Welcome to RF Current, a weekly electronic newsletter focusing on Broadcast technical and F.C.C. related issues. This newsletter is part of The RF Page @ www.transmitter.com, a web site devoted to TV Broadcast RF engineering. For more information see the What is... guide to the R.F. Page site.

Issues are dated each Monday, although recently I've needed an extra day(week) or two to complete each issue. Articles may be posted earlier if time permits or if there is a major, breaking story.

<<< Back to January 15 - Issue 247

January 22, 2001 - Issue 248 Final Edition

FCC Sets Rules for Broadcast DTV Cable Carriage (Jan. 22)
The FCC released the First Report and Order and Further Notice of Proposed Rule Making regarding cable carriage of DTV broadcast signals. This report will focus on the technical issues related to DTV cable carriage. For detailed information on must-carry requirements, retransmission consent and cable channel capacity limitations, see Cable Carriage of Digital TV Signals - Summary of FCC Rules Adopted January 18, 2001.

Stations broadcasting in both analog and digital have must-carry rights only on their analog signal, but can negotiate for retransmission consent on their DTV channel. Stations which are broadcasting with digital only are entitled to must-carry and the station can choose to have its digital-only signal carried on the cable system in analog format. Cable systems are required to carry only the "primary" DTV program when a station is broadcasting more than one program stream on its DTV channel. The station decides which program stream is primary. Cable companies are not required to carry non-program related ancilliary data. Program related data that must be carried includes closed captioning; V-chip data; Nielsen ratings data; and channel mapping and tuning protocols (PSIP). The FCC said, "Whether a cable operator would be required to carry electronic program guides is subject to a fact-based program-related analysis."

Current FCC cable rules require the signal to be carried without material degradation. The FCC found, "a cable operator would not necessarily be materially degrading a digital television signal if it carries less than the full 19.4 mbps transmitted by a broadcaster." The cable system, however, may not carry the DTV signal in "a lesser format or lower resolution than that afforded to a non-broadcast digital programmer carried on the cable system." This rule does not apply to digital-only TV stations seeking must-carry on an analog cable channel.

Cable operators are not required to pass through the 8-VSB signal. They are allowed to remodulate the signals from 8-VSB to 64- or 256-QAM. Cable operators are "not required under the Act to provide subscribers with a set-top box capable of processing digital television signals for display on analog sets." Because channel branding can be done through PSIP, the Report and Ordeer found there was no need to implement channel positioning requirements. However, the broadcast DTV channels must be available to subscribers on a basic service tier.

DTV broadcasters are required to deliver a signal level of -61 dBm to the cable system headend. The FCC said this would provide an extra 20 dB margin for propagation variability and signal impairments above the minimum signal to noise ratio required for DTV reception. For comparison, the signal level for analog TV signals is -49 dBm at VHF and -45 dBm at UHF. -61 dbm equates to -12.25 dBmV or 244 microvolts.

This value can't be directly converted to a field strength contour as it depends on the gain of the antenna used to receive the signal. A 41 dBu field strength equates to 112.2 microvolts/meter. On channel 38, a 75 ohm dipole in this field will deliver a signal level of only 8.8 microvolts, approximately 29 dB below the minimum signal level required. This difference will have to be made up with increased receive antenna gain or a stronger signal. For example, at a cable headend with an antenna gain (after line losses, if any) of 9 dB, a UHF station operating on channel 38 would have to put a 61 dBu DTV contour over the cable system's headend. Note that due to the dipole effect, higher field strength will be required for channels above 38 and less for channels below 38. VHF field strength requirement are significantly lower.

In the Further Notice of Proposed Rule Making, the FCC seeks comment on the necessity of a dual carriage requirement to hasten the digital transition, the status and scope of digital retransmission consent agreements, the proper scope of the program related carriage requirements, current technologies that conserve or recapture cable channel capacity, and several other issues.

The complete text of the First Report and Order And Further Notice of Proposed Rule Making - Carriage of Digital Television Broadcast Signals... is available on the FCC web site as text file fcc01022.txt or Word document fcc01022.doc (released Jan. 23). For a summary of the document, refer to the FCC Factsheet Cable Carriage of Digital TV Signals - Summary of FCC Rules Adopted January 18, 2001 and the FCC News Release FCC Adopts Rules For Cable Carriage of Digital TV Signals.

In the first application of the new rules, the FCC granted mandatory carriage rights to WHDT-DT, channel 59, in Stuart, Florida. WHDT does not have an analog channel. Under the new rules, the FCC said WHDT-DT could elect whether its signal will be carried as a digital or converted analog signal. For additional details on this action, see FCC new releae FCC Grants "Must Carry" Status to Digital-Only TV Station.

FCC Releases R&O and Further NPRM On DTV Transition, Defines DTV City-Grade coverage and sets coverage requiements. (Jan. 19)
The FCC issued a Report and Order that addresses some of the issues surrounding the DTV transition. In addition to the Report and Order, the FCC requested comments on new rules and changes in a Further Notice of Proposed Rule Making (NPRM).

The FCC reaffirmed the selection of 8-VSB and declined to revisit its decision not to allow the use of alternative DTV modulation standards.

The FCC also denied requests to set a performance standard for DTV receivers. The R&O said, "We agree with Philips and Thomson that the effect of setting such standards at this point would be to stifle the innovation and limit performance to current capabilities. Moreover, as those pressing for DTV receiver standards acknowledge, more work is needed before it would even be possible to make specific proposals for such standards. In addition, we note that further enhancements to the 8-VSB modulation standard are being developed through the ATSC process. We therefore are denying broadcasters’ requests that we move to set performance standards for DTV receivers. We will, however, continue to monitor receiver issues throughout the transition and will take appropriate action on receiver standards if necessary."

The FCC will require that commercial DTV stations place stronger signal over their community of license by December 31, 2004. The FCC said the higher signal level would increae the number of locations where a good signal is present. It also noted that the requirement "helps prevent the migration of licensees from their community of license, thus furthering the purposes of Section 307(b) of the Communications Act." Non-commercial stations must meet the signal strength requirement by December 31, 2005. The DTV "City-Grade" field strength requirement is 7 dB higher than the noise-limited threshold set used in the ATSC planning factors for low-VHF, high-VHF and UHF. The values are:
DTV City Grade Signal Levels
Channel Field Strength (dBu)
2 - 6 35
7 - 13 43
14 - 69 48

The FCC based its selection of 7 dB on two factors. It noted that the analog B grade field strength, like the DTV noise-limited field strength, is based on 50 percent of the locations in the coverage area being able to receive ths signal. For Grade A NTSC the availability increases to 70 percent. NTSC City Grade availability was not defined. The Report and Order said increasing the DTV service availability to 70 percent requires "about a 4 dB increase in field strength, if all other assumed planning factors remain the same." For Grade B NTSC service, receive antenna gains are assumed to be 5 to 6 dB higher than for Grade A service.

The FCC assumes consumers will use different antennas for DTV reception than for NTSC reception. It said, "DTV antenna assumptions are generally that higher gain antennas will be used than have been assumed for NTSC TV reception. Conservatively, we assume that a DTV receiving antenna for use in a station's city of license can be at least 3 dB lower gain than the assumed receiving antenna for the edge of the station's service area."

The FCC Report and Order also noted that DTV reception is different than NTSC reception; "The NTSC signal strength degrades over distance from the transmitter, with picture quality declining accordingly. As we pointed out in the Notice, however, in DTV there are virtually no gradations in picture quality that are dependent on signal strength. If the signal strength is above a certain threshold it will produce an excellent picture. The degree to which the signal exceeds that threshold requirement does not matter; the picture quality will not change and would not change even if we were to require that the community of license be provided with a more robust signal than that currently required. The higher signal level requirement should increase the number of locations where a good signal is present."

The FCC decided it would not require broadcasters' DTV coverage replicate their NTSC coverage, commenting that it expected most DTV broadcasters "will eventually choose to replicate their NTSC service areas to serve their viewers." The FCC agreed with arguments by Joint Broadcasters that the migration to final DTV channels is not complete and requiring NTSC service replication by DTV stations would be premature and cause excessive expense to commercial and non-commercial broadcasters. Also, not requiring replication allows more flexibility in allowing broadcasters to collocate their transmitters, reducing the impact on the environment. The Report and Order warned, however, "Having afforded digital broadcasters the flexibility they requested in this area, we expect that they will redouble their efforts to assure that the build out continues expeditiously and that, barring circumstances beyond their control, construction deadlines are met."

The FCC addressed several other technical issues in the Report and Order. The R&O said: "We continue to believe that an industry approach is generally the most appropriate means for managing the implementation of a PSIP system. However, we do recognize that the transport stream identifiers (TSIDs) must be unique to each individual television station and that there is a need to coordinate TSID assignments for stations in the border areas with our neighbors in Canada and Mexico. We therefore agree that TSID assignments should be made part of the Commission's licensing process for broadcast television stations and will begin the process to incorporate this function into that process in the near future. Until negotiations with Canada and Mexico on this matter are complete and we have modified our licensing process and records management systems, we will continue to rely on the industry to make TSID assignments."

The FCC defered action on DTV boosters. "While we recognize the desire to initiate DTV booster operations, we believe there are fundamental issues surrounding their authorization and protection that must be addressed in a more comprehensive manner than can be accomplished based on the limited record on this issue in this proceeding. Therefore, we will defer this consideration to the rulemaking proceeding on digital LPTV and DTV translator stations that we expect to initiate within the next few months."

The FCC recognized comments from Hammett and Edison and others expressing concerns about elements in the FCC's interference analysis program used to process applications. However, the R&O said, "We have found it necessary to balance ideas and recommendations for refining the program with the disruption and uncertainty that would occur when a change is made. In the case of each of these proposals, we believe that the disruption of altering the program would be more severe than warranted by the possible improvement in the accuracy of the analysis results provided by the program. We have an administrative process that relies on comparison of interference and service predictions with the analysis performed in creating the table of allotments. Recalculating the entire table would be an enormous undertaking. Additionally, reconciling calculations using a new methodology with the table calculations based on different methodology is difficult and likely to result in uncertainty in the results and contested decisions." The FCC noted, "in a special case, where one of the suggested revisions would improve the accuracy of the analysis and would make a critical difference, an application may contain a showing using an alternate analysis in support of a waiver request."

In response to a request that the FCC immediately release to the public all software it uses in its DTV, TV and LPTV/translator evaluation procedures, the R&O said, "Some of the software requested by Everist is still in a development and testing phase and we believe it would be premature and, indeed, confusing to release it to the public while it is undergoing review and revision. Software that is relied upon in processing TV and DTV applications has been, and will continue to be, made available to the public in the same way that evaluation software for other video broadcast services is made available."

The R&O rejected calls to change receiving antenna pattern assumptions. With regards to population calculations, the FCC said it had not made plans to convert its processing analysis to use new census data and noted using the new census data would "necessitate re-evaluation of the entire DTV table to establish 'baseline' values against which application proposals can be measured." It will allow submission of additional information about population shifts with an application "where such information is crucial and decisional."

The FCC clarified its rules with regards to the maximum ERP stations can request:
First, the maximum ERP limits (1000 kW for UHF channels 14-69 in any zone; 30 kW for VHF channels 7-13 in Zone 1; 160 kW for VHF channels 7- 13 in Zone 2 or 3; 10 kW for VHF channels 2-6 in Zone 1; and 45 kW for VHF channels 2-6 in Zone 2 or 3) may not be exceeded. The “largest station” provision applies only where the rules normally require a reduction in the maximum power because a specified antenna HAAT is exceeded. That is, it does not allow power higher than the maximum ERP to compensate for an antenna HAAT that is lower than the value specified in the rule. Second, the “largest station” provision is only triggered where a station in the same market is serving a larger area than could be covered with the standard maximum power and antenna height specified in Section 73.622(f) of the Rules. Otherwise, applicants must comply with the maximum power and antenna height in that rule section. Third, for the purpose of this rule, stations in the same DMA are considered to be in the same market. Fourth, the geographical coverage determination is based on the area within the DTV station’s noise-limited contour, calculated using predicted F(50,90) field strengths as set forth in Section 73.622(e) of the Rules and the procedure specified in Section 73.625(b) of the Rules. Under this provision an application may not request a power and antenna height combination that would result in coverage of more square kilometers of area than the largest station in the market. It is not necessary that the application specify coverage that is congruent with or encompassed by the coverage area of the largest station. Stations are not expected to shift their coverage area in order to use this provision of the maximum power rules. Finally, DTV stations are still subject to the interference protection requirements, even when availing themselves of this provision."

The FCC agreed with Hammett and Edison's request for a blanket waiver of the envelop delay requirement for NTSC stations with upper-adjacent channel DTV assignments that use a common transmitting antenna. It stated, "we authorize all NTSC TV stations with a DTV signal on the first-adjacent channel above the NTSC channel and with a common transmission line and antenna, to operate at variance with the envelope delay requirements of Section 73.687(a)(3) for frequencies between 3.9 and 4.2 MHz above the visual carrier."

Attached to the Report and Order was a Notice of Proposed Rule Making. The major topic in the NPRM is whether the FCC should require digital reception capability in all receivers. There are several legal issues at stake. NAB and other broadcasters argue the FCC has the authority to require DTV tuners. Consumer electronics manufacturers argue it doesn't.

The R&O noted, "While Congress in 1962 did not anticipate the advent of digital television service, a plain language reading of this section does not limit our authority to analog television receivers, nor does it limit our authority to channels in the UHF band. Inasmuch as the frequencies allocated to television broadcasting now include those channels allotted for DTV service, Section 303(s) provides the Commission with authority to require that television receivers be capable of adequately receiving those channels. receiving those channels. Moreover, the ACRA's legislative history suggests that Congress' reasoning in enacting the statute supports such a conclusion." The FCC seeks comment on "how to construct any DTV tuner requirement consistent with any relevant statutory authority, including Section 303(s) and any other relevant sections of the Communications Act of 1934, as amended."

The FCC is considering how to proceed with this requirement. "We request comment on how best to implement DTV reception capability requirements, if we were to adopt them." The FCC recognized it would not be economically feasible to include DTV capability in smaller screen receivers. It asked for comment on what would be an appropriate minimum screen size for the initial DTV requirement. The NPRM also asked for comment on the cost implications of DTV reception capability for both consumers and manufacturers. The FCC invited "interested parties to submit other plans that would result in new TV receivers being equipped with DTV capability that would result in widespread penetration of TV receivers in households to enable the transition from analog to digital TV service consistent with the intent of Congress in Section 309(j)(14) of the Communications Act, and a discussion of the likely effectiveness of such alternative plans."

The complete Report and Order and Further Notice of Proposed Rule Making, Review of the Commission's Rules and Policies Affecting the Conversion to Digital Television (MM Docket 00-39) is available on the FCC web site as an Adobe Acrobat document - fcc01024.pdf or as an ASCII text file, fcc01024.txt. Refer to it for information other technical and legal issues regarding the DTV conversion. The FCC News Release FCC Issues Further Order In Digital Television Transition; Asks For Further Comments On DTV Receiver Issues.

DTV - ATSC Chairman Graves Comments on NAB/MSTV Decision Supporting 8VSB (Jan. 19)
Robert Graves, Chairman of ATSC, stated, "The decisions this week by the NAB and MSTV and by the FCC put an end to the debate surrounding the ATSC/VSB transmission system used for terrestrial DTV broadcasts in the U.S. With the transmission system debate behind us, with the impressive array of DTV and HDTV products now available at ever lower prices, and with the increasing amount of compelling DTV content becoming available from broadcasters, the outlook for DTV services in the U.S. is bright. And we expect this week's actions by the broadcast industry and the FCC to enhance the prospects for adoption of the ATSC Digital Television Standard in other countries."

"Significant improvements have already been made in the performance of VSB receivers, and further improvements are in the pipeline from a variety of manufacturers. Moreover, work is under way within the ATSC to further enhance the ATSC/VSB standard by adding more robust transmission modes that address emerging DTV applications, and we expect to issue a Request for Proposals for these enhancements shortly. We invite interested parties in all segments of the industry to join us in the effort to continue to enhance the ATSC DTV Standard."

From Word document - ATSC Statement Dated January 19, 2001.

DTV - Manufacturers Applaud NAB/MSTV 8VSB Decision and FCC DTV Actions (Jan. 19)
Consumer Electronics Association (CEA) President and CEO Gary Shapiro, in a statement released today said, "...we applaud the Commission for again reaffirming the 8-VSB transmission standard as the best standard for the United States. This action, combined with the recommendation released earlier this week by the National Association of Broadcasters and the Association for Maximum Service Television, definitively ends the debate over the DTV modulation standard. It is time to move on. We are encouraged that the FCC is setting deadlines to encourage broadcasters to provide digital service to their full service area. This will help ensure that all Americans have access to a digital signal. We also commend the Commission for recognizing that innovation and market forces will result in continued improvements in already strong-performing DTV products. Continual innovation is a hallmark of our industry. The history of our industry shows that consumer electronics improve in performance even as new features and enhancements are added."

Shapiro was not as happy about the FCC's exploring requiring DTV tuners in TV sets: "Finally, we again express our concern about the proposal mandating the inclusion of digital receivers in a specific category of analog television sets. As Commissioner Tristani and many consumer groups have said, this mandate would increase the cost of television sets and limit consumer choice. The proposal is anti-consumer and would slow the transition to DTV."

The CEA CEO said, "The debate over the modulation standard is over. All broadcasters who are seriously committed to the DTV transition should now recommit to the transition by continuing the buildout and producing more high-definition and digital content. The results of the joint NAB/MSTV testing confirm what we have long believed: the Federal Communications Commission (FCC)-approved 8VSB modulation system is the best choice for broadcasting digital television (DTV) in the United States. These results also reaffirm that the FCC made the correct decision in initially selecting, and again re-endorsing 8VSB last year. It is time to return to the key element of the transition - providing consumers with the full benefits of digital television."

Richard M. Lewis, Zenith senior vice president, said, "Having lost at the FCC last year and now having suffered yet another stinging defeat, COFDM zealots should abandon the politics of obstruction and admit that their delay strategy has failed. We hope they will now join the leading broadcasters in moving the DTV transition forward -- by completing DTV station conversions and providing compelling HDTV content."

This information was obtained from the CEA Newsroom and Zenith press release Zenith Hails Broadcast Industry Decision to Stay the Course on Digital Television Standard.

DTV - Zenith Pledges Cooperation on DTV Tuner Issues (Jan. 22)
Zenith welcomed the FCC Report and Order reaffirming the selection of 8-VSB for the U.S. DTV modulation standard. Richard Lewis, Zenith senior vice president said, "The Commission's strong endorsement of its VSB transmission system, on the heels of last week's reaffirmation of the VSB standard by the broadcasters, means that it is time for all of us -- local TV stations, networks, program providers and manufacturers -- to move ahead quickly to bring the benefits of DTV to the American public."

Lewis also commented on the FCC's consideration of mandatory DTV reception capability in some TV sets. "Zenith is fully committed to television's digital future and is moving aggressively to introduce a host of new digital TV products. We are prepared to cooperate with the FCC on a phased-in approach to DTV tuner deployment in a way that will benefit consumers, broadcasters and manufacturers alike." A Zenith press release Zenith Applauds FCC's Reaffirmation of VSB Standard, Pledges Cooperation on DTV Tuner Issue noted that Zenith had recently announced the first integrated DTV set expected to sell for under $1,000.

OTHER Items of Interest

>>>>Next January 29 - Issue 245

RF Current Index

Return to The RF Page @ www.transmitter.com

Last modified March 30, 2001 by Doug Lung dlung@xmtr.com
Copyright ©2001 H. Douglas Lung