Pulse or digital communications – Receivers – Amplitude modulation
Reexamination Certificate
1999-10-21
2001-09-18
Ghebretinsae, Temesghen (Department: 2631)
Pulse or digital communications
Receivers
Amplitude modulation
C375S324000, C329S304000, C329S357000, C348S726000
Reexamination Certificate
active
06292518
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to digital television (DTV) and, in particular, to use of 64-QAM (quadrature amplitude modulation) receiver design methodologies in the reception of 8-VSB (vestigial sideband) signals as specified in the Advanced Television Standards Committee (ATSC) television standards.
2. Background Art
Digital television (DTV) signals in the USA are broadcast using the Advanced Television Standards Committee (ATSC) television standard modulation system which is eight level vestigial sideband (8-VSB) modulation with a suppressed carrier signal. Conventional 8-VSB receiver designs complex demodulate the received signal with a pilot tone on zero frequency. Under ideal channel conditions, this allows the data symbols to stream on only one of two complex demodulated channels (known as I-channel only processing).
BRIEF SUMMARY OF THE INVENTION
An 8-VSB receiver designed using methodologies of 64-QAM receiver design converts the received 8-VSB modulation into a signal which can be processed by circuitry intended to decode 64 level quadratureamplitude modulation (64-QAM) signals. This results in a better signal to noise ratio (SNR) reception than the conventional I-channel only decoding circuitry of most 8-VSB receivers. This methodology also allows use of training and equalizing algorithms developed for 64-QAM which are superior to equivalent algorithms for 8-VSB receivers. The invention can be generalized to N-VSB conversion into M-QAM where M=N
2
.
The MPEG-2 (Motion Picture Experts Group) packets comprise 208 bytes or 1664 bits corresponding to 832 symbols. There are eight symbol levels. A pilot tone is included in the 8-VSB signal design. The symbol values entering a zero-ISI( )VSB filter are offset by a DC value to generate the pilot tone. This approach causes the pilot tone to have a particular phase with respect to the symbol detection timing. Present receiver implementations may cause this phase to be of no consequence when I-channel only receiver processing is conducted, because the pilot tone is used for frequency acquisition only.
REFERENCES:
patent: 5477199 (1995-12-01), Montreuil
patent: 5673293 (1997-09-01), Scarpa et al.
patent: 6067329 (2000-05-01), Kato et al.
Grabb Mark Lewis
Hershey John Erik
Welles II Kenneth Brakeley
Breedlove Jill M.
General Electric Company
Ghebretinsae Temesghen
Stoner Douglas E.
LandOfFree
Use of 64-QAM circuitry for receiving and decoding 8-VSB... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Use of 64-QAM circuitry for receiving and decoding 8-VSB..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Use of 64-QAM circuitry for receiving and decoding 8-VSB... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2439512