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Proposed Rule

Establishment of an Improved Model for Predicting the Broadcast Television Field Strength Received at Individual Locations

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Federal Communications Commission.


Proposed rule.


This document requests comment on a proposed prediction model for determining presumptively the ability of individual locations to receive over-the-air television signals broadcast by local television stations. The Commission believes this model will be a useful means for establishing the eligibility of individual households to receive the signals of television broadcast network stations through satellite carriers. The Commission is complying with new statutory requirements set forth in the Satellite Home Viewer Improvement Act of 1999.


Comments must be received on or before February 22, 2000, and reply comments on or before March 7, 2000.


All filings must be sent to the Commission's Secretary, Magalie Roman Salas, Office of the Secretary, Federal Communications Commission, 445 12th Street, SW, TW-A325, Washington, DC 20554.

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Robert Eckert, Office of Engineering and Technology, (202-418-2433).

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This is a summary of the Commission's Notice of Proposed Rule Making in ET Docket No. 00-11, FCC 00-17, adopted January 13, 2000, and released January 20, 2000. The full text of this Commission decision is available for inspection and copying during normal business hours in the FCC Reference Center (Room CY-A257), 445 12th Street, SW, Washington, DC, and also may be purchased from the Commission's copy contractor, International Transcription Services, Inc., (202) 857-3800, 1231 20th Street, NW, Washington, DC 20036.

Summary of the Notice of Proposed Rule Making

1. In the Notice of Proposed Rule Making (NPRM), the Commission proposes rules prescribing a point-to-point predictive model for determining the ability of individual locations to receive an over-the-air television broadcast signal of a specific intensity through the use of a conventional, stationary, outdoor rooftop receiving antenna. Our goal in developing this model is to provide a means for reliably and presumptively determining whether the over-the-air signals of network affiliated television stations can be received at individual locations. Such determinations are used in establishing the eligibility of individual households to receive the signals of television broadcast network stations by satellite carriers. In issuing this proposal, we are complying with new statutory requirements set forth in the Satellite Home Viewer Improvement Act of 1999 (SHVIA). The signal intensity for determining eligibility is the Grade B standard set forth in § 73.683(a) of the Commission's rules.

2. The SHVIA revises and extends statutory provisions established by Congress in the 1988 Satellite Home Viewer Act (SHVA). With regard to prediction of signal availability, the SHVIA adds a new section 339(c)(3) to the Communications Act of 1934, as amended, which requires that “[W]ithin 180 days after the date of enactment of the Satellite Home Viewer Improvement Act of 1999, the Commission shall take all actions necessary, including any reconsideration, to develop and prescribe by rule a point-to-point predictive model for reliably and presumptively determining the ability of individual locations to receive signals in accordance with the signal intensity standard in effect under section 119(d)(10)(A) of title 17, United States Code.” Section 339(c)(3) further provides that “[I]n prescribing such a model, the Commission shall rely on the Individual Location Longley-Rice model set forth by the Federal Communications Commission in Docket No. 98-201, and ensure that such model takes into account terrain, building structures, and other land cover variations. The Commission shall establish procedures for the continued refinement in the application of the model by the use of additional data as it becomes available.” The SHVIA also requires that the courts rely on the Individual Location Longley Rice model established by the Commission for making presumptive determinations of whether a household is capable of receiving broadcast television signals of Grade B intensity.

3. In its Report and Order in CS Docket No. 98-201, 64 FR 7113 (February 12, 1999), (SHVA Report and Order), the Commission endorsed the use of a specific model for predicting signal strength at individual locations. This model, which the Commission termed “Individual Location Longley-Rice” or “ILLR,” is a version of Longley-Rice 1.2.2. The Commission recommended that the ILLR model be used for determining a presumption of service or lack of service by local over-the-air television signals at individual locations for purposes of establishing a household's eligibility to receive network television programming by satellite carriers under the SHVA.

4. The Commission found that vegetation and buildings affect signal intensity at individual locations. However, it also found that at the time of the SHVA Report and Order, there was no standard means of including Start Printed Page 4924such information in the ILLR that had been accepted by the technical and scientific community. The Commission therefore stated that land use and cover information will be included in the ILLR when an appropriate method for using such information in the context of determining the field strength of broadcast television signals at individual locations has been developed and accepted. In its Order on Reconsideration in CS Docket 98-201, 64 FR 73429 (December 30, 1999), the Commission denied DirecTV's petition for reconsideration, in part, on the basis that it failed to provide the information and details necessary to evaluate an application to consider land use and cover in the ILLR.

5. Subsequent to the SHVA Report and Order, the ILLR has been implemented by several commercial companies as a tool for determining whether particular households, identified by street address, are served or unserved for purposes of the SHVA. Providers of programming service by satellite carriers are screening potential customers for eligibility at the point-of-sale using the ILLR model.

6. Following the direction of Congress in the SHVIA, we are proposing to define an improved model for predicting the field strength produced by a television network affiliate broadcasting station at individual locations, using as a guide the ILLR model as described in the SHVA Report and Order. This model would be incorporated into our rules as the required method for making presumptive determinations of individual household's eligibility for satellite retransmission of distant network signals. The prediction model we are proposing takes into account terrain, building structures, and other land cover variations, some of which are yet to be evaluated and accepted by the scientific and technical community. We therefore are also outlining a process through which values can be developed for these parameters. This process provides for continued refinement of the model on the basis of reliable technical evidence, as it becomes available.

A. The Current ILLR Prediction Model

7. The current ILLR model is the version of Longley-Rice 1.2.2 that we endorsed in the SHVA Report and Order. It is similar to the point-to-point predictive model we established for digital television (DTV) coverage and interference prediction. The ILLR model does not replace the current Commission rules for field strength contours (§ 73.683) or prediction of coverage for non-SHVA purposes (§ 73.684). In fact, the ILLR model may identify unserved households lying within a station's Grade B contour and may, likewise, identify served households outside a Grade B contour.

8. In Appendix A, we specify the technical details that are to be used with Longley-Rice 1.2.2 to qualify the latter as the ILLR model required under the SHVIA. The SHVA Report and Order left some of these details to choice since it offered ILLR only as a means to make administration of the unserved household rule under SHVA easier and more cost-effective. Here, some of the Longley-Rice 1.2.2 input parameters have values different from those utilized for application of the model to DTV.

B. Improvements in the Model

9. We propose to improve the ILLR model by adding clutter loss parameters. The clutter loss includes the effects of both vegetation and buildings and is dependent upon the environment of the individual household reception point. Reception point environments are to be classified in terms of the codes used in the Land Use and Land Cover (LULC) database of the United States Geological Survey, and clutter loss values are to be added to the radio propagation loss predicted by basic Longley-Rice 1.2.2.

10. To simplify use of the database for ILLR purposes, we have reorganized the LULC categories in a way specifically relevant to radio propagation. After regrouping, we identify 10 environmental classes, almost all of which are combinations of several of the original LULC categories. Since many of the original LULC categories distinguish between environments in ways that are unimportant for propagation prediction, it is clear that simplification is in order. The particular simplification we are proposing for the ILLR is defined in Appendix A along with other details of the ILLR model. This simplification is the same as a classification system currently under consideration by an industry standardization committee.

11. In the improved ILLR model, it is contemplated that a clutter loss value (a reduction in available signal intensity) will be associated with each and every LULC classification in a way that is also dependent upon frequency. However, the available data for assigning values to these parameters is limited, and we believe it is reasonable to assign values only in situations for which measurement data have been analyzed and published, or for which we have some confidence in deriving such values. We are basing the ILLR table of clutter loss on the results published in a recent engineering journal by Thomas N. Rubinstein. Since the Rubinstein values of clutter loss are derived exclusively from measurements made at receiver sites with Fresnel clearance, the values should apply only to matching situations. For other situations, the clutter loss will have to remain equal to the default value of zero dB, the value it effectively has in the current ILLR model where LULC data is not used. We recognize that, under this approach, the number of situations in which clutter loss may be taken into account will be limited. We therefore request comment on whether other data are available that would allow us to expand the application of clutter loss considerations, and whether there are other approaches that are scientifically supported and could be integrated into the ILLR model to take into account losses due to vegetation and man-made structures.

12. It is particularly problematic that the Rubinstein table of losses does not cover low band VHF television, channels 2 through 5, so that no clutter loss can be assigned to reception on these channels without introducing an exception to our principle of not assigning values unless measurement data have been analyzed and published for matching situations. We are proposing to address this problem by using clutter loss values for low band channels that are derived by applying frequency trend data to the Rubinstein clutter loss values for high band VHF. The frequency trend we have applied is that found by Okumura. The low band values obtained in this way are tabulated in Appendix A. Comments are requested on the acceptability of this approach.

C. Procedures for Continued Refinement

13. Because of copyright law implications addressed by the SHVIA, we believe that formal rule making is appropriate to make changes in the future in the ILLR model that we adopt in this proceeding. We seek comment on this proposed procedure and any other suggestions for revising the ILLR in a timely fashion.

D. Designation of Neutral and Independent Entity for Signal Tests Purposes

14. In addition to requiring that the Commission conduct a rule making to improve the ILLR predictive model, section 339 prescribes procedures for selecting a qualified, independent person to test the signal at a household. In particular, section 339(c)(4)(B) provides:

If the satellite carrier and the network station or stations asserting that the retransmission [of a signal of a distant Start Printed Page 4925network station] is prohibited are unable to agree on such a person to conduct the test, the person shall be designated by an independent and neutral entity designated by the Commission by rule.

15. We seek comment on how to identify qualified entities as candidates to fulfill this legislative requirement. What types of qualifications should such an entity possess? Are there industry testing labs in existence that could fill this role? What characteristics will demonstrate the independence and neutrality contemplated by the statute? Should there be multiple designating entities across the country or one central clearinghouse?

16. We recognize the importance of completing the proceeding to determine the designated tester as quickly as possible and, therefore, include this issue in this expedited proceeding to revise the ILLR.

Appendix A—Technical Data

This appendix specifies technical details and input parameters that are to be used with Longley-Rice Version 1.2.2 to qualify the latter as the Individual Location Longley-Rice (ILLR) propagation prediction model per § 73.683(d) of the FCC rules. The method for including Land Use and Land Clutter (LULC) classifications of locations with attributed clutter loss values is defined here. This appendix will be republished as OET Bulletin No. 70 and included in FCC rules by reference.

Computer code for the Longley-Rice radio propagation prediction model is published in an appendix of NTIA Report 82-100, A Guide to the Use of the ITS Irregular Terrain Model in the Area Prediction Mode, authors G.A. Hufford, A.G. Longley and W.A. Kissick, U.S. Department of Commerce, April 1982. The report may be obtained from the U.S. Department of Commerce, National Technical Information Service, Springfield, Virginia, by requesting Accession No. PB 82-217977. Some modifications to the code were described by G.A. Hufford in a memorandum to users of the model dated January 30, 1985. With these modifications, the code is referred to as Version 1.2.2 of the Longley-Rice model. It is available for downloading at the U.S. Department of Commerce Web site, <​itm.html>.

When run under the conditions given in Table 1, the Longley-Rice model becomes the ILLR per § 73.683(d) of the FCC rules. Note especially the following unique features of the ILLR prediction procedure (they distinguish the ILLR model from, for instance, the use of Longley-Rice for digital television coverage and interference calculations as detailed in OET Bulletin No. 69):

  • The time variability factor is 50% presuming that the ILLR field strength prediction is to be compared with a required field (the Grade B field intensity defined in § 73.683(d) of the FCC rules) that already includes an allowance for long term (daily and seasonal) time fading;
  • The confidence variability factor is 50% indicating median situations;
  • The model is run in individual mode;
  • Terrain elevation is considered every 1/10 of a kilometer;
  • Receiving antenna height is assumed to be 6 m (20 feet) above ground for one-story buildings and 9 m (30 feet) above ground for buildings taller than one-story;
  • Where error codes indicate a severe error, the field strength is deemed inadequate for TV service;
  • Land use and land cover (e.g., vegetation and buildings) considerations are included.

The field strength of a network TV station at an individual location is predicted as follows:

(1) Find engineering data for the network affiliate station of interest by, for example, consulting the FCC Web site at (​mmb/​vsd/​). Necessary data are station latitude and longitude, height above mean sea level of the radiation center, and the effective radiated power (ERP) in the direction of the individual location under study.

(2) Run Longley-Rice 1.2.2 in the point-to-point mode with the parameters specified in Table 1 to find the propagation path loss relative to free space propagation.

(3) Examine the path terrain profile and direct ray from the transmitter radiation center to the 6- or 9-meter receiving point to determine whether the ray clears by at least 0.6 of the radius of the first Fresnel zone. If not, the ILLR Clutter Loss is 0 dB and steps 4 and 5 should be omitted.

(4) Find the USGS Land Use and Land Cover classification of the individual location under study by consulting the LULC database, available from the USGS web page <​glis/​hyper/​guide/​1_​250_​lulc>.

(5) Convert the USGS Land Use and Land Cover classification to the corresponding ILLR category using Table 2, and find the associated clutter loss from Table 3.

(6) Finally, calculate the ILLR field strength prediction from the formula

Field = (Free Space Field) − (Longley-Rice 1.2.2 Path Loss) − (ILLR Clutter Loss)

where the Free Space Field in dBμ = 106.92 + 10log10 (ERP) − 20log10 (distance), and distance is the path length in kilometers from transmitter to the individual location under study.

HG(1) in Table 1 is the height of the radiation center above ground. It is determined by subtracting the ground elevation above mean sea level (AMSL) at the transmitter location from the height of the radiation center AMSL. The latter may be found in the FCC's TV Engineering Data Base while the former is retrieved from the terrain elevation data base as a function of the transmitter site coordinates also found in the TV Engineering Data Base.

Terrain elevation data at uniformly spaced points between the transmitter and receiver must be provided. The ILLR computer program must be linked to a terrain elevation data base with values every 3 arc-seconds of latitude and longitude or closer. The program should retrieve elevations from this data base at regular intervals with a spacing increment of 0.1 kilometer (parameter XI in Table 1). The elevation of a point of interest is determined by linear interpolation of the values retrieved for the corners of the coordinate rectangle in which the point of interest lies.

Table 1.—Parameter Values for ILLR Implementation of the Longley-Rice Fortran Code

EPS15.0Relative permittivity of ground.
SGM0.005Ground conductivity, Siemens per meter.
ZSYS0.0Coordinated with setting of EN0. See page 72 of NTIA Report.
EN0301.0Surface refractivity in N-units (parts per million).
IPOL0Denotes horizontal polarization.
MDVAR1Code 1 sets individual mode of variability calculations.
KLIM5Climate code 5 for continental temperate.
XI0.1 mDistance between successive points along the radial from transmitter to individual reception point.
HG(1)See textHeight of the radiation center above ground.
HG(2)6m, or 9 mHeight of TV receiving antenna above ground. Use 6 m for one-story building; otherwise 9 m.
KWXNumeric error markerKWX is an output indicating the severity of a possible error due to parameters being out of range. Accept the field strength prediction when KWX equals 0 or 1, otherwise (KWX = 2, 3, or 4) presume the field is inadequate for TV reception.
LULC Category1 to 10This parameter is added to Longley-Rice for ILLR purposes. See Tables 2 and 3.
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Table 2.—Regrouping of LULC Categories for ILLR Applications

[The United States Geological Survey (USGS) maintains a database on land use and land cover indicating features such as vegetation and man-made structures. It is often called the LULC database and is available from the USGS web page at <​glis/​hyper/​guide/​1;​ 250; lulc)

LULC classification numberLULC classification descriptionILLR clutter category numberILLR clutter category description
12Commercial and services9Commercial/industrial.
14Transportation, communications, & utilities1Open land.
15Industrial and commercial complexes9Commercial/industrial.
16Mixed urban and built-up lands8Mixed urban/buildings.
17Other urban and built-up land8Mixed urban/buildings.
21Cropland and pasture2Agricultural.
22Orchards, groves, vineyards, nurseries, and horticultural2Agricultural.
23Confined feeding operations2Agricultural.
24Other agricultural land2Agricultural.
31Herbaceous rangeland3Rangeland.
32Shrub and brush rangeland3Rangeland.
33Mixed rangeland3Rangeland.
41Deciduous forest land5Forest land.
42Evergreen forest land5Forest land.
43Mixed forest land5Forest land.
51Streams and canals4Water.
54Bays and estuaries4Water.
61Forested wetland5Forest land.
62Non-forest wetland6Wetland.
71Dry salt flats1Open land.
72Beaches1Open land.
73Sandy areas other than beaches1Open land.
74Bare exposed rock1Open land.
75Strip mines, quarries, and gravel pits1Open land.
76Transitional areas1Open land.
77Mixed barren land1Open land.
81Shrub and brush tundra1Open land.
82Herbaceous tundra1Open land.
83Bare ground1Open land.
84Wet tundra1Open land.
85Mixed tundra1Open land.
91Perennial snowfields10Snow & ice.
92Glaciers10Snow & ice.

Table 3.—Clutter Loss as a Function of ILLR LULC Clutter Category and TV Channel

[Clutter loss values in this table have been estimated based on the test data published by Thomas N. Rubinstein, “Clutter Losses and Environmental Noise Characteristics Associated with Various LULC Categories,” IEEE Transactions on Broadcasting, Vol. 44, No. 3, September 1998. Values for low band VHF have been added by extrapolation from higher frequencies using frequency trends developed by Okumura, Yoshihisa et al, “Field Strength and its Variability in VHF and UHF Land Mobile Radio Service,” Rev. Electrical Comm Lab, Vol. 16, Sept-Oct 1968, pp 825-873.]

ILLR clutter category numberILLR clutter category descriptionClutter Loss—dB to be added to Longley-Rice prediction of path loss provided the path profile shows 0.6 Fresnel clearance
Low band VHF, channels 2-5High band VHF, channels 7-13UHF band
Channels 14-36Channels 38-69
1Open Land671216
5Forest Land781625
8Mixed Urban/Buildings10151718
10Snow and Ice0000
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List of Subjects in 47 CFR Part 73

  • Television
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Federal Communications Commission.

Magalie Roman Salas,


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[FR Doc. 00-2143 Filed 2-1-00; 8:45 am]