From: Joerg Hansmann (info_at_jhansmann.de)
Date: 2001-05-18 11:24:58
Hi,
----- Original Message -----
From: <jiva_at_humboldt1.com>
To: <buildcheapeeg_at_yahoogroups.com>
Sent: Friday, May 18, 2001 7:10 AM
Subject: [buildcheapeeg] Re: Sound Card-Summary
...
>
> I was picturing a soundcard project as a very low cost
> 2 channel unit (at least initially). Probably with performance
> limitations. Basicly requiring a preamp and some way around
> the low frequency issue. (And much more software support!)
> That is ... an alternative to the exisisting project(s), not
> replacement.
For 2 channels I think the VCO-solution as suggested by
Praveen Kumar <pkk7_at_y...>, Sent: Tuesday, May 15, 2001 6:49 PM
Subject: [buildcheapeeg] Re: Sound Card-Mixer,
is better and cheaper than the time-multiplexer.
An additional advantage is, that the opto-isolator (discrete IR-emitter and
photodiode or transistor ) does not need linearization, because
the information is primarily encoded in the frequency and not in the magnitude
of the signal.
Decoding the signal in software could be done with two PLL algorithm instances
("VCO"-oscillator, phase-detector, servo circuit with low-pass).
Regards,
Joerg
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:29 BST