From: Joerg Hansmann (info_at_jhansmann.de)
Date: 2002-03-14 15:25:30
Hi,
----- Original Message -----
From: Sar Saloth <sarsaloth_at_yahoo.com>
To: <buildcheapeeg_at_yahoogroups.com>
Sent: Thursday, March 14, 2002 3:52 PM
Subject: Re: [buildcheapeeg] Re: EMI filtering for the HiresEEG
...
> If you wanted to be ultra paranoid, you could always lay out your board to
> take your shielded ideas as an option.
> My suspicion is that many devices with no shielding at all are improperly
> tested and approved.
Theoretically (I do have no practical experience with HF) a low Z groundplane
as a part of the pcb should create a shielded zone up to 1/10th of the HF wavelength
in height.
If all components are inside of this zone, they are shielded.
> I have seen one EMI test report from a European
> notified body for a medical device that clearly did not understand the test
> specifications. Some other Europeans I had spoken with also didn't
> comprehend some of the important points of the test specification (most
> importantly the requirement to modulate the carrier to at least 80%
I guess this is AM ?
> with a
> frequency approximately in the middle of the pass-band for the device under
> test).
To detect the effect of demodulated HF instead of only a seemingly drifting
offset voltage ?
Regards,
Joerg
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:40 BST