Few questions about new Pi usage for ADS-B Rx.
Does image file exist for new generation of Pi (5) ?
How does RAM (8 or 16 instead of 2GB) impact MLAT ?
Is amplifier allowed in antenna-chain towards SMA-in on the box/stick, and what is max mV level it can handle ?
E.G. RTL-SDR has LNA amplifier, with 27 dB in 1GHz range, such as this:
https://www.rtl-sdr.com/new-product-rtl-sdr-blog-1090-mhz-ads-b-lna/
Does image file exist for new generation of Pi (5) ?
There is currently no PiAware sdcard image that supports the Pi 5 (we plan to do one, but it’s not ready yet as we need to port it to bookworm).
However, you can use the upstream Raspberry Pi OS bookworm image and then install PiAware via packages: PiAware - dump1090 ADS-B integration with FlightAware - FlightAware
How does RAM (8 or 16 instead of 2GB) impact MLAT ?
No effect, mlat does not need much RAM while running.
Is amplifier allowed in antenna-chain towards SMA-in on the box/stick, and what is max mV level it can handle ?
Depends on your receiver hardware.
For a R820T/R860T tuner the theoretical max input at the tuner chip is 10dBm. Some dongles will have an additional LNA before the tuner that you’ll need to account for. Note that you’ll need to account for the strength of out-of-band signals too, not only 1090MHz.
Unfortunately the RTL-SDR 1090 amp has been unavailable for a while.
There is a comment from last year “The chip we used for this design went EOL and all existing stock is gone now. We’re currently in the process of redesigning it to use other chips, but it won’t be ready until around late Q1 2023 / early Q2 2023.”
I’ll also add the Pi5 is overkill for just ADSB with any of the common SDRs.
My experience with RTL-SDR v3 and Flightaware SDRs
Pi4b (the first rev which was clocked 1.5Ghz) ~8% CPU
Pi3b ~12% CPU
Pi Zero2W ~13% CPU
Pi 5 with an Airspy Mini, ~25% CPU
replying to:
Is amplifier allowed in antenna-chain towards SMA-in on the box/stick, and what is max mV level it can handle ?
Depends on your receiver hardware.
For a R820T/R860T tuner the theoretical max input at the tuner chip is 10dBm. >>Some dongles will have an additional LNA before the tuner that you’ll need to >>account for. Note that you’ll need to account for the strength of out-of-band signals >>too, not only 1090MHz.
So as properly understood, if we want to utilize amplifier, we should instead of filter with integrated stick, use stick that does not have a filter and use external filter after antenna, and before amplifier. Or…
…as modern DVB-T2 amps which have LTE filters…
So choice is, STICK+FILTER
…where, LNA is put after filter (to reduce out of band noise), possibly in some outdoor antenna (shielded waterproof) proximity housing, as close to antenna as possible (to reduce cable and connector loss), and then it will amplify only usefull signals.
However, scientific work exists, which esplain how ADSB-specific amplifier should work, and some have proper filters. They come in 9xx and 1xxx flavors.
For those willing to explore deeper this matter, 1GHz low noise amplifier (LNA) optimisation (furhter reading):
Blockquote
kmm0000–> I’ll also add the Pi5 is overkill for just ADSB …
Depends if Pi5 is also used for e.g. VHF LiveATC recording/streaming and other signals (e.g. AIS for amphibian/hydro fleet of airplanes)
Whether you need LNA → filter or filter → LNA depends a lot on what your RF environment looks like.
Welcome to the forum.
A 32bit OS can’t address more than 4Gb or memory, so that’s your first limitation.
As above; where the amp & filter should go in the chain is a point of perpetual debate, but there is no substitute for trying both and seeing what works in your location.
Before you start throwing money at the problem, do a site survey and check you aren’t already hitting your limit.
As seen here, Bookworm exist also in 64-bit environments.
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