Receptors' range is too small for a weather station
in [Basics]
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From: Merciadri Luca on 15 Apr 2010 06:21 Hi, I have a small greenhouse which is mostly constituted by plastic. I also have a small weather station BLUESKY BWS688, with two receptors. The manual stipulates that the working range of the receptors is ~30 meters, but I rather think that it is ~3 meters: my greenhouse is at ~5 meters, and its signal is not received. As my greenhouse is not surrounded by some metal stuff, I would be very surprised to learn that the Faraday effect would take place into it. Consequently, the receptor's range seems too weak. What could I do to solve this problem? Would it be possible to hack some antenna or some conductor, say on one or two meters? Would it work better? I have exchanged my two receptors, and they all work properly. Once a length ~4 meters separates the principal station and one of the receptors, the receptor's signal is not received anymore. Thanks.
From: Rich Webb on 15 Apr 2010 08:10 On Thu, 15 Apr 2010 03:21:19 -0700 (PDT), Merciadri Luca <merciadriluca(a)gmail.com> wrote: >Hi, > >I have a small greenhouse which is mostly constituted by plastic. I >also have a small weather station BLUESKY BWS688, with two receptors. >The manual stipulates that the working range of the receptors is ~30 >meters, but I rather think that it is ~3 meters: my greenhouse is at >~5 meters, and its signal is not received. As my greenhouse is not >surrounded by some metal stuff, I would be very surprised to learn >that the Faraday effect would take place into it. I'm not familiar with the construction of modern greenhouses, but it may be that the transparent windows contain some metalization in order to optimize the transmissive and reflective properties. Have you tried the performance of the transmitter/receiver pairs when they are both outside of the greenhouse? >Consequently, the receptor's range seems too weak. What could I do to >solve this problem? Would it be possible to hack some antenna or some >conductor, say on one or two meters? Would it work better? I have >exchanged my two receptors, and they all work properly. Once a length >~4 meters separates the principal station and one of the receptors, >the receptor's signal is not received anymore. The simplest way may be to boost the antenna gain. The simplest way to do that is probably by adding a directional reflector "behind" each receiving antenna (and the transmitter, if the receivers can be situated in the main lobe). Here's one site that discusses a quick and cheap home-made version: http://www.freeantennas.com/projects/template/ -- Rich Webb Norfolk, VA
From: Merciadri Luca on 15 Apr 2010 09:27 On Apr 15, 2:10 pm, Rich Webb <bbew...(a)mapson.nozirev.ten> wrote: > > I'm not familiar with the construction of modern greenhouses, but it may > be that the transparent windows contain some metalization in order to > optimize the transmissive and reflective properties. This is simple plastic, not some kind of glasses, etc.! I am doubtful about the fact that they could contain some metalization, as they are purely transparent. > Have you tried the performance of the transmitter/receiver pairs when > they are both outside of the greenhouse? Yes, and it does not change anything, i.e. the greenhouse seems not to affect the transmitter. But two meters nearer the weather station, everything is fine. > The simplest way may be to boost the antenna gain. The simplest way to > do that is probably by adding a directional reflector "behind" each > receiving antenna (and the transmitter, if the receivers can be situated > in the main lobe). > > Here's one site that discusses a quick and cheap home-made version:http://www.freeantennas.com/projects/template/ Thanks for the pointer. I would come with http://www.freeantennas.com/projects/Ez-10/pic2.JPG, but the problem is that my two small receivers (which compute the temperature around them) have no `outgoing' antenna, and I thus do not know if the antenna is at their top, their bottom, `behind' or `in front' of them. And if I put some metal around the whole receiver, the Faraday effect will annihilate all our chances!
From: Tim Wescott on 15 Apr 2010 09:59 Merciadri Luca wrote: > On Apr 15, 2:10 pm, Rich Webb <bbew...(a)mapson.nozirev.ten> wrote: >> I'm not familiar with the construction of modern greenhouses, but it may >> be that the transparent windows contain some metalization in order to >> optimize the transmissive and reflective properties. > This is simple plastic, not some kind of glasses, etc.! I am doubtful > about the fact that they could contain some metalization, as they are > purely transparent. > >> Have you tried the performance of the transmitter/receiver pairs when >> they are both outside of the greenhouse? > Yes, and it does not change anything, i.e. the greenhouse seems not to > affect the transmitter. But two meters nearer the weather station, > everything is fine. > >> The simplest way may be to boost the antenna gain. The simplest way to >> do that is probably by adding a directional reflector "behind" each >> receiving antenna (and the transmitter, if the receivers can be situated >> in the main lobe). >> >> Here's one site that discusses a quick and cheap home-made version:http://www.freeantennas.com/projects/template/ > Thanks for the pointer. I would come with http://www.freeantennas.com/projects/Ez-10/pic2.JPG, > but the problem is that my two small receivers (which compute the > temperature around them) have no `outgoing' antenna, and I thus do not > know if the antenna is at their top, their bottom, `behind' or `in > front' of them. And if I put some metal around the whole receiver, the > Faraday effect will annihilate all our chances! Make a parabolic reflector (it doesn't have to be executed very well -- tin foil and cardboard would do), with the whole unit at the focus, pointed at the base station. See if it works. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
From: ehsjr on 15 Apr 2010 12:51
Merciadri Luca wrote: > On Apr 15, 2:10 pm, Rich Webb <bbew...(a)mapson.nozirev.ten> wrote: > >>I'm not familiar with the construction of modern greenhouses, but it may >>be that the transparent windows contain some metalization in order to >>optimize the transmissive and reflective properties. > > This is simple plastic, not some kind of glasses, etc.! I am doubtful > about the fact that they could contain some metalization, as they are > purely transparent. > > >>Have you tried the performance of the transmitter/receiver pairs when >>they are both outside of the greenhouse? > > Yes, and it does not change anything, i.e. the greenhouse seems not to > affect the transmitter. But two meters nearer the weather station, > everything is fine. > > >>The simplest way may be to boost the antenna gain. The simplest way to >>do that is probably by adding a directional reflector "behind" each >>receiving antenna (and the transmitter, if the receivers can be situated >>in the main lobe). >> >>Here's one site that discusses a quick and cheap home-made version:http://www.freeantennas.com/projects/template/ > > Thanks for the pointer. I would come with http://www.freeantennas.com/projects/Ez-10/pic2.JPG, > but the problem is that my two small receivers (which compute the > temperature around them) have no `outgoing' antenna, and I thus do not > know if the antenna is at their top, their bottom, `behind' or `in > front' of them. And if I put some metal around the whole receiver, the > Faraday effect will annihilate all our chances! | | Reflector=>| Sensor Station |<=Reflector | | The antenna is inside the remote temperature sensor. It does not matter where the antenna is inside the sensor, but make sure that both the sensor and the station stand upright, and have new batteries. BTW what you are calling a "receiver" is actually a transmitter. It detects the temperature around itself, and transmits that information to your weather station display. I have 2 different brands of wireless thermometers. With both brands, laying the devices horizontal affects the range. Height above ground may play a role, depending on environment. Also, it is possible there is another source of RF signal nearby that is de-sensing the receiver inside the display station. Ed |