Blog de notas, sem fugir muito do assunto, da minha estação de radioamador.
Este blog é pessoal e de conteúdo variado, mas essencialmente polarizado para os rádios e a electrónica. A expectativa é que alguém ache as minhas experiências úteis.
Normalmente não aplico o método cientifico, por isso cuidado. Não quer dizer que não encontre muitas informações precisas, no entanto, tenha clara noção de que vai estragar alguma coisa.
I getting an hard time to decode some ADS-B signals, my antenna is not ideal (using a J-Pole for 2 M 70 CM) and only aeroplanes right on top of my location wore decoded, so time for a filter. I got an ADS-B filter for 1090 MHz and now I can pick up ADS-B signals in a 150 Km radius, the next pictures show why:
With the filter the main difference is obvious, no more FM stations an less GSM.
These pictures wore made using qspectrum, and the filter is this one.
I have an old 433MHz remote temperature sensor laying around and decide to do some testing. I've used my Hackrf One to probe the frequency and the modulation type using the osmocom_fft and the insepctrum application. First run on a terminalosmocom_fft -a hackrf -v -f 433e6 -s 8e6 -g 0 If you are using an rlt-sdr useosmocom_fft -a rtl=0 -v -f 433e6 -s 2048e3 -g 0 .Notice that on the right lower corner there is a rec button just record some transitions from the sensor and notice the frequency.
Using the REC button record the sensor activity and use inspectrum to analyse it by open the recorded file.
Now we can clearly see what is append. This is much better than use audacity to look at the demodulated signal. The ASK/OOK signal is clear now, we can demodulate and "time travel" our signal at will, you can even try several types of modulations at the same time and figure which apply. There is also rtl_433 application that will decode the temperature sensor, or your car tire pressure sensor or many things from an rtl-sdr, on your terminal just use rtl_433 -G