Did you have any problems with MLAT? Both times I tried 20MHz on my x86_64 Ubuntu box with Intel i5 and 8gb RAM and a mini, MLAT became unsynchronized until I switched back to 12MHz.
I can recommend the Uputronics filtered LNA. I do have it in front of my Airspy and a friend of mine has upgraded his blue FA stick with it. Gain has set to 25 only and this is the result.
I would assume itâs clear visible by when it was installed.
The filter can be powered either by Bias-T or via power from the Raspberry rsp. external USB power. I have it connected with an additional cable to USB
And with wrong gain settings, you have a mass of single track messages:
Together with that a new Vinnant antenna was installed, but the one before was already good.
As far as i understand itâs not recommended as the Mini gets pretty hot.
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Iâve been running my mini for 2 years at 20 MHz with no heat problems at all. Itâs in the loft space which gets very hot in summer.
Just be aware that itâs very susceptible to complete overload from strong signals close by.
Same. Mine is up the top of the mast in direct sunlight. Same at the MTG site.
no problems at all, but iâm running a RPI 3B+. always stays synchronizedâŚbut only if i use wifi. with ethernet it wonât work.
I am using it since June and with wind from east i have daily close by aircraft approaching Frankfurt. Directly above my location with <3000 ft altitude.
Never seen a single issue with overload
Is it required to reduce -C ?
So it seems to me the HABamp is still doing its job.
dump1090-fa increased the gain but also the signal level rose by maybe 8 dB.
So the HABAMP probably still has 12 dB of gain which is fine.
The level of the messages on the airspy didnât change because the amplification is still the same, but some messages that previously got lost because they weaker than the LNA noise are now being received.
I suppose a new LNA could still help but not as convinced anymore that it will be a big improvement.
You also seem to be range limited by terrain or similar.
As such you might be able to tweak the setup but i wouldnât expect huge gains.
(otherwise iâd probably recommend considering new better coax but probably not worth it)
Thatâs a bit strange. I have no problems what so ever with MLAT on my PC (older Pentium G3240) running Debian x86_64. 8 GB ram. I have an R2 and MLAT works flawless even with 24MHz.
Have you tried different USB ports? Do you have anything connected to the other USB ports of the computer (hdd/ssd, mouse, keyboard, another SDR-stick, etc)?
Switched to 20MHz on my Raspberry 4B with no success. Flightaware disabled MLAT due to reliiability. And the preamble filters dropped significantly:
Going back to 12 MHz now
regarding your change from 12MHz to 20MHzâŚare you using wifi or ethernet. i could only use wifi as it wouldnât work with ethernet (on 3B+)
Any other USB devices on the same pi make running anything but 12 MSPS unlikely to work for MLAT.
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Have you tried putting the airspy in one of the USB3 ports? Works fine on my backup-station (Pi4 with a mini) with 20 MHz and MLAT. And Iâm using ethernet as well.
Ahhhh, thatâs why 20 MSPS never goes well here â> UAT/FA orange stick for 978 sharing a Pi with Airspy. I always wondered why it never worked, even with bin packing.
It is already connected to USB 3
But i am using WiFi and the Uputronics is powered from a free USB2 port.
I would assume that this combination doesnât work well for 20 MHz
The USB to power the LNA doesnât count.
USB 3 / 2 doesnât matter, the device is USB 2 and there is only USB 2 chip on the pi4, no matter which port you connect it to.
That chip is limited to a certain speed.
I also powered my LNA from the USB, sure, it draws some power, but shouldnât use any bandwidthâŚ
Donât know if wifi and USB share the same bus on the Pi4, that could explain ut
Then i have no clue why itâs not working ÂŻ\_(ă)_/ÂŻ
I have not been able to use 20 or 24 MSPS since receiving my R2. ( MLAT never sycs. )
I have tried this with -p several times.
From what I have read this is most likely due to also running dump978-fa on the same PI.
I have not been able to detect any power supply issues.
Ssyem setup here is
PI4 1600Mhz
POE+ Hat (4 amp)
Uputronics GPS/RTC Hat
Airspy R2 (1090 USB 3 slot)
-v -t 60 -f 1 -w 5 -C 90 -P 7 -l 47787:beast -g auto -m 12 -S /run/airspy_adsb/stats.json
100ft Times Microwave LMR400
Kuhne 1090 mast mount preamp (30db)
15ft Times Microwave LMR400
DPD 1090 Antenna ( 65ft above GL)
FA Orange (978 USB 2) slot
Bias T
100ft Times Microwave LMR400
Uputronics 978 Preamp
FA 978 antenna ( 55ft above GL)
I have another PI3 that I use an NTP serever
Uputronics GPS/RTC Hat
Graphs can be seen here
Graphs1090
Isnât the USB ports connected via the USB controller (VL805) that in turn is connected to one of the PCIe-lanes on the board (4 Gbps)?
And itâs the power distribution that is f*ck up on the usb system since it isnât capable of supplying all 4 usb ports simultaneously with the maximun power each port can draw according to the standard?
No.
USB2 is limited for all devices on the same bus.
As in the devices will share 480 MBit/s theoretical bandwidth.
In practice itâs less.
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