Re: RFI on LW and MW with RPI and AS HF+
I had the same issue. My problem was infact the Ac adapter. Even though it was an "official" one, it was garbage. It was a big source of noise on my Icom R-75. I ended up using a spare samsung cell phone charger and an aftermarket usb cable to power it, and all the noise went away. This feeds a flightaware raspberry pi host. And yes, the pi works perfectly fine?
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Re: RFI on LW and MW with RPI and AS HF+
And THAT could be the power brick. They are notorious for this.
{^_^}.
On 20250407 13:55:37, Martin via
groups.io wrote:
toggle quoted message
Show quoted text
I was using an expensive high quality HDMI cable, which
did not help.
Using a small form factor PC has no issues though, even with
cheap Chinese cables.
I tried with the Pi4 in a shielded case and that didn't
help either.
My Pi 4 is no longer used for anything radio related and is
only powered on in a headless configuration for things like
Octoprint.
My Pi 3 is old now and has power supply issues, so that is
not often used. Not sure where the fault is, no its not the
Micro-USB connection, I wired directly to the IO header and
had the same problem, brown out pretty much all the time.
I use a couple of small PC's now, all is fine.
However, solar inverter for my panels, now that is a
different story.
Anyway, I don't want to change the direction of the thread.
Thanks
Martin
HDMI
is an extremely bad RFI generator and radiator.? I've
tested several for radiated emissions.? If you can find a
WELL SHIELDED and PROPERLY TERMINATED SHIELD you might
have a chance.? Any and nearly all HDMI cables from China
will likely be RFI antennas.
Dave
- W?LEV
I'm surprised how Raspberry get away with the
amount of RFI the Pi's cause.
I purchased an RPi 4 when they first released, I had
to return it thinking it was faulty but the
replacement was as bad.
Turns out I could not use wireless keyboard and mouse
at the same time that I used HDMI cable as the noise
emitted by the video signal would wipe out the 2.4Ghz
wireless connection.
My RPi 3 isn't as bad, but if you are using HDMI
with your RPi3, then maybe try to unplug it and maybe
use remote access to your Pi.
Martin
You described everything except the most
important part: The antenna.
--
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Re: RFI on LW and MW with RPI and AS HF+
That could even be noise from the monitor. I had a case like that
here some years ago.
{^_^}
On 20250407 13:39:10, Martin via
groups.io wrote:
toggle quoted message
Show quoted text
I'm surprised how Raspberry get away with the amount of
RFI the Pi's cause.
I purchased an RPi 4 when they first released, I had to
return it thinking it was faulty but the replacement was as
bad.
Turns out I could not use wireless keyboard and mouse at the
same time that I used HDMI cable as the noise emitted by the
video signal would wipe out the 2.4Ghz wireless connection.
My RPi 3 isn't as bad, but if you are using HDMI with your
RPi3, then maybe try to unplug it and maybe use remote access
to your Pi.
Martin
You described everything except the most important part:
The antenna.
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Re: RFI on LW and MW with RPI and AS HF+
Distance is probably your best shot. A 16' or so USB cable with
the AirSpy at the far end would help, some. A metal box around the
RPi would help some. Then we can talk about large chunks of
ferrite with high permeability designed for EMI reduction with as
many turns of the cable as will wrapped around it. The
experimental tradeoff is between turns and distance in that case.
The ferrite would go up near the AirSpy. The box should be gently
scraped clean where top and bottom mate for a slightly better RF
shield.
Generally distance between radiator and receiver is your best
friend. In the near field, where you will be at MW and frequencies
below, the attenuation is related to the cube of the distance
between them, That means every time you double the distance you
get about 9 dB of improvement.
{^_^}
On 20250407 11:34:05, e.j. Fr?lich via
groups.io wrote:
toggle quoted message
Show quoted text
Hello all,
?
I use my Airspy HF+ via a Raspberry PI 3B and spyserver. This
works fine on HF and above.
On LW and MW the PI generates a lot of RFI. This makes these
bands not usable.
I use a PI approved power supply and the original Airspy
cable.
?
Does somebody know of a good solution for this problem
?
Spoiler, using the Airspy HF+ direct to my laptop or tablet
works fine...
?
Ernst-Jan
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Additionally, do not overlap turns.? If turns are overlapped, that will add capacitive coupling around the ferrite.
Dave - W?LEV
I use FT240 cores of 31 mix on my USB cables. Wrap as many turns as your excess CAT5/6 cable will allow. Tie wrap the last turn to the core to keep it from unraveling. Remember the more wraps through the core, the more effective the choke resistance.
?
73 Kriss KA1GJU
--
?
?
73 Kriss KA1GJU
Home of the KA1GJU Super Station SDRC Servers in NH, USA? (FN42mw, FN43na, and FN43lt)
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I use FT240 cores of 31 mix on my USB cables. Wrap as many turns as your excess CAT5/6 cable will allow. Tie wrap the last turn to the core to keep it from unraveling. Remember the more wraps through the core, the more effective the choke resistance.
?
73 Kriss KA1GJU
--
?
?
73 Kriss KA1GJU
Home of the KA1GJU Super Station SDRC Servers in NH, USA? (FN42mw, FN43na, and FN43lt)
|
Re: RFI on LW and MW with RPI and AS HF+
You can try a couple of clamp-on ferrite "beads" of either 43 or 31 material.? It might at least reduce the RFI.? I don't have a Pi, so can't directly offer suggestions, but only from my experience as an EMC/RFI entineer (retired).
Dave - W?LEV
I was using an expensive high quality HDMI cable, which did not help.
Using a small form factor PC has no issues though, even with cheap Chinese cables. I tried with the Pi4 in a shielded case and that didn't help either.
My Pi 4 is no longer used for anything radio related and is only powered on in a headless configuration for things like Octoprint.
My Pi 3 is old now and has power supply issues, so that is not often used. Not sure where the fault is, no its not the Micro-USB connection, I wired directly to the IO header and had the same problem, brown out pretty much all the time.
I use a couple of small PC's now, all is fine.
However, solar inverter for my panels, now that is a different story.
Anyway, I don't want to change the direction of the thread.
Thanks Martin
HDMI is an extremely bad RFI generator and radiator.? I've tested several for radiated emissions.? If you can find a WELL SHIELDED and PROPERLY TERMINATED SHIELD you might have a chance.? Any and nearly all HDMI cables from China will likely be RFI antennas.
Dave - W?LEV
I'm surprised how Raspberry get away with the amount of RFI the Pi's cause.
I purchased an RPi 4 when they first released, I had to return it thinking it was faulty but the replacement was as bad. Turns out I could not use wireless keyboard and mouse at the same time that I used HDMI cable as the noise emitted by the video signal would wipe out the 2.4Ghz wireless connection. My RPi 3 isn't as bad, but if you are using HDMI with your RPi3, then maybe try to unplug it and maybe use remote access to your Pi.
Martin
You described everything except the most important part: The antenna.
--
|
Re: RFI on LW and MW with RPI and AS HF+
I was using an expensive high quality HDMI cable, which did not help.
Using a small form factor PC has no issues though, even with cheap Chinese cables. I tried with the Pi4 in a shielded case and that didn't help either.
My Pi 4 is no longer used for anything radio related and is only powered on in a headless configuration for things like Octoprint.
My Pi 3 is old now and has power supply issues, so that is not often used. Not sure where the fault is, no its not the Micro-USB connection, I wired directly to the IO header and had the same problem, brown out pretty much all the time.
I use a couple of small PC's now, all is fine.
However, solar inverter for my panels, now that is a different story.
Anyway, I don't want to change the direction of the thread.
Thanks Martin
HDMI is an extremely bad RFI generator and radiator.? I've tested several for radiated emissions.? If you can find a WELL SHIELDED and PROPERLY TERMINATED SHIELD you might have a chance.? Any and nearly all HDMI cables from China will likely be RFI antennas.
Dave - W?LEV
I'm surprised how Raspberry get away with the amount of RFI the Pi's cause.
I purchased an RPi 4 when they first released, I had to return it thinking it was faulty but the replacement was as bad. Turns out I could not use wireless keyboard and mouse at the same time that I used HDMI cable as the noise emitted by the video signal would wipe out the 2.4Ghz wireless connection. My RPi 3 isn't as bad, but if you are using HDMI with your RPi3, then maybe try to unplug it and maybe use remote access to your Pi.
Martin
You described everything except the most important part: The antenna.
--
|
Re: RFI on LW and MW with RPI and AS HF+
HDMI is an extremely bad RFI generator and radiator.? I've tested several for radiated emissions.? If you can find a WELL SHIELDED and PROPERLY TERMINATED SHIELD you might have a chance.? Any and nearly all HDMI cables from China will likely be RFI antennas.
Dave - W?LEV
I'm surprised how Raspberry get away with the amount of RFI the Pi's cause.
I purchased an RPi 4 when they first released, I had to return it thinking it was faulty but the replacement was as bad. Turns out I could not use wireless keyboard and mouse at the same time that I used HDMI cable as the noise emitted by the video signal would wipe out the 2.4Ghz wireless connection. My RPi 3 isn't as bad, but if you are using HDMI with your RPi3, then maybe try to unplug it and maybe use remote access to your Pi.
Martin
You described everything except the most important part: The antenna.
|
Re: RFI on LW and MW with RPI and AS HF+
I'm surprised how Raspberry get away with the amount of RFI the Pi's cause.
I purchased an RPi 4 when they first released, I had to return it thinking it was faulty but the replacement was as bad. Turns out I could not use wireless keyboard and mouse at the same time that I used HDMI cable as the noise emitted by the video signal would wipe out the 2.4Ghz wireless connection. My RPi 3 isn't as bad, but if you are using HDMI with your RPi3, then maybe try to unplug it and maybe use remote access to your Pi.
Martin
You described everything except the most important part: The antenna.
|
Re: RFI on LW and MW with RPI and AS HF+
You described everything except the most important part: The antenna.
|
RFI on LW and MW with RPI and AS HF+
Hello all,
?
I use my Airspy HF+ via a Raspberry PI 3B and spyserver. This works fine on HF and above.
On LW and MW the PI generates a lot of RFI. This makes these bands not usable.
I use a PI approved power supply and the original Airspy cable.
?
Does somebody know of a good solution for this problem
?
Spoiler, using the Airspy HF+ direct to my laptop or tablet works fine...
?
Ernst-Jan
|
You can use ChatGPT or Claude to get familiar with general Linux stuff.?
?
The CPU governor controls how your processor scales its frequency based on system load. On Raspberry Pi systems, this can significantly impact real-time data processing applications like yours.
Here's how to check and potentially modify your CPU governor:
1. First, check your current CPU governor setting:
```bash
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
```
2. For consistent real-time processing of streaming data, you'll likely want to use the "performance" governor instead of the default "ondemand" governor:
```bash
sudo apt install cpufrequtils
sudo cpufreq-set -g performance
```
3. To make this change permanent across reboots, add this to `/etc/rc.local` before the `exit 0` line:
```bash
cpufreq-set -g performance
```
The default "ondemand" governor might be causing your processor to scale down when it shouldn't, leading to dropped samples during high data rate operations. The "performance" governor keeps the CPU running at maximum frequency, which should help with consistent data processing from your AirSpyHF+.
Would you like me to provide any additional suggestions for optimizing your Raspberry Pi for this SDR application?
|
CPU governor - where to check this? Is this a Rpi thing? On Mon, Apr 7, 2025 at 6:49?PM prog via groups.io <info@...> wrote:
On Mon, Apr 7, 2025 at 08:47 AM, Al Grant wrote:
Is there anything else at the radio side of this that could be a factor?
No. Check the CPU governor.
-- "Beat it punk!" - Clint Eastwood
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On Mon, Apr 7, 2025 at 08:47 AM, Al Grant wrote:
Is there anything else at the radio side of this that could be a factor?
No. Check the CPU governor.
|
Hello,
I think what I am about to outline below probably has nothing to do
with my SDR, but I am at a loss to work out whats going on, so just in
case.....
I have a python project on Rpi5 hardware which uses a AirSpyHF+ to
stream in the data at 768000. It was working beautifully on a RPi5
with libairspyhf and ctypes to get it into python.
But then my Rpi5 died and I had to get a new one - I thought I could
just swap over the SD card into the new one and be up and running
again, but it was not the case.
The RPi5 I had used a version of the BCM2712 called BCM2712 c0, the
new one uses BCM2712 d0 - something to do with saving space on the dye
of the chip - anyway the upshot was that I needed to upgrade bookworm
on the SD card, and doing this offline didn't work.
So I tried to reinstall my python project on a fresh SD card with a
fresh build of libairspyhf and a fresh build of my python project - it
runs but now my code is dropping samples.
In theory there should be no reason for this, the changes to the Rpi
hardware have same performance, and I am using v1.8 of libairspyhf -
so thats the same too.
Is there anything else at the radio side of this that could be a factor?
Thanks
Al
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Back on list (never left really, but had some stuff to deal with)
Hey guys,
I am finally back. I had some issues over the last couple of years dealing with the after effects of a house fire and an insurance company that was fighting me over the losses. Btw, I got lucky on some stuff and not so much on others. The Airspy R2 and other units I won in the giveaway prior to 2023 are still with me (I had taken them buy a friends place to have him help me set it up). Unfortunately, the windows machine I was going to use here at home got destroyed in a fire and it has taken me this long to get a used Mac mini to replace it (2012 late model). Anyway, I need to update the firmware on the units and am not sure how to do it from a Mac. Still don’t have a replacement windows machine, so I am wondering how I can update the firmware on my OS X machine. Also looking at using either the macports air spy command line server or the home-brew open source version. Some help here would be appreciated.
Btw, here’s the news story from June 27th, 2023. The house on the east-west street there was mine and that fire spread from his to mine, destroying my room in the add-on. Btw, this fire was caused by improper charging of 2 e-bike lithium battery packs. I was not at home at the time the fire broke out. Here’s the story:
Sorry if that seems a bit off topic in the latter half of this mailing, but I wanted you guys to know that this blind radio enthusiast was still alive and kicking. Btw, the only laptop I had was a windows 7 machine and it broke while I was staying at a hotel during the house repairs. Never could get a replacement.
-Eric
Ham radio operator n7zzt
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Re: What is the best AGC threshold for AM monitoring
#airspyr2
On Fri, Apr 4, 2025 at 10:28 PM, Vince Cavaseno wrote:
strong signals will blast my ears off.
Lower the AGC threshold AND lower the volume.?
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TL:DR
Place the R2 on its own USB controller if you need best
performance with no dropped packets. At high usage packets may not
arrive in real-time due to competition for time resources. The
mini works nicely at 6 Msps with limited other use. Don't try to
back up a file to a memory stick on the same controller. 10 Msps
is OK probably with things like a keyboard and mouse.
Consult your motherboard manual for which ports go directly to
the CPU and which go through internal hubs.
{^_^}
On 20250404 10:15:55, Jonathan
Winterflood via groups.io wrote:
toggle quoted message
Show quoted text
>
> just analyze this file with claude?
?
with or without,?and the firmware too :)
?
Either way in ideal conditions the required "useful"
bandwidth is well known, as you & joanne have noted :-)
?
If there are retransmissions though, they're invisible to
libairspy, and possibly even to libusb.? there might be some
debug counters available though.
Trying to find out the actual "bus time usage" of a
particular device could be harder, unless it's also in debug
info
?
That said I'm not sure what Dennis really needs/wants.
?
I'm more "concerned" about the firmware side:
If there are too many retransmissions, or bus contention,
the ADC/DMA and USB can start using the same buffer
Besides corruption if the ADC catches up with the USB
transfer, the ADC FIFO can drop samples (Real, not I/Q) due to
memory bus speed limitations - seen in LPC_ADCHS->STATUS0
& STAT0_FIFO_OVERFLOW
The LTC usb stack might eventually complain if the USB link
is chronically slower than the ADC, or maybe it'll just drop
buffers (blocks)
?
Of course these are firmly in the "fix your setup" realm
A way of checking for overflows could be nice - but not a
hard abort of course.
A missed sample here or there is not catastrophic in most
applications though
?
Have a great weekend :)
J
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Re: What is the best AGC threshold for AM monitoring
#airspyr2
I'm interested in this thread because I'm having an issue with the AGC on v. 1920. Unless I have it set really low, like 20, strong signals will blast my ears off. When I have to tune in a weak signal, I have to manually increase the AGC threshold. Is there some setting that I'm missing? If I push the Learn button, it sets the system at 64 or so, at which point strong signals completely overload the system.
?
Vince C.
Mashpee, MA
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Kriss Kliegle
Martin
prog