Value in Signal display with rulers

Obtaining data from various hardware devices
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tsvs.lc
Posts: 7
Joined: Fri Sep 11, 2015 8:59 am

Value in Signal display with rulers

Post by tsvs.lc »

Hi There,

I use neurosky with single channel.
I would like to know that when in signal display box appeared , i can enable rules.
On the ruler, I can see start from 0 to ups down from + to - depending on the signal.

I want to know what it means it comes -1000 or 500 ? does it indicate the uV value or
something else

jtlindgren
Posts: 775
Joined: Tue Dec 04, 2012 3:53 pm
Location: INRIA Rennes, FRANCE

Re: Value in Signal display with rules

Post by jtlindgren »

Hi,

the NeuroSky driver seems to return directly what is returned by the manufacturers TG_GetValue() function. The unit is not indicated in the code that I can see. If you find out, please let us know. :)

ps. generally you can see the channel unit (voltage etc) by connecting the 'channel units' stream to the signal display and enabling the units. However the driver needs to provide this info, and not all of them do.


Cheers,
Jussi

tsvs.lc
Posts: 7
Joined: Fri Sep 11, 2015 8:59 am

Re: Value in Signal display with rulers

Post by tsvs.lc »

I get the info.

(rawValue * (1.8/4096)) / 2000
The unit is volt

How do we get the value using openvibe ?
do we need to do manually !

jtlindgren
Posts: 775
Joined: Tue Dec 04, 2012 3:53 pm
Location: INRIA Rennes, FRANCE

Re: Value in Signal display with rulers

Post by jtlindgren »

You can insert that formula to the simple dsp box.


Cheers,
Jussi

tsvs.lc
Posts: 7
Joined: Fri Sep 11, 2015 8:59 am

Re: Value in Signal display with rulers

Post by tsvs.lc »

Well, I tried that

from the signal ac. box to simple dsp box.
In dsp box :

(x * (1.8/4096)) / 2000

after that from dsp box to signal display. I cant see the channel units when I press the
channel units button and I cant see Y ruler when I click the ruler.

do we need to have another settings ?

jtlindgren
Posts: 775
Joined: Tue Dec 04, 2012 3:53 pm
Location: INRIA Rennes, FRANCE

Re: Value in Signal display with rulers

Post by jtlindgren »

You can use 'channel units generator' box then to generate a stream specifying the correct unit, and feed the output of that to 'signal display'. One reason why units are not carried in the signal stream is that its hard to automatically change the unit after transformations.


Best,
Jussi

tsvs.lc
Posts: 7
Joined: Fri Sep 11, 2015 8:59 am

Re: Value in Signal display with rulers

Post by tsvs.lc »

Thanks.
Please attached screem shot at http://imgur.com/a/DTE0g

in the first screen shot :

((x * (1.8/4096)) / 2000 ) * 1000000 ===> to convert from V to uV

in the second screen shot :

i can see y value change. Is this correct ?

I would like to know in dsp box , we mention x , the x is raw value.
The formula is calculated from rawValue.

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