EMA

 

A WEATHER STATION FOR ASTRONOMY (v2)

Cristobal Garcia, 11-2009.

 

 

                        

 

The station with all the sensors. The interconecting box with the optionals display and supply.

 

 

 

In addition to usual sensors in all weather stations, this station incorporates a 24 hours datalogger and specific sensors for astronomical observatory:

            - Cloud sensor.

            - Rain sensor.

            - Night Sky Quality Sensor.

 

To make automation easy, control outputs are available through two double circuits relays:

            - Relay for opening and closing the observatory.

            - Relay for anti-dew heaters.

 

You can program the automatic shutdown of the observatory when levels are exceeded for:

            - Wind speed of the mechanical anemometer.

            - Wind speed of the thermal anemometer.

            - Appearance of clouds.

            - A drop of rain.

            - Excessive time without the presence of the PC.

            - Sky brightness level.

            - Main battery low.

            - Physical disconnection of the station.

 

The disconnection of the station or a power supply faillure, causes the closure of the observatory, because the relay that controls the roof opening (by end of run switches) returns to the rest position, ie to the closure position.

In order to duplicate the wind protection, there are two anemometers, a mechanical one and a thermal one. The mechanical anemometer may be a commercial one (TX20 from Lacrosse Technology also gives the wind direction), or a specially built more robust one.

 

Every 5 seconds the station sends the readings through the serial port. These readings are internally stored every five minutes for the last 24 hours. The daily maximum and minimum are also stored for the last year.

 

 

             

 

The Main circuit board and the Relays board.

 

 

Communication with the station is done using a simple ascii protocol.

The program allows to configure the station and to collect data from the station in a very simple way. There are four windows: the main window showing data in text mode, a second window with the graph for the last 24h of data, a window used as a terminal and the configuration window.

 

 

 

The four windows of the acquisition program.

 

  The station can also generate messages in compatible format that can be received by commercial programs like Virtual Weather Station.

Weather Display is recommended because it can receive data via TCP from the station program itself.

 

 

 

 

 

   The station is designed to be home made. The cost of electronic material for the two plates and main sensors is around 120 . The total cost is about 240 .

For more details about the application and assembly see the Manual in pdf format.

 

Every detail related to its assembly and operation can be followed in the Yahoo group Observatorio Remoto Click here to join ObservatorioRemoto

 

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