OET Announces Release of Updated OET-69 Software
Federal Communications Commission
News Media Information 202 / 418-0500445 12th St., S.W.
Washington, D.C. 20554
Release Date: February 4, 2013
OFFICE OF ENGINEERING AND TECHNOLOGY
RELEASES AND SEEKS COMMENT ON UPDATED OET-69 SOFTWARE
Comment Sought on Software to be used in Conjunction
With Proposed Incentive Auction
ET Docket No. 13-26
GN Docket No. 12-268
Comment Date: March 21, 2013
Reply Comment Date: April 5, 2013
to perform interference analyses using the methodology described in its Bulletin No. 69 (OET-69).1 This
software, called TVStudy, provides analysis of coverage and interference of full-service digital and Class
A television stations. The Commission plans to use this new software in connection with the proposed
broadcast television spectrum incentive auction (incentive auction).2
OET seeks comment on the
software generally, as well as the identification of any errors, unexpected behaviors, or anomalous results
produced in running the software. In addition, OET solicits comment on the implementation of
various analytical elements in the software that are not specifically addressed in OET-69.
BackgroundThe Commission developed the software that is currently used to implement OET-69 to
support the DTV transition, and we have subsequently used it to analyze applications to modify the
DTV Table of Channel Allotments. As such, the software programs developed by the FCC for those
purposes are based fundamentally on source code and data from the 1990s and earlier. Since that time,
some of the underlying datasets have evolved or have been replaced. In addition, parties have gained
sufficient experience to have offered FCC staff informal feedback on the e xisting programs’ relative
strengths and weaknesses.
It is with these matters in mind that we have developed the TVStudy software. The new
software operates on modern computer systems, and it runs much faster, provides greater accuracy
in modeling and analysis, and is easier to use and more versatile than the existing software. In
OET Bulletin No. 69, “Longley-Rice Methodology for Evaluating TV Coverage and Interference,” Feb. 6, 2004. Available at
See Expanding the Economic and Innovation Opportunities of Spectrum Through Incentive Auctions, Notice of Proposed
Rulemaking, FCC 12-118, Docket No. 12-268, 27 FCC Rcd. 12357 (2012) (Incentive Auction NPRM). Available at
addition, the TVStudy software will allow us to perform the types of analyses that are needed to
support the proposed incentive auction.3
An important component of the proposed incentive auction is the repacking of broadcast
television stations, including the potential reassignment of stations to new operating channels. The
Middle Class Tax Relief and Job Creation Act of 2012 (Spectrum Act) requires the Commission to “make
all reasonable efforts to preserve, as of the date of the enactment of this Act, the coverage area and
population served of each broadcast television licensee, as determined using the methodology described
in OET Bulletin 69 of the Office of Engineering and Technology.”4 OET-69 describes a methodology
that divides the area within a digital television station’s noise-limited coverage contour into
approximately rectangular “grid cells,” and then evaluates these cells for coverage and, where present,
interference. The Commission’s Incentive Auction NPRM proposes to define the “coverage area” of full-
power stations as the geographic area within a station’s noise-limited contour where its signal strength is
predicted to exceed the noise-limited service level, both levels calculated on an F(50,90) basis.5
Similarly, the Incentive Auction NPRM proposes to define the “coverage area” for Class A stations as the
geographic area within a station’s protected contour where its signal strength is predicted to exceed the
protected service level, both levels calculated on an F(50,90) basis.6
The Incentive Auction NPRM also proposes to define the “population served” by full-power
stations as the population within a station’s noise-limited contour where its signal strength is predicted to
exceed the noise-limited service level on an F(50,90) basis and is not subject to predicted interference
from other stations, using the protection ratios specified in OET-69 and the rules.7 Similarly, the
Incentive Auction NPRM proposes to define the “population served” by Class A stations as the population
within a station’s protected contour where its signal strength is predicted to exceed the protected service
level on an F(50,90) basis and is not subject to predicted interference from other stations, using the
protection ratios specified in OET-69 and the rules.8
OET-69 defines certain parameter values for programmers to use when developing the software
to implement OET-69’s methodology. In particular, Table 4 of OET-69 lists parameter values used by
the Fortran Code for the Longley-Rice (L-R) radio signal propagation model used in the implementing
software, Tables 5A and 5B list the D/U ratios to be used in predicting interference, Table 6 describes the
performance of the assumed receiving antennas, and Table 8 describes the elevation-plane performance of
the assumed transmitting antennas. The foregoing is not an exhaustive list; OET-69 provides additional
definitions and guidance. OET-69 does not, however, specify all of the parameters and methods required
when developing software to implement OET-69’s methodology. The choices made in implementing the
methodology of OET-69 can produce different results, and such differences can affect a station’s
coverage area and population served. By making the new TVStudy software as well as reference copies of
the various databases necessary to run that software available to the public, we provide a means for
implementing the OET-69 methodology that ensures consistency in the results obtained by the
Commission and interested parties.
The TVStudy software will allow us to produce television station service and interference data that, under the proposals in
the Incentive Auction NPRM, will serve as an input to the algorithms that will be used to select operating channels.
Middle Class Tax Relief and Job Creation Act of 2012, Pub. L. No. 112-96, §§ 6402, 6403, 125 Stat. 156 (2012).
Incentive Auction NPRM, 27 FCC Rcd at 12390 ¶ 99.
See id., 27 FCC Rcd at 12388 ¶ 94.
Id. We note that the Incentive Auction NPRM asks for comment on a number of possible options for maintaining the
population served as stations transition from existing to new channels. However, it is not the purpose of this Public Notice
to solicit comment on those options.
SoftwareThe new TVStudy software is designed for making rapid coverage and interference calculations
involving many stations and provides highly-detailed outputs. It is intuitive in its operation and rapidly
produces useful results. It has been developed in two parts: 1) a graphical user interface (implemented in
Java), used to establish the parameters of the study and which draws data from appropriate databases; and
2) an analysis engine (implemented in C), which makes the necessary calculations to establish coverage
and interference. The outputs include both summaries of area and population by station, and detailed
signal level predictions by cell.
We are interested in feedback that discusses the capabilities of the TVStudy software to support
the incentive auction and to implement whatever decisions are made in the rulemaking proceeding. For
example, one of the options discussed in the Incentive Auction NPRM requires identifying specific
populations presently subject to interference so that new interference is not created.9 As a practical
matter, such an approach requires maintaining a database of interference status at the cell level. The
present software implementing OET-69 that the Commission uses for processing applications for new TV
stations and modifications to existing stations does not support creation of such a database. The present
software was designed for processing individual applications rather than the concurrent study of
complete, nationwide assignments. We also seek comment on the new software generally as a tool for
analyzing the service area coverage, population served, and interference received by broadcast television
In developing the TVStudy software, we have identified various parameter choices consistent with
but not specified in OET-69 that we believe are necessary for improved accuracy in our modeling and
analysis. We incorporated “soft-switches” into the TVStudy software to permit the user to evaluate the
effects of the different choices. We note that the different parameter choices may yield results for both
coverage and interference different from legacy versions of software that have been used in the past.
In conducting the proposed incentive auction, an important objective is that we use software with
improved accuracy and that makes use of the best available data to compute estimates of the coverage
area and population served of each broadcast television licensee consistent with the provisions of the
Spectrum Act. To that end, we solicit feedback from stakeholders, experts, and others on the
implementation of the TVStudy software. Specifically, we discuss below and invite comment in the
Treatment of inaccurate data in FCC database
Treatment of antenna beam tilt
Calculation of depression angles
Level of precision of geographic coordinates
Establishment of calculation (cell) grid
Treatment of internal (Longley-Rice) warnings
Population Data. Population coverage in the original DTV Table of Allotments was calculated
using data from the 1990 U.S. Census. According to the U.S. Census, the population of the United States
increased by about 24 percent between 1990 and 2010, and the distribution of population has also
Incentive Auction NPRM, 27 FCC Rcd at 12394 ¶ 106.
changed. Because the use of 1990 Census data in the present OET-69 software is unlikely to produce an
accurate depiction of present-day DTV station population coverage, the TVStudy software is designed to
use 2010 U.S. Census data.
Terrain Data. Three-arcsecond digital terrain data are used in the present OET-69 software that
we used to develop the original DTV Table of Allotments. This means that land elevations are reported
every three seconds of geographic latitude and longitude (about every 300 feet). The three-arcsecond
database was produced primarily by automatically scanning and interpolating large-scale (such as
1:250,000) paper maps, which often used relatively coarse elevation contours. A number of versions of
the three-arcsecond terrain database were released by various agencies, some of which contained errors.
Moreover, the three-arcsecond terrain database is no longer being revised, maintained, or supported by
the U.S. Geological Survey. A new one-arcsecond terrain database, which has greater resolution
(elevation points are spaced about every 100 feet), has replaced the old three-arcsecond terrain database.
Additionally, the one-arcsecond terrain database is derived from smaller-scale (e.g. 1:24,000) topographic
maps with more granular elevation data, and the method for extracting elevation data from those maps has
been improved. Because continued use of an unsupported terrain database is likely to lead to
obsolescence and potentially inaccurate results, the TVStudy software is designed to use one-arcsecond
Treatment of Inaccurate Data in FCC Database. We recognize that there may be instances
where the information entered into the FCC’s broadcast station database (CDBS) may not be fully
accurate. Examples may include:
Negative values for beam tilt
Swapped values for mechanical beam tilt and orientation
Missing maximum values for directional antenna patterns
Missing or incorrect directional antenna flags
ERP value entered in dBk instead of kilowatts
These sorts of inaccuracies can lead to incorrect or nonsensical results when used in a computer
program to predict coverage and interference. We are not proposing to modify the information in the
underlying CBDS database. However, we seek comment on what methods we should use to detect
information that may be inaccurate and what correction methods we should incorporate into our use of
Treatment of Antenna Beam Tilt. All DTV stations operate directionally in the elevation plane.
That is, the transmitting antenna is engineered to focus energy toward populated areas while minimizing
energy radiated skyward. To accomplish this, most transmitting antennas are tilted downward, usually
uniformly (electrically) but sometimes non-uniformly (mechanically), or both. The actual amount of tilt,
if any, is contained in the CDBS record for each station. The present software used to implement OET-69
uses elevation patterns with a fixed electrical beam tilt (e.g., 0.75° for full-power stations operating on
UHF channels), and in the development of the original DTV Table of Allotments, the actual amount of tilt
given in CDBS was ignored. As a result of ignoring the actual beam tilt, the direction of main beam
radiation used to project coverage in the present software may be incorrect, which can effectively cause it
to “miss” the population being served. We believe that a better practice in implementing OET-69 would
be to use the value for electrical downtilt specified in CDBS to correct the generic elevation pattern such
that the main beam is at the angle specified in CDBS rather than using a fixed value. Because sufficient
information is typically not available to correctly project the antenna patterns of stations having
mechanical beam tilt, we do not propose to use mechanical beam tilt in OET-69 calculations.
Calculation of Depression Angles. The depression angle is the vertical angle between the
horizontal (at the location of the DTV transmitting antenna) and the location of the receive site under
study (cell centroid). An error in the present software used to implement OET-69 and to develop the
original DTV Table of Allotments caused this angle to be incorrectly calculated based on the antenna
height above ground, rather than the height above mean sea level. This error can cause the radiated power
toward the cell under study to be incorrectly calculated, particularly for stations that have antennas atop
tall mountains (as opposed to tall towers). The TVStudy software is designed to avoid causing this error.
Precision of Geographic Coordinates. The fundamental unit of the U.S. Census is the Census
Block, which specifies locations to a precision of 0.0000001° (about 0.0004 seconds) of latitude and
longitude. Earlier versions of software implementing OET-69 rounded or truncated this location data to
the nearest second, discarding some three orders of precision. This action often causes the centroid
locations of cells under study to be shifted. While the original reason for this reduction in precision are
unknown, we believe that it may have been related to computational limitations at the time of
development. At this time, there appears to be no reason to intentionally reduce numerical precision and
we believe that full-precision location data should be used in the TVStudy software.
Establishment of Calculation (cell) Grid. The present OET-69 software is designed to establish
calculation grids that are for the most part unique to each station considered. This approach requires that
all desired and undesired signal levels be calculated for each cell of each station studied and results in
cell-level data that cannot be directly compared between different potential channel allotments and/or
stations. Another approach is to establish a single, global calculation grid, common to all stations. Such
a global approach results in data that can be used to directly compare interference impacts at the cell
level, and also speeds calculations since the study grid only needs to be established one time. The
TVStudy software is designed to generate and use a global calculation grid.
Treatment of Internal (Longley-Rice) Warnings.The propagation algorithm underlying OET-
69 is the Irregular Terrain Model (ITM), also known as Longley-Rice (or simply L-R). It is based in part
on actual measurements of path loss made by the Department of Commerce over different terrain profiles.
Although the measurement data collected were used to create generalized computational models of
different types of terrain profiles, not every single terrain profile possible was represented. In particular,
terrain profiles lying outside the range of collected data still produce results, but those results are
“flagged” as being “unusable or dubious.”
The software used to develop the original DTV Table of Allotments treated cells having such
“flags” (whether from desired or interfering stations) as having coverage. This determination results in
areas where we have no real information about predicted coverage or interference. Such cells are
assumed to have coverage, even if neighboring cells do not. This treatment of “flagged” results
implemented the Commission’s decision that assumption of service is appropriate where the Longley-
Rice propagation model indicates that service calculations may be dubious or unreliable.10 Comparisons
with other propagation models suggest that the “flagged” results are typically not unreasonable.
We note that while this approach was taken for purposes of implementing OET-69, a different
approach was taken in implementing OET Bulletins 72 and 73 (OET-72 and OET-73, respectively)
See Advanced Television Systems and Their Impact upon the Existing Television Broadcast Service, Memorandum Opinion
and Order on Reconsideration of the Sixth Report and Order, ET Docket No. 87-268, 13 FCC Rcd 7418, 7489 at para. 181
(1998); Review of the Commission’s Rules and Policies Affecting the Conversion to Digital Television, Report and Order
and Further Notice of Proposed Rulemaking, MM Docket No. 00-39, 16 FCC Rcd 5946, 5971-72 at paras. 64-66 (2001).
dealing with the availability of TV service for purposes of the Satellite Home Viewer Act and subsequent
legislation.11 In those cases, the L-R propagation model is used differently and for different purposes.
Specifically, OET-72 and OET-73 use the L-R model to estimate whether a TV station’s signal is
receivable at an individual location (a viewer’s home), whereas OET-69 estimates a station’s signal
coverage, population served and interference received over the entire geographic area it serves. With
regard to OET-72 and OET-73, the Commission found that ignoring the appearance of so-called “error
codes” and accepting the calculated field strength value was appropriate for determining eligibility for
satellite delivery of network programming at individual locations.12
We ask whether we should to continue to assume coverage in areas that have flagged results in
implementing the Commisison’s decision that assumption of service is appropriate where the Longley-
Rice propagation model indicates that service calculations may be dubious or unreliable. If not, we ask
what assumptions should be made relative to coverage and population served under such conditions to
more effectively implement the Commission’s decision.
Availability of Developmental Software and DataThe Commission is making available its developmental TVStudy software and the data required to
run it on its website at:
Installation and operating instructions are included as separate files.
The software was developed on an Apple iMac, but it is expected that the source code can be
compiled on other Unix-like platforms (e.g. Linux). Compatibility of the C source-code with Microsoft
Windows-based compilers is not guaranteed, but only minor modification would be expected. The Java
code, which was developed in Java version 1.6, is expected to be platform independent. In addition to the
source code, a fully-compiled version of the software is supplied for use on Apple computers running
OS10.6 or higher. The software also requires certain MySQL client libraries, which can be obtained by
installing MySQL Community Server (available at no cost from Oracle). To ensure compatibility,
MySQL Community Server version 5.529 is recommended.
Parties seeking to evaluate the TVStudy software will also need various data files for terrain and
population. Some of the necessary data files are quite large and so have been archived using TAR and
GZip (collectively TGZ)13 and encoded using PAR214 to facilitate error detection and correction. The
necessary data files for population and terrain are supplied at the URL given above, together with a
reference copy of CDBS for television stations as of February 22, 2012.
See OET Bulletin No. 73, “The ILLR Computer Program for Predicting Digital Television Signal Strengths at Individual
Locations,” Nov. 23, 2010, and OET Bulletin No. 72, “The ILLR Computer Program,” July 2, 2002. These OET Bulletins
are available at http://www.fcc.gov/encyclopedia/oet-bulletins-line.
See Satellite Delivery of Network Signals to Unserved Households for Purposes of the Satellite Home Viewer Act, Report
and Order, CS Docket No. 98-201, 14 FCC Rcd 2654 (1999).
“Tarball” format combines tar archives with the open-source gnu-zip file-based compression scheme. See
http://en.wikipedia.org/wiki/.tgz for more information.
PAR2 (Parity archive volume set, version 2) provides checksum verification and can repair corrupted or missing data. See
http://en.wikipedia.org/wiki/Parchive for more information.
How to CommentComments on the matters discussed in this Public Notice should be filed in Dockets 13-26 and
12-268. Pursuant to sections 1.415 and 1.419 of the Commission’s rules, 47 CFR §§ 1.415, 1.419,
interested parties may file comments and reply comments on or before the dates indicated on the first
page of this document. We encourage parties to bring reports of errors or anomalous results in the
running of the TVStudy software to our attention as soon as they are identified.
Comments may be filed using the Commission’s Electronic Comment Filing System (ECFS).
See Electronic Filing of Documents in Rulemaking Proceedings, 63 FR 24121 (1998).
Electronic Filers: Comments may be filed electronically using the Internet by accessing
the ECFS: http://fjallfoss.fcc.gov/ecfs2/.
Paper Filers: Parties who choose to file by paper must file an original and one copy of
each filing. If more than one docket or rulemaking number appears in the caption of this proceeding, filers
must submit two additional copies for each additional docket or rulemaking number.
Filings can be sent by hand or messenger delivery, by commercial overnight courier, or by first-
class or overnight U.S. Postal Service mail. All filings must be addressed to the Commission’s Secretary,
Office of the Secretary, Federal Communications Commission.
All hand-delivered or messenger-delivered paper filings for the Commission’s Secretary
must be delivered to FCC Headquarters at 445 12th St., SW, Room TW-A325, Washington, DC 20554.
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fasteners. Any envelopes and boxes must be disposed of before entering the building.
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– FCC –
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