The tools and models are as good as the info that we feed; if there is 'garbage in'; there will only be garbage out! Board level EMC simulations: > Most of the tools provide means to 'check' against set of rules and identify violations; yes using 3D field solver type of tools give prediction, still those also can do the job if you have the models created with accuracy > On the near-filed probing: there is a misconception that we can take the near- filed probes/sniffing devices and pin-point the device or area of trouble; this for sure is an 'imaginary' wish! Overall system level testing:=20 > In the EMC testing one of the main area of subjectivity is 'typical configuration'; since this is application and usage dependant, some individuals push for so called 'worst case' and give nightmare to teams and poor engineers; as many of you know there is nothing like perfect 100% in real world... > Once test configuration is identified and all concerned agree, then the process is not that bad; certain notorious frequencies do pop-up depending on technology/interface used like SAS, Ethernet... as long as the circuit deign was done right (avoid big current loops, proper decoupling, enough copper for power as well as GND) and proper grounding & shielding techniques used, you can be sure of a solid design. Why the tweaking is costly? > The reason why 'tweaking cost is pretty big' as the original poster wrote is because people try to 'band-aid' solutions and try to get an 'eye catching' result quickly! Consider EMI as a water-balloon. If you press in one place it WILL pop- up in another area! So there is no magic; the only way is to attack at the source. > So doing a good review at the design stage is the cost effective and proper way to avoid EMI problems later; if you want to quickly build the board and take care of EMI later, then its perfect path for disaster! The reason EMC is such a complicated filed and lot of 'brainy' folks work tirelessly is because of the combinational effects; let's say clock "A" radiates certain energy; if there is another clock "B" that radiates some energy as well; now the combinational effect could only be predicted by using complicated field-solver tools (creating correct models is another big headache). Since it's not too simple to create such models and simulate, invariably companies prefer to test in the real board; this way there is no need to do second guessing. Thanks, Kannan -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Silqun Leung Sent: Monday, May 29, 2006 9:31 AM To: kalevi@xxxxxxxxxx; weirsi@xxxxxxxxxx; Shiraz.Bashir@xxxxxx; SI-List Subject: [SI-LIST] Re: How good are tools to predict Radiated Emissions ? Actually, there is something. For the complex board one can use Ansoft SIwave to compute the radiated far and near fields. If you want to place this board into a housing/enclosure, this near or far field solution can be passed via co-simulation to HFSS for the 3D analysis. Regards, Silqun -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Kai Keskinen Sent: Saturday, May 27, 2006 7:31 PM To: weirsi@xxxxxxxxxx; Shiraz.Bashir@xxxxxx; SI-List Subject: [SI-LIST] Re: How good are tools to predict Radiated Emissions ? FloEMC passes the IEEE test cases for radiated emissions. It is intended to model the effects of packaging and takes into account things such as slots, cavities, EMI gaskets with lower conductivity than metal etc. It is helpful in creating packaging with high shielding effectiveness. None of the tools let you take a complex board, stick it into a package or housing, and then push a button to predict far field emissions. -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of steve weir Sent: Friday, May 26, 2006 12:57 PM To: Shiraz.Bashir@xxxxxx; SI-List Subject: [SI-LIST] Re: How good are tools to predict Radiated Emissions ? There has been much disappointment in this area. Tools can show relative noise sources. Absolute accuracy seems poor. Steve. At 09:48 AM 5/26/2006, Bashir, Shiraz \(GE Healthcare\) wrote: >How good are tools to predict Radiated Emissions ? > >I mean..we can layout a board using some flow. Then use a tool to see=3D20 >how this design will do from Radiated Emissions perspective.. >Did anyone of you have experience in this area ? > >Are there any tools which can pull in products' packaging (mechanical=3D20 >housing/ plastics, connectors location, length of slots etc..) and take >into account for analysis for Radiated Emissions.. > >Reason I am asking is that most of the company I know including = mine=3D20 >heavily rely on actual testing in-house (3 meter chambers) and outside=3D20 >(10 Meters) which is risky.. >Because project is near completion and any tweaks cost big $s. > >Please let me know. >Shiraz Bashir >GE Healthcare >------------------------------------------------------------------ >To unsubscribe from si-list: >si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > >or to administer your membership from a web page, go to: >//www.freelists.org/webpage/si-list > >For help: >si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >List FAQ wiki page is located at: > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > >List technical documents are available at: > http://www.si-list.org > >List archives are viewable at: > //www.freelists.org/archives/si-list >or at our remote archives: > http://groups.yahoo.com/group/si-list/messages >Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: =3D20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =3D20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: =20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu