Hall effect sensor for wind vane, or ultrasonic sensors
Posted: Fri 23 Dec 2011 10:05 pm
OK, here we go. I have an (Maplin) FO 1080 station that's been on the roof for a couple of years, and it recently stopped recording rain, which is the main reason I need the station, as it's my early warning of the danger of flooding. I've also been casting roung the threads here recently, and come across several areas that have been thought provoking,
The thing that got me going on this is that I've had to take the external devices off the pole on the chimney to fix the rain recorder, and when I did eventually get it down to investigate, it wasn't spiders, which was the main suspect, but the reed switch had failed. It's been up there for a couple of years unattended, I don't use batteries in the unit, it's powered by a battery backed regulated PSU at ground level, the batteries are there to provide cover for power outages, so that I don't lose the signal if there's a cut.
As part of the whole exercise, I'm putting up a higher pole to get the wind sensors out of the turbulence that's thrown up by the dormer roof. We're not in a good location from that aspect, there's a lot close to us that messes the wind flow up, so a higher pole will help. Anyway, I've also been looking at the wind vane, it had a fin on it made from corrie board, the plastic cardboard that Estate Agents use for house sale signs, and it lasted quite well, until the wet got behind the duck tape holding it to the fin, so that's getting an upgrade as well,
The rain measure is also sheathed in some more of the same "cardboard", to prevent spiders from getting in to it, and to stop strong winds from getting into the holes at the bottom and triggering false rain detects, and so far, it's worked well.
The main transmitter is shrouded, a simple shield, a piece of 4" plastic drainpipe, covered with White Vinyl to help reflect the heat, and it too seems to work well, and has the advantage of being real cheap to do.
So, while I'm doing all this, Im also adding a second base station so that I can capture all the readings to a PC and still have an immediate view station in a location where a USB connect is not viable, ( Maplin have the stations real cheap at the moment, and this way, I get a full set of spare sensors) so a second base in the office connected to a permanently live PC is a much easier solution
In among all the fiddling, the pole is going up an additional 6 Metres, I got to thinking about and reading some of the threads here, and that triggered some Google searches, mainly looking at the areas we have problems with on the FO stations
I have seen 2 possible options for the wind vane, the first is a small potentiometer that's not mechanical, and can cope with continuous rotation, gives a variable output based on input voltage, the other, which is even more appealing, is a solid state device that can recognise the rotational position of a magnet above it, and does not require a "home" position device to work out where it is. The other option that was interesting, but horribly expensive in the commercial form is a device that's using 3 or 4 ultrasonic sensors to measure both wind speed and direction in the one device, and there are no moving parts with it, which has to be attractive.
For our purposes, the factors to consider are accuracy, cost and reliability. At present, I don't know what resolution we're looking for in terms of direction and speed, but I would reckon that the devices I've been looking at will more than meet the requirements.
The devices I'm looking at here won't work with the FO station, but with the hardware that's available now, that's not an issue, licence free TX & RX devices that would be suitable for weather stations are disgustingly cheap now, and available from many sources, so that side of the station is not an issue, and Arduino micro processors to collect the raw data and forward it to a central receiver are also not going to be an issue. I am also active in a Radio model forum, and there are some very interesting things happening in that market place, and some of that hardware would be ideal for weather stations as well.
With me so far? Good,
Now, the questions. Has anyone else thought of going down this road, or even making an interface that could connect some or all of these devices to the existing FO station that we're using.
If we were to start looking at a home brew station, ( This bit's for Steve), what format would the captured data need to be in to make it viable to interface to Cumulus. If we went that route, the absence of a dedicated display station may not be an issue, in that the Cumulus display covers the items that need reporting, and something like a tablet, or even an App capable phone type device might be suitable. The other option is an old, cheap PC that could be used as the capture and recording station. A Netbook would also work,
So, am I barking up the wrong tree, or reinventing the wheel?
Cheers
Steve
The thing that got me going on this is that I've had to take the external devices off the pole on the chimney to fix the rain recorder, and when I did eventually get it down to investigate, it wasn't spiders, which was the main suspect, but the reed switch had failed. It's been up there for a couple of years unattended, I don't use batteries in the unit, it's powered by a battery backed regulated PSU at ground level, the batteries are there to provide cover for power outages, so that I don't lose the signal if there's a cut.
As part of the whole exercise, I'm putting up a higher pole to get the wind sensors out of the turbulence that's thrown up by the dormer roof. We're not in a good location from that aspect, there's a lot close to us that messes the wind flow up, so a higher pole will help. Anyway, I've also been looking at the wind vane, it had a fin on it made from corrie board, the plastic cardboard that Estate Agents use for house sale signs, and it lasted quite well, until the wet got behind the duck tape holding it to the fin, so that's getting an upgrade as well,
The rain measure is also sheathed in some more of the same "cardboard", to prevent spiders from getting in to it, and to stop strong winds from getting into the holes at the bottom and triggering false rain detects, and so far, it's worked well.
The main transmitter is shrouded, a simple shield, a piece of 4" plastic drainpipe, covered with White Vinyl to help reflect the heat, and it too seems to work well, and has the advantage of being real cheap to do.
So, while I'm doing all this, Im also adding a second base station so that I can capture all the readings to a PC and still have an immediate view station in a location where a USB connect is not viable, ( Maplin have the stations real cheap at the moment, and this way, I get a full set of spare sensors) so a second base in the office connected to a permanently live PC is a much easier solution
In among all the fiddling, the pole is going up an additional 6 Metres, I got to thinking about and reading some of the threads here, and that triggered some Google searches, mainly looking at the areas we have problems with on the FO stations
I have seen 2 possible options for the wind vane, the first is a small potentiometer that's not mechanical, and can cope with continuous rotation, gives a variable output based on input voltage, the other, which is even more appealing, is a solid state device that can recognise the rotational position of a magnet above it, and does not require a "home" position device to work out where it is. The other option that was interesting, but horribly expensive in the commercial form is a device that's using 3 or 4 ultrasonic sensors to measure both wind speed and direction in the one device, and there are no moving parts with it, which has to be attractive.
For our purposes, the factors to consider are accuracy, cost and reliability. At present, I don't know what resolution we're looking for in terms of direction and speed, but I would reckon that the devices I've been looking at will more than meet the requirements.
The devices I'm looking at here won't work with the FO station, but with the hardware that's available now, that's not an issue, licence free TX & RX devices that would be suitable for weather stations are disgustingly cheap now, and available from many sources, so that side of the station is not an issue, and Arduino micro processors to collect the raw data and forward it to a central receiver are also not going to be an issue. I am also active in a Radio model forum, and there are some very interesting things happening in that market place, and some of that hardware would be ideal for weather stations as well.
With me so far? Good,
Now, the questions. Has anyone else thought of going down this road, or even making an interface that could connect some or all of these devices to the existing FO station that we're using.
If we were to start looking at a home brew station, ( This bit's for Steve), what format would the captured data need to be in to make it viable to interface to Cumulus. If we went that route, the absence of a dedicated display station may not be an issue, in that the Cumulus display covers the items that need reporting, and something like a tablet, or even an App capable phone type device might be suitable. The other option is an old, cheap PC that could be used as the capture and recording station. A Netbook would also work,
So, am I barking up the wrong tree, or reinventing the wheel?
Cheers
Steve