Re: Comb Filter
Hello everyone, I am looking for a manufacturer of an active comb filter to notch out 50Hz+harmonics noise from bio-medical signals. Can anyone help. Regards Shaike Raz I encountered a similar problem almost 20 years ago and thought about using a digital delay line to generate a powerline period delayed signal and combining it with the original. In the end, and for our test lab, I could not justify the cost and effort to build this. Have you considered injecting a small amount of the 50 Hz noise antiphase into the signal chain? In vacuum tube days this was known as a hum-bucker. Cortland This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Comb Filter
Are you really wanting to notch out all of the 50 Hz harmonics, or go with a low pass filter? The LP filter is the simple solution and can be implemented in analog form or DSP. A notch filter to remove only the 50 Hz harmonics would best be done with DSP. Stanford Research makes a amplifier/filter box that might be suitable if all you need is a LP filter. I don't know if it is differential or only single ended. A DSP can be designed to have a shorter settling time than the analog filter. Dave Cuthbert Micron Technology From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Monday, August 25, 2003 2:47 PM To: emc-p...@majordomo.ieee.org Subject: Re: Comb Filter I read in !emc-pstc that ITL-EMC User Group itl-...@itl.co.il wrote (in 2D1037012914D4118DB8204C4F4F5020275AD4@ITLLTD01) about 'Comb Filter' on Sun, 24 Aug 2003: I am looking for a manufacturer of an active comb filter to notch out 50Hz+harmonics noise from bio-medical signals. I can't tell you of any suppliers, but since this is a common problem, it would be surprising if nothing is available commercially. There are two ways to do this: either split the signal into two, delay one by 20 ms and re-combine them, and use a DSP chip to achieve the same effect. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Comb Filter
I read in !emc-pstc that ITL-EMC User Group itl-...@itl.co.il wrote (in 2D1037012914D4118DB8204C4F4F5020275AD4@ITLLTD01) about 'Comb Filter' on Sun, 24 Aug 2003: I am looking for a manufacturer of an active comb filter to notch out 50Hz+harmonics noise from bio-medical signals. I can't tell you of any suppliers, but since this is a common problem, it would be surprising if nothing is available commercially. There are two ways to do this: either split the signal into two, delay one by 20 ms and re-combine them, and use a DSP chip to achieve the same effect. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Comb Filter
This sounds like a job for DSP. Dave Cuthbert Micron Technology From: ITL-EMC User Group [mailto:itl-...@itl.co.il] Sent: Sunday, August 24, 2003 9:12 AM To: Emc-Pstc Group (E-mail) Subject: Comb Filter Hello everyone, I am looking for a manufacturer of an active comb filter to notch out 50Hz+harmonics noise from bio-medical signals. Can anyone help. Regards Shaike Raz EMC Laboratory Manager EMC Laboratory ITL (Product Testing) Ltd. Kfar Bin Nun Israel Tel: +972-8-9797799 Fax: +972-8-9797702 Email: s...@itl.co.il http://www.itl.co.il http://www.i-spec.com This e-mail message may contain privileged or confidential information. If you are not the intended recipient, you may not disclose, use, disseminate, distribute, copy or rely upon this message or attachment in any way. If you received this e-mail message in error, please return by forwarding the message and its attachments to the sender.
