[Eeglablist] where to find good EEG amplifiers + AD conversio n

Fri Oct 15 09:41:43 PDT 2004

Hello to those interested in noise from their EEG amplifiers.

I have never found that amplifier noise (i.e. that produced by the
amplification electronics) was a problem with recording the EEG - it is
certainly possible to usually record EEG out to 100 Hz or more with a good
signal-to-amplifier noise ratio (better than 10 dB) with many different
amplifiers - I think the real issue is the pickup of extraneous
environmental noise between the subject and the first  stage of
amplification.  Clearly the best is something like Biosemi with the
amplifier right at the electrode in a shielded room however we have for
years collected EEG with 20 foot or longer (!) shielded leads between the
EEG amplifier and the subject - power line frequency cancellation was needed
and sometimes other interference of unknown origin showed up but not so
often as to be unworkable.

Phil Grieve
Dept. of Pediatrics
Columbia University

-----Original Message-----
From: eeglablist-admin at sccn.ucsd.edu [mailto:eeglablist-admin at sccn.ucsd.edu]
On Behalf Of Hovagim Bakardjian
Sent: Friday, October 15, 2004 4:24 AM
To: 'Tom Campbell, Ph.D.'
Cc: eeglablist at sccn.ucsd.edu
Subject: RE: [Eeglablist] where to find good EEG amplifiers + AD conversio n

Hi,

We have several EEG systems in our lab, among which Biosemi and Neuroscan.
For the frequency range 0.1- 100 Hz, Biosemi has 3 uV pp input noise, while
Neuroscan's (with SynAmps2 amplifiers) has 4 uV pp input noise. The
interpretation as to if this is a significant reduction of noise is up 
the reader.

(It is clear that the merits of an EEG system can be estimated only as a 
combination
of its hardware and software capabilities, as well as of price, support and 
usability, of course.)

Let me know, if you want to know more.
Best Regards,
Hova
------------------------------------------------
Hovagim Bakardjian
Laboratory for Advanced Brain Signal Processing
Brain Science Institute, RIKEN

At 12:49 AM 10/15/2004, you wrote:
>Yes Parhain,
>We have observed an improvement in the signal-to-noise ratio using the 
>Biosemi ActiveTwo system. We record brainstem evoked potentials and 
>have observed better signal quality with the active electrode. I have 
>not crunched the numbers and we have only run a couple of subjects 
>using the new system, but the signals are noticeably less noisy than 
>they were with our Nicolet system. Best,
>CJP
>Christopher J. Poletto, Ph.D.
>Staff Research Biomedical Engineer
>Laryngeal and Speech Section
>Medical Neurology Branch, NINDS
>National Institutes of Health
>Building 10, Room 5D38
>10 Center Drive, MSC 1416
>Bethesda, MD 20892-1416
>
>
>-----Original Message-----
>From: Tom Campbell, Ph.D. [mailto:tom.campbell at helsinki.fi]
>Sent: Thursday, October 14, 2004 10:50 AM
>To: Robert Oostenveld
>Cc: eeglablist at sccn.ucsd.edu; M.J.A.M. van Putten (Clinical Science 
>Systems)
>Subject: Re: [Eeglablist] where to find good EEG amplifiers + AD conversion
>
>
>Hoi,
>
>I would be curious to hear what you think of the BioSemi system: 
>http://www.biosemi.com/
>
>The idea of having the amplifier on the electrode seems an interesting 
>one. In practice, has anyone found an improvement in signal-to-noise 
>with this approach?
>
>--
>Parhain terveisin,
>
>Tom Campbell, Ph.D.
>
>Room 137
>Helsinki Collegium for Advanced Studies
>University of Helsinki, Finland
>P.O.Box 4 (Fabianinkatu 24)
>FIN-00014 University of Helsinki
>Finland
>
>Phone: +358-9 191 23256
>Telefax: +358-9 191 22924
>Mobile: +358-4 154 09764 87
>E-mail: tom.campbell at helsinki.fi
>
>URL: http://tomcampbell.dyndns.org/
>
>
>Quoting Robert Oostenveld <roberto at smi.auc.dk>:
>
> > Hi Michel,
> >
> > A company that sells EEG amplifiers that completely work with Linux
> > (drivers+aquisition+analsyis) is ANT Software, see 
> > http://www.ant-software.nl. The amplifier that they include in their 
> > Cognitrace system is a TMS Refa amplifier (see http://www.tmsi.com), 
> > but I think that TMS as a mainly hardware company does not support 
> > linux. I believe the amplifier is pretty good, but I have not done 
> > any serious measurements with it myself.
> >
> > best regards,
> > Robert
> >
> > On 12 Oct 2004, at 14:28, M.J.A.M. van Putten (Clinical Science
> > Systems) wrote:
> >
> > > Hi,
> > >
> > > does anyone know a company that sells good EEG amplifiers, 
> > > including A/D conversion, at least 8 bipolar inputs plus some aux 
> > > inputs (for ECG, oxygen saturation, etc), with drivers for Linux 
> > > and/or Windows?
> > >
> > > Thanks.
> > >
> > > Michel van Putten
> > > ---------------------------------------------
> > > Michel J.A.M. van Putten MD PhD
> > > Neurologist/clinical neurophysiologist
> > > Haga Ziekenhuis, lokatie Leyenburg
> > > Leyweg 275, 2545 CH The Hague
> > > Netherlands
> > > TEL: +31 (0)70 359 2000
> > > FAX: +31 (0)70 359 2189 
> > > m.j.a.m.vanputten at clinicalsciencesystems.com
> > > ----------------------------------------------
> > >
> > --------------------------------------------------------------------
> > --
> > Robert Oostenveld, PhD
> > Center for Sensory-Motor Interaction (SMI)
> > Aalborg University, Denmark

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