FlightAware Discussions

Performance between Raspberry Pi's

Has anyone had varing performance between different Raspberry Pi’s. I’m on Rasberry Pi Zero Wireless but not sure if its worth upgrading i.e to Rasberry Pi 2/3+/4?

I use a Pi2, Pi3 and 2 Orange Pi’s H3.

Between them there isn’t much difference, what I do see is that fitting them with a wired ethernet connection does give the most reliable results.

Same goes for the temperature, the Pi2 generates a little less high temperature due to the design of the board and processor, but I have very little difference between them in the performance of processing the messages of the flightaware dongles.

It depends on what you’re going to do.
Many are using a Zero with the default Flightaware Stick and a good antenna.

I do have an Airspy since a couple of days in test.
This is a well known SDR Stick with an outstanding performance.
I have tested it on a Pi 3B and on a 4B
As long as you do not try too much tweaking, both show the same performance, but the device can benefit from the faster USB slot of a 4B in some cases.

I started with the 3B two years ago and would still use it if i would not use the 4B for some additional stuff.

Cool, I havent got 4B on hand, but just switched to 3B from 0W so will see how much of an improvement I get after having 70% load vs a 9% load now. Will report back.

So I switched from a 3B to a 4B… I saw a drastic reduction in range, aircraft counts, etc… No other changes (that I know of)…

The 4B was a fresh raspberry pi os install on a SSD…

I tried playing around with gain but that did not help.
I went back to the 3B and magically it got better again…

Anyone have any ideas?

One thing… are you using one of the USB3 ports on the Pi4 for your dongle?

I believe I read somewhere that the dongle should be plugged into a USB2 port.

1 Like

Never heard of that, couldn’t imagine a reason why.
Trying different ports is a good idea though, mostly because there can be damage and bad contacts on one of the ports.

Most likely reason is insufficient power on the pi4.

Try without an SSD and use an sd-card instead.

I also have a downturn in stats comparing my 3B + FA dongle to new 4B with Airspy mini… (i’ve put it down to not getting config dialed in for the mini as yet)

I’ve switched from USB3 port to USB2 port this morning, so far do not see a difference comparing stats on GRAPHS1090 though

I also moved last year from a 3B to a 4B.

No significant change in the values. The two main reasons on a Pi4 is using a wrong Power Supply and or a wrong USB-Extension (if stick not attached directly).

The usage of a USB3 port is not necessary.

It isn’t something i have experienced myself but I definitely read it somewhere when I was initially setting up my RTL-SDR Blog V3s.

It might be an old wives tale that has no relevance anymore although there is mention of issue with USB3 ports when using high sampling rates on their web site.

Someone also mentioned that early USB3 ports weren’t great with USB2 devices and that IS something I have experienced myself with USB2 scanners and cameras that refuse to work on USB3.

Now that i think about it, i’m not aware of any issues with the ports themselves.

But using an USB3 device like the SSD can create enormous interference depending on the cable and electronics.
How problematic the stuff on the pi4 itself is i don’t know.

Anyhow i’d just recommend sticking with the sd-card, usually one doesn’t need fast read/write for an ADS-B receiver.

It may be necessary to turn off the HDMI video output.
https://www.rtl-sdr.com/using-a-hackrf-to-investigate-why-wifi-on-the-raspberry-pi-4-doesnt-work-when-running-hdmi-at-1440p/

It seems pretty good to me but I don’t use RTL-SDR devices on either of my Pi4s because they collect their data from the receivers. But they’re both installed on HDDs because one runs VRS and one runs FlightAirMap so they are pretty heavy on disk writes and were destroying SD cards. They both ran happily with the drives in USB2 caddies plugged into the USB3 socket for a while and have run happily with the drives in USB3 caddies ever since.

I think raspberry devices are very good for the money.

I use SSD as I have lost several SD cards. The power supply is the official RPI supply.
My 3B also uses SSD. I had the SSD and one of the radios on usb 3, and one radio on usb2, but I don’t remember which. Ill check out the HDMI thing mentioned by rugomol because the wifi seemed really flaky as well which was not making sense.

Three devices, two of them on USB3

I am not that technical, but could it be that devices connected to USB3 need a bit more power?

I never tried this combination. Maybe an active USB hub can solve the problem

This explains how USB is handled on the Pi4 and Pi3:
https://www.raspberrypi.org/documentation/hardware/raspberrypi/usb/README.md

It says that it doesn’t matter if you plug your USB2 devices into the USB2 or USB3 ports as the USB2 lines all go through a single USB2 hub that limits total bandwidth to 480mbps.

The total “power” budget is the same on the Pi3 and the Pi4 - 1200mA

I think @wiedehopf is right that the issue is USB3 induced interference from the SSD - when plugged into the Pi3 it falls back to USB2 and will not have the problem. A lot of WiFi Routers with a USB3 port have a software option for downgrading that port to USB2 to prevent USB3 device interference reducing WiFi performance.

That’s actually a good idea.
Do a shutdown, plug the SSD in one of the USB2 ports so it can’t use USB3.
Should still be much quicker than an sd-card and not interfere as much.

Though if you do heavy file transfers it’s gonna saturate the USB2 and cause MLAT to fail.

Well, I have slowly been troubleshooting it.
I disabled 4k video - no change
I disabled HDMI - no change
I plugged the SSD into USB 2 - no change
I swapped the USB/SATA cables - no change
I unplugged the UAT radio and only had the ADSB radio on USB 2 - no change

Of course, when I plugged the 3B back in, it was better, but not where it was supposed to be. I reseated all the connectors and now its back to where it was… the investigation continues…

Running the receiver on the USB3 port should force the port back to USB2, so this should get around both problems?

Not how it works …