Television – Plural transmitter system considerations
Reexamination Certificate
1998-03-25
2001-02-06
Lee, Michael (Department: 2714)
Television
Plural transmitter system considerations
C348S723000, C348S608000, C348S725000, C348S014160
Reexamination Certificate
active
06184921
ABSTRACT:
BACKGROUND OF THE INVENTION
The specification and drawing of U.S. Pat. No. 5,087,975 issued Feb. 11, 1992 to R. W. Citta et alii and entitled VSB HDTV TRANSMISSION SYSTEM WITH REDUCED NTSC CO-CHANNEL INTERFERENCE are incorporated herein by reference. Citta et alii describe a television signal transmission signal for broadcast television comprising a suppressed carrier, a VSB signal having respective Nyquist slopes at the lower- and upper-frequency edges of a television channel with 6-MHz bandwidth, the center frequency of the Nyquist slope at the lower-frequency edge of the channel being substantially coincident with the frequency of the suppressed carrier, and a pilot signal in quadrature relation with the suppressed carrier. The television signal transmission signal is susceptible to cochannel interference from NTSC television signal with a video carrier 1.25 MHz above the lower-frequency edge of the channel, a color subcarrier 3.58 MHz above the video carrier in frequency, and an audio carrier 0.25 MHz below the upper-frequency edge of the channel. The suppressed carrier is modulated by an N-level digitally encoded signal having a sample rate f
s
substantially equal to three times the NTSC color subcarrier frequency, with the frequency of the suppressed carrier being closer to the lower-frequency edge of the channel than the co-channel NTSC picture carrier by an amount equal to about f
s
/12. The received signal is demodulated by a synchronous detector in response to the received pilot signal and interfering NTSC beat components are attenuated by a linear filter having notches at f
s
/1, at 5 f
s
/12 and at f
s
/2.
A Digital Television Standard published Sep. 16, 1995 by the Advanced Television Systems Committee (ATSC) specifies VSB signals for transmitting digital television (DTV) signals in 6-MHz-bandwidth television channels such as those currently used in over-the-air broadcasting of National Television System Committee (NTSC) analog television signals within the United States. These VSB signals differ from those described by Citta et alii in that each uses a pilot signal in phase with its suppressed carrier, rather than in quadrature therewith. These VSB signals each comprise a vestigial sideband near the lower upper-frequency edge of the television broadcast channel and a full sideband extending upward in frequency therefrom to the upper-frequency edge of the channel.
SUMMARY OF THE INVENTION
The invention is directed to the transmitting of a television signal transmission signal comprising a suppressed carrier, a pilot signal in phase with the suppressed carrier, and a VSB signal having its vestigial sideband near the upper-frequency edge of a television broadcast channel and its full sideband near the lower-frequency edge of the channel. The suppressed carrier is modulated by an N-level digitally encoded signal having a sample rate f
s
substantially equal to three times the NTSC color subcarrier frequency, with the frequency of the suppressed carrier being further from the lower-frequency edge of the channel than the co-channel NTSC picture carrier by an amount equal to about 5f
s
/12. The received signal can be demodulated by a synchronous detector in response to the received pilot signal and interfering NTSC beat components are attenuated by a linear filter having notches at f
s
/12, at f
s
/4 and at 5f
s
/12.
REFERENCES:
patent: 5087975 (1992-02-01), Citta et al.
patent: 5121203 (1992-06-01), Citta
patent: 5243304 (1993-09-01), Rixon
patent: 5285470 (1994-02-01), Schreiber
patent: 5311547 (1994-05-01), Wei
patent: 5408262 (1995-04-01), Kim et al.
patent: 5452015 (1995-09-01), Hulyalkar
patent: 5512957 (1996-04-01), Hulyalkar
patent: 5534933 (1996-07-01), Yang
patent: 5559561 (1996-09-01), Wei
patent: 5574496 (1996-11-01), Nielsen et al.
patent: 5602583 (1997-02-01), Citta
patent: 5619534 (1997-04-01), Hulyalkar
patent: 5629958 (1997-05-01), Willming
patent: 5764701 (1998-06-01), Horwitz
patent: 5801759 (1998-09-01), Limberg
Bushnell , Esq. Robert E.
Desir Jean W.
Lee Michael
Samsung Electronics Co,. Ltd.
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