Intro: Cheapest Way to Receive Weather Satellite Images
Some time ago I heared about the possibility to receive weather satellite images. So I informed myself about this topic, and learned that I would need a SDR and an Antenna to receive the given frequencies. I didn't have these items ready, but still wanted to give it a try.
I remebered some time ago I learned about WEBSDR, which are Software defined Radios, which are made public in the Internet. So I gave it a try, it worked out, and I decided to write my first Instructable.
Step 1: Everything You Need
At first you need a computer or laptop to use all the needed software. The operating system does not matter, because they will work on nearly every, but I will describe it for Windows, which won't be much different to the other.
- Any Browser with HTML5 Support:
Step 2: Setup WXtoIMG
At first I recommend to enable the expert mode. You can find this setting under Options->GUI Options. After this you have to close and reopen the software.
Next you set the location of your antenna, which is located in Noordwijk, Netherlands. For this you go to Options->Ground Station Location and set it to:
as shown in the first picture.
Next make sure that the Options on the top of the Options bar are as in the second Image, except the Crop Telemetry setting does not have to be selected, it just removes the border of the images later.
Then you update the Keplers, which is located under File. When it is finished you open the Satellite Pass List. This will show you, when satellites will be in the zone to be received. There is a UTC Time given, with wich you can calculate, which time it is at your place. Also the frequency on which the signal will be sent is given.
Step 3: Receiving the Signal
Open your Browser a few Minutes before a satellite passes. Go to the site: http://erc-websdr.esa.int/
The frequency you read from the Satellite Pass List is given in MHz, and on this site you have to set the frequency in kHz. So just multiply the given Frequency with 1000. Enter this into the Frequency field, shown in the second picture.
Select FM, and widen the Bandwith to 30.09kHz, as in picture 3. You can just stretch the barriers out with your mouse.
The optimum would be 34kHz, but the used hardware doesn't allow this. You may also enable Autonotch.
You may add 2-5kHz to the frequency because of the Doppler effect.
About 1-2 minutes before the start, beginn the recording. Stop it when the signal isn't visible any more for about a minute, since you can later crop the picture, but can't add anything you haven't recorded.
During the recording you can adjust the frequency to counteract the Doppler effect. This will increase the quality slightly, but mostly not very significant.
Then click the now visible "Download" button next to the "Audio recording: Start/Stop" button, if it doesn't download automatically.
Step 4: Make the Signal Ready for Processing
Open up Audacity and open the recorded file.
Change the Project Rate to 11025Hz, as in the first picture.
Then resample the audio to 11025Hz, as in the second picture.
Then just save the new audio as WAV, and make sure, that the name of the file ends with .wav
Step 5: Creating the Image
Back in WXtoIMG go to File->Open Audio File, and open the edited audio file. Make sure to select the right Satellite.
The software will do everything else for you.
There will just be two black and white pictures, which you now can edit with the enhancements, options, projections, and images. To get a coloured Image try the HVCT or HVC false colour. Also click Image->Histogram Equalise Image once, and it will be a really good picture if everything worked out.
Don't be sad if it doesn't work out the first time, just try some times, and you will get better and better.