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Over-the-Air (OTA) Bit Management

David Felland

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OTA Bit Management New impacts on your transport stream

Better coding efficiency in new HD encoders○ Claims of 10-15% improvement○ Potential for two 720p HD services in one

transport stream – or other servicesMore SD services from which to chooseMobile DTVFixed and Mobile DTV Data Services

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OTA Bit Management Options for broadcasters

Reduced horizontal resolution (1440 vs 1920)Noise reduction of both HD and SDModern statistical multiplexing720p vs. 1080i

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Sampling of Current Practice Surveyed the ETAC

1-3 OTA servicesDifferent services plans among all membersFocus on HD + national/local SD services

Surveyed the Washington stationsCommercial stations have a much more consistent

approach: ○ HD + Weather (and perhaps one other service)

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HD SD1 SD2 SD3 SD4 PSIP Data

#1 15 3 - - - 150k 128k

#2 12 2.5 2.5 - - 250k 1M+

128k

#3a 12 3 1.5 - - 565k 128k

#3b - 4 2 - - 256k 100k

ETAC Members’ OTA

Italics = Stat Mux Pool

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HD SD1 SD2 SD3 SD4 PSIP Data

#4 16 2 - - - 300k 128k+

100k

#5a 18 - - - - ~200k 128k

#5b - 4 3.5 0.7 0.7 242k 128k

#6 14 - - - - 200k 1M

ETAC Members’ OTA

(x4) (x2) (x2)

Italics = Stat Mux Pool

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HD SD1 SD2 SD3 SD4 PSIP Data

#7 11 2 2 2 - 250k -

#8 11.5 4 4 0.3 - 250k 250k+

128k

#9 - 3 3 3 3 150k 6M

#10 11 1.5 3.5 - - 2M -

ETAC Members’ OTA

Italics = Stat Mux Pool

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HD SD1 SD2 SD3 SD4 PSIP Data

#11a 12.5 3.4 3.4 - - 150k 128k+110k

#11b - 3.4 3.4 3.4 3.4 150k 128k+

110k

#11c 12.5 3.4 3.4 - - 150k 128k+110k

#12 12 2.1 2.1 - - 200k -

ETAC Members’ OTA

(x2)

Italics = Stat Mux Pool

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HD SD1 SD2 SD3 SD4 PSIP Data

#13 11 6 - - - 180k 128k

#14 10 3 3 - - 150k 1M+

300k

ETAC Members’ OTA

Italics = Stat Mux Pool

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Comparison of Video Performance Clip #1: 1080i @ 14 Mbps (MV500) Clip #2: 1080i @ 12 Mbps (MV500) Clip #3: 1080i @ 10 Mbps (MV500) Clip #4: 720p @ 12 Mbps (MV500) Clip #5: 720p @ 10 Mbps (MV500) Clip #6: 720p @ 8 Mbps (MV500) Clip #7: 720p @ 9 Mbps (Electra 8000)

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Mobile DTV Bandwidth UsageHow much OTA spectrum is needed?

Mobile / Handheld service requirementsMultiple modes – e.g., “Half-rate”,

“Quarter-rate”, or a variety of “Mixed Modes”

Many broadcasters will use Quarter or Mixed○Quarter ~17% payload (83% FEC)○Mixed (e.g., ½, ¼, ¼, ¼) ~ 26% (74% FEC)○Half ~34% payload (66% FEC)

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Bandwidth Usage (bits)How much OTA spectrum is needed?

Mixed Mode examples (26%):One 500 kbps stream ~1.92 Mbps

○Video@400kbps; Audio@64kbps; Data@30kbpsTwo 500 kbps streams ~3.85 Mbps

Quarter Rate examples (17%):One 500 kbps stream ~2.94 Mbps

○Video@400kbps; Audio@64kbps; Data@30kbpsTwo 500 kbps streams ~5.88 Mbps

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DTV Spectrum Usage:ETAC Member #1

~15 Mbps

~3 Mbps

150 kbps128 kbps

• HD program

• PSIP• SD program

• Data/Ancillary

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

Po

ol

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DTV Spectrum Usage:ETAC Member #2

~12 Mbps

~2.5 Mbps250 kbps

1Mbps+128 kbps

• HD program

• PSIP

• SD program

• Data/Ancillary

~2.5 Mbps • SD program

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

Po

ol

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ETAC Member #1:One Mobile Service (Mixed)

~13.5 Mbps

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

~2.5 Mbps

150 kbps128 kbps

• HD program

• PSIP• SD program

• Data/Ancillary~2 Mbps • Mobile program

Sta

t M

ux

Po

ol

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ETAC Member #2:One Mobile Service (Mixed)

~11 Mbps

~2 Mbps250 kbps

1Mbps+128 kbps

• HD program

• PSIP• SD program

• Data/Ancillary

~2 Mbps • SD program

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

Po

ol

~2 Mbps • Mobile program

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Some Mobile Services Simulcast of Local HD or SD Services Simulcast of National HD or SD Services Stand alone Local Mobile Services National or Local Kids Service “Radio” Services

Audio Only – 16 – 48 kbps“Audio with Pictures” – same as Video/Audio

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DTV Spectrum Usage:ETAC Member #14

~10 Mbps

~3 Mbps

150 kbps

1Mbps

• HD program

• PSIP• SD program

• Data/Ancillary

~3 Mbps • SD program

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

Po

ol

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ETAC Member #14:Multiple Mobile Services (Mixed)

~9.5 Mbps

~1.8 Mbps250 kbps

1Mbps

• HD program

• PSIP• SD program

• Data/Ancillary

~1.8 Mbps • SD program

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

Po

ol

~2 Mbps • Mobile program~2 Mbps • Mobile program

• Radio Services (100k)

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Other Stations:Possible Mobile Services (Mixed)

~11 Mbps

250 kbps

• HD program

• PSIP

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

P

oo

l~2 Mbps • Mobile program~2 Mbps • Mobile program~2 Mbps

~2 Mbps • Weather

• Mobile program

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Other Stations:Possible Mobile Services (1/4 rate)

~11 Mbps

250 kbps

• HD program

• PSIP

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

P

oo

l~3 Mbps • Mobile program

~3 Mbps • Mobile program

~2 Mbps • Weather

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Other Stations:Possible Mobile Services (Mixed)

~4.5 Mbps

100 kbps

• SD program

• PSIP

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

~2 Mbps • Mobile program• Mobile program• Mobile program

~2 Mbps~2 Mbps~2 Mbps~2 Mbps~2 Mbps~2 Mbps

• Mobile program• Mobile program• Mobile program• Mobile program

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Public television has used its spectrum to serve diverse audiences with more variety in content (“multicasting”)Pluses: greater range of services; potential higher

value to individual communitiesMinuses: locked into audience expectations;

stations are forced to balance video quality with service quantity

Observations:

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Observations : Many stations are moving to 720p replacing spatial

resolution with temporal resolutionSignificantly reducing their blocking artifactsReducing horizontal resolution

With an increase in demand for more services stations can improve their performance byMoving to 720pReplacing their HD encoders with the next generation

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Video Examples

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Questions?