friends I want to ask about my confusion. i’m confused actually the performance of signal capture it’s dominated by RTL-SDR or Raspberry Pi? in the process of decoding
The RTL-SDR dongle is a receiver that is tuned to 1090 MHz (or 978 MHz) and does amplifying and then mixing to an IF. This is followed by A/D sampling and mixing to baseband I/Q then low-pass filtering and downsampling. The I/Q samples are output to a USB port on the RTL-SDR dongle. The RTL-SDR USB port is plugged into one of the USB ports on the Raspberry PI (RPi). Software in the RPi (dump1090) does the decoding. So, in terms of how things are split up, the RTL-SDR is a generic front end that is not ADS-B specific. The ADS-B specific part is in the RPi.
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Here’s basically how it works:
The RTL-SDR USB dongle is a wide-band (20MHz-2000MHz) radio receiver and tuner. Like most radios it has internal filters and things. It’s controlled by computer software. You use the software to tune the radio to a specific frequency. The dongle also contains an analog to digital converter that does what the name suggests then ships the digitalized signal to the software over the computer’s USB bus. The Raspberry Pi is simply an inexpensive, small computer that consumes very little electricity so it can be left running 24x7 without increasing your monthly power utility’s bill (by more than a small amount, like pennies per month.) The radio also requires an antenna that’s been designed to receive the frequency band that you want to receives, along with coaxial cable to connect the antenna to the radio. In the case of ADS-B at 1090MHz this needs to be coax with a low attenuation (signal loss factor) at that frequency. Most ADS-B software requires that your computer use the Debian Linux operation system, or one that’s based on Debian such as Raspbian (Debian for Raspberry Pis.)
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Both. You need a good signal at the SDR front end and good decoding of that RF to produce clear data (samples) on USB. And you need to have sufficient processing power in the Pi not to drop any of those samples.
The number of samples depends of the maximum amount of traffic that you theoretically could see at your location.
Thanks for the information SoNic, I have one more question. Can you help me ? my question is, is it by tracking the plane with raspberry and RTL-SDR running on Flight aware. did it automatically share data from the aircraft signal capture or not?
is there a special setting so that my receiver can share data directly to flightaware and other people can see the results of my receiver capture
Yes. You can claim that build from inside your network:
PiAware - Claim and Link a Brand New PiAware Ground Station - FlightAware