Overcoming Obstacles to Design a Robust Single Frequency Network in San Francisco

Authors

Eric DausmanSVP, RF Technology

Public Media Group

Ryan C. Wilhour Kessler and Gehman

Associates, Inc.

Overview of the San Francisco-Oakland-San Jose DMA

• Includes 10 counties

• 2.3 million TV households

• Close to 9 million people

• Varied terrain

Post Repack Stations

Call Letters Channel

KRCB 5

KRON 7

KQSL 8

KGO-TV 12

KNTV 13

KSTS 19

KDTV-DT 20

KCNZ-CD 21

KDTV-CD 21

KATX-CD 22

Call Letters Channel

KPJK 27

KBCW 28

KPIX-TV 29

KQED 30

KTVU 31

KCNS 32

KKPX-TV 33

KFSS-DT 34

KICU 36

Good OTA reception

Poor OTA reception

City Grade

Grade A

Grade B

Boost signal strength to provide better service to more people

• Overcome terrain problems

• Provide consistent indoor reception

• Provide consistent portable and handheld reception

• Provide consistent mobile reception

Why Build SFNs

Designing an SFN

Starting with Site Selection

• In the Bay Area, terrain features determine the site selections

• Any tower or building work in California requires environmental review

• There are developed sites on most ridge tops around the bay

• Many are already broadcast sites

• All will need some work to make them SFN ready

Determining Coverage Area

• What are the use cases?

• What is the expected height above ground of the device(s) you are trying to reach?

• Mobile or Fixed?

• Each case should be studied to understand coverage

Largest Contour

• The largest station provision in the FCC’s Report and Order 08-256 will determine the limits of the SFN

Predicting Theoretical SFN Azimuth Patterns

• Start with main site at licensed ERP and SFN sites omni directional azimuth pattern with ERP of 200kW

• Reduce power in all directions to meet FCC interference protection requirements (FCC 17-158 R&O)

• Results predict best theoretical azimuth patterns to be applied at each site and ERPs for main site and SFN sites

SFN Antenna Design

• Antenna patters will likely be directional with high front-to-back ratios due to current DTS rules

• One approach to achieve this:• Stacked antennas with physical

offset and phase relationship

• Allows for full optimization of back lobe level

• Simple and future proof

Eliminating Adjacent Channel Interference

• Analysis is based on population served as if it were an ATSC-3.0 station with current facilities

• The market serves over 7 million homes with a 41 dBu signal strength

• In-market adjacent channel facilities will have much more impact on SFN power levels

Real Patterns

• Replace theoretical azimuth patterns with real antenna designs

Preliminary Study Results: Three Channels, Three Different Issues

• Modeled out • A UHF channel without in-market adjacent channels

• A UHF channel with in-market adjacent channels

• A VHF channel

KRON

• Channel 7

• Located on Sutro Tower in San Francisco

• Post-repack facility of 50kW ERP, directional antenna

• In-market adjacent channel to the north, out-of-market adjacent channel to the south, requiring power reductions in the north and south transmitters

KRONPredicted Service – Main Site Only Predicted Service – FCC Compliant SFN

KRONPredicted Service – SFN IndoorPredicted Service – SFN at 1.5 Meters

KICU

• Channel 36

• Located in the area south of San Francisco bay

• Licensed at 550kW ERP directional

• No in-market adjacent channels

KICUPredicted Service – Main Site Only Predicted Service – FCC Compliant SFN

KICUPredicted Service – SFN IndoorPredicted Service – SFN at 1.5 Meters

KBCW

• Channel 28

• Located on Sutro Tower in San Francisco

• Post-repack facility of 714kW ERP directional

• Upper and lower in-market adjacent channels (27, 29)

KBCWPredicted Service – Main Site Only Predicted Service – FCC Compliant SFN

KBCWPredicted Service – SFN IndoorPredicted Service – SFN at 1.5 Meters

Population Gains Station 10 M Pop 1.5 M Pop

KRON 7 4,854,209 3,391,510

KRON 7 with SFN 6,934,042 5,715,114

Pop Gain 2,079,833 2,323,604

KBCW 28 5,382,824 3,722,186

KBCW 28 with SFN 6,404,428 4,240,821

Pop Gain 1,021,604 518,635

KICU 36 4,809,247 3,781,687

KICU 36 with SFN 6,832,201 5,211,788

Pop Gain 2,022,954 1,430,101

Conclusions

• Reach more people and more devices with SFNs

• Signal density improvement using SFN allows more bits to be used for data and less for coding

• Plan for SFNs when you are planning your market transition to ATSC 3.0

• This represents preliminary design work in San Francisco

About Public Media Group

PMG is a technology infrastructure company with a mission to advance the interests and opportunities of the entire broadcast industry. Founded in part by thirty-one public broadcasters that operate 118 stations and reach over 230 million Americans, PMG was established to build and operate the physical and digital infrastructure to enable all broadcasters -- commercial and public --to leverage the full power and revenue opportunities of next generation broadcasting standards. Our team is comprised of trusted industry veterans, each with a passion for building the future of broadcasting.

About Kessler and Gehman Associates, Inc.

Kessler and Gehman Associates, Inc. (KGA) is a recognized leader in the telecommunications consulting engineering industry with over 150 years of combined technical communications experience specializing in broadcast consulting for commercial and noncommercial television and radio broadcast stations. KGA was recognized in the Digital Tech Consulting Report from October 2015 as one of very few professional consulting engineering firms capable of providing relevant services during the repack process, and KGA has been successfully engineering, designing, and repacking almost 20% of all repacked stations across all ten Phases.

For more information about SFNs, visit publicmediagroup.comor email me at edausman@publicmediagroup.com

Thank you!

This paper is available in the 2020 BEIT Conference Proceedings

Purchase access at nabpilot.org/proceedings