RE: Antenna Calibration/Site Attenuation
Ed brings up a good point. This forum is designed to allow communications between EMC and Product Safety professionals who are looking to help each other in the interest of the advancement of the compliance industry. If there is a certain test house or equipment manufacturer that provides inadequite services or products, why shouldn't that be disclosed on this forum? Why would anyone want me to find out on my own that a certain manufacturer has probelms with Biconical Antennas? It seems to me that an open channel of communication would help convince the manufacturers or service providers in the industry who are lacking to shape up. Is it simply an issue of fear of litigation? Regards, Randy Flinders EMC Test Engineer Emulex Network Systems Corporation Phone: (714) 513-8012 Fax: (714) 513-8265 E-Mail: r_flind...@emulex.com WebSite: www.emulex.com * opinions expressed herein are personal, and in no way reflect the position of Emulex Corporation. -- From: ed.price[SMTP:ed.pr...@cubic.com] Sent: Tuesday, August 26, 1997 8:32 AM To: UMBDENSTOCK, DON Cc: 'EMC-PSTC Discussion Group' Subject: Re: Antenna Calibration/Site Attenuation --- On Tue, 26 Aug 1997 08:12:00 -0400 "UMBDENSTOCK, DON" wrote: > > Great dialog, just the path that I was hoping would develop. > > One thing I have learned since the question was first asked, all > biconical antennas are not made equal. The original antenna calibrated > at an outside test organization, exhibited a 5 dB difference between the > vertical and horizontal polarizations at 3 meters in the frequency range > of 30 - 50 MHz. > > Another antenna subsequently calibrated at the same organization had > less than 1 dB difference between v and h, 1m and 10 m. This outcome > was more in line with the expected outcome of the calibration per C63.5 > which stated "minor variations with polarizations and geometries" where > geometries is understood to mean test distances. > > Don Umbdenstock > Sensormatic ---End of Original Message- Don: Not meaning to single you out, but your post tweaked a concern of mine. Are we all operating in a sense of fear in this forum? Do we really have to obfuscate the facts by referring to an "original antenna" and "another antenna"? Or am I the only one who would like to know exactly which antenna and test lab that you're talking about? Ed -- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: emc-pstc@listserv.ieee.org Date: 08/26/97 Time: 08:32:35 --
Re: New ZH1/618 Ergonomics Requirements
--- On Tue, 26 Aug 1997 08:57:56 -0700 Patricia Elliot wrote: > At 08:49 AM 8/26/97 -0500, Lesmeister, Glenn wrote: > >Does anyone know where I can get a copy of the latest version of the > >ZH1/618 testing principles that are translated into English. My TUV > >rep only has it in German. > > > >Glenn Lesmeister > >Product Regulatory Compliance > >Compaq Computer Corporation > >(281) 514-5163 > >(281) 514-8029 fax > >(713) 786-4930 pager > >glenn.lesmeis...@compaq.com > >glesmeis...@netgate.compaq.com > > > > > You can try the National Center for Standards and Certification Information > (NCSCI), they provide translations of standards for > a fee. The address is below: > > NCSCI > National Institute of Standards and Technology > Bldg. 820, Room A164 > Gaithersburg, MD 20899 (USA) > (301) 975-4040, FAX (301) 926-1559 > e-mail: joanne over...@nist.gov > > > ~ > Patty Elliot| Qualcomm, Inc. > Senior Product Safety Engineer | 6455 Lusk Blvd. > Voice: (619) 651-3457 | San Diego, CA 92121 > Fax: (619) 658-1845 | USA > p...@qualcomm.com | www.qualcomm.com > ~ > Try Mertel Associates at 619-741-3301 (Voice) or 619-741-5327 (Fax) or on the net with hmer...@pacbell.net. Herb Mertel has long been a source of translations from the original German documents. -- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: emc-pstc@listserv.ieee.org Date: 08/26/97 Time: 12:16:03 --
RE: FCC Part 68 new Surge requirements
Hello SGour and fellow emc-pstc colleagues: I understand that the FCC has finally adopted the long awaited harmonized FCC/CS-03 requirements. They come into effect 90 days after the publication of the new requirements. I just don't know when the 90 days begins. The new surge requirements take effect at that time. I thought that the new surge test was the same as the ITU K.21 surge, 10x700us. Any comments from TREG? Mel Pedersen Midcom, Inc. Homologations Engineer Phone: (605) 882-8535 mpeder...@midcom.anza.com Fax: (605) 886-6752 -- From: SGour[SMTP:sg...@brother.com] Sent: Tuesday, August 26, 1997 4:52 AM To: emc-p...@majordomo.ieee.org Subject:FCC Part 68 new Surge requirements Hello group Is anyone aware when the new part FCC pt 68 (68.302)surge (9x720us) requirements actually coming into effect. Has anybody bought the equipment--any recommendations. Is this requirement similar to a EU Surge requirement? Can one tester cover both?? Thanks in advance for the suggestions/comments. sg...@brother.com RCIC - http://www.rcic.com Regulatory Compliance Information Center
Austin EMC-IEEE Show feedback
Hi all, As the Local Arrangements Chair of the organising committe for the IEEE 1998 International Syposium on EMC to be held in Denver, Colorado I am interested in any feedback from those who attended last weeks 1997 symposium in Austin. The Austin Symposium was great but we plan to be even greater!! So:- Please e-mail direct to me, at the address below, any comments you may have, positive or negative! However I would prefer the following outline:- What went well? What needed improvement? Suggestions of any kind? Thank you. You may access our symposium web site in about 1 week at http://www.ball.com/aerospace/IEEE_EMC.HTML Regards, Tony O'Hara TMC-EMC Sales Lakewood, Colorado tonyoh...@compuserve.com (303)-948-2576
Re: New ZH1/618 Ergonomics Requirements
At 08:49 AM 8/26/97 -0500, Lesmeister, Glenn wrote: >Does anyone know where I can get a copy of the latest version of the >ZH1/618 testing principles that are translated into English. My TUV >rep only has it in German. > >Glenn Lesmeister >Product Regulatory Compliance >Compaq Computer Corporation >(281) 514-5163 >(281) 514-8029 fax >(713) 786-4930 pager >glenn.lesmeis...@compaq.com >glesmeis...@netgate.compaq.com > > You can try the National Center for Standards and Certification Information (NCSCI), they provide translations of standards for a fee. The address is below: NCSCI National Institute of Standards and Technology Bldg. 820, Room A164 Gaithersburg, MD 20899 (USA) (301) 975-4040, FAX (301) 926-1559 e-mail: joanne over...@nist.gov ~ Patty Elliot| Qualcomm, Inc. Senior Product Safety Engineer | 6455 Lusk Blvd. Voice: (619) 651-3457 | San Diego, CA 92121 Fax: (619) 658-1845 | USA p...@qualcomm.com | www.qualcomm.com ~
Re: Antenna Calibration/Site Attenuation
--- On Tue, 26 Aug 1997 08:12:00 -0400 "UMBDENSTOCK, DON" wrote: > > Great dialog, just the path that I was hoping would develop. > > One thing I have learned since the question was first asked, all > biconical antennas are not made equal. The original antenna calibrated > at an outside test organization, exhibited a 5 dB difference between the > vertical and horizontal polarizations at 3 meters in the frequency range > of 30 - 50 MHz. > > Another antenna subsequently calibrated at the same organization had > less than 1 dB difference between v and h, 1m and 10 m. This outcome > was more in line with the expected outcome of the calibration per C63.5 > which stated "minor variations with polarizations and geometries" where > geometries is understood to mean test distances. > > Don Umbdenstock > Sensormatic ---End of Original Message- Don: Not meaning to single you out, but your post tweaked a concern of mine. Are we all operating in a sense of fear in this forum? Do we really have to obfuscate the facts by referring to an "original antenna" and "another antenna"? Or am I the only one who would like to know exactly which antenna and test lab that you're talking about? Ed -- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: emc-pstc@listserv.ieee.org Date: 08/26/97 Time: 08:32:35 --
EU Commission Advice on EMC Directive
A few weeks ago, a posting reported on a meeting between "a well known computer manufacturer" and Mrs Elena Santiago of the European Commission. I was surprised at the content of this report, since it did not appear to be consistent with the recently-produced Guidelines, so I checked with the Department of Trade and Industry (who are responsible here in the UK for the Directive). They in turn checked with the Commission. The DTI have asked me to copy the following response back to the discussion group. Best wishes to all Brian Jones TO WHOM IT MAY CONCERN From: Department of Trade and Industry 151 Buckingham Palace Road London SW1W 9SS Enquiries +44 171-215 5000 Fax+44 171-215 1529 INCORRECT/INCOMPLETE INTERPRETATION OF INFORMATION ORIGINATING FROM THE EUROPEAN COMMISSION (DGIII) REGARDING SYSTEM INTEGRATORS - EMC DIRECTIVE The following information has been placed on a web site accessed by many manufacturers in the UK. ___ " Ladies & Gentlemen, I thought that you may be interested in the outcome of a meeting between a well-known PC manufacturer and the European Commission, DGIII (Elena Santiago) concerning the legalities of System Integration 1. An integrator of a "Core PC" (motherboard, power supply, case & drives - 6.4.2 pare. 4 of the EMC Directive Guidelines) need only follow the Conformity Assessment Guidelines (10.1 or 10.2 of the Directive, 8.1 or 8.2 of the Guidelines). This entails using CE Marked modules, following module instructions exactly, providing a Declaration of Conformity, and providing a CE Marking on the product. If he/she does this, then the resultant product NEED NOT BE TESTED. Further, if an enforcement organization later tests the product and it fails the emissions limits, the System integrator will still be considered in compliance! The enforcer is then supposed to turn his/her sights on the module suppliers for not providing sufficient instructions, and leave the System Integrator alone. Accordingly, if the System Integrators under prosecution in the UK followed the Guidelines but did not test, they should not be prosecuted. 2. EMC auditing of production is not mandatory. Even though EN55022, in describing the 80/80 rule, indicates that auditing is mandatory, the European Commission views this as not a standards issue and beyond the scope of CENELEC to specify. They also consider this requirement in conflict with their guidelines and are taking steps to have CENELEC remove this wording from EN55022. 3. We also brought up an issue regarding the use of prototypes for evaluation and demonstration, and of development units for customers to use to simultaneously prepare new designs. Ms. Santiago agreed to bring the matter up with the horizontal National Authorities. The above will obviously have a major impact on all PC manufacturers and system integrators! Perhaps someone within this newsgroup is able to confirm (or otherwise) this ground-shift." Mrs Santiago the Commission Official named above has asked the DTI, as the UK Competent Authority responsible for the EMC Directive, to put out a "correct statement" to counter the erroneous information appearing on the website Mrs Santiago was not consulted or warned that the private discussions she had with a well known personal computer company were going to be published and appear on the website. Mrs Santiago "fully disagrees" with what has been included under item 1 above. Mrs Santiago was trying to give the company an interpretation of 6.4.2 of the new EMC guidelines, insisting on the fact that the "guidelines are publicly available, but they are not legally binding in the sense of legal acts adopted by the Community. The legally binding provisions are those transposing the EMC Directive". Mrs Santiago further clarifies as follows. " The manufacturer of the system assumes the responsibility for the compliance of the system as a whole but after carrying out his verification according to the provisions of the EMC Directive. We do not enter into the verification procedure, and there is no mandatory testing according to the provisions of the Directive. A system assembled from only CE Marked apparatus should be aware that combining two or more CE marked sub-assemblies 'May not' automatically produce a system which meets the requirements of the Directive. It is the full responsibility of the manufacturer (system integrator in this case) to ensure conformity with the Directive. Of course in case of challenge it will be investigated to establish the reason for non-compliance. However, the system integrator must be able to technically justify his verification procedure." Certai
Re: Antenna Calibration/Site Attenuation
The common bicon balun (the traditional long-neck variety) may explain the differences encountered between V & H. If my feeble memory is correct, the balun is only marginally "balanced". Consequently, it could be sensitive to cable length and routing. (An easy test for imbalance would be to slide a ferrite along the coax and see if the measurement is affected.) I wouldn't be surprised to see such differences from V to H as reported by Don et al simply by turning the bicon around - while remaining at the same polarity. I'm not sure this problem exists on the small metal-box style of balun, or could it be worse somehow? Anyway, sometimes I wonder if shielded twinaxial cable, with a remotely placed balun, might perform more consistently. Regards, Eric Lifsey National Instruments
New ZH1/618 Ergonomics Requirements
Does anyone know where I can get a copy of the latest version of the ZH1/618 testing principles that are translated into English. My TUV rep only has it in German. Glenn Lesmeister Product Regulatory Compliance Compaq Computer Corporation (281) 514-5163 (281) 514-8029 fax (713) 786-4930 pager glenn.lesmeis...@compaq.com glesmeis...@netgate.compaq.com
FCC Part 68 new Surge requirements
Hello group Is anyone aware when the new part FCC pt 68 (68.302)surge (9x720us) requirements actually coming into effect. Has anybody bought the equipment--any recommendations. Is this requirement similar to a EU Surge requirement? Can one tester cover both?? Thanks in advance for the suggestions/comments. sg...@brother.com RCIC - http://www.rcic.com Regulatory Compliance Information Center
(Fwd) Status of IEC601-1-2 ? -Svar
The SC62A WG13, producing the second edition of IEC 60601-1-2 will have a meeting at DELTA Electronics Testing, Copenhagen, during this week. The first CD has been commented and the work for the second CD is in progress. The second CD can be expected later this year and can then be viewed at your national standards organisation. It will not be for sale then. Regards Vagn Sylvest DELTA Electronics Testing -- Original message: >>> "Massimo Polignano" 970826-11.46 >>> For internal net problems I've lost the answers (if any) to the following message. Could you please send them again? Thanks. M.P. --- Forwarded Message Follows --- From: plaw...@west.net (Patrick Lawler) To:emc-p...@majordomo.ieee.org Subject: Status of IEC601-1-2 ? List-Post: emc-pstc@listserv.ieee.org Date: Wed, 30 Jul 1997 19:07:55 GMT Reply-to: plaw...@west.net (Patrick Lawler) In June of last year, a draft of IEC601-1-2 Second Edition was released. Does anyone know the current status? How has the draft changed? Pat Lawler plaw...@west.net = ESAOTE S.p.A. Ing. Massimo Polignano Research & Product Development Regulatory Affairs Via di Caciolle, 15 Tel: ++ 39 (0)55 4229 402 50127 Firenze - Italy Fax: ++ 39 (0)55 4223305 e-mail: reg...@esaote.com =
Re: Antenna Calibration/Site Attenuation
Great dialog, just the path that I was hoping would develop. One thing I have learned since the question was first asked, all biconical antennas are not made equal. The original antenna calibrated at an outside test organization, exhibited a 5 dB difference between the vertical and horizontal polarizations at 3 meters in the frequency range of 30 - 50 MHz. Another antenna subsequently calibrated at the same organization had less than 1 dB difference between v and h, 1m and 10 m. This outcome was more in line with the expected outcome of the calibration per C63.5 which stated "minor variations with polarizations and geometries" where geometries is understood to mean test distances. Don Umbdenstock Sensormatic -- From: chasgra...@aol.com To: 72146@compuserve.com; chris_dup...@compuserve.com; emc-p...@ieee.org Subject: Re: Antenna Calibration/Site Attenuation List-Post: emc-pstc@listserv.ieee.org Date: Tuesday, August 26, 1997 5:20AM This has turned into an interesting discussion. 1. On the question of Class A vs Class B etc.. I vaguely remember that the genesis of the FCC limits for Class A & Class B were indeed derived from the concerns of installation. As I recall, extensive research went into examination of the sensitivities of television receivers and apatment complexes and as a result the 3M test distance and Class B limits were born for residential applications. Of course this was back in the 70s when 300 ohm cabling for TVs was in vogue!!. Naturally the FCC recognized that not all EMI problems would be resolved by design/testing alone. Chris is correct in his statement that the emissions test bears little resemblelance to reality. The FCC ( & others) insist on warning statements etc. (I believe the VDE has the honor of having the FIRST legal EMI requirements. In the original 0871 standards they were more concerned with conducted limits - hence their severity. The Class A radiated limits had relief in certain bands that allowed for very high emissions indeed.) 2. Mutual coupling (?) Reading the e-mails on enhanced emissions at 3M vertically polarized generated some thoughts. 2.1 I have discussed the issue of calibrating an antenna using ANSI C63.5 (horizontal only) and testing using ANSI C63.4 (v&h) with one of the authors involved in BOTH standards. The answer I get consistently is that: a) we need to calibrate in "free space" ( or close to it) b) calibrating an antenna with V& H makes the test look like the NSA and
Re: Antenna Calibration/Site Attenuation #2
***MESSAGE #2*** Ignore first message!! *** This has turned into an interesting discussion. 1. On the question of Class A vs Class B etc.. I vaguely remember that the genesis of the FCC limits for Class A & Class B were indeed derived from the concerns of installation. As I recall, extensive research went into examination of the sensitivities of television receivers and apatment complexes and as a result the 3M test distance and Class B limits were born for residential applications. Of course this was back in the 70s when 300 ohm cabling for TVs was in vogue!!. Naturally the FCC recognized that not all EMI problems would be resolved by design/testing alone. Chris is correct in his statement that the emissions test bears little resemblelance to reality. The FCC ( & others) insist on warning statements etc. (I believe the VDE has the honor of having the FIRST legal EMI requirements. In the original 0871 standards they were more concerned with conducted limits - hence their severity. The Class A radiated limits had relief in certain bands that allowed for very high emissions indeed.) 2. Mutual coupling (?) Reading the e-mails on enhanced emissions at 3M vertically polarized generated some thoughts. 2.1 I have discussed the issue of calibrating an antenna using ANSI C63.5 (horizontal only) and testing using ANSI C63.4 (v&h) with one of the authors involved in BOTH standards. The answer I get consistently is that: a) we need to calibrate in "free space" ( or close to it) b) calibrating an antenna with V& H makes the test look like the NSA and hence site anomilies dominate the vertical readings. 2.2 For my type of products (floor standing), Vert 1M seems to be worst case. This has more to do with the install than mutual coupling - I test at 10M. My humble opinion only. Charles Grasso EMC Engineer
Re: Theory behind Bundling Long Cabels during emisssions
Message received. I believe you are referring to ANSI C63.4. This is a result of much controversy in the EMC community - what to do with cables? The FCC took a lot of heat for maximizing cables in ways that the industry did not agree with. So, after much discussion, industry & the FCC agreed on a set of standard test set-ups that included a distinct way of dressing the cables. Sorry - no fancy theory here!!
Re: Antenna Calibration/Site Attenuation
This has turned into an interesting discussion. 1. On the question of Class A vs Class B etc.. I vaguely remember that the genesis of the FCC limits for Class A & Class B were indeed derived from the concerns of installation. As I recall, extensive research went into examination of the sensitivities of television receivers and apatment complexes and as a result the 3M test distance and Class B limits were born for residential applications. Of course this was back in the 70s when 300 ohm cabling for TVs was in vogue!!. Naturally the FCC recognized that not all EMI problems would be resolved by design/testing alone. Chris is correct in his statement that the emissions test bears little resemblelance to reality. The FCC ( & others) insist on warning statements etc. (I believe the VDE has the honor of having the FIRST legal EMI requirements. In the original 0871 standards they were more concerned with conducted limits - hence their severity. The Class A radiated limits had relief in certain bands that allowed for very high emissions indeed.) 2. Mutual coupling (?) Reading the e-mails on enhanced emissions at 3M vertically polarized generated some thoughts. 2.1 I have discussed the issue of calibrating an antenna using ANSI C63.5 (horizontal only) and testing using ANSI C63.4 (v&h) with one of the authors involved in BOTH standards. The answer I get consistently is that: a) we need to calibrate in "free space" ( or close to it) b) calibrating an antenna with V& H makes the test look like the NSA and
(Fwd) Status of IEC601-1-2 ?
For internal net problems I've lost the answers (if any) to the following message. Could you please send them again? Thanks. M.P. --- Forwarded Message Follows --- From: plaw...@west.net (Patrick Lawler) To:emc-p...@majordomo.ieee.org Subject: Status of IEC601-1-2 ? List-Post: emc-pstc@listserv.ieee.org Date: Wed, 30 Jul 1997 19:07:55 GMT Reply-to: plaw...@west.net (Patrick Lawler) In June of last year, a draft of IEC601-1-2 Second Edition was released. Does anyone know the current status? How has the draft changed? Pat Lawler plaw...@west.net = ESAOTE S.p.A. Ing. Massimo Polignano Research & Product Development Regulatory Affairs Via di Caciolle, 15 Tel: ++ 39 (0)55 4229 402 50127 Firenze - Italy Fax: ++ 39 (0)55 4223305 e-mail: reg...@esaote.com =
Re: Antenna Calibration/Site Attenuation
Right. Harmful interference makes any classification meaningless. Cortland == Original Message Follows >> Date: 25-Aug-97 18:43:26 MsgID: 1054-4643 ToID: 72146,373 From: Doug McKean >INTERNET:dmck...@paragon-networks.com Subj: Re: Antenna Calibration/Site Attenuation Chrg: $0.00 Imp: Norm Sens: StdReceipt: NoParts: 1 > From: Cortland Richmond <72146@compuserve.com> > To: "Grasso, Charles (Chaz)" ; ieee pstc list > Subject: RE: Antenna Calibration/Site Attenuation > Date: Monday, August 25, 1997 11:19 AM > > If it's mutual coupling... sure. But if it's a surface wave, that's real field > strength. If the reason for 3 meters -- an approximation of distance to the > victim receiver in a residential area -- is to be preserved, then perhaps this > is a non-issue, as the error is all on the high side, and emissions will be > reduced even lower than they would be on a ten meter site. > > (As an aside, can anyone here say if the COmmission has ever specifically ruled > on how far away from residences Class A equipment must be kept? I remember a > few years ago some chap got a NAL for operating a graphics work station in his > home... but what about separate buildings out back, etc. ?) > > Cortland It would seem that businesses run in homes would tend to violate *any* distance requirement. I believe that the wording of the labeling specifically addresses "may not cause harmful interference" which could be at any distance. == End of Original Message =
RE: Antenna Calibration/Site Attenuation
Chris, The rule that supersedes the others is: Don't interfere. However... there's a general perception that Class A is cheaper to build than Class B and not to ask for stricter standards if aiming at a better deal. This can result in specifying Class A limits if there is any justification at all for claiming non-residential operation. We do know that even Class B isn't good enough all the time, and Class A would not be better, but worse than that, but what I am looking for is some evidence that there is a de-facto standard applied by the regulatory authorities (in my case the FCC) to the introduction into or near a residential neighborhood of equipment only verified to meet Class A. Cortland == Original Message Follows >> Date: 25-Aug-97 13:20:16 MsgID: 1054-3884 ToID: 72146,373 From: Chris Dupres chris_dupres Subj: RE: Antenna Calibration/Site Attenuation Chrg: $0.00 Imp: Norm Sens: StdReceipt: NoParts: 1 Hi Cortland. You asked: <(As an aside, can anyone here say if the COmmission has ever specifically ruled on how far away from residences Class A equipment must be kept? > In my meanderings around the Compliance Biosphere, I've spoken to many enforcement people, competent bodies, even Government administrators. The general opinion seems to be 'If you meet the general intention of the Directives via the Standards, then the world will be a better trading place'. Note the deliberate absence of the word 'distance' and 'field strength, and 'interference'. In general, the advice I live with, and give, is that you shouldn't expect a TV to work perfectly on top of a Microwave cooker, and you wouldn't expect an electric pencil sharpener to reverse if you use a portable phone nearby. I feel that in any one typical domestic situation, the RF signature of a location is so far removed from an OATS or screened room as to be almost meaningless in practical terms, but you gotta put some rules down somewhere. I akin it to judging how fast a car can go by the shape of the hub caps. (They only put Hot Hub Caps on fast cars?) I had a case of a TIG welder interfering with a VHF radio some 200 metres away, awful wide band hash whenever the TIG fired up. I've also had Quadrupole Mass Spectrometers (pico and femto amps) behaving perfectly when 600mA 2kV Argon Arcs are being started in the same vacuum chamber. In answer to your question, I'm not aware of any requirements for distances between emitters and receptors, notwithstanding that there may be local by-laws which prohibit people camping beside arc furnaces, or something. In the UK, if you regularly get nuisance interference from anything at all, one can approach British Telecom, the monopoly holder, who will investigate and find the source of the intereference, and politely suggest to the source that they do something about it, but I'm not sure what teeth they have. The point is, is that they don't seem to take distance into account. It's all to do with the Wireless Telegraphy act, I think. That should be as clear as mud... Chris Dupres Surrey, UK. **Primary Recipient: Cortland Richmond 72146,373 == End of Original Message =
Re: Antenna Calibration/Site Attenuation
> From: Cortland Richmond <72146@compuserve.com> > To: "Grasso, Charles (Chaz)" ; ieee pstc list > Subject: RE: Antenna Calibration/Site Attenuation > Date: Monday, August 25, 1997 11:19 AM > > If it's mutual coupling... sure. But if it's a surface wave, that's real field > strength. If the reason for 3 meters -- an approximation of distance to the > victim receiver in a residential area -- is to be preserved, then perhaps this > is a non-issue, as the error is all on the high side, and emissions will be > reduced even lower than they would be on a ten meter site. > > (As an aside, can anyone here say if the COmmission has ever specifically ruled > on how far away from residences Class A equipment must be kept? I remember a > few years ago some chap got a NAL for operating a graphics work station in his > home... but what about separate buildings out back, etc. ?) > > Cortland It would seem that businesses run in homes would tend to violate *any* distance requirement. I believe that the wording of the labeling specifically addresses "may not cause harmful interference" which could be at any distance.