Re: Q. on Res Bandwith performace traceabiity
I read in !emc-pstc that Coleman, David david.cole...@racalinst.co.uk wrote (in 7103C9D213EBD111971400104B4968149EC0CD@ntexch- f.racalinst.co.uk) about 'Q. on Res Bandwith performace traceabiity' on Wed, 3 Sep 2003: Why would the IEC standard for miniature fuses detail these abbreviations??? I think you have the wrong standard! Yes, typo, sorry. IEC 60027-3. -- 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: Q. on Res Bandwith performace traceabiity
John, Why would the IEC standard for miniature fuses detail these abbreviations??? I think you have the wrong standard! Dave C. From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Wednesday, September 03, 2003 7:42 AM To: emc-p...@majordomo.ieee.org Subject: Re: Q. on Res Bandwith performace traceabiity I read in !emc-pstc that Brent DeWitt bdew...@ix.netcom.com wrote (in jfekiiblahflflapjdmdeecadfaa.bdew...@ix.netcom.com) about 'Q. on Res Bandwith performace traceabiity' on Tue, 2 Sep 2003: Are we done now? No. All you guys are using non-standard abbreviations. Go read IEC 60127-3. (;-) -- 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 ** IMPORTANT NOTICE The information contained in this e-mail is confidential. It may also be legally privileged. It is intended only for the stated addressee(s) and access to it by any other person is unauthorised. If you are not an addressee, you must not disclose, copy, circulate or in any other way use or rely on the information contained in this e-mail. Such unauthorised use may be unlawful. If you have received this e-mail in error, please inform Racal Instruments Group Ltd. immediately by emailing postmas...@racalinstrumentsgroup.co.uk or phoning +44 (0)1202 872800 (ask for the I.T. Dept.) and delete it and all copies from your system. www.racalinstrumentsgroup.co.uk ** 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: Q. on Res Bandwith performace traceabiity
I read in !emc-pstc that Brent DeWitt bdew...@ix.netcom.com wrote (in jfekiiblahflflapjdmdeecadfaa.bdew...@ix.netcom.com) about 'Q. on Res Bandwith performace traceabiity' on Tue, 2 Sep 2003: Are we done now? No. All you guys are using non-standard abbreviations. Go read IEC 60127-3. (;-) -- 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: Q. on Res Bandwith performace traceabiity
I read in !emc-pstc that f...@dctolight.net wrote (in 41196.198.246.16. 251.1062534076.squir...@webmail.dctolight.net) about 'Q. on Res Bandwith performace traceabiity' on Tue, 2 Sep 2003: Since not everyone measures power we also define 0dbv = 1 mvolt into 600 ohms. Well, you might define it like that, but I hope that no-one else does. There is an international standard (IEC 60127-3) on the forms of decibel abbreviations, and 'dbv' is non-compliant. Many people define '0 dbv' as 1 volt, impedance not specified. If you use non-standard abbreviations, you WILL be misunderstood, as in this case. Abbreviations are 'words' in our technical language, and using the wrong word will obviously cause giraffe, no, I mean confusion. -- 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: Q. on Res Bandwith performace traceabiity
This is getting a wee bit silly. First (to be terribly nit-picky) it's dB not db. The unit is a Bel. Second, dBm does not carry with it an impedance specification. The milliwatt reference can be into anything slightly less than infinity to slightly greater than zero. Third, I believe dBV is dB referenced to one volt. The factor of two difference in power and voltage is simply the effect of pulling the log of the voltage squared term outside of the log operation. Not a great mystery. Are we done now? Brent DeWitt From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of f...@dctolight.net Sent: Tuesday, September 02, 2003 2:21 PM To: ken.ja...@emccompliance.com Cc: f...@dctolight.net; cgrassospri...@earthlink.net; emc-p...@ieee.org Subject: Re: Q. on Res Bandwith performace traceabiity Incorrect. A dB is a dB. Correct! But who is talking about db? I'm sure you know that db is a dimensionless ratio. I believe we were discussing power. Let’s make sure we all have the formula: db = 10 log (P1/P2) or = 20 log (V1/V2) + 10 log (Z2/Z1) A quick scan of the formula will show that we multiply the voltage term by twice as much as the power term. Also, if Z1=Z2, then we have 10 log of 1 or zero so the impedance (resistance in this case) term drops out. OK now here is the important part. To convert db from a ratio to units of power we define 0dbm = 1mwatt into 600 ohms. Since not everyone measures power we also define 0dbv = 1 mvolt into 600 ohms. Since a millivolt into 600 ohms is not a milliwatt into 600 ohms, using the formula P = (V squared)/R, we find that 0 dbm is (almost) equal to 6 dbv into 600 ohms. Finally back to the point at hand, if the scale on our meter is in dbm then the half power point is at -3 dbm (not -3 db). If the scale is in dbv then the half power point is – 6 dbv (not -6db). In this context -3 dbm is equivalent to -6 dbv. I apologize to all for using the equal sign instead of the equivalent. I think my statements are otherwise accurate. And to give Ken his due, a db is unquestionably equal to itself. QED Fred Townsend 3 dB down is half power but 70.7% voltage. 6 dB down is 1/4 power, or one half voltage or current. on 8/31/03 10:42 AM, f...@dctolight.net at f...@dctolight.net wrote: A few basics: If we are talking about power points (no software puns intended) then it is the 3 db points. If we are taking about voltage (or current) points then it is the 6 db points. As the professors would say, it is left to the student to prove that 3 dbm = 6 dbv through the formula P = EE/R. QED? My understanding is that it is the 6 dB points which are cited as the bandwidth. I'm not up on CISPR 16 but to entirely specify the bandwidth the 60 dB down points are also specified. The slope you get from the 6 dB to the 60 dB points is called the shape factor. From: Charles Grasso cgrassospri...@earthlink.net Reply-To: Charles Grasso cgrassospri...@earthlink.net Date: Thu, 28 Aug 2003 07:06:13 -0700 To: Emc-Pstc emc-p...@ieee.org Subject: Q. on Res Bandwith performace traceabiity Greetings: Does anyone know if the Resolution Bandwidth filter performance is tracable to a given standard and which standard that might be? I was wondering if the rool-off after the 3dB points is specificed as a standard for ALL analysers. I am assuming that the anaswer is Yes as chaos would reign!! --- 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: Q. on Res Bandwith performace traceabiity
Fred: Correction - a dBV is referenced to 1 Volt. R or Z has nothing to do with it. A dBmv is referenced to one millivolt. R or Z has nothing to do with it. You are correct in stating a dBm is referenced to 1 milliwatt into a specific Z (600 ohms). Also note that a dB is dimensionless. However, when we add various notations after the dB part, it is no longer dimensionless. For example, what is the dimensions of an antenna factor in dB? John Shinn, P.E. From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of f...@dctolight.net Sent: Tuesday, September 02, 2003 1:21 PM To: ken.ja...@emccompliance.com Cc: f...@dctolight.net; cgrassospri...@earthlink.net; emc-p...@ieee.org Subject: Re: Q. on Res Bandwith performace traceabiity Incorrect. A dB is a dB. Correct! But who is talking about db? I'm sure you know that db is a dimensionless ratio. I believe we were discussing power. Let’s make sure we all have the formula: db = 10 log (P1/P2) or = 20 log (V1/V2) + 10 log (Z2/Z1) A quick scan of the formula will show that we multiply the voltage term by twice as much as the power term. Also, if Z1=Z2, then we have 10 log of 1 or zero so the impedance (resistance in this case) term drops out. OK now here is the important part. To convert db from a ratio to units of power we define 0dbm = 1mwatt into 600 ohms. Since not everyone measures power we also define 0dbv = 1 mvolt into 600 ohms. Since a millivolt into 600 ohms is not a milliwatt into 600 ohms, using the formula P = (V squared)/R, we find that 0 dbm is (almost) equal to 6 dbv into 600 ohms. Finally back to the point at hand, if the scale on our meter is in dbm then the half power point is at -3 dbm (not -3 db). If the scale is in dbv then the half power point is – 6 dbv (not -6db). In this context -3 dbm is equivalent to -6 dbv. I apologize to all for using the equal sign instead of the equivalent. I think my statements are otherwise accurate. And to give Ken his due, a db is unquestionably equal to itself. QED Fred Townsend 3 dB down is half power but 70.7% voltage. 6 dB down is 1/4 power, or one half voltage or current. on 8/31/03 10:42 AM, f...@dctolight.net at f...@dctolight.net wrote: A few basics: If we are talking about power points (no software puns intended) then it is the 3 db points. If we are taking about voltage (or current) points then it is the 6 db points. As the professors would say, it is left to the student to prove that 3 dbm = 6 dbv through the formula P = EE/R. QED? My understanding is that it is the 6 dB points which are cited as the bandwidth. I'm not up on CISPR 16 but to entirely specify the bandwidth the 60 dB down points are also specified. The slope you get from the 6 dB to the 60 dB points is called the shape factor. From: Charles Grasso cgrassospri...@earthlink.net Reply-To: Charles Grasso cgrassospri...@earthlink.net Date: Thu, 28 Aug 2003 07:06:13 -0700 To: Emc-Pstc emc-p...@ieee.org Subject: Q. on Res Bandwith performace traceabiity Greetings: Does anyone know if the Resolution Bandwidth filter performance is tracable to a given standard and which standard that might be? I was wondering if the rool-off after the 3dB points is specificed as a standard for ALL analysers. I am assuming that the anaswer is Yes as chaos would reign!! --- 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 -- Ken Javor EMC Compliance Huntsville, Alabama 256/650-5261
Re: Q. on Res Bandwith performace traceabiity
Precisely speaking, the dimensions of antenna factor are inverse meters. Antenna factor is the reciprocal of antenna effective height, which has mks units of meters. In log space, antenna factor units are: dB above one meter^-1 or in shorthand: dB/m From: John Shinn john.sh...@sanmina-sci.com Reply-To: john.sh...@sanmina-sci.com Date: Tue, 2 Sep 2003 15:08:57 -0700 To: f...@dctolight.net, ken.ja...@emccompliance.com Cc: cgrassospri...@earthlink.net, emc-p...@ieee.org Subject: RE: Q. on Res Bandwith performace traceabiity Fred: Correction - a dBV is referenced to 1 Volt. R or Z has nothing to do with it. A dBmv is referenced to one millivolt. R or Z has nothing to do with it. You are correct in stating a dBm is referenced to 1 milliwatt into a specific Z (600 ohms). Also note that a dB is dimensionless. However, when we add various notations after the dB part, it is no longer dimensionless. For example, what is the dimensions of an antenna factor in dB? John Shinn, P.E. -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of f...@dctolight.net Sent: Tuesday, September 02, 2003 1:21 PM To: ken.ja...@emccompliance.com Cc: f...@dctolight.net; cgrassospri...@earthlink.net; emc-p...@ieee.org Subject: Re: Q. on Res Bandwith performace traceabiity Incorrect. A dB is a dB. Correct! But who is talking about db? I'm sure you know that db is a dimensionless ratio. I believe we were discussing power. Let’s make sure we all have the formula: db = 10 log (P1/P2) or = 20 log (V1/V2) + 10 log (Z2/Z1) A quick scan of the formula will show that we multiply the voltage term by twice as much as the power term. Also, if Z1=Z2, then we have 10 log of 1 or zero so the impedance (resistance in this case) term drops out. OK now here is the important part. To convert db from a ratio to units of power we define 0dbm = 1mwatt into 600 ohms. Since not everyone measures power we also define 0dbv = 1 mvolt into 600 ohms. Since a millivolt into 600 ohms is not a milliwatt into 600 ohms, using the formula P = (V squared)/R, we find that 0 dbm is (almost) equal to 6 dbv into 600 ohms. Finally back to the point at hand, if the scale on our meter is in dbm then the half power point is at -3 dbm (not -3 db). If the scale is in dbv then the half power point is – 6 dbv (not -6db). In this context -3 dbm is equivalent to -6 dbv. I apologize to all for using the equal sign instead of the equivalent. I think my statements are otherwise accurate. And to give Ken his due, a db is unquestionably equal to itself. QED Fred Townsend 3 dB down is half power but 70.7% voltage. 6 dB down is 1/4 power, or one half voltage or current. on 8/31/03 10:42 AM, f...@dctolight.net at f...@dctolight.net wrote: A few basics: If we are talking about power points (no software puns intended) then it is the 3 db points. If we are taking about voltage (or current) points then it is the 6 db points. As the professors would say, it is left to the student to prove that 3 dbm = 6 dbv through the formula P = EE/R. QED? My understanding is that it is the 6 dB points which are cited as the bandwidth. I'm not up on CISPR 16 but to entirely specify the bandwidth the 60 dB down points are also specified. The slope you get from the 6 dB to the 60 dB points is called the shape factor. From: Charles Grasso cgrassospri...@earthlink.net Reply-To: Charles Grasso cgrassospri...@earthlink.net Date: Thu, 28 Aug 2003 07:06:13 -0700 To: Emc-Pstc emc-p...@ieee.org Subject: Q. on Res Bandwith performace traceabiity Greetings: Does anyone know if the Resolution Bandwidth filter performance is tracable to a given standard and which standard that might be? I was wondering if the rool-off after the 3dB points is specificed as a standard for ALL analysers. I am assuming that the anaswer is Yes as chaos would reign!! --- 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
Re: Q. on Res Bandwith performace traceabiity
Well I sure didn't think my response to Mr. Grasso's post would generate any controversy. I am humbled by how many times I am wrong. But, my original post was right. First of all, using 600 Ohms as an impedance is an audio, not rf practice. 50 Ohms is the standard for rf test work, as 75 Ohms is for cable-distributed video-modulated rf. Mr. Grasso's original post was about rf test measurements in a 50 Ohm system. However, regardless of the impedance, the appeal to absolute measures (dB referenced to 1 mW or 1 mV) is invalid in the context of how an intermediate filter (if) band-pass is defined. The critical issues are the bandwidth where the response of the filter is down X dB, where X might be 3, 6, or 60. It is purely a ratio to the response on center, and has nothing whatsoever to do with any absolute measure. From: f...@dctolight.net Date: Tue, 2 Sep 2003 13:21:16 -0700 (PDT) To: ken.ja...@emccompliance.com Cc: f...@dctolight.net, cgrassospri...@earthlink.net, emc-p...@ieee.org Subject: Re: Q. on Res Bandwith performace traceabiity Incorrect. A dB is a dB. Correct! But who is talking about db? I'm sure you know that db is a dimensionless ratio. I believe we were discussing power. Let’s make sure we all have the formula: db = 10 log (P1/P2) or = 20 log (V1/V2) + 10 log (Z2/Z1) A quick scan of the formula will show that we multiply the voltage term by twice as much as the power term. Also, if Z1=Z2, then we have 10 log of 1 or zero so the impedance (resistance in this case) term drops out. OK now here is the important part. To convert db from a ratio to units of power we define 0dbm = 1mwatt into 600 ohms. Since not everyone measures power we also define 0dbv = 1 mvolt into 600 ohms. Since a millivolt into 600 ohms is not a milliwatt into 600 ohms, using the formula P = (V squared)/R, we find that 0 dbm is (almost) equal to 6 dbv into 600 ohms. Finally back to the point at hand, if the scale on our meter is in dbm then the half power point is at -3 dbm (not -3 db). If the scale is in dbv then the half power point is – 6 dbv (not -6db). In this context -3 dbm is equivalent to -6 dbv. I apologize to all for using the equal sign instead of the equivalent. I think my statements are otherwise accurate. And to give Ken his due, a db is unquestionably equal to itself. QED Fred Townsend 3 dB down is half power but 70.7% voltage. 6 dB down is 1/4 power, or one half voltage or current. on 8/31/03 10:42 AM, f...@dctolight.net at f...@dctolight.net wrote: A few basics: If we are talking about power points (no software puns intended) then it is the 3 db points. If we are taking about voltage (or current) points then it is the 6 db points. As the professors would say, it is left to the student to prove that 3 dbm = 6 dbv through the formula P = EE/R. QED? My understanding is that it is the 6 dB points which are cited as the bandwidth. I'm not up on CISPR 16 but to entirely specify the bandwidth the 60 dB down points are also specified. The slope you get from the 6 dB to the 60 dB points is called the shape factor. From: Charles Grasso cgrassospri...@earthlink.net Reply-To: Charles Grasso cgrassospri...@earthlink.net Date: Thu, 28 Aug 2003 07:06:13 -0700 To: Emc-Pstc emc-p...@ieee.org Subject: Q. on Res Bandwith performace traceabiity Greetings: Does anyone know if the Resolution Bandwidth filter performance is tracable to a given standard and which standard that might be? I was wondering if the rool-off after the 3dB points is specificed as a standard for ALL analysers. I am assuming that the anaswer is Yes as chaos would reign!! --- 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
Re: Q. on Res Bandwith performace traceabiity
Incorrect. A dB is a dB. Correct! But who is talking about db? I'm sure you know that db is a dimensionless ratio. I believe we were discussing power. Let’s make sure we all have the formula: db = 10 log (P1/P2) or = 20 log (V1/V2) + 10 log (Z2/Z1) A quick scan of the formula will show that we multiply the voltage term by twice as much as the power term. Also, if Z1=Z2, then we have 10 log of 1 or zero so the impedance (resistance in this case) term drops out. OK now here is the important part. To convert db from a ratio to units of power we define 0dbm = 1mwatt into 600 ohms. Since not everyone measures power we also define 0dbv = 1 mvolt into 600 ohms. Since a millivolt into 600 ohms is not a milliwatt into 600 ohms, using the formula P = (V squared)/R, we find that 0 dbm is (almost) equal to 6 dbv into 600 ohms. Finally back to the point at hand, if the scale on our meter is in dbm then the half power point is at -3 dbm (not -3 db). If the scale is in dbv then the half power point is – 6 dbv (not -6db). In this context -3 dbm is equivalent to -6 dbv. I apologize to all for using the equal sign instead of the equivalent. I think my statements are otherwise accurate. And to give Ken his due, a db is unquestionably equal to itself. QED Fred Townsend 3 dB down is half power but 70.7% voltage. 6 dB down is 1/4 power, or one half voltage or current. on 8/31/03 10:42 AM, f...@dctolight.net at f...@dctolight.net wrote: A few basics: If we are talking about power points (no software puns intended) then it is the 3 db points. If we are taking about voltage (or current) points then it is the 6 db points. As the professors would say, it is left to the student to prove that 3 dbm = 6 dbv through the formula P = EE/R. QED? My understanding is that it is the 6 dB points which are cited as the bandwidth. I'm not up on CISPR 16 but to entirely specify the bandwidth the 60 dB down points are also specified. The slope you get from the 6 dB to the 60 dB points is called the shape factor. From: Charles Grasso cgrassospri...@earthlink.net Reply-To: Charles Grasso cgrassospri...@earthlink.net Date: Thu, 28 Aug 2003 07:06:13 -0700 To: Emc-Pstc emc-p...@ieee.org Subject: Q. on Res Bandwith performace traceabiity Greetings: Does anyone know if the Resolution Bandwidth filter performance is tracable to a given standard and which standard that might be? I was wondering if the rool-off after the 3dB points is specificed as a standard for ALL analysers. I am assuming that the anaswer is Yes as chaos would reign!! --- 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 -- Ken Javor EMC Compliance Huntsville, Alabama 256/650-5261 --- 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:
Re: Q. on Res Bandwith performace traceabiity
CISPR 16-1 and C63.2. I seem to recall seeing a bandwidth mask in CISPR 16 which specified both width and slope of the filter attenuation in three ranges, from 0 to 3 dB down, 3 to 6 dB down and 6 db to (I think) 40 or 50 dB down. 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: Q. on Res Bandwith performace traceabiity
Incorrect. A dB is a dB. 3 dB down is half power but 70.7% voltage. 6 dB down is 1/4 power, or one half voltage or current. on 8/31/03 10:42 AM, f...@dctolight.net at f...@dctolight.net wrote: A few basics: If we are talking about power points (no software puns intended) then it is the 3 db points. If we are taking about voltage (or current) points then it is the 6 db points. As the professors would say, it is left to the student to prove that 3 dbm = 6 dbv through the formula P = EE/R. QED? My understanding is that it is the 6 dB points which are cited as the bandwidth. I'm not up on CISPR 16 but to entirely specify the bandwidth the 60 dB down points are also specified. The slope you get from the 6 dB to the 60 dB points is called the shape factor. From: Charles Grasso cgrassospri...@earthlink.net Reply-To: Charles Grasso cgrassospri...@earthlink.net Date: Thu, 28 Aug 2003 07:06:13 -0700 To: Emc-Pstc emc-p...@ieee.org Subject: Q. on Res Bandwith performace traceabiity Greetings: Does anyone know if the Resolution Bandwidth filter performance is tracable to a given standard and which standard that might be? I was wondering if the rool-off after the 3dB points is specificed as a standard for ALL analysers. I am assuming that the anaswer is Yes as chaos would reign!! --- 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 -- Ken Javor EMC Compliance Huntsville, Alabama 256/650-5261 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: Q. on Res Bandwith performace traceabiity
I believe Mr. Cuthbert is correct, but that doesn't change the fact that CISPR 16 specifies 6 dB bandwidths. From: drcuthb...@micron.com Date: Thu, 28 Aug 2003 15:47:55 -0600 To: ken.ja...@emccompliance.com, cgrassospri...@earthlink.net, emc-p...@ieee.org Subject: RE: Q. on Res Bandwith performace traceabiity I think that Spectrum Analyzer IF filters are specified at the 3 dB points. Communication receivers are spec'ed at the 6 dB and 60 dB points. Dave Cuthbert Micron Technology -Original Message- From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Thursday, August 28, 2003 1:48 PM To: Charles Grasso; Emc-Pstc Subject: Re: Q. on Res Bandwith performace traceabiity My understanding is that it is the 6 dB points which are cited as the bandwidth. I'm not up on CISPR 16 but to entirely specify the bandwidth the 60 dB down points are also specified. The slope you get from the 6 dB to the 60 dB points is called the shape factor. From: Charles Grasso cgrassospri...@earthlink.net Reply-To: Charles Grasso cgrassospri...@earthlink.net Date: Thu, 28 Aug 2003 07:06:13 -0700 To: Emc-Pstc emc-p...@ieee.org Subject: Q. on Res Bandwith performace traceabiity Greetings: Does anyone know if the Resolution Bandwidth filter performance is tracable to a given standard and which standard that might be? I was wondering if the rool-off after the 3dB points is specificed as a standard for ALL analysers. I am assuming that the anaswer is Yes as chaos would reign!! --- 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 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: Q. on Res Bandwith performace traceabiity
My understanding is that it is the 6 dB points which are cited as the bandwidth. I'm not up on CISPR 16 but to entirely specify the bandwidth the 60 dB down points are also specified. The slope you get from the 6 dB to the 60 dB points is called the shape factor. From: Charles Grasso cgrassospri...@earthlink.net Reply-To: Charles Grasso cgrassospri...@earthlink.net Date: Thu, 28 Aug 2003 07:06:13 -0700 To: Emc-Pstc emc-p...@ieee.org Subject: Q. on Res Bandwith performace traceabiity Greetings: Does anyone know if the Resolution Bandwidth filter performance is tracable to a given standard and which standard that might be? I was wondering if the rool-off after the 3dB points is specificed as a standard for ALL analysers. I am assuming that the anaswer is Yes as chaos would reign!! --- 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
