(12) United States Patent ao) Patent No.: us 6,333,767 Bi
Patel et al. (45) Date of Patent: *Dec. 25,2001
(54) RADIO RECEIVERS FOR RECEIVING BOTH VSB AND QAM DIGITAL TELEVISION SIGNALS WITH CARRIERS OFFSET BY 2.69 MHZ
(75) Inventors: Chandrakant B. Patel, Hopewell Township, NJ (US); Allen LeRoy Limberg, Fairfax County, VA (US)
(73) Assignee: Samsung Electronics Co., Ltd., Kyungki-do (KR)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
This patent is subject to a terminal disclaimer.
(21) Appl. No.: 09/066,893
(22) Filed: Apr. 28, 1998
Related U.S. Application Data
(63) Continuation-in-part of application No. 08/773,949, filed on Dec. 26, 1996, now abandoned.
(51) Int. CI.7 H04N 3/27; H04N 7/04;
H04N 5/46; H04N 5/44; H04N 5/52; H04L 27/14;
(52) U.S. CI 348/725; 348/726; 348/558;
348/555; 348/554; 348/678; 348/470; 375/324;
(58) Field of Search 348/725, 726,
348/678, 558, 554, 555, 470; 375/324, 321, 316; H04N 5/455
(56) References Cited
U.S. PATENT DOCUMENTS
5,506,636 * 4/1996 Patel et al 348/725
A radio receiver uses the same tuner for receiving a selected digital television (DTV) signal, irrespective of whether it is a quadrature-amplitude-modulation (QAM) or a vestigial sideband (VSB) signal. The tuner supplies a final IF signal in a 6-MHz-wide frequency band, the lowest frequency of which is not appreciably more than 2.69 MHz. The final IF signal is digitized at a rate that is a multiple of both the symbol frequencies of the QAM and VSB signals, for synchrodyning to baseband, with the 2.69 MHz difference between the carrier frequencies of QAM and VSB signals being taken into account in the digital synchrodyning circuitry. The carrier frequencies of the QAM and VSB final IF signals are regulated to be submultiples of the multiple of both the symbol frequencies of the QAM and VSB signals by applying automatic frequency and phase control signals developed in the digital circuitry to a local oscillator of the tuner.
23 Claims, 11 Drawing Sheets