Reaching Across Europe with a Raspberry Pi Zero and WsprryPi
Over on YouTube user Techminds has uploaded a video that shows how he is using a Raspberry Pi Zero to transmit WSPR. To do this he uses the WsprryPi software which allows you to transmit WSPR by connecting an antenna directly to a GPIO pin on the Pi Zero. With this no extra hardware is required, although a filter is highly recommended to reduce spurious emissions from harmonics.
In his test Tech Minds directly connected the Pi Zero to an unun and HF wire antenna and ran WsprryPi. His results showed that even with the tiny 10mW output power of the Pi Zero's GPIO port his WSPR messages were able to reach several receivers halfway across Europe, and even to Iceland and Morocco from his home in the UK.
WSPR is an amateur radio digital HF mode designed to be decodable even if the signal is transmitted with very low power and is very weak. It can be used to help determine HF radio propagation conditions as WSPR reception reports are typically automatically uploaded to wsprnet.
There aren’t shop in europe?
There are other band-pass filter? Where I find the project?
Thankyou!
the increased visits depleted their gmaps api contigent
Actually no, they haven’t had an API key for the last couple of months at least. You can create a user account and add your own API key to get around it.
A low-pass or band-pass filter between the Pi’s GPIO output and an antenna isn’t just recommended, in most countries it is most likely legally required to comply to comply with various laws and regulations regarding spurious RF emissions (for instance, FCC part 15 in the U.S.) An example of a proper filter might be this one: https://tapr.org/kits_20M-wspr-pi.html
You could start with something like this filter kit which is well priced and simple to understand.
https://www.ebay.co.uk/itm/LFCN-HFCN-FV1206-Filter-Design-Kit-Mini-Circuits-LTCC-Filters-2-Unsoldered/282814870813
Many companies such as AnalogDevices and Texas Instruments will have online filter calculators to help you find component values.
Another suggestion, ready-made inline low pass filters: http://www.crystek.com/home/filter/filterLP.aspx