FlightAware Discussions

Where are the typical processing bottlenecks?

I’m curious if the processor is a bottleneck to collecting detections? I’m running a Raspberry Pi3 now and it works fine, but if I upgraded to a Pi4 or even something bigger would the number of detections increase? Is the SDR a bottleneck? As the number of detections available increases, where do the bottlenecks tend to start occurring?

Next, if I wanted to look at my current system and see if it looks like anything is saturating, what would be the first things to check?

Curious! Thanks!

The most likely place you’ll cause a degradation is the USB path.
The USB dongle is not a complete radio in the traditional sense, so any contention on the USB path will degrade your performance.
CPU performance on a quad core Pi is further down the list.

Try SSH’ing into the Pi and type ‘top’ - you can see how hard your CPU is working.

Edit: Comments regarding the CPU assume it’s not working hard with other tasks

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The only typical bottleneck are power supplies not providing 5.2 V to the pi messing up the SDR because it gets less than 5.0 V.

Pi3 with dump1090-fa wouldn’t hit any CPU limitations, no matter where you are.

Not really aware of the CPU ever being the bottleneck.

I’d say typical bottlenecks are antenna location / antenna / insufficient filtering.
An AirSpy with filtered LNA or a ModeS Beast are also typically gonna perform better than a rtl-sdr compatible SDR.
But that needs changes in software / configuration as well, so be aware of that.

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No, it will not as long as the Pi3 works without issues.

I have two receivers here. One is a Pi3B and the other one is a Pi4.
Both are equipped with the blue FA Pro Plus stick and antennas with similar performance.

Based on the issues i had with regular network disconnects, i swapped the receivers and the Pi3 is now outdoor as main receiver.
From the performance there is no difference compared to the Pi4

You should more look on good cabling, not only antenna, but also USB (if in use).
I do have a 1 meter extension and a 2.5 meter USB-Extension. While the longer one does not cause any performance issues, the shorter one reduced the reception of aircraft by 30%

long story short: As long as you have good cabling and everything in place, the RPi should not be the bottleneck.
One exception might be using an Airspy receiver (stick). As far as i follow here the discussions, that stick works better with a RPi 4

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