There are a lot of satellites above our heads. Did You know, that using only Your computer, TV Tuner and simple DIY antena You could recieve the transmissions from them ? For example real time pictures of earth. I'll show You how.
You will need:
- 2 wires (could be from ordinary electrical cable)
- some plywood or wood for an antena
- coaxial cable (TV cable)
- computer (Windows/Mac/Linux)
Step 1: Weather Satellites
We will be picking the signal from NOAA weather satellites because it is the easiest and good for the beginning. It is also possible to recieve the informations from other satellites-I'll write about at the end of this instructable.
The NOA satellites are over 800 km above earth and they are flying around the world in just 100minutes. During this flight they are taking the photos of earth and those imgase are then trasmitted via 137Mhz FM frequency to earth.
Step 2: Antena
To recieve the satellite transmission You will need an antena. The easiest one is just two 53 cm long copper wires connected in V shape under 120 degrees. Such antena is made for a 137Mhz frequencies.
I made antena from plywood as the holder and from ordinary electric copper wires. Those wires are then connected to the TV coaxial cable and thats all. Nothing more is needed. The whole antena took me no more than 20 minutes to built.
Step 3: Reciever
For reciever we can use TV Tuner based on the RTL2832U chipset. Such device cost about 10 USD, so it is very cheap and it allows You to watch the TV on Your laptop.
The tuner is in fact SDR device - Software Defined Radio - it means that it could recieve the FM frequencies and could be controlled with the computer software and that's all we need.
After installing the Tuner on Windows, You have to 'hack' it by replacing the original drivers by Zadig software. Run it and click replace the drivers.
On Linux, the procedure is different and could be found under this link
Step 4: Software to Track the Sattelites
You will need the software to track and predict when satellite will be over Your area. I recommend to use WXTOIMG because this is super easy program, available for all systems and it also decodes the signal from satellite.
To predict the NOAA satellites, You have to set Your ground station in the options for Your location. Then select the Satellite Pass List option and You will see when and on what frequencies You have to listen for the signal (complete step by step tutorial is in the video attachet to this instructable)
Step 5: Software to Record the Signal
You will need another program, to controll Your TV Tuner, recieve and record the signal from satellite.
For Widnows I recommend SDR Sharp, for Linux/Mac You can use GQRX.
Both software works in the same manner.
You select the frequency, on what You want to listen and You will not only hear the signal but You can see it on the diagrams in the SDR software.
Step 6: Recording the Signal and Decoding It
Now we have all we need. So when the satellite is above us, open the SDR software, set the frequency for 137,XXX MHz and set the reciver options like this:
- modulation FM
- band: 44khz
and push the record button when the signals will start appearing.
After You recorded the signal, You have to change it's frequency from 44khz to 11025 Hz. I used the Audacity software for that. Just open the wav file, change the frequency and write it once again.
The last step is to open the WAV in WXTOIMG. After this the program will automatically decode the signal and.. that's all! You have Your pictures of earth.
You can select different types of decoding in Wxtoimg like temperature, continents, seas etc.
Step 7: What Next ?
That's not all. With such configuration (only maybe with additional LNA amplifier) like in this instructable You can pick a lot more.
You can recieve better photos from METEOR 1 and 2 sattelites (different decoding software is needed)
You can listen to ISS SSTV (pictures from International Space Station)
You can pick some local transmissions over wide FM band.