The Oxbow Weather Station
The what about:
Playing golf is very reliable on the weather conditions.
No question that golfers like to know how wet they possibly could get.
As part of the website for the Labelle Oxbow Golf club which is maintained by Southern DataStream it was a project to set up a Weather Station on the property of the Oxbow Golf club and display the actual weather conditions on their web page.
Weather Data is collected by sensors,
electronically measured, transformed, stored and finally transmitted by radio to
the head office of Southern DataStream where the actual data will be put every
20 Minutes on the web page of the Oxbow Golf club.
see an example table
The bolts and nuts:
Sensors:
The Weather Station measures these conditions using following sensors:
|
Condition |
Device |
| Temperature | Thermocouple
and reference temperature module AD590 Temperature sensor |
| Rainfall | Rain gauge, tipping bucket |
| Humidity | RHT-2 humidity sensor |
|
Wind speed |
Anemometer |
| Solar radiation | LI-COR 200SZ |
DataLogger:
A CR-10X data logger measures the values delivered by the sensors every 20 seconds and creates every 20 Minutes an output line which is transmitted via the serial CR-10 port. At midnight there is also a daily line produced to get Min/Max values of the day.
example of a typical 20 Minute output line:
111,329,2000,205,1320,101.2,95.9,103.1,107.2,0,37.63,74,1079,4,816
The
meaning of this line
RF-Modem transceiver & Receiver:
This output is converted to a RS-232 signal and transmitted by a wireless RF-GINA
data modem. This modem has a output power of 700mW and is able to reach
12+ Miles. In our configuration a Yagi antenna is used. Since the
modem is using around 350mA in Stand By and above 500mA in transmitting mode, it
is important to save the batteries energy. Therefore the transmitting
modem is only turned on the needed times, one minute before to one minute after
the transmission. To control this the programmable switched power feature
using an extra relay to deliver the needed current is used.
To connect the CR-10 and the Gina modem, the SC32A adapter has to be used.
Between the SC32A and the GINA modem a Null modem cable has to be used.
PC-Input & web preparation:
At the Southern DataStream office the data is received and constantly monitored by a PC using the serial RS-232 port. Everything that hits the transmission channel is recorded by an accustomed CR-10 receiver program and saved in a file in the company network. Since the transmitting modem is using switched power unpredictable transmission occurs when turning the modem on/off. To catch these errors the first and last values of the transmitted lines are only dummy numbers (i.e. 111 and 816). The reason is that these trash signals usually only occur at the beginning/end of the transmitted lines. An embedded Java program can now use those comma separated ASCII lines to publish the results on the web.
example of a received 20 Minute output line with trash signals at the end:
111,329,2000,205,1320,101.2,95.9,103.1,107.2,0,37.63,74,1079,4, 816ÿ
Power:
The CR-10 and the sensors do usually only use a few milli Amps that easily can be generated by a solar panel and stored in a 7Ah battery. Using the RF-modem changes things dramatically. It has to be considered that even using switched power for the modem the device has to be working at nighttime when no sun is available. For this setting it is necessary to the big solar panel (as seen in the picture) with an output (800W per m-2) of 1Amps/12Volts and a car size deep cycle battery.
Whoever has to deal with this station, this link should be a big help!!!