the documentation, but the first three sensors were easy to set up in ~/.config/w1retap/sensors:
# w1retap sensors
26BD60B50000002D:HB-BARO:Pressure:PRES:hPa::
108FB1130208003E:DS1820:Temperature:TEMP0:⁰C::
26C1E0F1000000ED:MS-TH:Humidity:HUMI:%::
And the results:
Pressure=986.59 hPa
Temperature=32.25 ⁰C
Humidity=29.06 %
udate=1304169061
date=2011-04-30T15:11:01+0200
It took a bit more to get the Solar sensor working. The DS2438 is used for both the humidity and the solar sensor according to the hobby-boards documentation for the Humidity / Temperature / Solar sensor. Browsing the samples suggests I should configure it as a DS2438 sensor with dual measurements, like
26C1E0F1000000ED:DS2438:Solar:Solar (Vsens):mV:VTMP:Temperature GHT2:⁰C::
And indeed I get a reading:
Solar=0.49 mV
VTMP=33.34 ⁰C
Switching the light in the shed back off makes the readout drop to 0, so I believe I am looking at the right value.

And now the logging works too, after waiting a bit:
2011-04-30T15:42:00+0200 Pressure 986.591492 hPa
2011-04-30T15:42:00+0200 Temperature 31.312500 ⁰C
2011-04-30T15:42:00+0200 Humidity 29.057188 %
2011-04-30T15:42:00+0200 Solar 0.000000 mV
2011-04-30T15:42:00+0200 VTMP 32.531250 ⁰C
2011-04-30T15:44:00+0200 Pressure 986.369263 hPa
2011-04-30T15:44:00+0200 Temperature 31.312500 ⁰C
2011-04-30T15:44:00+0200 Humidity 29.373028 %
2011-04-30T15:44:00+0200 Solar 0.000000 mV
2011-04-30T15:44:00+0200 VTMP 32.531250 ⁰C

Update 2011-05-01: Found the udev rule in the w1retap documentation:
root@metcalfe:/etc/udev/rules.d# cat 45-local-usb-special.rules 
#
SUBSYSTEMS=="usb", GOTO="usb_w1_start"
GOTO="usb_w1_end"
LABEL="usb_w1_start"
ATTRS{idVendor}=="04fa", ATTRS{idProduct}=="2490", GROUP="w1retap",
MODE="0666"
LABEL="usb_w1_end"

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2011-04-02 (#) 6 years ago
Project sundial, my project for a low-power weather-station / ntp server in the shed still lives. I have thought about the software setup and I think w1retap, developed for the Netley Marsh 1-wire weather station is an ideal candidate as it deals with the usb-1-wire interface without a hitch. But I want the project sundial 'computer' to be a minimal system and I want the data to be logged to the home server. So I checked whether w1retap can work in this setup. The simplest solution would be to use the postgres database on the server and install a postgres database on the client.

I can develop/debug this on the shednet computer and weather station. Time to whip out the plastic and order weather sensors at Hobby-boards. Ordered: USB 1-wire interface, barometer, thermometer and humidity sensor with needed powersupply and all with moisture-resistant coating.

The Netley Marsh weather station also has nice pictures how to house the outside weather sensors nicely. I'll use those as inspiration.
Update 2011-04-04: Order status: Processing...
Update 2011-04-07: Order status: Shipped...
Update 2011-04-28: Package received! It took a while.

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2011-03-31 (#) 6 years ago
I wanted to test the old gpskit gps receiver I originally bought for wardriving with the shednet computer. I had the gps antenna on the roof of the shed and the gps module inside and wanted to hook up the serial cable to the back of the PC.

One minor detail: the PC only has one serial port...
[   12.874582] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[   12.875353] 00:07: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
which is in use by the weather station in the shed. So.. back into the crate with old but usable computer hardware with the gpskit.

What is it with modern PCs and the shortage of serial ports (or complete lack of them). I want to test gps timekeeping over serial, so usb to serial is not usable (introduces jitter). Time to make sure the planned hardware for project sundial has enough 'real' serial ports.

And it has, the dmesg for an alix.1c mainboard from the wardriving box shows the right answer:
Serial: 8250/16550 driver $Revision: 1.90 $ 4 ports, IRQ sharing disabled
serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
00:07: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
00:08: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A

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2011-02-10 (#) 6 years ago
I've been mailing a few times with Varia store about parts I want to order for building project sundial, my weather station and ntp refclock. They are very good at helping me with the right case and configuration.

So one of these days I'll start ordering real hardware and this long running idea for a project may actually start to become real.

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2011-01-31 (#) 6 years ago
Found via quite other ways, but something to keep in mind when rebuilding the kernel for the wardriving box or building a kernel for the future weather station: Debian on Soekris lists some specific Linux kernel compile settings for Geode processors. Another powersaving option could always be a good idea for both. Although I plan to make the weather station also work as ntp server so any power saving which influences timing is a bad idea.

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2011-01-18 (#) 6 years ago
Searching for weather stations I ran into the wireless sensors on ISM frequencies again. Somehow manufacturers of these sensors seem to want to limit the customer to receiving the data on their equipment. For the well-known wireless sensors on 433 MHz this is 'fixed', nicely described in Sniffing Oregon Scientific Weather Sensor Data. RFXCOM sells receivers which decode a lot of the telemetry and home automation signals. The receiving of oregon scientific sensors is thanks to reverse engineering. The protocol is not properly documented, but I guess it was simple enough to decode.

I asked RFXCOM about the weather sensors on 868 MHz but the lack of documentation on the exact frequency, encoding, protocol I found matches their experience, so they don't offer hardware / software for receiving it. Too bad the makers of the weather stations do not open up their protocols so you can receive your weather station on something besides the display.

Anyway, time to fire up the scanner and see whether specific frequencies carry anything which sounds like data transmissions. Maybe some of our neighbours are sharing temperature and other sensors.
Update : Found some time for the scanner and listened while keeping an eye on my watch:
433.920 listed in some places as 'oregon scientific' frequency, 433.9250 on my scanner:

22:33:13 databurst
22:33:22 databurst
22:33:27 faint databurst
22:33:52 databurst
22:34:01 faint databurst
22:34:16 databurst
22:34:32 databurst
22:35:11 databurst

433.840 listed in some places, 433.8375 on my scanner:
22:36:07 faint databurst
22:36:59 faint databurst
Nothing (sofar..) on the 868 MHz frequencies. But the description "instant transmission" can also mean the weather station only sends out data when it has something to report such as a change in temperature or other measurement, and not constantly.
Given the around 40 second updates mentioned by Sean Dague I guess there are 2 or 3 'usable' sensors in the neighbourhood. With no warranty of them staying available. That means it is a bit much to invest 115 euros in for an RFXCOM receiver.

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2010-11-28 (#) 6 years ago
This morning it was 2⁰C out in the shed as measured by the weather station. The computer is still running ok, according to smartmontools the current disk temperature is 22⁰C so that is still reasonable.

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2010-11-23 (#) 6 years ago
Shednet with weatherstation
Shednet with weatherstation
In the recent days I have been running the shednet computer again, this time with the conrad weather station attached. This is mainly for finding out what the climate in the shed is to help decide on hardware choices and setup.

The climate (in the shed) is different from what I expected: humidity is (so far) within limits of what the current PC (a Dell optiplex GX270) can handle. I expected humidity to become a problem before temperature. Temperatures are at the moment dropping below 'operating range' and a couple of cold days are coming up here in the Netherlands.

You can view the results at the weather station page but remember this is in the shed. Real measurements done with (something resembling) meteorological standards will be later.

But these measurements have learned me a few things and helped with a few decisions for the project sundial weather station:

  • The humidity in the shed is not much of a problem.
  • The temperature might be, but if a really low-power PC in an IP66 housing can survive an outdoor climate, it should survive in the shed.
  • The conrad temperature sensor is not very precise in outdoor temperatures. So the 'outdoor' temperature / humidity will be measured using 1-wire sensors hooked up to the future weather station computer. The Netley Marsh 1 wire weather station has nice ideas and pictures how this can be done and a small 'sensor house' like the one they use would fit better in our back garden than a full-size Stevenson Screen (the official name of the white 'meteorological hut' which tries to shield thermometer and hygrometer from local influences).
The flickr picture is also some experimenting with the gimp.

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2010-08-02 (#) 6 years ago
I wanted to install an extra package on the wardriving box but found out that the choice of distribution: Debian etch is not available anymore, not even as 'oldstable'. A bit of searching finds that I need to look in the Debian distribution archives.

I'm not sure whether I'll keep using Debian versions for the wardrive-box. I want something nice and small and manageable, and the option for a custom kernel (no initrd, preferably no udev).

The interesting bit is that I built the wardriving box in January - February 2008 and it basically ran regularly since that time without software problems.

The extra package I wanted to try is lm_sensors, for the other project: Sundial. I was wondering how high/low the system temperature would get, and whether it would stay within the 0 - 50 ⁰C range. An IP55 rated case might be a good idea for use in the garden shed (which is semi-outdoors). The question is will the mainboard stay above 0 ⁰C when it is -15 ⁰C outside. I know from the wardriving box the Alix board generates some heat, but is it enough to keep itself warm.

The Alix.1c/1d have a temperature sensor, according to Getting started with voyage linux it should work with the w83627hf driver which indeed loads and gives a readout.

I came across the alix.1 series hardware while looking for something low-power for project sundial. Later calculations showed the 'powered by the sun or wind' part of that project would be too expensive compared to just using a plug.

Update: The archived etch works, but lm-sensors wants perl, which is not part of the stripped down debian on the wardrive box. For as far as I can see that is because there is one perl script included. Time to rebuild from source with that script removed.

Update 2010-08-03: Looking where you are going helps too: Voyage Linux is Debian-based but optimized for embedded apps. With debootstrap under Ubuntu or Debian I could set up a newer development environment for the wardrive box and test Voyage Linux.

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