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In the Matter of )
)
1998 Biennial Regulatory Review -- ) ET Docket No. 98-80
Conducted Emission Limits Below 30 MHz )
For Equipment Regulated Under Parts 15 )
and 18 of the Commission's Rules )
To: The Commission
IN RESPONSE TO NOTICE OF PROPOSED RULE MAKING
ARRL, The National Association For Amateur Radio, (ARRL), on behalf of its members and of the more than 650,000 licensed amateur radio operators in the United States, by counsel and pursuant to Section 1.415 of the Commission's Rules [47 C.F.R. §97.415], hereby respectfully submits its comments in response to the Notice of Proposed Rule Making (the Notice), FCC 99-296, released October 18, 1999 in the captioned proceeding. For its comments, ARRL states as follows:
1. The Notice proposes to amend Parts 15 and 18 of the Rules to revise the limits on the extent to which unlicensed electronic devices (regulated under Part 15 of the Commission's rules) and Industrial, Scientific and Medical Devices (regulated under Part 18 of the Commission's Rules), are permitted to conduct RF voltages onto the AC power lines on frequencies below 30 MHz. Conducted RF energy is a particularly significant concern in the high-frequency (HF) range due to the efficiency of the AC power lines as antennas, given the long wavelengths of the frequencies at issue. Conducted emissions are of particular concern to the Amateur Radio Service, given: (1) the extremely heavy use of the amateur allocations spaced throughout the HF spectrum, and (2) the geographic proximity of amateur stations, generally operated from residences, to the AC power lines, and to Part 15 and 18 devices. ARRL participated in the Notice of Inquiry phase of this proceeding(1), and urged that the Commission continue to regulate conducted emissions as a means of protecting extensive amateur radio worldwide communications, principally conducted from residences and residential areas. ARRL's comments also noted that the present Part 15 regulations provide only the most minimal degree of protection against interference to amateur radio receivers, which in many cases is insufficient. Therefore, ARRL noted, there is no justification for making those limits more liberal than they are now. Conducted limits must, of course, be imposed at the equipment authorization stage, because it is not at all likely that the operators of Part 15 or Part 18 devices will be able, or willing, to resolve interference in situ. The Commission, understandably, is unable to devote technical or enforcement staff time to interference resolution in these cases, and ARRL is unaware of any manufacturers who have expressed a willingness to address aftermarket interference cases on a voluntary basis.(2) Thus, ARRL again urges the Commission to confirm in the Report and Order in this proceeding the necessity for retaining conducted emission limits in the equipment authorization regulations in the future.
2. The current conducted emission limitation for Part 15 devices (both intentional and unintentional radiators) on frequencies between 450 kHz and 30 MHz is 250 microvolts, except that for Class A digital devices operating in the vicinity of the AM Broadcast band, the limit is 1 millivolt, and on HF frequencies, 3 millivolts.(3) Conducted emissions from Part 18 devices are governed by Section 18.307 of the Commission's rules, and the limits are device-specific. The most liberal regulation applies to non-consumer RF lighting devices, which are permitted conducted emissions in the 1.6 to 30 MHz range of up to 3 millivolts.
3. The Notice proposes to adopt the CISPR standard for conducted emissions employed in the European Union, which will provide a global standard for such devices. As the Commission notes, this will reduce costs for manufacturers and consumers. Because the CISPR conducted emission limits are slightly more stringent than the current Part 15 and 18 regulations applicable to such devices, offering at least a few dB of additional protection for HF communications over the existing Part 15 standard,(4) they are from ARRL's perspective preferable to existing rules. The HF bands allocated to the Amateur Radio Service are extensively used for worldwide communications around the clock, using extremely sensitive receivers and high-gain antenna systems. The communications conducted include public service and emergency communications, and those which foster international goodwill. Severe interference is noted regularly at United States amateur stations in HF bands due to conducted RF energy caused by devices such as microwave ovens, television receivers, Class B computing devices, wireless modem jacks, and numerous consumer Part 15 devices. Any decrease in conducted emissions limits from those presently permitted is useful in reducing interference levels, especially in metropolitan and suburban areas. The number of new devices that can cause interference by conducted emissions has been steadily increasing, thus significantly increasing the interference levels, and the potential for harmful interference to many amateur stations. This would generally indicate that the slightly more restrictive CISPR standard would contribute to at least a reduction in the rate of increase of RF noise in the HF spectrum overall. The CISPR limits incorporate separate limits for digital devices and ISM equipment used in residential areas (digital devices are now regularly incorporated in the vast majority of modern amateur stations in residential areas) and those used in business or industrial environments. This factor makes the CISPR limits appropriate from the perspective of radio amateurs as well.
4. ARRL suggests, however, that in addition to adoption of the CISPR standard for conducted emissions, the Commission should conduct empirical studies, over time, of the levels of noise in the HF spectrum created by unlicensed devices in an effort to quantify the rate of increase in RF interference in urban and suburban environments. Such data would better serve as a guideline for the Commission in determining the proper regulatory approach to conducted (and radiated) emission levels, given the burgeoning consumer market for Part 15 and Part 18 devices. Certainly, radio amateurs could contribute substantially to such a study, and ARRL would be eager to work with the Office of Engineering and Technology on a project of this nature.
5. In ARRL's comments in response to the Notice of Inquiry, ARRL asked that the Commission clarify that the conducted emission limits apply to common-mode signals. Typical measurement techniques usually measure differential-mode signals. However, some devices can generate common-mode conducted emissions as well. These common-mode signals will generally be radiated very efficiently by AC wiring, much more efficiently than typical differential-mode signals. Together with the determination of the proper conducted emission limits in this proceeding, the Commission should clarify that both common-mode and differential-mode emissions should be regulated and tested for compliance.
6. The alternative measurement technique proposed in paragraph 7 of the Notice is confusing, and should not be adopted as proposed in the Notice. The Commission's alternative measurement system to permit device manufacturers to test devices for compliance with the radiated limits for intentional radiators creates potential misinterpretation and possible avoidance of the intent of the rule. The present measurement standards rules, at Section 15.31(d), stipulate that in the case of equipment that can only be measured at the installation site, measurements must be made at a minimum of three installations that can be demonstrated to be "representative of typical installation sites". The inherent vagueness of this "typical installation site" rule has, in at least one notable case in ARRL's experience, led to many dozens of serious interference problems involving amateur stations which persist today. The case involves wireless modem jacks extensively deployed by one particular manufacturer. The devices were verified, using data from three ostensibly "typical" installations, but the devices, as deployed in residences, have resulted in more than 100 reports to ARRL of harmful, and in many cases, severe interference in the amateur 3.5-4.0 MHz band. Technical investigation by ARRL staff resulted in findings that the radiated field strength of the devices was more than 10 dB over the intentional emitter limits, but it appears that the devices were properly tested pursuant to the Section 15.31(d) standard. The language of Section 15.31(d) in that section is simply too vague to be interpreted properly by manufacturers eager to move their products to the marketplace. Measuring the actual conducted emissions using a LISN device, which tests such limits, in a laboratory is an easy test to perform, and should be required. Prudence would dictate that both conducted and radiated emissions testing should be performed if radiated testing is being performed.
7. On a related subject, the Commission should clarify in this proceeding the provisions of Section 15.205 of the Rules. It would be helpful to manufacturers to clarify in that rule, or in the definitional section of Part 15, that "spurious emissions" do not include the necessary bandwidth modulation products (i.e. "out-of-band emissions" within 250% of necessary bandwidth). It should also be made clear that the table of restricted bands in Section 15.205 applies to those carrier current devices and other devices that conduct signals over wires as outlined in Section 15.109. This is because conducted emissions lead to radiated emissions which could (and do) cause interference, as the Commission has determined at Paragraph 8 of the Notice. Thus, Section 15.205(c) could be amended to read as follows:
(c) Except as provided in paragraphs (d) and (e), regardless of the field strength limits specified elsewhere in this subpart, the provisions of this section apply to emissions from any intentional radiator, carrier current device, or other intentional radiator designed to conduct their radio frequency emissions via connecting wires or cables.
8. At paragraph 10 of the Notice, the Commission holds that compliance with the conducted emission limits is achieved principally through RF filtering, the techniques for which are well-known. ARRL agrees, and notes that most products require some degree of filtering to meet any conducted emission limit. Once filtering is required, the incremental cost of "good" versus "better" filters is relatively small. Such incremental improvement is useful in preventing interference at the manufacturing stage of the unlicensed devices, the least expensive stage of the process.
9. For reasons stated above, ARRL disagrees with the proffer of GE Lighting and the Information Technology Industry Council (ITI) that relaxed limits on Part 18 devices can be adopted without increasing interference to communications services. It is absolutely untrue, notwithstanding ITI's representation to the contrary, that the conducted limits employed in the United States have resulted in an "interference-free" situation. ARRL cannot accept any liberalization of limits for broadband emissions that may result from the use of fluorescent lighting devices or RF light bulbs, as the limits presently applicable to such devices are already extremely liberal. ARRL concurs with the Commission's conclusion at paragraph 20 of the Notice, that consumers have no way to tell at the time of purchase whether a product emits high levels of conducted emissions that are capable of causing interference to communications services, and that therefore, mandatory conducted emission limits continue to be necessary to control interference to communications services.
10. At paragraphs 19 and 26 of the Notice, the Commission attempts to accommodate Microsoft, which asks for relief from the limits for conducted emissions appearing at the fundamental frequencies of intentional radiators operating below 30 MHz. The assertion is that it is "difficult and costly" to suppress conducted emissions at the fundamental frequency of the transmitter due to coupling between the antenna and the power wiring. Thus, the Commission proposes to permit the responsible party to ignore the level of emissions conducted onto the AC power line at the transmitter's fundamental frequency, provided that the energy radiated from the AC power lines is included in the determination of total radiated emissions from the intentional radiator. This is not objectionable as far as it goes, but in addition, the Commission also suggests alternative test procedures, including such as would enable the equipment to be subjected to a single test at a laboratory open field test site. The Commission also proposes to allow the testing to be made at a minimum of three installations that are representative of typical installation sites, as it does with carrier current systems. As discussed hereinabove, this is a vague, and therefore meaningless, provision that is insufficient to keep interference-causing devices off the market. In the experience of the ARRL Laboratory staff, there can be more than a 20 dB change in the NEC-4 modeled, simple electrical wiring model if a light switch is opened or closed. The concept of a "single test at an open field test site" is therefore insufficient as a means of interference avoidance. Conducted emissions tests are not difficult to perform, and the tests should be meaningful. The limits are necessary, and in order to serve their function of interference avoidance, it is reasonable to expect manufacturers to comply with them, especially because post-market interference resolution is simply impossible as a practical matter.
11. The Commission asks, at paragraph 29 of the Notice, for comment on the proposal to maintain the current Part 18 conducted emission exemptions for non-consumer ultrasonic and magnetic resonance equipment that are used for medical diagnostic and monitoring applications. ARRL has not noted significant instances of interference to amateur stations from conducted emissions from such devices to date, and therefore interposes no objection to the proposal.
12. At paragraph 31 of the Notice, the Commission asks for comment on the proposal of Microsoft to limit the power line conducted emissions used by carrier current systems as an optional alternative method of demonstrating compliance with the radiated limits outside of the AM broadcast band. This is an interesting alternative. If the limit is established correctly, it would at once make it easier for manufacturers to comply and might result in an overall improvement in interference levels. If done incorrectly, there could be a resultant increase in radiated levels permitted for carrier current systems. Prior to implementing such a means of demonstrating compliance, there should be studies based on tests of residential electrical wiring to determine whether such wiring will, in general, meet the limits.
13. The Commission also proposes a clarifying modification of Section 15.109(e) based on a request from Inline Connection Corporation, a manufacturer of TV interface devices. The clarification is with respect to radiated emissions measurements below 30 MHz, and when such are required. The Commission proposes to amend its rules to require radiated emission measurements below 30 MHz for connecting cables of unintentional radiators only when the length of the connecting cable is at least one-fourth of the wavelength of the center of the transmitted signal or is of unknown length. ARRL welcomes such a clarification, because it would clearly state for the first time that devices which incorporate interconnecting cables of moderate length necessitate compliance with radiation limits. This will serve as notice to various home networking device manufacturers that their devices, because of the interconnecting cables, are subject to radiated emission measurements below 30 MHz, rather than just the Class B digital device emission standard.
14. However, setting the cutoff limit for this requirement at connecting cables of 1/4 wavelength or more would appear to ARRL to be arbitrarily high. Many antennas in common use in Amateur Radio and in commercial services are a quarter wavelength in length. A better trigger for this requirement would be cables of 1/8th or 1/10th wavelength; about half the size commonly used as antennas, and which are less efficient as radiators.
15. In summary, ARRL supports the Commission's proposal to modify its Part 15 and Part 18 rules to incorporate the CISPR standard for conducted emission limits as very much in the interest of all concerned. The Commission at once proposes a standard that will reduce manufacturers' costs, foster a global market for unlicensed and ISM devices, and somewhat reduce the increasing levels of interference to communications services, including the Amateur Service, in the high-frequency bands below 30 MHz. At the same time, however, there are several clarifications necessary relative to the testing of such devices, and the means by which compliance with the limits is demonstrated. If those clarifications are not made in this proceeding, the vagueness of the present testing requirements will not (and in ARRL's recent experience, have not) adequately limit these devices to the limits specified in the rules when deployed by consumers, and interference to communications services operating at HF will continue to increase.
Therefore, the foregoing considered, the American Radio Relay League, Incorporated respectfully requests that the Commission replace the present conducted emission limits in Parts 15 and 18 of its rules with the CISPR limits as proposed, and that the remaining clarifications
and modifications in the Part 15 and 18 rules requested herein be implemented in any Report and Order adopted in this proceeding.
Respectfully submitted,
ARRL, THE NATIONAL ASSOCIATION
FOR AMATEUR RADIO
225 Main Street
Newington, CT 06111
By: ____________________________
Christopher D. Imlay
Its General Counsel
BOOTH FRERET IMLAY & TEPPER, P.C.
5101 Wisconsin Avenue, NW
Suite 307
Washington, DC 20016-4120
(202) 686-9600
January 31, 2000
Notes:
1 See the Notice of Inquiry, FCC 98-102, released June 8, 1998.
2 ARRL has, however, devoted significant technical staff resources toward efforts at cooperative interference resolution involving these devices, most notably involving wireless modem jacks in residences. While some manufacturers in ARRL's experience have attempted to cooperate in these efforts, the extensive deployment of Part 15 consumer devices which generate conducted emissions makes any aftermarket interference resolution difficult or impossible.
3 See 47 C.F.R. §§15.107 (unintentional radiators), 15.207 (intentional radiators).
4 The Notice states, at paragraph 22, that the CISPR quasi-peak limits are less severe than the FCC quasi-peak limits (because the CISPR Publication 22 standards for quasi-peak limits take into account adjustments for broadband emissions, and for other reasons) but that overall, the CISPR emission limits for consumer equipment are approximately 5 dB more stringent below 5 MHz and 1 dB more stringent above 5 MHz.