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TV Spectrum Repacking
Jay AdrickConsulting Engineer Cavell Mertz and Associates
FCC Auction Status Dashboard
$10 B $20 B
New UHF Band Plan
•TV UHF spectrum reduced to channels 14 - 36• 600 MHz Wireless spectrum channelized into 5 MHz pairs•TV service remains 6 MHz channels •Duplex gap between wireless uplink and downlink•Guard band spectrum between services
WHITE – TV Channels Gray – Guard bands Blue – Wireless Channels
How Many Stations Directly Impacted?
Spectrum Recovered
MHz
Highest Remaining TV
Channel
Full PowerStations
Class AStations
Total Stations Directly
Impacted*
84 36 593 144 737
Directly impacted stations are those currently assigned to spectrum that is to be cleared for wireless services
*Some participated in the auction, thus reducing the number of directly impacted stations
LOW High
Eligible UHF Stations 1706 1706
Stations Eliminated to Clear Spectrum
222 249
Stations Remaining On Channel 433 262
Stations Required to Repack* 1020 1164
Spectrum Clearing Impact For 84 MHzEstimated Range
Estimated ranges based on DTC Study and FCC’s simulations* Numbers do not include the impact on Canadian stations
Action as a Result of the Spectrum Auction Number
Stations Eliminated (Not Including Channel Sharing)* 145
Stations Moving From UHF to VHF* 30
Stations Relocated Within the UHF Band* 917
Stations Relocated Within the VHF Bands* 70
Canadian Stations Forced to Relocate 62
TV Repack Report Card
* US stations Only
17 LB13 HB
Are Stations Not Changing Channels Impacted?• Yes if stations….
• Share a Tower• Have stacked tower top antennas• Operate on a shared antenna and
transmission line …with a station that is forced to change channel• FM stations on a shared tower with TV
• Additional issues
• Potential increased interference from neighboring stations (0.5% of population per other station)
Repack TimelineWe’re on the clock!
Construction Phases
April 13 April 2018 April 2019 April 2020 July 2020July 12
Repack Issues
Impact on Broadcast Technical Resources
• Large demand on consulting engineers time
• Structural analysis
• Transmitter installers
• Tower crews – new towers and antenna installation
• May impact planned radio projects.
• May need to look for alternative resources.
• Projects may get delayed.
A Typical DTV Transmission Plant• Basic transmission system blocks:
• External RF Items:• Mask Filter• RF Combiner• Transmission line• Antenna
ProgramMaterial
(Video, Audio,Data)
RFPOWERAMPLIFIER
RF
Control
Power Supplies
TRANSMITTER
Cooling
MASK FILTER
COMBINER TRANSMISSION LINE
Other transmitter(s)(if applicable)
ANTENNA
RFEXCITER
LP F
ILT
ER
• Transmitter, comprising:• Exciter• Amplifier• Power Supplies• Control• Cooling System
What’s Impacted by Repack?
ProgramMaterial
(Video, Audio,Data)
RFPOWERAMPLIFIER
RF
Control
Power Supplies
TRANSMITTER
Cooling
MASK FILTER
COMBINER TRANSMISSION LINE
Other transmitter(s)(if applicable)
ANTENNA
RFEXCITER
LP F
ILT
ER
Very Likely
Very Likely
Likely100%
Very Likely
Possibly
• If moving from an affected channel to a new one:• The following items will need to be looked at for
retune or replacement:
Transmitter Replacement is Likely• Most transmitters are ~10 - 20 years old
• Older UHF transmitters designed around band segments
• May require new amplifier pallets, combiners or driver modules - availability of obsolete devices unlikely
High Power RF Output Systems• Waveguide bands, generally: • WR1800, Ch’s 14-21• WR1500, Ch.’s 18-49• WR1150, Ch.’s 46-69
• Above isn’t exhaustive. Waveguide also has prohibited line lengths on a per channel basis. Consult Manufacturer.
• Mask Filter Cavities are per Channel• In general, a new RF system will be needed
Channel Compatibility of Coaxial Transmission Line
3 MHz guard band dates back to analog with aural carrier 0.25 MHz from band edge. DTV signal enables a relaxing in guard band requirements.
Tower Structural Analysis• TIA-222 Rev G
• Ice
• Wind Speed
• Topography
• Shape Factors
• Tower owner will need to get a structural analysis
Channel change effects• Higher channel moving down-band
• Less power for equivalent coverage
• Larger antenna
• Lower channel moving up-band
• If station was maximized at 1 MW ERP, likely that coverage will be lost
• Smaller antenna
• OET-69, F(50,90)
• dBu
• Example
• Moving from Ch. 51 to Ch. 24
2.3 dB
•
Dipole Factor, equivalent coverage
Replicate with Same Size Antenna
Channel 51TFU-30JTH-R O4Ø10.75” Pipe27 Gain14.1 dB
(EPA) = 42.4 ft2
W = 3800 lbs.
45.2 ft.
Channel 24TFU-22JTH-R O4Ø10.75” Pipe20 Gain13 dB
(EPA) = 45.0 ft2
W = 3600 lbs.
43.5 ft.
Similar size and wind load.Lower gain, but still more than dipole factor -> Could re-use transmitter if it has been determined that it is feasible to do so.
Replicate with Same Gain Antenna
Channel 51TFU-30JTH-R O4Ø10.75” Pipe27 Gain
(EPA) = 42.4 ft2
W = 3800 lbs.
45.2 ft.
Channel 24TFU-30JTH-R O4Ø14” Pipe27 Gain
(EPA) = 68.7 ft2
W = 7000 lbs.
58.3 ft.
Requires larger, heavier antenna.
Cincinnati Market RepackOctober 18, 2019
• 1947 Analog channel 4• 1952 Analog channel 5• Pre-repack DTV channel 35• Post repack DTV channel 20• Virtual channel 5
WLWT
• 1949 Analog channel 7• 1952 Analog channel 9• Transition DTV channel 10• Pre-repack DTV channel 35• Post repack DTV channel 20• Virtual channel 9
WCPO-TV
• 1949 Analog channel 11• 1952 Analog channel 12• Transition DTV channel 31• Pre-repack DTV channel 12• Post repack DTV channel 12• Virtual channel 12
WKRC-TV
• Analog channel 19• Pre-repack DTV channel 29• Post repack DTV channel 15• Virtual channel 19
WXIX-TV
• Analog channel 48• Pre-repack DTV channel 34• Post repack DTV channel 17• Virtual channel 48
WCET-TV
• Analog channel 64• Pre-repack DTV channel 334• Post repack DTV channel 18• Virtual channel 64
WSTR-TV
• Analog channel 14• Pre-repack DTV channel 28• Post repack DTV channel 29• Virtual channel 14
WPTO-TV
• Analog channel 54• Pre-repack DTV channel 24• Post repack DTV channel 22• Virtual channel 54
WCVN-TV
• Original Analog channel 25• Later Analog channel 38• Original DTV channel 47• Repack Transition channel 20• Post repack DTV channel 28• Virtual channel 25
WBQC-CD
• Analog channel 36• Pre-repack DTV channel 36• Post repack DTV channel 14• Virtual channel 43
WYDC-CD
• First Analog channel 39• Second Analog channel 38• Third Analog channel 25• Pre-repack DTV channel 38• Post repack OFF Air• Virtual channel 25
WOTH-TV
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