A single ADS-B receiver most likely isn’t going to tax the processor of a Pi3 or Pi4. If you’re running multiple receivers (Flight Aware, FlightRadar24, etc.) all on the same SDR, then you’re going to start hitting some thermal limits on your Pi.
On a Pi4 cooling is recommended but not required, and again a single ADS-B isn’t going to force that.
Those aren’t receivers, those are feeders. The receiver (aka demodulator) is dump1090-fa, dump1090-mutability or readsb. Feeders use very few CPU resources compared to the receiver (and you can only have one receiver per SDR dongle because it’ll claim the dongle so nothing else can control it.) The receiver is actually what decodes the ADS-B data packets and converts the messages to beast format which is what’s sent to the feeders and to your own local skyaware, tar1090 or virtual radar server. That’s what uses CPU. Feeders just ship the information out to various IP addresses and ports.
You’re correct that dedicating a Pi 3 or 4 to ADS-B feeding isn’t going to tax its resources. Lots of people are using theirs to feed multiple aggregation sites: FA, FR24, ADSBx, with no problems.
Pi 3 B+ in a ventilated aluminum case with a fan (I live in the tropics and don’t have air conditioning.) I currently only feed one aggregator bust used to feed two with no discernible difference in resource usage or temperature.
Your temperature is not bad for your described location.
My zero (single core) usually gets around 45-49c feeding three sites, obviously no cooling on the zero.
Appreciate fans and heatsinks really control higher temperatures.
Geoff
Sorry, wrong terminology. Sometimes my brain refuses to access the correct file!
The RPi temps remain constant. I have no fans and the ambient air temperature is a steady 26°C in my comm closet. The temperature variation is due to work load differences. The RPi’s also drive print 3 printers, 2 scanners and 8 security cameras. The RPi 4 on the left of the image (45.2°C) does nothing but feed FA, FR24 and ADSBEX.
Not so fortunate with the cooling, but doing well enough with the outdoor enclosure. Added an ACInfinity S2 blower and Controller-1 to the enclosure, and so far its keeping things below the throttle thresholds.
I use a Pi 3b with a home made 1090 Mhz Slim Jjim antenna. A Flight Aware Pro stick is mounted to the antenna with 12 inches of feeder, The stick is connected to The Pi3 with 30 feet of good quality usb extension cable. Hence there is no feeder loss. The Pi is currently 7% CPU and 46 deg C The Pro stick and usb unit is sealed inside a 32mm plastic tube at 25 feet above the ground.
Pi 3B+
Waveshare Raspberry Pi LCD Display
Nooelec Nano 3 SDRs
Stratux GPYes 2.0 u-blox 8 USB GPS
OS is Raspian from the flightaware pi image with LCD support. I would pass on that next time around. I thought one would get more from it… I was thinking it would be a little display of the area and flights…
1090 + 978 and MLAT using the FA dump daemons.
Now one thing I did to reduce the CPU usage (not that it was too much) was to follow the instructions on generating a wisdom file. I did the following before generating the wisdom file:
Do the normal housekeeping and run an overall update:
sudo apt update -y
sudo apt upgrade -y
sudo reboot
sudo apt install cpufrequtils
cpufreq-info. # get a look at before
sudo cpufreq-set -g performance
cpufreq-info # get a look after adjusting the governor
Make note of the output from the cpufreq-info.
This is to disable CPU scaling for when you are generating the wisdom file.
This next step is optional but I like the idea of using the hardware to create entropy for the random number generator…
sudo apt install rng-tools
edit /etc/default/rng-tools or /etc/default/rng-tools-debian
Uncomment the line with “HRNGDEVICE=/dev/hwrng” and then restart the rng-tools
sudo systemctl restart rng-tools
See this for more details - hardware - How to know if /dev/hwrng is working - Raspberry Pi Stack Exchange
So now you have the updates done and the cpu feeding entropy into the rng along with CPU scaling off, check the dump1090-fa runtime features beforehand and make note of the values printed out:
dump1090-fa --version
Then stop the CPU intensive services on your piaware. You might want to stop more depending what you have installed.
sudo systemctl stop dump978-fa
sudo systemctl stop dump1090-fa
sudo systemctl stop piaware
Check everything is all quiet with htop and stop any other services that are using more than a 1% CPU longer than a couple seconds.
Then at the bottom of this page are the details generating a wisdom file:
Once generated you can set the cpu governor
Once generated I’d just suggest doing normal housekeeping and run an overall update:
sudo apt update -y
sudo apt upgrade -y
sudo reboot
And then following the reboot, everything should be running and you can continue with your day. If curious you can check the difference in what dump1090-fa is using:
dump1090-fa --version
If you want you can also set the cpu governor hack to ondemand or whatever you like using this:
sudo cpufreq-set -g ondemand
I did all this last week and here is what my graph looks like:
I was using a Raspberry 3 and changed it to a Raspberry 4B after a year.
Both were running with passive heatsinks, never causing any issues. The installed feeders never caused thermal problems.
For a Raspberry 4 i can recommend one of the armor cases which is the heatsink itself.
A different story is it, if an Airspy stick is used. This is using lots of CPU and an active cooling is recommended, especially during summer and if you are adjusting the airspy settings to the limit.
Say that again to those of us using Airspy receivers 
Constant 45% CPU over all the cores is quite a high load for a Pi and some active cooling is really essential.
I am using a 4. Issue is my USB keyboard and mouse will not work. Does this OS support it? If yes, is there something I needed to do to activate them? I am building a new system so I can get latest OS. Thanks
Did you install the desktop version? I have several 3 and 4 RPi’s that work seamlessly with usb keyboard, mouse and display.
Thanks for the reply. I download from the website the following “PiAware with LCD display support - PiAware LCD Image on Raspbian Linux 7.2 ZIP (674MB)” and followed the steps found on PiAware - build your own ADS-B ground station for integration with FlightAware - FlightAware
It depends… i had mine outside with the fans turned off in this aluminium case. Only during high summer temperatures i activated them which reduced the temp by 5-8 °C
The LCD image does not have a standard desktop on it. It runs a special script for the LCD. This is available to the hdmi port but it is only expecting touchsceen inputs. While you can add a desktop, It won’t display the standard desktop on a monitor at the same time as the LCD GUI without some complex changes, otherwise it is one or the other. You could enable VNC and remote to it and use a mouse. I have tried VNC to the LCD image but did not not test a virtual mouse.
The standard image fully supports the desktop.
See here:
VNC to LCD image
Using an external monitor on port 1 I could see the GUI which if the keyboard and mouse worked I can use. But I have now placed that unit into production with 7.2 in place of my older unit running 6. The keyboard/mouse was just so I can work the unit before I moved it. Thanks again for the response.
I just bought a dongle at a HamFest and set it up a couple of days ago. All my Pi device are in use, but I bought a few Pi400 units back when the shortage started. They were the only reasonably priced option, but even they have skyrocketed in price. Mine is running on a Pi400 and currently using a 2m/70cm mag-mount antenna in the window. Surprisingly, the antenna shows a 1.7SWR at 1090mhz and appears to be doing a decent job. I plan on adding an external antenna using some spare LMR-400 left over from my dual band install a few months ago. I also have an N-connector window passthrough with 3 empty ports so I’ll run the LMR400 to the external connector and some RG8 from the internal connector to the receiver.
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