Poster Matt wrote:
> Paul wrote:
>> Poster Matt wrote:
>>> Sorry if this is OT, I've had no luck getting this question answered
>>> elsewhere (on web forums) and these groups tend to be populated by
>>> people who have a higher degree of technical expertise.
>>>
>>> Hi,
>>>
>>> I've just got a new Sennheiser headset microphone and a Buddy USB
>>> sound adaptor for my speech recognition software, the combination of
>>> which is supposed to be among the best set-ups for getting the best
>>> possible levels of speech recognition accuracy.
>>>
>>> I'm told the Buddy USB sound adaptor should be put in the, or one of
>>> the, Primary USB ports - I've got 8 USB ports and can't work out
>>> which of these are Primary USB ports. Device Manager hasn't helped
>>> me, but I'm not exactly sure what I'm looking for.
>>>
>>> How can I tell which is a Primary USB Port, and specifically if my
>>> Buddy USB sound adaptor is plugged into a Primary USB Port?
>>>
>>> Thanks guys.
>>
>> In the world of USB, there are no "second class citizens" :-)
>>
>> You can have more than one controller chip, which controls USB ports.
>>
>> USB USB
>> chip chip
>> / | | \ / \
>> / | | \ / \
>>
>> In Device Manager, you aren't looking at physical ports, but at the logic
>> blocks that control the USB ports. So don't be concerned, if you have
>> eight physical USB ports, and only five things show up in Device Manager.
>> Those five things are the logic blocks that control the eight ports.
>> There will be more USB 1.1 logic blocks, than USB 2.0 logic blocks, and
>> the logic blocks are bound dynamically to the physical ports, as a
>> function
>> of the device type (i.e. a USB 1.1 peripheral or a USB 2.0 peripheral).
>>
>> In terms of electrical qualities, the ports on the back of the computer,
>> in the I/O area (that metal plate with all the connectors on it), are the
>> best connectors. Some DIY computer builds, have poor quality wiring to
>> the front mounted ports, and sometimes the front ports suffer from
>> problems
>> as a result. So start your testing, using the ports on the back of the
>> computer, to get a good idea of how the stuff should be working.
>>
>> That is as close to "Primary" as I can get for you, because the USB ports
>> don't have artificial titles.
>>
>> If you later switch to the front mounted ports, and experience problems,
>> while the back ports did not give you problems, then you'll have a better
>> idea as to where you should be connecting.
>
> What I have gleaned from reading various faqs and threads is that
> interference from other electronics affects the audio quality. My goal
> is to get up to 99% accuracy from the speech recognition software, I
> already have a high level of accuracy, I just want to get up as high as
> possible which people say is currently (with today's technology) about
> 99%. Just a little electronic interference brings that down a little. So
> the advise is not to use an internal soundcard because that can be
> housed near electronics which can interfere a little. So you use an
> (external) USB sound card and make sure that other USB devices don't
> interfere at all by making sure that the USB port is a 'Primary' one and
> is directly connected to the motherboard. If there is no distinction
> between 'Primary' and 'Secondary' in the USB standard might it be what
> is meant is as simple as the wiring passing through several USB ports on
> the way to the motherboard (and that this is to be avoided)?
>
> I was hoping to find a quick and easy way to identify which was the
> 'Primary' port without running a sound test -which the software has
> available- for each USB port until I find the lowest interference level.
> But from what you say I think that's what needs to be done, try each
> port and run a sound test and measure it's levels and final score.
> Tedious with 8 ports. Still it's Sunday tomorrow, I can spare an hour or
> two.
>
> Thanks very much.
There is an example of a USB audio device here. It uses isochronous
endpoints, one for transmit and one for receive, and the purpose of
those, is to guarantee bandwidth and low latency for the sampling
process. (The USB20.pdf 650 page standard, from usb.org, has more
details on this.)
Any analog to digital conversion process, has the opportunity to add
background noise to the signal. And that wouldn't change, whether a regular PCI
sound card was used, or a USB audio solution was used. You would need to
check the quotations of noise floor, to see if there was a significant
difference between the various sound input solutions.
I know that it is possible for the position or shielding of a sound
card, to make a difference to audio performance. A poster here, a few
years back, mentioned doing an experiment, where he moved a sound
card to the last slot, and put a metal cover over it. He got something
like a 10dB improvement in the noise floor. And that would be caused by
reducing electromagnetic interference coming from the rest of the
computer, to the ADC.
Those are the kinds of effects that would be harder to predict (there is
no way to know how good or diligent, the designer of the USB microphone
is). As an example, there have been motherboards, where the built-in sound
was a disaster, and implies no one bothered to verify the audio performance
before the motherboard was put into production.
But as far as the USB transfer protocol goes, about the only thing
that can go wrong, is for packets to be corrupted in transit. Reading
the USB20 spec, it mentions that isochronous transfers don't have
provisions for error detection and retransmission (which might be used
for normal asynchronous transfers to peripherals). So if a packet has
bad data in it (would sound like a burst of static perhaps), USB doesn't
have a provision to fix it. This is similar to some other media, that
have no opportunity to correct errored bits. (The DVI interface to an
LCD monitor would be an example - if the signal on the cable is weak,
snow shows up, and the interface is not designed to ask for a
retransmission of any corrupted parts of the image, because the
interface is unidirectional.)
I think, by all means now, you should carry out your test cases, to
see if there is any effect. But you should be careful in your test
design, to come up with a way to measure the differences, if they
exist. I would think the design of the microphone itself, may be
more significant than the rest of the transfer process.
In article <s5s994l4rtvlfm239o0bc5heq8v3dq1cej@4ax.com>, kony
<spam@spam.com> wrote:
>
> As Paul mentioned, any of the motherboard mounted USB2 ports
> should be equally good. With some caveats.
Exept that's not true, even in my limited experience.
I have quite often run across a PC or laptop with two USB ports on the
back. Plugging the mouse into one works, but plugging the mouse into
the other refuses to work. Anything else I've tried plugged into the
second port works. Whether this is a power issue or a Windows software
issue or something else, it definitely proves that not all USB ports
are created equal in every way. :-)
_-_
It's Me /o o\
Over Here < U >
\ v /
/ \
"Poster Matt" <postermatt@no_spam_for_me.org> wrote...
>
> I'm not an electrical engineer and have no experience of how computer
> components can individually affect each other inside a PC. I was trying to
> come up with a logical reason why a signal from one USB port might degrade a
> little while that not happening from another port a cm or 2 or 3 away.
I suspect your hardware vendor just doesn't want you using an external hub,
which may be sharing power or bandwidth with other devices. Any USB port either
directly connected to the MoBo (sometimes up to 8 on the backplane) or connected
directly to an internal header (often 2 or more) should be fine.
On Sat, 02 Aug 2008 18:16:01 GMT, Poster Matt
<postermatt@no_spam_for_me.org> put finger to keyboard and composed:
>Sorry if this is OT, I've had no luck getting this question answered
>elsewhere (on web forums) and these groups tend to be populated by
>people who have a higher degree of technical expertise.
>
>Hi,
>
>I've just got a new Sennheiser headset microphone and a Buddy USB sound
>adaptor for my speech recognition software, the combination of which is
>supposed to be among the best set-ups for getting the best possible
>levels of speech recognition accuracy.
>
>I'm told the Buddy USB sound adaptor should be put in the, or one of
>the, Primary USB ports - I've got 8 USB ports and can't work out which
>of these are Primary USB ports. Device Manager hasn't helped me, but I'm
>not exactly sure what I'm looking for.
>
>How can I tell which is a Primary USB Port, and specifically if my Buddy
>USB sound adaptor is plugged into a Primary USB Port?
>
>Thanks guys.
You can use Microsoft's UVCview utility to show you how your 8 ports
and devices connect to your USB root hubs:
I'm not sure how critical a consideration bandwidth would be for an
audio application, but you could try to arrange your devices so that
your microphone is the only device on a particular hub.
- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
Franc Zabkar wrote:
> You can use Microsoft's UVCview utility to show you how your 8 ports
> and devices connect to your USB root hubs:
>
> http://www.users.on.net/~fzabkar/USB...VCView.x86.exe
>
> I'm not sure how critical a consideration bandwidth would be for an
> audio application, but you could try to arrange your devices so that
> your microphone is the only device on a particular hub.
Thanks Franc. I'll take a look. Cheers for the file link.
On 2008-08-03, Franc Zabkar <fzabkar@iinternode.on.net> wrote:
>
> I'm not sure how critical a consideration bandwidth would be for an
> audio application, but you could try to arrange your devices so that
> your microphone is the only device on a particular hub.
I had exactly the same thoughts. The only rational reasons I can
see for demanding a root hub is if there is any concern about
latency - but if that is the case then recommending USB in the
first place is ridiculous since it is something that USB does poorly
at the best of times.
Reading through the OP's requirements I can't help thinking that
they have been attacked by a marketroid somewhere along the line.
Speech recognition should need a decent mic and that is about it.
I suspect that if the software really requests all this it is simply
an attempt to pass off poor product performance onto the hardware.
In any case you may find that you don't have any root hubs that
you can connect to. It is not unusual for the USB bus to be broken
up by a hub either onboard or integrated into the USB chipset
itself. In such circumstances there may be no socket that connects
directly to the root hub.
Andrew Smallshaw wrote:
> On 2008-08-03, Franc Zabkar <fzabkar@iinternode.on.net> wrote:
>> I'm not sure how critical a consideration bandwidth would be for an
>> audio application, but you could try to arrange your devices so that
>> your microphone is the only device on a particular hub.
>
> I had exactly the same thoughts. The only rational reasons I can
> see for demanding a root hub is if there is any concern about
> latency - but if that is the case then recommending USB in the
> first place is ridiculous since it is something that USB does poorly
> at the best of times.
>
> Reading through the OP's requirements I can't help thinking that
> they have been attacked by a marketroid somewhere along the line.
> Speech recognition should need a decent mic and that is about it.
> I suspect that if the software really requests all this it is simply
> an attempt to pass off poor product performance onto the hardware.
>
> In any case you may find that you don't have any root hubs that
> you can connect to. It is not unusual for the USB bus to be broken
> up by a hub either onboard or integrated into the USB chipset
> itself. In such circumstances there may be no socket that connects
> directly to the root hub.
>
USB has isochronous capability, for reserving bandwidth for things
like audio applications. That means continuous bit rate applications
were not an afterthought.
This USB audio chip, has an isochronous block for input and one
for output.
On Mon, 04 Aug 2008 12:04:20 -0400, Paul <nospam@needed.com> put
finger to keyboard and composed:
>Andrew Smallshaw wrote:
>> On 2008-08-03, Franc Zabkar <fzabkar@iinternode.on.net> wrote:
>>> I'm not sure how critical a consideration bandwidth would be for an
>>> audio application, but you could try to arrange your devices so that
>>> your microphone is the only device on a particular hub.
>>
>> I had exactly the same thoughts. The only rational reasons I can
>> see for demanding a root hub is if there is any concern about
>> latency - but if that is the case then recommending USB in the
>> first place is ridiculous since it is something that USB does poorly
>> at the best of times.
>>
>> Reading through the OP's requirements I can't help thinking that
>> they have been attacked by a marketroid somewhere along the line.
>> Speech recognition should need a decent mic and that is about it.
>> I suspect that if the software really requests all this it is simply
>> an attempt to pass off poor product performance onto the hardware.
>>
>> In any case you may find that you don't have any root hubs that
>> you can connect to. It is not unusual for the USB bus to be broken
>> up by a hub either onboard or integrated into the USB chipset
>> itself. In such circumstances there may be no socket that connects
>> directly to the root hub.
>>
>
>USB has isochronous capability, for reserving bandwidth for things
>like audio applications. That means continuous bit rate applications
>were not an afterthought.
>
>This USB audio chip, has an isochronous block for input and one
>for output.
>
>http://www.cmedia.com.tw/files/doc/U...eet%20v1.6.pdf
>
>This article summarizes the characteristics.
>
>http://www.beyondlogic.org/usbnutshell/usb4.htm
>
> "Isochronous Transfers provide
>
> * Guaranteed access to USB bandwidth.
> * Bounded latency."
>
>HTH,
> Paul
On 2008-08-04, Paul <nospam@needed.com> wrote:
>
> USB has isochronous capability, for reserving bandwidth for things
> like audio applications. That means continuous bit rate applications
> were not an afterthought.
I am more than familar with USB's different transfer modes, you
don't need to start quoting web sites in that regard. However,
don't confuse bounded latency with _low_ latency - it is still
quite high by historical standards. You won't get a lantency of
less than 1 or 2 ms using USB even directly connected to the root
hub - this may go up to perhaps 10 ms if it is going through a
couple of hubs first. If you think this doesn't sound too bad
consider that good ol' RS232 allowed responses within a couple of
_microseconds_.
Andrew Smallshaw wrote:
> On 2008-08-04, Paul <nospam@needed.com> wrote:
>> USB has isochronous capability, for reserving bandwidth for things
>> like audio applications. That means continuous bit rate applications
>> were not an afterthought.
>
> I am more than familar with USB's different transfer modes, you
> don't need to start quoting web sites in that regard. However,
> don't confuse bounded latency with _low_ latency - it is still
> quite high by historical standards. You won't get a lantency of
> less than 1 or 2 ms using USB even directly connected to the root
> hub - this may go up to perhaps 10 ms if it is going through a
> couple of hubs first. If you think this doesn't sound too bad
> consider that good ol' RS232 allowed responses within a couple of
> _microseconds_.
>
The info was more for the benefit of the OP, who appears spooked
by USB.
Re: Determining Which Is The Primary USB Port. 
Linear Mode
