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Ensemble RX II interference source solved and question about magnetic loop!

 

I finally figured out the source of my interference- my USB powered speakers!? Never thought it would be those, so never checked them. However, no matter if I plug in on the desktop USB or the little USB 5V module that plugs into the AC, I get the noise! Unfortunately, I really like these little speakers but I don't absolutely have to use them and the headphones are doing fine for now.

I tried wrapping the USB wires around a couple snap closed ferrite cores I have here.? This did help somewhat, but there's still a nasty central interference band at random on HF (about 5 Khz wide). Other than not using the speakers, might there be something else I could do to stop the interference?? Could I build a better USB filter or do something to the speaker circuit?

Just some thoughts, not critical and thanks in advance.


On a separate note, I would appreciate some thoughts on a Wellbrook loop and how it works with the Softrock as well as performance with a short (less than 8 feet) active antenna.? The loop would primarily be used indoors or perhaps in a 15 foot high attic; the active whip outdoors maybe 15 feet high.? I've seen plenty of videos on these loops/ antennas, but nothing Softrock specific.? Thanks.


Jon
 

Cheap USB speakers are likely moving data on the USB bus at 12 Mbps, the
speed of full speed USB. Really cheap ones might be using low speed, 1.5
Mbps; that has enough bandwidth for mono but would be tight at best for
stereo. (Typically USB audio devices are using 44.1 KHz sampling and 16 bit
depth, so a single channel of audio uses 705.6 Kbps.) Those speeds mean
that the USB data stream itself is the likely source of HF interference,
especially low speed because it has harmonics all over the bands. The most
likely mitigation would be a better USB cable. It might also be necessary
to add shielding to the speakers themselves.

Fancy new stuff might use high speed from USB 2.0; that runs at 480 Mbps,
moving the frequencies outside the HF bands. USB 2.0 devices also come with
better cables because it's necessary for integrity of the faster signals.
Super Speed from USB 3.0 (5 Gbps and up) is not seen on audio devices
except for very large multichannel interfaces; the new generation of
smaller interfaces with USB-C ports are still using 480 Mbps data
transmission.

On Fri, Jun 4, 2021 at 10:51 AM JonI via groups.io <ji425bt=
verizon.net@groups.io> wrote:

I finally figured out the source of my interference- my USB powered
speakers! Never thought it would be those, so never checked them.
However, no matter if I plug in on the desktop USB or the little USB 5V
module that plugs into the AC, I get the noise! Unfortunately, I really
like these little speakers but I don't absolutely have to use them and
the headphones are doing fine for now.

I tried wrapping the USB wires around a couple snap closed ferrite cores
I have here. This did help somewhat, but there's still a nasty central
interference band at random on HF (about 5 Khz wide). Other than not
using the speakers, might there be something else I could do to stop the
interference? Could I build a better USB filter or do something to the
speaker circuit?

Just some thoughts, not critical and thanks in advance.


On a separate note, I would appreciate some thoughts on a Wellbrook loop
and how it works with the Softrock as well as performance with a short
(less than 8 feet) active antenna. The loop would primarily be used
indoors or perhaps in a 15 foot high attic; the active whip outdoors
maybe 15 feet high. I've seen plenty of videos on these loops/
antennas, but nothing Softrock specific. Thanks.


Jon
 

Thanks, Shirley.? As I tune HF, I find that sometimes the interference isn't completely gone, but then again I still have a USB keyboard and other USB devices plugged in.? The USB keyboard is known to cause a lot of interference, but snap closed ferrite has helped with it.

Another interference I'm seeing are carriers spaced about 30 Khz or so apart.? Not everywhere, but certain parts of HF.? The auto notch can take care of them as long as they're not too wide, but sometimes they are a bit wide for auto notch.? I was just reading what the source could be, but I have forgotten and didn't bookmark it.? Rats.

Jon

On 6/4/21 11:13 AM, Shirley Dulcey KE1L wrote:
Cheap USB speakers are likely moving data on the USB bus at 12 Mbps, the
speed of full speed USB. Really cheap ones might be using low speed, 1.5
Mbps; that has enough bandwidth for mono but would be tight at best for
stereo. (Typically USB audio devices are using 44.1 KHz sampling and 16 bit
depth, so a single channel of audio uses 705.6 Kbps.) Those speeds mean
that the USB data stream itself is the likely source of HF interference,
especially low speed because it has harmonics all over the bands. The most
likely mitigation would be a better USB cable. It might also be necessary
to add shielding to the speakers themselves.

Fancy new stuff might use high speed from USB 2.0; that runs at 480 Mbps,
moving the frequencies outside the HF bands. USB 2.0 devices also come with
better cables because it's necessary for integrity of the faster signals.
Super Speed from USB 3.0 (5 Gbps and up) is not seen on audio devices
except for very large multichannel interfaces; the new generation of
smaller interfaces with USB-C ports are still using 480 Mbps data
transmission.

On Fri, Jun 4, 2021 at 10:51 AM JonI via groups.io <ji425bt=
verizon.net@groups.io> wrote:

I finally figured out the source of my interference- my USB powered
speakers! Never thought it would be those, so never checked them.
However, no matter if I plug in on the desktop USB or the little USB 5V
module that plugs into the AC, I get the noise! Unfortunately, I really
like these little speakers but I don't absolutely have to use them and
the headphones are doing fine for now.

I tried wrapping the USB wires around a couple snap closed ferrite cores
I have here. This did help somewhat, but there's still a nasty central
interference band at random on HF (about 5 Khz wide). Other than not
using the speakers, might there be something else I could do to stop the
interference? Could I build a better USB filter or do something to the
speaker circuit?

Just some thoughts, not critical and thanks in advance.


On a separate note, I would appreciate some thoughts on a Wellbrook loop
and how it works with the Softrock as well as performance with a short
(less than 8 feet) active antenna. The loop would primarily be used
indoors or perhaps in a 15 foot high attic; the active whip outdoors
maybe 15 feet high. I've seen plenty of videos on these loops/
antennas, but nothing Softrock specific. Thanks.


Jon
 

no matter if I plug in on the desktop USB or the little USB 5V module that plugs into the AC, I get the noise!
Jon

As it occurs with both power feeds I wonder if it is the speaker amplifier?
There are cheap class D amps around that may well radiate the switching frequency + harmonics.

On a separate note, I would appreciate some thoughts on a Wellbrook loop and how it works with the Softrock as well as performance with a short (less than 8 feet) active antenna.
I've not done any tests but these should give a good signal for a Softrock, maybe more than it actually needs.

73 Alan G4ZFQ
 

Hi Alan,

Yes, I am suspecting the amplifier inside the tiny speaker volume control.? Needless to say, I won't be using it anymore.

Today has been an interference tracking day.? Another source is apparently the Netgear N3100 USB stick I use to WIFI to the router.? I didn't have issues at first, but since I re-ran all the cables today for easier access, I started having issues.? It took two snap together ferrite cores to stop it.

Finally, the source of the tones that get closer as I increase in frequency.? Seems to be the monitor.? If I turn off the monitor, the tones disappear.? Winding the monitor cable through two ferrite cores has curtailed the tones but not completely as I believe it would take additional cores which I don't have.

Once I solve all of this interference, I'm going to have to take pictures of how it all goes as I find special routing, number of cores per cable, etc all custom done.? Any movement of cables, re-routing, etc could jeopardize all of the solved interference.

Jon

On 6/4/21 1:18 PM, Alan G4ZFQ wrote:
no matter if I plug in on the desktop USB or the little USB 5V module that plugs into the AC, I get the noise!
?Jon

As it occurs with both power feeds I wonder if it is the speaker amplifier?
There are cheap class D amps around that may well radiate the switching frequency + harmonics.


On a separate note, I would appreciate some thoughts on a Wellbrook loop and how it works with the Softrock as well as performance with a short (less than 8 feet) active antenna.
I've not done any tests but these should give a good signal for a Softrock, maybe more than it actually needs.

73 Alan G4ZFQ
 

Once I solve all of this interference, I'm going to have to take pictures of how it all goes as I find special routing, number of cores per cable, etc all custom done.? Any movement of cables, re-routing, etc could jeopardize all of the solved interference.
Jon,

You seem to have an exceptional amount of interference problems. I wonder if you have ground loop problems.
Here is a logical way of checking connections /g/softrock40/message/82427

73 Alan G4ZFQ
 

Jon,

As you are having a lot of USB related problems, that's making me think it could be the power supply for the USB circuits in your PC. I suggest you get a powered USB hub and plug everything into the hub to see if that helps.

John D
KC8OFW
 

Hi John,

Well, I have a lot of things going on at the moment.? I'm using an indoor loop which has a preamp, two peaking controls that I can control remotely, and also a relay for switching to lower bands. So a lot of wiring runs from the SDR to where the switches and peaking controls are. One thing I did do this week is take the "wall warts" I've been using and add capacitance and a regulator to a couple to get ripple way down.? I also run a lot of snap closed ferrite cores which help, but I have now run out of them with my extra equipment.

Getting there.? The biggest offender, the USB speakers, disconnected and the result has been greatly improved just from that alone.

Jon

On 6/5/21 4:47 PM, John Duquette wrote:
Jon,

As you are having a lot of USB related problems, that's making me think it could be the power supply for the USB circuits in your PC. I suggest you get a powered USB hub and plug everything into the hub to see if that helps.

John D
KC8OFW

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