Multiplex communications – Communication techniques for information carried in plural... – Transmission bandwidth conservation
Reexamination Certificate
1999-08-24
2004-04-13
Chin, Wellington (Department: 2664)
Multiplex communications
Communication techniques for information carried in plural...
Transmission bandwidth conservation
C370S468000, C370S204000, C370S312000, C370S326000
Reexamination Certificate
active
06721337
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to methods and apparatus for transmitting and receiving digital data, and more particularly, to such methods and apparatus for use in digital audio broadcasting systems.
Digital Audio Broadcasting (DAB) is a medium for providing digital-quality audio, superior to existing analog broadcasting formats. Both AM and FM DAB signals can be transmitted in a hybrid format where the digitally modulated signal coexists with the currently broadcast analog AM or FM signal, or in an all-digital format without an analog signal. In-band-on-channel (IBOC) DAB systems require no new spectral allocations because each DAB signal is simultaneously transmitted within the same spectral mask of an existing AM or FM channel allocation. IBOC DAB promotes economy of spectrum while enabling broadcasters to supply digital quality audio to their present base of listeners. Several IBOC DAB approaches have been suggested. One such approach, set forth in U.S. Pat. No. 5,588,022, presents a method for simultaneously broadcasting analog and digital signals in a standard AM broadcasting channel. Using this approach, an amplitude-modulated radio frequency signal having a first frequency spectrum is broadcast. The amplitude-modulated radio frequency signal includes a first carrier modulated by an analog program signal. Simultaneously, a plurality of digitally-modulated carrier signals are broadcast within a bandwidth that encompasses the first frequency spectrum. Each digitally-modulated carrier signal is modulated by a portion of a digital program signal. A first group of the digitally-modulated carrier signals lies within the first frequency spectrum and is modulated in quadrature with the first carrier signal. Second and third groups of the digitally-modulated carrier signals lie outside of the first frequency spectrum and are modulated both in-phase and in-quadrature with the first carrier signal. Multiple carriers are employed by means of orthogonal frequency division multiplexing (OFDM) to bear the communicated information.
FM IBOC DAB broadcasting systems have been the subject of several United States patents including U.S. Pat. Nos. 5,465,396; 5,315,583; 5,278,844 and 5,278,826. One hybrid FM IBOC DAB signal combines an analog modulated carrier with a plurality of orthogonal frequency division multiplexed (OFDM) sub-carriers placed in the region from about 129 kHz to about 199 kHz away from the FM center frequency, both above and below the spectrum occupied by an analog modulated host FM carrier. An all-digital IBOC DAB system eliminates the analog modulated host signal while retaining the above sub-carriers and adding additional sub-carriers in the regions from about 100 kHz to about 129 kHz from the FM center frequency. These additional sub-carriers can transmit a backup signal that can be used to produce an output at the receivers in the event of a loss of the main, or core, signal.
One feature of digital transmission systems is the inherent ability to simultaneously transmit both digitized audio and data. Digital audio information is often compressed for transmission over a bandlimited channel. For example, it is possible to compress the digital source information from a stereo compact disk (CD) at approximately 1.5 Mbps down to 96 kbps while maintaining the virtual-CD sound quality for FM IBOC DAB. Further compression down to 48 kbps and below can still offer good stereo audio quality, which is useful for the AM DAB system or a low-latency backup and tuning channel for the FM DAB system. Effective compression schemes employ variable rate source encoding where fixed time segments of audio are encoded into digital packets of variable length, i.e. audio segments of varying “complexity” are converted into audio frames of varying length.
Audio frames generated by typical audio encoders are in formats that are not efficient for transmission as an IBOC DAB signal. There is a need for an efficient method for transmission and reception of compressed audio frames for digital audio broadcasting.
SUMMARY OF THE INVENTION
A method for transmission of compressed data for a digital audio broadcasting system comprises the steps of receiving digital information representative of an audio signal; estimating the number of bits to be allocated to the digital information in a modem frame; encoding the digital information within the estimated number of bits to produce encoded data; adding bits corresponding to digital messages to the encoded information to form a composite modem frame; formatting the composite modem frame bits to produce formatted composite modem frame bits; and transmitting the formatted composite modem frame bits.
The invention also encompasses modem frame formats produced by the method and transmitters that perform the method. The modem frame formats include a plurality of backup core audio fields, an enhanced audio/data field, and a header field. Each of the backup core audio fields includes a core audio frame, a cyclic redundancy check bit, a redundant header field, and flush bits.
REFERENCES:
patent: 4379947 (1983-04-01), Warner
patent: 4425642 (1984-01-01), Moses et al.
patent: 4534054 (1985-08-01), Maisel
patent: 4660193 (1987-04-01), Young et al.
patent: 4817116 (1989-03-01), Akaiwa et al.
patent: 4866719 (1989-09-01), Morgan et al.
patent: 4881241 (1989-11-01), Pommier et al.
patent: 4881245 (1989-11-01), Walker et al.
patent: 4998252 (1991-03-01), Suzuki et al.
patent: 5020076 (1991-05-01), Cahill et al.
patent: 5117195 (1992-05-01), Robbins
patent: 5128933 (1992-07-01), Baranoff-Rossine
patent: 5134630 (1992-07-01), Bateman
patent: 5134634 (1992-07-01), Yoshida
patent: 5251232 (1993-10-01), Nonami
patent: 5265128 (1993-11-01), Widmer et al.
patent: 5274629 (1993-12-01), Helard et al.
patent: 5278826 (1994-01-01), Murphy et al.
patent: 5278844 (1994-01-01), Murphy et al.
patent: 5283780 (1994-02-01), Schuchman et al.
patent: 5311550 (1994-05-01), Fouche et al.
patent: 5315583 (1994-05-01), Murphy et al.
patent: 5319792 (1994-06-01), Ehlig et al.
patent: 5390214 (1995-02-01), Hopkins et al.
patent: 5406551 (1995-04-01), Saito et al.
patent: 5465396 (1995-11-01), Hunsinger et al.
patent: 5499271 (1996-03-01), Plenge et al.
patent: 5584051 (1996-12-01), Göken
patent: 5588022 (1996-12-01), Dapper et al.
patent: 5592471 (1997-01-01), Briskman
patent: 5632005 (1997-05-01), Davis et al.
patent: 5633896 (1997-05-01), Carlin et al.
patent: 5673292 (1997-09-01), Carlin
patent: 5682461 (1997-10-01), Silzle et al.
patent: 5706396 (1998-01-01), Schroder et al.
patent: 5826227 (1998-10-01), Jayant
patent: 5850456 (1998-12-01), Ten Kate et al.
patent: 5949796 (1999-09-01), Kumar
patent: 5960037 (1999-09-01), Ten Kate
patent: 6023490 (2000-02-01), Ten Kate
patent: 6178317 (2001-01-01), Kroeger et al.
patent: 6201798 (2001-03-01), Campanella et al.
patent: WO97/49207 (1997-12-01), None
Kroeger, Brian W., D.SC., “Improved IBOC DAB Technology for AM and FM Broadcasting,”Westinghouse Wireless, pp. 1-14, Copyright 1996 USA Digital Radio.
Alard, M., Lassalle, R., “Principles of Modulation and Channel Coding for Digital Broadcasting for Mobile Receivers,”EBU Review—Technical, Aug. 1987, pp. 168-190.
A.J. Vigil, “Wireless data transmission through in-band on-channel digital audio broadcasting”,SPIE, vol. 2601, Jun. 1995, pp. 105-114.
C.P. Bell and W. F. Williams, “DAB: Digital Audio Broadcasting Coverage Aspects of a Single Frequency Network”,International Broadcasting Convention, Conference Publication No. 358, Jul. 1992, pp. 270-276.
European Telecommunications Standards Institute, “Radio Broadcasting Systems; Digital Audio Broadcasting (DAB) to Mobile, Portable and Fixed Receivers” European Telecommunication Standard, May 1997, pp. 1-226.
Kroeger Brian William
Mattson Stephen Douglas
Chin Wellington
Fox Jamal A.
iBiquity Digital Corporation
Lenart, Esq. Robert P.
Pietragallo Bosick & Gordon
LandOfFree
Method and apparatus for transmission and reception of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for transmission and reception of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for transmission and reception of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3221794