We have been RF for many years now, this include our mobile phone transmissions, FM radio, television, walkie-talkie, CB etc... I remember those movies with truckers talking on their CB or the Ham radio operator who was talking to himself in the past ("Frequency" 2000).
With the success of mobile phones, Ham radio is not as a popular hobby as it used to be. However, there are still a good number of Hams out there and this old radio technology has shown its usefulness during disaster events that rendered mobile phones useless.
When I'm going on a Kayak, I have a handheld VHF radio with me tuned to channel 16 listening to broadcasts from the Marine Rescue team and other ships. I also have a handheld UHF radio for communicating with my mate, it is tuned on the UHF CB (FM in Australia) as this band can be used without license.
I don't yet have a Ham Radio license, so meanwhile, I'm only listening to transmissions outside of the CB band and trying to have fun receiving image signals from the weather satellites NOAA 15, NOAA 18 and NOAA 19. I started with using my handheld radio and recording the signal with my iPhone but this is painful and the recording is of too low quality for the decoder to be able to produce good imagery. So I decided to buy a Software Defined Radio (SDR) and settled on a SDR-RTL v3 with its antenna kit.
A SDR is a radio hardware connected to a computer and controlled by a software. SDR-RTL is a small USB dongle:
It comes with:
- a SDR-RTL v3 (RTL2832U R820T2) USB Dongle capable of receiving TV and Radio signals (DVB-T, DAB, VHF, UHF, FM, AM, HF, etc...)
- a long antenna cable with SMA connector
- a mini tripod with flexible legs that can be wrapped around a lot of support (branches, chair etc...)
- a suction cup mount
- a pair of long telescopic antenna elements
- a pair of short telescopic antenna elements
I had to buy an extra USB to USB-C adaptor for the Macbook Pro.
For receiving NOAA signals, I use the pair of long antenna elements connected to the tripod and spread at 120 degrees angle pointing South bound. The antenna are pulled out to about 52cm to match the frequency of the signal emitted by the NOAA satellites.
The satellites pass over our head several times a day but each pass would be at different elevation. To get a good signal it's best when the max elevation is high, ideally 90 degrees when it passes right overhead. To maximise the reception time, I usually climb up the roof of our house or go in an open field.
Tonight, NOAA 18 went high enough for me to be bothered climbing on the house and this was my first success at recording a clear signal. Here is the raw image received using the SDR-RTL v3 using CubicSDR and decoded by WXTOIMG on a Mac:
Once processed, the image is brighter and clearer. Using difference processing filters I obtained various interesting weather images.
Here is the image with "Normal" enhancement filter and map overlay:
You can notice a left and right (channel A and B) image, they can be combined for different results.
MCIR colour map IR:
MCIR with precipitation:
Sear surface temperature:
Thermal:
NO colour IR:
My D.Tube video shows the recording process.
▶️ DTube