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: ESD from wiring
I'm not sure I fully understand the problem, but Teflon is of course a very good insulator with an extremely high dielectric breakdown strength, so I would look at a charging mechanism depositing charge on the insulation. on 8/31/03 2:49 PM, lfresea...@aol.com at lfresea...@aol.com wrote: Hi all, well, I have found myself involved with an interesing problem. I'm testing an aircraft system, that only has a few wires... 8 or so, that interface with the outside world. 28 volt dc power, an programming loop, a manually operated switch and an indicator. Well, evey time the push button is pressed, I see a 10 to 50 nS pulse, very consistant. The problem first was noticed during RE testing, and I found it easier to hook my scope to the antenna rather than use the SA. I have eliminated the EUT operating, since I have disabled the trigger by removing the component that allows it to trigger. I did leave in place the 2 resistors that terminate the push button wire. I have a predictable set up. I remove either of the two reminating components, and the signal drops, it almost goes away. Anyway, after I'd removed the circuit board to make a change, I pushed the wire harness and saw a very similar transient! So I jiggled the harness and saw many... Cursing a loose connection, I checked, they were all sound. Not sure what was going on, I disconnected power, I could still got them. So I stripped down to my cotton shorts.. still got them. One section of the harness is sleeved with heatshrink sleeving, it holds the wires tighly. Jiggling that produced no events. So, I can only conclude, that the wire is generating a charge during the movement/jiggling, that when it discharges any one of a number of places causes my event. The parasitics of the harness set the ringing frequency. When I press my push botton, I believe I also kick the wiring with the impulse, again it rings very close to the frequency when I jiggle the cables. My questions are, am I off base with the charging supposition? The cable appears to be a teflon type insulation. If so, how can I get around it. I can't really blame the EUT for it. Opinions very welcome Thanks, Derek Walton -- Ken Javor EMC Compliance Huntsville, Alabama 256/650-5261
Re: ESD from wiring
Sounds like you just described the triboelectric(sp?) effect and teflon insulation has one of the highest "electron work functions" you will find. Mechanical motion causes a separation of the insulation >from and along the conductor. That mechanical separation causes a GUARRANTEED charge separation. Generates a voltage. This effect is the bane of cable makers, that is why the insulation is so tightly wrapped and stuck to the conductor. If not, 1000 feet of cable and the slightest slippage and you have voltage. This principle is used in the security industry to make buried cables that detect any motion for the cable. Cables in walls detect drilling and digging through them. Cables buried in the ground detect footsteps of people walking around above ground. Yes, it is that sensitive. An example of such a cable is a coax made with teflon insulation, very loosely wrapped around the center conductor. So loose that if you grab the center conductor with pliers and pull, you can pull the whole 20 feet of center conductor right out of the coax. I thought we were talking millivolts when I first heard of such a cable. So to check signal level, used a scope on the cable and with a light tap produced over 8 volts! The scope is a high impedance load and the cable is a high impedance source, but still very energetic. It is my understanding that this is one of forms of deterioration for aging cables. Alas, the solution is to not let a cable move. - Robert - Robert A. Macy, PE .. m...@california.com 408 286 3985 . . . .. . . fx 408 297 9121 AJM International Electronics Consultants 101 E San Fernando, Suite 402 San Jose, CA 95112 On Sun, 31 Aug 2003 15:49:43 EDT lfresea...@aol.com wrote: > Hi all, > > well, I have found myself involved with an interesing > problem. I'm testing an > aircraft system, that only has a few wires... 8 or so, > that interface with > the outside world. 28 volt dc power, an programming loop, > a manually operated > switch and an indicator. > > Well, evey time the push button is pressed, I see a 10 to > 50 nS pulse, very > consistant. The problem first was noticed during RE > testing, and I found it > easier to hook my scope to the antenna rather than use > the SA. I have eliminated > the EUT operating, since I have disabled the trigger by > removing the component > that allows it to trigger. I did leave in place the 2 > resistors that > terminate the push button wire. I have a predictable set > up. > > I remove either of the two reminating components, and the > signal drops, it > almost goes away. > > Anyway, after I'd removed the circuit board to make a > change, I pushed the > wire harness and saw a very similar transient! So I > jiggled the harness and saw > many... Cursing a loose connection, I checked, they were > all sound. Not sure > what was going on, I disconnected power, I could still > got them. So I stripped > down to my cotton shorts.. still got them. > > One section of the harness is sleeved with heatshrink > sleeving, it holds the > wires tighly. Jiggling that produced no events. > > So, I can only conclude, that the wire is generating a > charge during the > movement/jiggling, that when it discharges any one of a > number of places causes my > event. The parasitics of the harness set the ringing > frequency. When I press > my push botton, I believe I also kick the wiring with the > impulse, again it > rings very close to the frequency when I jiggle the > cables. > > My questions are, am I off base with the charging > supposition? The cable > appears to be a teflon type insulation. > > If so, how can I get around it. I can't really blame the > EUT for it. > > Opinions very welcome > > Thanks, > > Derek Walton 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" >>> Reply-To: "Charles Grasso" >>> Date: Thu, 28 Aug 2003 07:06:13 -0700 >>> To: "Emc-Pstc" >>> 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
ESD from wiring
Hi all, well, I have found myself involved with an interesing problem. I'm testing an aircraft system, that only has a few wires... 8 or so, that interface with the outside world. 28 volt dc power, an programming loop, a manually operated switch and an indicator. Well, evey time the push button is pressed, I see a 10 to 50 nS pulse, very consistant. The problem first was noticed during RE testing, and I found it easier to hook my scope to the antenna rather than use the SA. I have eliminated the EUT operating, since I have disabled the trigger by removing the component that allows it to trigger. I did leave in place the 2 resistors that terminate the push button wire. I have a predictable set up. I remove either of the two reminating components, and the signal drops, it almost goes away. Anyway, after I'd removed the circuit board to make a change, I pushed the wire harness and saw a very similar transient! So I jiggled the harness and saw many... Cursing a loose connection, I checked, they were all sound. Not sure what was going on, I disconnected power, I could still got them. So I stripped down to my cotton shorts.. still got them. One section of the harness is sleeved with heatshrink sleeving, it holds the wires tighly. Jiggling that produced no events. So, I can only conclude, that the wire is generating a charge during the movement/jiggling, that when it discharges any one of a number of places causes my event. The parasitics of the harness set the ringing frequency. When I press my push botton, I believe I also kick the wiring with the impulse, again it rings very close to the frequency when I jiggle the cables. My questions are, am I off base with the charging supposition? The cable appears to be a teflon type insulation. If so, how can I get around it. I can't really blame the EUT for it. Opinions very welcome Thanks, Derek Walton
Re: Q. on Res Bandwith performace traceabiity
I read in !emc-pstc that f...@dctolight.net wrote (in <39029.198.246.16. 251.1062344564.squir...@webmail.dctolight.net>) about 'Q. on Res Bandwith performace traceabiity' on Sun, 31 Aug 2003: >As the professors would >say, it is left to the student to prove that 3 dbm = 6 dbv through the >formula P = EE/R. Except that it ABSOLUTELY ISN'T!!! Either way I interpret your ambiguous statement. If you mean absolute values, 3 dBm = 2 mW. 6 dB(V) = 2 V. OK, they happen to be equal in a 2 kohm system, but who has one of those? If you mean relative values, a difference of 3 dB in power level (a 'difference of 3 dBm' is a difference of 2 mW, which is not what you mean, if you think about it) is equal to a ratio of 2 in watts, which is, in a constant-resistance system, equal to a ratio of 1.414... in volts, which is 3 dB in voltage level. -- 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
> 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" >> Reply-To: "Charles Grasso" >> Date: Thu, 28 Aug 2003 07:06:13 -0700 >> To: "Emc-Pstc" >> 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
