HDTV Overview
Wayne Kube
Kube Broadcast Consulting, Inc.
wayne@kubebroadcast.com
n5wmk@verizon.net
NTSC & DTV Comparison
• NTSC was fully analog
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Amplitude Modulation (with vestigial sideband) for visual content
Upper sideband used for majority of picture information – not suppressed carrier
Lower sideband – most of content removed, but some (vestige) left – thus VSB
• (Reason was high quality filtering had not been developed that early)
Frequency Modulation for aural content
25 KHz deviation (FM broadcast is 75 KHz deviation)
Stereo developed in 1980s (BTSC)
Aural carrier typically 10% of visual carrier amplitude (average vs. peak)
Most receivers used inter-carrier demodulation of the aural carrier – used the
precise 4.5 MHz difference between visual and aural carriers. That required that
there always be some amount of the visual carrier present, or the audio would
buzz.
• ATSC is fully digital
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Amplitude Modulation for all content
8 levels of Amplitude Modulation – 8VSB
Video, audio, PSIP, other data all multiplexed into one stream
10.76 megabaud; gross bit rate of 32Mb/s; net bit rate of 19.39 Mb/s
19.39 Mb/s transmitted within one 6 MHz RF channel
http://www.arrl.org/files/file/Technology/TV_Channels/8_Bit_VSB.pdf
NTSC & DTV Comparison
316 KW ERP
31.6 KW ERP
NTSC & DTV Comparison
55 KW ERP (average)
NTSC & DTV Comparison
KERA-TV Channel 13
Physical Ch 14, Virtual Ch 13
Physical Channels vs. Virtual Channels
• The RF channel may or may not be the same as the
virtual channel
• Most stations kept their original analog channel
number as their virtual channel for branding
continuity
• This is because PSIP (Program and System
Information Protocol) makes it irrelevant to the
viewer
• DTV receivers will scan the channels and generate a
table that associates virtual channels with physical
channels
Studio End
Transmitter End
Dallas/Fort Worth DTV Stations
Station
Vir. Chan
RF. Chan
Freq
Programs
Streams
KDTN
2
43
647
2.1
1
KDFW
4
35
599
4.1
1
KXAS
5
41
635
5.1, 5.2
2
WFAA
8
8
183
8.1, 8.2, 8.3
3
KTVT
11
19
503
11.1, 11.2
2
KERA
13
14
473
13.1, 13.2
2
KPFW-LD
18
18
497
18.1, 18.2, 18.3, 18.4
4
KBOP-LD
20
20
509
20.1, 20.2, 20.3, 20.4
4
KTXA
21
29
563
21.1, 21.2
2
KUVN
23
23
527
23.1, 23.2, 23.3, 23.4
4
K25FW
25
25
539
25.1
1
KODF-LD
26
27
551
26.1, 26.2, 26.3, 26.4
4
KDFI
27
36
605
27.1, 27.2, 27.3
3
Station
Vir. Chan
RF. Chan
Freq
Programs
Streams
KHPK-LD
28
28
557
28.1, 28.2, 28.3, 28.4
4
KMPX
29
30
569
1
KWDA-LD
30
21
515
K31GL-LD
31
31
575
29.1
30.1, 30.2, 30.3, 30.4,
30.5, 30.6,.30.7,.30.8,
30.9
31.1, 31.2, 31.3, 31.4,
31.5
KDAF
33
32
581
3
KJJM-LD
34
34
593
33.1, 33.2, 33.3
34.1, 34.2, 34.3, 34.4,
34.5
KXTX
39
40
629
39.1, 39.2
2
KLEG-CD
44
44
653
4
KTXD
47
46
665
44.1, 44.2, 44.3, 44.4
47.1, 47.2, 47.3, 47.4,
47.5
KST
49
48
677
49.1, 49.2, 49.3
3
KATA-CD
50
50
689
4
KHFD-LD
51
51
695
50.1, 50.2, 50.3, 50.4
51.1, 51.2, 51.3, 51.4,
51.5, 51.6, 51.7, 51.8
KFWD
52
9
189
1
KAZD
55
39
623
KDTX
58
45
659
KPXD
68
42
641
52.1
55.1, 55.2, 55.3, 55.4,
55.5, 55.6, 55.7
58.1, 58.2, 58.3, 58.4,
58.5
68.1, 68.2, 68.3, 68.4,
(68.11-68.21
encrypted)
9
5
5
5
8
7
5
4
Chan. 17 – Dielectric TFU-20EBT
47 ft long, 10,600 lbs
Transmission Details
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ERP – 1,000 KW
Antenna Gain – 17.5 (12.43 dB) – Omnidirectional
Antenna Input Power – 57.14 kW
Transmission Line – 1,500 ft of 8-3/16” rigid coax
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Loss in the transmission line – 1.21 dB – 18.35 kW (75.7% efficiency)
Transmitter Power Output – 75.49 kW
Would require a three IOT transmitter, each IOT at 30 kW rating, water cooled
The IOT operates at about 25 kVDC, 3 amps
Transmitter efficiency in the 30% range
New solid state transmitters achieve >60% efficiency. 50 VDC, water cooled.
WFAA History
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WFAA Radio (AM) signed on June, 1922 (Working For All Alike)
Moved to 570 KC (not KHz back then) in 1938
Shared 570 and 820 with WBAP until 1970
WFAA-FM started October 1946.
WFAA-TV started as KBTV-TV in September, 1949 (Dumont network)
A. H. Belo purchased KBTV from oilman Tom Potter for $575K in March,
1950 and changed the call letters to WFAA-TV.
• First VHF DTV station in the nation, and first DTV station in Texas –
February 27, 1998
• Analog shut-down June 12, 2009
• 2013, Belo sold all TV stations to Gannett. 2015, Gannett Broadcast
changed its name to TEGNA.
January 4, 1987
Thanks for inviting me!