# Analog cable TV USB is detaching; related with power/antenna

## mv

This is a real hardware-only question for electro-engineers:

I have an analog (over cable) TV USB stick (sundtek) attached to a USB3 port.

Now my problem is that whenever something in the house needs some power (microwave, vacuum cleaner, freezer, ..., even if this device is far aways and runs over a different fuse), the stick gets detached, i.e. the kernel reacts as if it has been drawn; sometimes it is "reattached" for a few seconds (or sometimes less), but esentially it works only again if the power device is switched off.

The strange thing is that no other USB device is affected, and moreover, this does not happen if the antenna cable is removed.

So it appears that I need some sort of isolation of the antenna "power" (the antenna is fed by some cable provider).

Does such an "isolation device" exist or can be built?

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## Dominique_71

Such "isolation" devices are high frequency transformers. The radio amateurs call then baluns.

Your issue is very strange. I think more for a problem with the ground. An antenna installation must be grounded at the earth potential. Maybe just to put a wire between the ground of your antenna and a water pipe can solve your issue. Otherwise, for such a balun transformer, I would talk with some radio amateurs about it, because they are the only I know using such devices, and they know how to calculate and make them.

EDIT: Be aware a water pipe is not a regular electrical earth. In most countries, it is even completely forbidden to use them for that.

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## mv

Thanks a lot. I do not understand much about "ground" and why it is necesary, but I was also somehow suspecting that perhaps the "ground" of the cable and of the computer "differ". Perhaps I should try to connect them...

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## NeddySeagoon

mv,

Tell us more.  I assume the cable TV comes into your home and is terminated in a powered box of some kind?

Then you have an "antenna" cable from this box to your system.

Is your system a laptop or desktop?

Does this happen if its battery powered - with the power brick disconnected?

Beware plastic waterpipes if you are trying to use them for a ground  :)

Incidentally, too many grounds are as bad or worse than incorrect grounding. Then you get ground loops, which cause noise due to the induced currents caused by the AC in the power distribuion system in your home.  

Ideally, you need the grounds connected to a single 'star point', so there can be no loops but safety considerations associated with operating each piece of mains powered equipment independantly usually make that impossible.

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## mv

 *NeddySeagoon wrote:*   

> Tell us more.  I assume the cable TV comes into your home and is terminated in a powered box of some kind?

 

I have no idea: In my flat there is only an antenna connector socket; each flat has some. Probably there is some device of the cable company for the whole house, but I do not know what and where. Probably the host could show me, but even if I would see the device I could probably not tell what it is.

 *Quote:*   

> Is your system a laptop or desktop?

 

desktop; only USB3. It will take a while until I can organize a laptop here, but I will try and report when I find out something.

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## NeddySeagoon

mv,

The cable company will bring in one cable to a distribution amplifer, which will feed all the flats.

Its like a signal booster but with more outputs. It will be powered but its outside your control/influence.

Is your USB dongle USB2 or USB3?

A USB3 port can provide more power than a USB2 port so it should not be a power issue.

Can you put the output of lsusb -vvv onto a pastebin so we can check out your USB device tree. 

Do you have other USB ports you can test with?

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## mv

 *NeddySeagoon wrote:*   

> Is your USB dongle USB2 or USB3?

 

The stick is USB2. They told me at sundtek that there are some known problems when connecting to USB3 due to kernel usb3-driver bugs, but since the problem evidently can be caused by switching on some machine, I doubt now that it is a software problem in my case.

 *Quote:*   

> lsusb -vvv onto a pastebin

 

here you are

You should know that "main" sundtek driver is in userland, but it uses some generic USB kernel interface.

When I try the same command while e.g. the cooker is on, it can take ages to finish (depending on how quickly the device "reconnects"), and the bus numbers and device numbers are sorted differently. This is not surprising, since the kernel spits messages like this, usually with a dalay of 15 seconds in between:

 *Quote:*   

> 05:15:09 25.10.14 [kernel] usb 3-8: new high-speed USB device number 100 using xhci_hcd
> 
> 05:15:24 25.10.14 [kernel] usb 3-8: new high-speed USB device number 101 using xhci_hcd

 

The device number counts up to 127 and then restarts at 5 or so. Apparently, the device just disconnects and then reconnects (and the kernel has some timeout of 15 seconds somewhere to realize this).

 *Quote:*   

> Do you have other USB ports you can test with?

 

I tried all connectors on that machine, always with the same result. I am not completely sure that some of the ports are not USB3, but the kernel messages suggested that they are all USB3, too....Last edited by mv on Wed Oct 29, 2014 7:29 pm; edited 1 time in total

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## John R. Graham

@mv, what's the external connection to this device? RG-59 coax?

- John

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## mv

 *John R. Graham wrote:*   

> RG-59 coax?

 

I guess so. It is a "standard" antenna cable; never had any problems with it with other devices.

The USB-stick is put directly into the port. (There is a small USB "extension" cable of a few centimeters for better plugging, but I got the same result also when I removed it).

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## NeddySeagoon

mv,

You have four USB Busses (root hubs).  The controllers are

```
Bus 004 Device 001: ID 1d6b:0003

 iManufacturer           3 Linux 3.17.1-hardened-r1 xhci_hcd

Bus 003 Device 001: ID 1d6b:0002 

  iManufacturer           3 Linux 3.17.1-hardened-r1 xhci_hcd

Bus 002 Device 001: ID 1d6b:0002 

 iManufacturer           3 Linux 3.17.1-hardened-r1 ehci_hcd

Bus 001 Device 001: ID 1d6b:0002 

  iManufacturer           3 Linux 3.17.1-hardened-r1 ehci_hcd
```

So buses 003  anh 004 are USB3 anh buses 001 anh 002 are USB2.

Now, whats connected where

```
Bus 003 Device 005: ID 2659:1210  

  iManufacturer           1 Sundtek

  iProduct                2 MediaTV Pro III (EU)

    MaxPower              500mA
```

 That will be your TV card on bus 03 which is USB3

You might want to move it around to see if you can get it onto bus 001 or bus 002, so you con eliminate USB3 backwards compatibility issues.

That 500mA MaxPower is well within USB3 but its right on the limit for USB1/2.  This means when you move the dongle to a USB2 bus it must be the only bus powered device on the bus or you can expect USB power issues. 

You also have a mouse, keyboard and memery stick on bus 003.

lsusb will tell you what is where when you move things around.

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## mv

 *NeddySeagoon wrote:*   

> You also have a mouse, keyboard and memery stick on bus 003.

 

Yes, although they are connected to different USB sockets: All 6 USB sockets accessible from outside (2 in front, 4 in the back) apparently end in bus 003 and are reported by the kernel as usb 3-8: I reckognize no difference if I use a different socket. I guess the other buses are only used somehow internally (e.g. there is a card reader built in).

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## NeddySeagoon

mv,

This is a long shot ...

Some motherboards have an option to pawer some/all USB sockets from the +5v STBY.

Its a bad idea in that it is a poorly regulated low power supply but its always on, so a connected USB device can wake up the box.

Do you have such an option?

How is it set.?

Tell us your motherboard ... dmidecode  will save you looking inside.

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## mv

 *NeddySeagoon wrote:*   

> Some motherboards have an option to pawer some/all USB sockets from the +5v STBY.

 

Do you mean by BIOS/UEFI?  Concerning USB, I found only the options "USB Controller" and "Legacy USB Support" which are both enabled and which I might disable.

 *Quote:*   

> Tell us your motherboard ... dmidecode  will save you looking inside.

 

```
# dmidecode 2.11

SMBIOS 2.7 present.

78 structures occupying 2911 bytes.

Table at 0x000EB850.

Handle 0x0000, DMI type 0, 24 bytes

BIOS Information

   Vendor: American Megatrends Inc.

   Version: V4.0

   Release Date: 04/10/2013

[...]

      ACPI is supported

      USB legacy is supported

      BIOS boot specification is supported

      Targeted content distribution is supported

      UEFI is supported

   BIOS Revision: 4.6

[...]

Handle 0x0009, DMI type 8, 9 bytes

Port Connector Information

   Internal Reference Designator: J3A1

   Internal Connector Type: None

   External Reference Designator: USB1

   External Connector Type: Access Bus (USB)

   Port Type: USB

[...]
```

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## NeddySeagoon

mv,

Its usually a jumper, or several jubpers on the motherboard.

I was looking for 

```
Handle 0x0002, DMI type 2, 15 bytes

Base Board Information

        Manufacturer: ASUSTeK Computer INC.

        Product Name: M4A78T-E

        Version: Rev 1.xx
```

so I could look in the motherboard manual.

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## John R. Graham

 *mv wrote:*   

>  *John R. Graham wrote:*   RG-59 coax? 
> 
> I guess so. It is a "standard" antenna cable; never had any problems with it with other devices.
> 
> The USB-stick is put directly into the port. (There is a small USB "extension" cable of a few centimeters for better plugging, but I got the same result also when I removed it).

 Does it look like this?The connector on the card (right-hand side of this image). The cable connecting to it.If so, then the solution to your problem is something like this, which is an RF isolation transformer. Your issue is likely ground related, which is why isolating the RF input from local ground at the computer should eliminate the issue.

- John

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## John R. Graham

 *Dominique_71 wrote:*   

> Such "isolation" devices are high frequency transformers. The radio amateurs call then baluns.

 They're only called baluns when one side is a push-pull (i.e., balanced) line and the other is coaxial (i.e., unbalanced), thus "balun": balanced to unbalanced converter.

However, this is a technical nit; I agree with everything else you said except perhaps that the problem is strange. Ground potential related problems are fairly common.

- John

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## mv

The motherboard is MSI B85M-P33, and I also found a motherboard handbook to download (8 MB PDF, zipped). However, I could not find much useful concerning USB in it.

I guess I should find some cable for grounding. Is it correct to assume that the "outer" part of the cable adapter will be the ground one?

Antenna cables here in Germany look different: They are all like on this picture (male and female, respectively).

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## NeddySeagoon

It can also be a damaged connection between the PC and the building distrbution amplifer, so that there is no ground provided domn the antemma cable.

The antenna ground wends its way through the mains grounding system back to the distrbution amplifer instead.  This gives you a huge loop to pick up switching spikes.

The problem need not even be in your equipment nor in your flat.

If you have a multimeter, its easy to test by measuring the resistance from your unplugged antenna cable outer contact to mains ground.  It should be very low.

Be careful not to hold the mutimeter probes while you make the measurment.  It you get the right answer, it would have been safe.  If you get the wrong answer and some other equipment in the building has a earth fault at the time you make the measuremet, there could be mains voltage across your two contact points.  The multimeter is expendable ... you might not survive.

Do you have access to other antenna points?

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## mv

 *NeddySeagoon wrote:*   

> If you have a multimeter

 

I have one in another town, many miles away. Maybe next year I will be there to get it. Currently, I do not even have a cable for grounding at hand...

It will  probably take time, until I report back.

 *Quote:*   

> Do you have access to other antenna points?

 

Not in my flat.

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## NeddySeagoon

mv,

Your motherboard (page 11) has two jumpers JUSB_PW1 between the VGA connector and the CPU an JUSB_PW2 between the PCIe 1 lane slot and the edge of the board.

Page 13 lists them as 2x USB power jumpers.

Page 24 explains hom in set the jumpers.

The default settings are what you need.  The USB ports then do not support wakeup and are powered from the real +5v, not 5v STBY.

References are to the English vesion of the manual.

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## mv

 *NeddySeagoon wrote:*   

> The default settings are what you need.

 

Thanks a lot. Unfortunately, the jumpers are already in these default settings.

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## John R. Graham

 *mv wrote:*   

> Antenna cables here in Germany look different: They are all like on this picture (male and female, respectively).

 Those appear to be Philex connectors. Although I can't immediately find an RF isolation transformer with those ends on it, I do find adapters. Perhaps you could contact the cable company, tell them you have a probable ground loop issue, and ask them for an isolation transformer and the requisite cables.

Otherwise, at least one source:

Isolation transformer.

Various adapters that'll get you there.Local suppliers are better for you, of course, but these links will at least give you a set of part numbers.

- John

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## mv

Thanks to your link, I found the German names for these devices: The english term "ground-loop isolator" is used as well (or sometimes "Masse-Trennfilter").

There exist even some directly for antenna. I guess I will get one (in some days when I have more time).

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