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IEEE BTS Symposium 2015 Repack Considerations by K.Pelletier
- 1. TV Repack – RF & Antenna Transition Strategies K e it h Pe lle t ie r, O c t obe r, 2 0 1 5
- 2. • Timeline • Towers • Antennas • Transmission Line • RF Systems • Transition Scenarios O ve r v i e w 2
- 3. Repack / Transition Timeline ≥ 9 months 3
- 4. Clearing Goal for 84 MHz Rank DMA Size Ave # cleared Std Dev 1 NewYork, NY 23 10.2 1.2 2 Philadelphia, PA 23 8.3 1.3 3 Chicago, IL 21 8.1 1.3 4 San Francisco- Oakland, CA 23 7.9 1.2 5 Boston, MA 17 7.1 1.2 6 Los Angeles, CA 27 6.9 0.98 Michael Kearns and Lili Dworkin “A Computational Study of Feasible Repackings in the FCC IncentiveAuctions” 4
- 5. Size of Repack ? • 1600 to 1700 eligible stations • 200 + need to move toVHF / channel share or go dark • 1000 +/- 200 will be involved in the re-pack • To clear channel 37 and above all states are impacted except Alaska and possibly Wyoming 5
- 6. Towers • TIA-222 Rev G 6
- 7. Towers • TIA-222 Rev G Ice Wind Speed Topography Shape Factors Get structural analysis Need detailed site information 7
- 8. Towers • BasicWind Speed • Antenna Elevation onTower • Design Ice • Tower Height • Structure Class • Exposure Category • Topographic Category • Height of Crest Above AverageTerrain • Seismic Spectral Response Acceleration 8 Site Criteria Needed for 222-G Antenna Proposal: Much More Site Design Information is Required from Broadcasters and/or Tower Engineers in 222-G 8
- 9. Replication • OET-69 “dipole factor” ܲ ൌ ܲ௧ ܩ௧ܩߣଶ ሺ4ߨܴሻଶ 1 MW ERP AT CH49WILL BE ALLOCATED 622 KW ERP AT CH 25 ݔ ൌ ߣ ߣ௨ ൗ dB = 10 log x 2 9
- 10. Towers – Antenna Wind-load 10 Example: ChannelChanges Channel 51 TFU-30JTH-R O4 Ø10.75” Pipe 27 Gain (EPA) = 42.4 ft2 W = 3800 lbs. 45.2 ft. Channel 24 TFU-30JTH-R O4 Ø14” Pipe 27 Gain (EPA) = 68.7 ft2 W = 7000 lbs. 58.3 ft. Same Gain Antenna Most Likely Not Required Due to Reduction in ERP 10
- 11. Towers – Antenna Wind-load 11 Example: ChannelChanges Channel 51 TFU-30JTH-R O4 Ø10.75” Pipe 27 (14.13dB)Gain (EPA) = 42.4 ft2 W = 3800 lbs. 45.2 ft. Channel 24 TFU-22JTH-R O4 Ø10.75” Pipe 20 (13.01 dB) Gain (EPA) = 45.0 ft2 W = 3600 lbs. 43.5 ft. Due to Reduction in ERP for CH 24, Same Transmitter can be used 1 MW ERP Input Power = 37 kW 588 kW ERP Input Power = 29.4 kW 11
- 12. Antennas • Pylon • Narrowband • Moving down in channel = larger antenna (possibly) • Some may allow adjacent channel operation • Less ERP required at lower channels to replicate coverage • Antenna not necessarily longer Replace 12
- 13. Antennas • Panel • Broadband • All stations have common pattern • Number of channels can be limited by Power • Owned by “vertical real- estate” companies • Broadcaster going dark may open up space on panel Re-use • Joining a Panel • FCC is not considering movingTx location during “re-pack” phase of the auction • Application to move to a newTx site will be done post auction 13
- 14. Multi-Channel Pylon Example of a broadband slotted coaxial antenna design WNYT Glens Falls, NY TLP-12W/VP-R (SP) channels 39 & 45 • 12 layer antenna with 4 way split • Manufactured in ½” wall aluminum • Elliptically polarized Multi-sectional phase cancellation LowerQ from thin wall Leveraging Babinet’s principle Channels 38 to 47 under 1.1:1 14
- 15. Coaxial line “stick” length, 3 MHz Guard Band 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 20 19 ¾ 19 ½ 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 20 19 ¾ 19 ½ Prohibited Channel per catalog 15
- 16. Coaxial line “stick” length, 1.5 MHz Guard Band 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 20 19 ¾ 19 ½ 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 20 19 ¾ 19 ½ Prohibited Channel per catalog 16
- 17. Transmission line • Get a line sweep • 6 1/8” line 20’ stick length • Ch 16 and 20 are OK (<1.03:1) Maybe Re-use Sweep curtesy Ed Murlatt and associates Channels 14 to 24 1.5 MHz Guard 3.0 MHz Guard 17
- 18. RF Systems • High Power RF System Components (25kW-80 kW) WR1150 Ch44-69 WR1500 Ch18-48 WR1800 Ch14-17 18
- 19. RF Systems • High Power RF System Components Coax to Waveguide Transitions Narrowband Replace 19
- 20. RF Systems • High Power RF System Components Waveguide Magic Tee Combiner New Slabs Required Re-tune 20
- 21. RF Systems • High Power RF System Components Waffle Iron Low Pass Filter Re-tune 21
- 22. RF Systems • High Power RF System Components Constant Impedance Band-pass Filter Replace Lower Channel Equals Larger Foot Print 22
- 23. RF Systems • High Power RF System Components Waveguide Switch and Coaxial Water-load Re-tune 23
- 24. RF Systems • Medium Power RF System Components (10kW-25 kW) All components are broadband except waveguide filter Replace filter Re-use all else 24
- 25. RF Systems – Practical Considerations • Field re-tuning not practical – Limited qualified talent – Some parts may need to be replace • If you have a two tube system – Re-tune one tube and operate into new CIF – Send all other system parts for refurbishment 25
- 26. Transition Scenarios FLASH CUTFLASH CUTFLASH CUTFLASH CUT • On air with original channel today • On air with new channel tomorrow GOT BACKUP?GOT BACKUP?GOT BACKUP?GOT BACKUP? STAGEDSTAGEDSTAGEDSTAGED NEED TEMPORARY TRASMISSION FACILITY 26
- 27. Transition Scenario’s - Staged • Eliminates Nationwide Flash Cut • Potential Relieve for Tower Crews 27
- 28. If you have backup • Operate off backup site while work is done at main site to get ready for new channel • Expect several months of back-up operation • Reliable back-up is important • Back-up Antenna Must be Broadband 28
- 29. Analog antenna still up? • Operate off current digital channel • Replace analog antenna (top mount) 29
- 30. Currently no Aux Antenna ? • New side mount on new channel • Replace top mount post cut over • Side mount becomes backup • If re-using Tx line tower a top channel splitter can be used to feed side mount • Side mount can go at separate site and be used as part of SFN or as backup post transition • Put up side mount on current channel 30
- 31. Candelabra ? • Candelabra – New full power antenna • New Stacked antenna with another broadcaster • Space available by broadcaster going off air ? • SpaceAvailable by Old AnalogAntenna 31
- 32. Dual Channel Slot? • Several dual channel slots went up during DTV conversion • These are currently operating on one channel only • Antenna, line and combiner are ready for broadcaster in market repacked to that adjacent channel • Operation from same aperture on adjacent channel will mitigate interference • Apply to FCC to change broadcast site 32
- 33. Panel? • Join existing or new panel as tenant • Space made available by broadcaster going off air ? • Will require combiner work • New manifold combiner • Possible broadband port addition or module replacement in CIF • Vertical real estate company owns and upgrade hardware, broadcasters lease 33
- 34. New Multi-Channel Pylon 9 % = ch14-21 (8 channels) ch30-38 (9 channels) ch34-42 (9 channels) ch42-51 (10 channels) Channels 38 to 47 under 1.1:1 34
- 35. ATSC 3.0 • AddV-Pol to help mobile reception • Single Frequency Network (SFN) topology 35
- 36. Conclusions • A temporary or back up transmission facility will be required • Antennas will most likely have to be replaced • Good chance that transmission line can be re-used • Some RF system components can be re-used • Don’t plan on field re-tuning (resource limited) • Least expensive option would be to move to existing transmission site if it is available in the market 36