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WO1997039544A1 - Procede de transmission de signaux numeriques sur une bande mf commerciale - Google Patents

Procede de transmission de signaux numeriques sur une bande mf commerciale Download PDF

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Publication number
WO1997039544A1
WO1997039544A1 PCT/US1996/005284 US9605284W WO9739544A1 WO 1997039544 A1 WO1997039544 A1 WO 1997039544A1 US 9605284 W US9605284 W US 9605284W WO 9739544 A1 WO9739544 A1 WO 9739544A1
Authority
WO
WIPO (PCT)
Prior art keywords
signal
digital data
modulating
modulated
channel
Prior art date
Application number
PCT/US1996/005284
Other languages
English (en)
Inventor
David L. Herrick
David K. Murotake
Original Assignee
Lockheed Martin Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lockheed Martin Corporation filed Critical Lockheed Martin Corporation
Priority to PCT/US1996/005284 priority Critical patent/WO1997039544A1/fr
Priority to AU55512/96A priority patent/AU5551296A/en
Publication of WO1997039544A1 publication Critical patent/WO1997039544A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/28—Arrangements for simultaneous broadcast of plural pieces of information
    • H04H20/33—Arrangements for simultaneous broadcast of plural pieces of information by plural channels
    • H04H20/34—Arrangements for simultaneous broadcast of plural pieces of information by plural channels using an out-of-band subcarrier signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H2201/00—Aspects of broadcast communication
    • H04H2201/10—Aspects of broadcast communication characterised by the type of broadcast system
    • H04H2201/18—Aspects of broadcast communication characterised by the type of broadcast system in band on channel [IBOC]
    • H04H2201/183—FM digital or hybrid

Definitions

  • the present invention generally relates to commercial FM broadcasting, and particularly, to digital broadcasting over existing FM station allocations.
  • FM broadcast stations and information service providers use a 20 MHz. frequency band which is divided by Federal regulation into 100 channels of 200 kHz. for each station.
  • Currently provided services are typically analog and include either a monaural or stereo primary baseband signal and a maximum of two or three subcarrier or subsidiary broadcast signals. Broadcasters are prohibited from charging for their primary or main broadcast signal, but are permitted to use their subsidiary broadcasts for revenue bearing services such as functional or background music, specialized foreign language programs, radio reading services, utility load management, market and financial data and news, paging and calling, traffic control signal switching, bilingual television audio, and point to point or multipoint messages.
  • the present invention provides a method for FM broadcasting digital data over a limited bandwidth, FM broadcast channel in addition to a normal monaural or stereophonic analog signal, comprising the steps of compressing or decimating the digital data to be transmitted, phase modulating the compressed or decimated digital data onto a subcarrier signal within an unused upper portion of the limited bandwidth channel to form a modulated digital data signal, modulating an FM transmission carrier signal with the digital data signal and a baseband monaural or stereophonic analog signal, and transmitting the modulated FM carrier signal.
  • Fig. 1 is a baseband frequency spectrum diagram ofthe currently regulated FM broadcast format showing transmission schemes used in the Prior Art;
  • Fig. 2 is a baseband frequency spectrum diagram of an FM broadcast signal used in accordance with one embodiment of the present invention.
  • FIG. 3 is a block diagram of a system constructed in accordance with another embodiment of the present invention. Detailed Description of the Drawings
  • Fig. 1 shows a frequency spectrum diagram of a single sideband of a 200 kHz. wide commercial FM broadcast channel as established by 47 C.F.R. 73.201.
  • the horizontal axis shows frequency in kHz. and thus spans 1 00 kHz., or a full side band of the normal FM channel allocation.
  • the signals represented would be used to frequency modulate a carrier signal in accordance with a regulated channel assignment.
  • the arrow or signal spike 1 10 would represent the location of the carrier frequency upon modulation.
  • the standard FM signal shown includes a baseband monaural signal 1 12 which spans 50 Hz. to 15 kHz., a stereo pilot signal 1 14 at 19 kHz., and a suppressed stereo subcarrier 1 15 at 38 kHz. surrounded by lower and upper stereo sidebands 1 16, 1 17, respectively, between 23 kHz. and 53 kHz..
  • the signal includes a pair of subsidiary signals 1 1 8, 1 19 at 63 kHz. and 93 kHz., located within the subsidiary communications allocation (SCA) 120 between 53 kHz and 99 kHz., as defined by 47 C.F.R. 73.319.
  • supplemental carriers 1 18, 1 19 are currently used by a number of FM stations to transmit revenue bearing, subscriber services such as background music and data (i.e. stock quotes).
  • the SCA 120 is limited in the percentage of overall station power it can contain and signals therein are restricted from interfering with the primary signal or adjacent channels.
  • Fig. 2 shows an FM broadcast spectrum diagram 123 used in accordance with the present invention.
  • the spectrum diagram 123 is similar to that of Fig. 1 except that the supplemental carriers 1 1 8, 1 19 are replaced by a modulated signal 122 in accordance with the method of the present invention.
  • SUBSTITUTE S8EET (RULE 26) 122 may take the form of a single signal or a plurality of signals.
  • the remaining elements shown in Fig. 2 are identical to the elements in Fig. 1 which bear the same identification numbers.
  • the signal 122 is located in the SCA 120 between 53 kHz. and 99 kHz. and it may be modulated by any suitably efficient method.
  • the subsidiary signal may be produced by quadrature amplitude modulation (QAM) of a subcarrier signal by the digital data to be transmitted. This method varies the phase and amplitude ofthe subcarrier in accordance with the digital data.
  • QAM quadrature amplitude modulation
  • a sixteen point constellation is used made up of four different amplitude levels and four different phase values between - ⁇ and + ⁇ , with each point representing a binary value between 0 and 15.
  • the digital data to be transmitted would be directly represented by the constellation points during transmission.
  • the digital data used for transmission may be of any form such as unprocessed, compressed, decimated, coded, etc., depending upon the desired transmission efficiency.
  • Fig. 3 shows a block diagram of a transmitter/receiver system 130 generally including transmitter portion 132 and at least one receiver portion 134.
  • Transmitter portion 132 includes an analog transmitter 136 coupled to an antenna 138.
  • the input signal for transmitter 136 is formed in a phase linear pre-equalizer 140 which receives a baseband signal from a summation module 142 and a subcarrier modulated subsidiary signal from a digital SCA modulator/multiplexer (digital m/m) 144.
  • Pre-equalizer 140 pre-compensates for phase nonlinearity which is inherent in transmitter 136.
  • the inputs to summation module 142 are the traditional elements depicted in Fig. 1 and are labeled accordingly. Provision is even made for optionally inputting traditional SCA signals 1 18,1 19.
  • Digital m/m 144 alternatively receives inputs from the various types of digital data which may be transmitted. Included in this variety are ordinary
  • SUBS ⁇ TUTE SHEET (RULE 26) digital data 146, digital audio which is first passed through a decimation module 148 and digital multimedia 150 which is first passed through a decimation/compression module 152.
  • the decimation and/or compression modules 148, 152 are required for the efficient use of the limited broadcast spectrum of the SCA 122. This allows the SCA to accommodate a pair of digital quality audio channels to be broadcast in a single SCA as well as for higher speed video than would otherwise be available in a single SCA. Maintaining the necessary bandwidth below that of a single SCA allows optimum usefulness by single station broadcasters. Dual station broadcasters benefit from a proportional bandwidth increase.
  • Receiver portion 134 may be one of many within system 130 and includes an analog receiver 160 having an input coupled to an antenna 162 and a demodulated output coupled to a channel equalizer 164.
  • the output of channel equalizer 164 is coupled to a digital SCA demodulator/demultiplexer (digital d/d) 166 which separates whichever form of digital data has been transmitted over the SCA 120.
  • the baseband audio signal which is also transmitted may be demodulated elsewhere by an ordinary FM receiver such as 160. Any decimated and/or compressed digital multimedia may be coupled through a comparable bit smoother/decompressor 168 for the appropriate signal reconditioning.
  • the benefits of decimation, compression, etc. in combination with the remainder of the described embodiments are readily apparent.
  • the standard data rate for digital audio compact disc (CD) and CD- ROM playback is 1.5 mbps.
  • Psychoacoustic decimation techniques such as the Bose AC-2 method, can reduce the required signal data rate to 180-256 kbps, depending upon a quality factor, which decimated signal, according to broadcast industry experts, cannot be aurally differentiated from an undecimated CD playback by a human listener.
  • digital compression and video frame decimation methods can be used to reduce the required signal data rate to 180-256 kbps, depending upon a quality factor, which decimated signal, according to broadcast industry experts, cannot be aurally differentiated from an undecimated CD playback by a human listener.
  • SUBS ⁇ TUTE SHEET reduces the data rate of multimedia transmissions to 420 kbps or less, resulting in an audio-visual multimedia presentation similar in quality to current music videos.
  • full motion video frame update rates of 30 frames per second are decimated to an average of 8 frames per second or less, with interpolation used for "bit smoothing".
  • Multipath signal reception may be as problematic with embodiments ofthe present invention as it is with existing FM broadcasts.
  • Basic multipath causes interference as a delayed echo of the received signal.
  • Receiver 160 may include one or more algorithms for reducing the problem.
  • One simple approach would be to subtract a delayed fraction of the received signal from itself to cancel the delayed multipath signal.
  • Monitoring the phase synchronism ofthe QAM signal would provide data for adjusting the delay and determining the appropriate fraction of the received signal.
  • the delay could be smoothly adjusted by use of a dispersive delay line whose delay is proportional to it's center frequency. This dispersive delay line would have an up converter on the input and a down converter on the output, with both converters being fed by the same local oscillator to cancel short term frequency drift. Varying the frequency of this local oscillator would allow for smooth and continuous adjustment of the time delay.
  • Multipath compensation may also be accomplished by digital algorithms which would also provide greater flexibility for dealing with more than one multipath signal.
  • the present invention enables FM broadcast stations to add revenue bearing broadcast services within the subsidiary communications allocation without interfering with existing "free access" broadcast services.
  • Such services may include one or two CD quality digital stereo audio channels, or some combination of digital multimedia, digital audio, and digital data services.
  • SUBS ⁇ E SHEET (Mft£ 26> existing transmitters and receivers would remain in use while the market is expanded via the subsidiary broadcasts. Optimum use is made of the limited SCA bandwidth, enabling income producing use by even single station broadcasters.
  • the present invention further avoids any need for changing current broadcast regulations and readily accommodates future digital upgrades io the main broadcast signals of any station.

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Stereo-Broadcasting Methods (AREA)
  • Circuits Of Receivers In General (AREA)
  • Transmitters (AREA)

Abstract

L'invention porte sur un procédé de transmission de signaux numériques (146, 150) sur un canal de radiodiffusion en MF à largeur de bande limitée, en plus des signaux analogiques normaux en monophonie ou stéréophonie. Ledit procédé consiste à comprimer (152) ou décimer (148) le signal numérique à transmettre, à moduler en phase (140) le signal numérique comprimé ou décimé en signal de sous-porteuse dans la partie supérieure non utilisée d'un canal à largeur de bande limitée pour obtenir un signal modulé de données numériques, à moduler (144) le signal de transmission en MF de la porteuse avec le signal de données numériques et un signal analogique de bande de base en monophonie ou en stéréophonie, puis à émettre (136) le signal de porteuse MF modulé. L'invention, qui peut s'appliquer à tout spectre d'émission MF régulé comportant une largeur de bande inutilisée entre stations, permet une meilleure utilisation de la largeur de bande sans ajouter d'interférences.
PCT/US1996/005284 1996-04-17 1996-04-17 Procede de transmission de signaux numeriques sur une bande mf commerciale WO1997039544A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/US1996/005284 WO1997039544A1 (fr) 1996-04-17 1996-04-17 Procede de transmission de signaux numeriques sur une bande mf commerciale
AU55512/96A AU5551296A (en) 1996-04-17 1996-04-17 Method for digital broadcasting over the commercial fm band

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1996/005284 WO1997039544A1 (fr) 1996-04-17 1996-04-17 Procede de transmission de signaux numeriques sur une bande mf commerciale

Publications (1)

Publication Number Publication Date
WO1997039544A1 true WO1997039544A1 (fr) 1997-10-23

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1996/005284 WO1997039544A1 (fr) 1996-04-17 1996-04-17 Procede de transmission de signaux numeriques sur une bande mf commerciale

Country Status (2)

Country Link
AU (1) AU5551296A (fr)
WO (1) WO1997039544A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002009329A3 (fr) * 2000-07-25 2003-03-27 Thomson Licensing Sa Systeme de radiodiffusion iboc pour donnees numeriques

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4803727A (en) * 1986-11-24 1989-02-07 British Telecommunications Public Limited Company Transmission system
US5155769A (en) * 1991-04-12 1992-10-13 Aphex Systems, Ltd. Discrete parallel path modulation multiplexer
US5161251A (en) * 1991-02-19 1992-11-03 Mankovitz Roy J Apparatus and methods for providing text information identifying audio program selections
US5191615A (en) * 1990-01-17 1993-03-02 The Drummer Group Interrelational audio kinetic entertainment system
US5315583A (en) * 1991-04-11 1994-05-24 Usa Digital Radio Method and apparatus for digital audio broadcasting and reception
US5408686A (en) * 1991-02-19 1995-04-18 Mankovitz; Roy J. Apparatus and methods for music and lyrics broadcasting

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4803727A (en) * 1986-11-24 1989-02-07 British Telecommunications Public Limited Company Transmission system
US5191615A (en) * 1990-01-17 1993-03-02 The Drummer Group Interrelational audio kinetic entertainment system
US5161251A (en) * 1991-02-19 1992-11-03 Mankovitz Roy J Apparatus and methods for providing text information identifying audio program selections
US5408686A (en) * 1991-02-19 1995-04-18 Mankovitz; Roy J. Apparatus and methods for music and lyrics broadcasting
US5315583A (en) * 1991-04-11 1994-05-24 Usa Digital Radio Method and apparatus for digital audio broadcasting and reception
US5155769A (en) * 1991-04-12 1992-10-13 Aphex Systems, Ltd. Discrete parallel path modulation multiplexer

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002009329A3 (fr) * 2000-07-25 2003-03-27 Thomson Licensing Sa Systeme de radiodiffusion iboc pour donnees numeriques
JP2004509487A (ja) * 2000-07-25 2004-03-25 トムソン　ライセンシング　ソシエテ　アノニム デジタル・データのためのイン・バンド・オン・チャネル放送システム
US6792051B1 (en) 2000-07-25 2004-09-14 Thomson Licensing S.A. In-band-on-channel broadcast system for digital data
US7388911B2 (en) 2000-07-25 2008-06-17 Thomson Licensing In-band-on-channel broadcast system for digital data
SG144728A1 (en) * 2000-07-25 2008-08-28 Thomson Licensing Sa An in-band-on-channel broadcast system for digital data
KR100811570B1 (ko) * 2000-07-25 2008-10-27 톰슨 라이센싱 에스.에이. 디지털 데이터에 대한 인 밴드 온 채널 방송 시스템
JP4651910B2 (ja) * 2000-07-25 2011-03-16 トムソン ライセンシング デジタル・データのためのイン・バンド・オン・チャネル放送システム

Also Published As

Publication number Publication date
AU5551296A (en) 1997-11-07

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