Introduction: Satellite Assisted Weather Station
This project is meant for people who want to collect their own weather data. It can measure wind speed and direction, temperature and air humidity. It's also capable of listening to weather satellites orbiting the Earth once every 100 minutes. I will use this project later to create my own weather forecasting using AI trained on these images.
- Aluminium U-profile 15mm and 12mm, 1 meter long
- Aluminium tubes 10mm diameter, 4.5m
- 8 brass tube holders
- 8 M2 nuts and bolts
- 2x4.5 cm wooden beam, 1.2m long
- 2 M8 nuts and bolts
- 3m 50ohm coax
- 12x12 cm electrical box
- heat shrinks
- tripod with hole to fit M8 bolt
- some Legos
- 2 plastic containers
- hot glue
- Raspberry Pi 3 or 4
- Raspberry Pi power supply
- ethernet cable
- usb extension cord (at least 40 cm long)
- raspberry pi power supply
- Arduino Nano
- DHT11 sensor
- reed switch
- rotary encoder
- Nooelec NESDR mini
- soldering iron
- screw driver set
- hot glue gun
Step 1: Building the Antenna
Make 2 54.2cm long pieces of wood. Drill a hole in the middle for an M8 bolt and mount the two pieces in a cross. Then make 4 pieces of 4cm long and saw one end at 45 degree angle. Srew these on top of the ends of the cross. This will make the ends flush with each other. In the centre of each end, drill a hole large enough for your coax cable.Now mark a 30 angle from vertical. On this angle mount 2 tube holders aprox. 1.5 cm from centre. If you want you can drill holes in the cross to make it lighter.
Cut 8 50 cm aluminium tubes. 2 tubes form 1 dipole.
Cutting The Coax
Cut two 36cm pieces of coax. Cut 2 more pieces this time being 72cm long. Cut one more 60 cm piece, this will be the main line to the receiver.
Mount the coax cables with the same length opposite to each other. The sides with 36 cm coax are dipoles 1 and 2, the sides with 72 cm dipoles 3 and 4.
Strip the ends of the coax for soldering. The SDR receiver comes with its own antenna and coax, cut the wire at its connector. Later we solder this to our main coax form our own antenna.
At the ends of the cross, connect the core of the coax to the upper part of the dipole, the shielding goes the lower part. In the centre, solder the shielding of dipoles 1 and 2 together. Do the same for 3 and 4. Now solder the cores from dipoles 1 and 3 together, same for 2 and 4. Now you're left with only 2 wires.
Solder the cores from dipole 1 and 3 to the shielding of the receiver line. Solder cores from dipoles 2 and 4 to the core of the receiver line.
Mounting The Cross
Place the 2 aluminium U-profiles in each other. At one end place the bolt in the centre of the cross on top. Drill 2 holes throught the profiles and the bolt to fit the M2 bolts. Do the same with the other M8 bolt on the other side of the profiles. Place the Antenna in the tripod.
If you want you can test your antenna by following this tutorial on rtl-sdr.com.
Step 2: Making the Wind Sensors
You can find the parts and instructions in the pdf building guide. Its made out of simple and common Lego bricks.
Once you finished building the Lego structure, solder two 110 cm long wires to the pins of the reed switch. thread one of the wires through the tube on the side of the beam. You then bend the metal legs of the reed switch on top so it sits securely on top of the tube. Then glue the magnet on the bottom of one of the dishes so it barely touches the reed switch. Whenever the magnet is above the reed switch the circuit should be closed. Test with a multimeter and refit if necessary. Attach the Lego beam with a wood screw to the antenna.
The direction sensor consists of a rotary encoder with a 3D printed wind vane. The inventor and STL file are included here. Firmly press the vane on the axle of the rotary encoder. Drill a 7 mm hole in a plastic box and mount the rotary encoder thought it. The encoder comes with a nut that screws on top of the plastic box. Use two wood screws to mount the box to one of the beams of the antenna.
Once mounted use heat shrinks to neatly cover the wires. The length has to be 86 cm and the width has to be 2.5cm.
Step 3: Making the Enclosure for the SDR
For this simple enclosure you'll need to saw these plywood parts:
- two 9.5x1.6 cm
- two 9.5x4.2 cm
- one 3x4.2 cm
Step 4: Enclosure for the Raspberry Pi
Take the power supply pcb out of its casing. The capacitor shown in the picture is too big to fit in the new case.
Desolder it and place extensions (wire, old resistor legs,..). Solder the cap to those extensions and bend it so it fits tightly in the case. Solder the 5V and GND wires from the power pcb to the pads on the PI (shown in pictures).
The power cords fits through the hole in the case on the side.
Cut a rectangular hole in the front lid. Hot glue the lcd to the inside making sure that the pins on the lcd faces upward.
Solder female wires to the black pcb and plug them into the Pi. Remove the hole on the bottom left side and glue the Pi-fan to suck air in from that hole.
Solder female jumper wires to the dht sensor and plug them into the Pi. Hot glue the sensor just below the Pi's ethernet port so the fan next to it blows fresh air over the sensor.
Step 5: Software
All the software is available on Git. Make sure you clone it in your Pi's home folder