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`US005544198A
`Patent Number:
`Date of Patent:
`
`[11]
`
`[45]
`
`5,544,198
`Aug. 6, 1996
`
`United States Patent [19]
`Saalfrank
`
`[54] PROCEDURE FOR THE IDENTIFICATION
`OF TRANSMITTER OR REGION IN
`COMMON· WAVE BROADCASTING
`NETWORKS
`
`[75]
`
`Inventor: Werner SaaIfrank, Herzogenaurach,
`Germany
`
`[73] Assignee: Grundig E.M.V., Furth/Bay, Germany
`
`[21] Appl. No.:
`
`94,080
`
`[22] PCT Filed:
`
`Dec. 18, 1991
`
`[86] PCT No.:
`
`PCTIEP91102438
`
`§ 371 Date:
`
`Sep. 10, 1993
`
`§ 102(e) Date: Sep. 10, 1993
`
`4,144,496
`4,541,118
`5,230,081
`
`3/1979 Cunningham et al. ................ 455/54.1
`911985 Eastmond et al ......................... 455/59
`711993 Yamada et al ......................... 455/54.1
`
`FOREIGN PATENT DOCUMENTS
`
`8200074
`
`111982 WIPO ...................................... 370176
`
`OTHER PUBLICATIONS
`
`"Station and Programme Identification in FM Journal
`Broadcasting" Grelis et al. Philips Tech Rev. 39 1980 pp.
`216-226.
`
`Primary Examiner-Stephen Chin
`Assistant Examiner-T. Ghebretinsae
`Attorney, Agent, or Firm-Kane, Dalsimer, Sullivan,
`Kurucz, Levy, Eisele & Richard
`
`[87] PCT Pub. No.: W092113403
`
`[57]
`
`ABSTRACT
`
`PCT Pub. Date: Aug. 6, 1992
`
`[30]
`
`Foreign Application Priority Data
`
`Jan. 28, 1991
`
`[DE] Gennany .......................... 41 02408.7
`
`Int. C1.6
`..................................................... H04L 27/28
`[51]
`[52] U.S. CI. ............................................ 375/260; 370/69.1
`[58] Field of Search ................................. 375/38; 370/21,
`3701110.1,69.1,74,76; 455/44, 59, 60,
`103, 104
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`The method pertains to wireless transmission in the com(cid:173)
`mon-wave operation. For the operation of common-wave
`networks, it is required that the modulation contents of the
`transmission frequencies (1 . . . m) transmitted by the
`individual transmitting stations are identical. However, in
`order to enable a station or regional identification, one or
`more regionally differing additional carrier frequencies (n-3
`... n) are transmitted, whose reception permits the selection
`of specific regionally related news or messages in the
`receiver. The demand of additional carrier frequencies may
`be reduced to four individual frequencies or frequency
`groups, if these additional carriers are modulated.
`
`3,596,001
`
`711971 Adrian ...................................... 370/20
`
`6 Claims, 3 Drawing Sheets
`
`1
`
`TMO1015
`
`

`
`u.s. Patent
`A
`
`Aug. 6, 1996
`
`Sheet 1 of 3
`
`5,544,198
`
`1 2 3 •••••••••• m-2 m-1 m
`
`FIG~ 1 a
`
`A
`
`1 2 n-3 3 • • • • • •• n-2 m-2 m·1 m n·1 n
`
`I
`I
`I
`I
`I
`~----~~~I~~»I~--~'~~~_~'~I-.f
`
`1 ...... 1 - - - - - - - - B I:: (1 + ~) x 8 - -__ ~~I
`FIG. 1 b
`
`2
`
`

`
`u.s. Patent
`
`Aug. 6, 1996
`
`Sheet 2 of 3
`
`5,544,198
`
`FIG.2
`
`3
`
`

`
`U.S. Patent
`
`Aug. 6, 1996
`
`Sheet 3 of 3
`
`5,544,198
`
`TRANSMISSION OF
`ADDITIONAL CARRI ERS
`
`••
`RECEPTION OF
`ADDITIONAL CARRIERS
`
`EVALUATION OF
`CLOSEST TRANSM ITTER
`
`EVALUATION OF THE
`ARRANGEMENT OF
`ADDITIONAL CARRIER
`FREQUENCIES
`
`FIG.3
`
`4
`
`

`
`1
`PROCEDURE FOR THE IDENTIFICATION
`OF TRANSMITTER OR REGION IN
`COMMON-WAVE BROADCASTING
`NETWORKS
`
`BACKGROUND OF THE INVENTION
`
`5,544,198
`
`5
`
`2
`not interfere with each other. With the aid of four different
`transmission channels, it is possible to plan the frequency
`distribution to the individual transmission regions in the
`form of a four cluster, so that an overlapping region or
`international transmission network has no adjacent joining
`zones with a different program, but the same transmission
`frequency. For the common-wave configuration of the DAB(cid:173)
`audio broadcasting, a frequency band with a bandwidth of a
`total of 4xB is required. Naturally, within a transmission
`10 region, also a network of locally limited stations may be
`established with the aid of the remaining three-cluster(cid:173)
`frequencies, so that in addition to the 5 ... 6 (European)
`country-wide programs, 6 to 18 local programs may be
`transmitted.
`As previously mentioned, the common-wave operation of
`a (European) country-wide
`transmission network, for
`example, requires 100 percent conformity of the modulation
`content of the frequency proportion transmitted simulta(cid:173)
`neously by the individual broadcasting stations, in order to
`20 enable interference-free decoding ofthe program data. How(cid:173)
`ever, since the future of DAB-network may soon supersede
`the current VHF radio traffic, the (European) country-wide
`transmission of the same traffic news, for example, may
`contradict the goal of direct region or local traffic broadcasts.
`25 Furthermore, a driver who drives from one broadcasting
`region to another should be provided with rough positional
`information, so that the driver's receiver can be automati(cid:173)
`cally or manually set to the receiving channel of the neigh(cid:173)
`boring region.
`
`40
`
`It is therefore an object of the present invention to provide
`a method and procedure for the identification of a transmitter
`35 or region which does not interfere with the common-wave
`broadcasting operation of the network.
`It is therefore a further object of the present invention that
`the procedure should be able to transmit not regionally
`related further transmisssion data.
`.
`These and other objects are achieved by providing a
`method and procedure for wireless transmission of digital
`signals through a broadcasting network operating in the
`common-wave frequency which simultaneously transmits a
`plurality of different individual carrier frequencies for all the
`transmitting stations in the network, which are equidistantly
`arranged in the frequency axis of a defined transmission
`frequency band and which are only modulated with portions
`of the bit sequence representing the digital signals, whereby
`the modulation contents of the individual carrier frequencies
`50 are identical for all transmitting stations of the transmitting
`region, characterized in that for identifying at least one
`transmitting station in a local transmitting region, at least
`one transmission specific or regionally differing unmodu(cid:173)
`lated individual carrier frequencies are simultaneously trans-
`55 mitted from this and, if necessary, other transmitting sta(cid:173)
`tions, whose configuration in the frequency domain are
`evaluated for station identification and which do not inter(cid:173)
`fere with the transmission of these signals in the common(cid:173)
`wave operation within overlapping transmission areas of
`individual transmitting stations, due to the reception of these
`60 signals separately from the information and control signal
`modulation.
`
`OBJECTS AND SUMMARY OF THE
`INVENTION
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Further objects and advantages of the invention will
`become apparent from the following description and claims,
`and from the accompanying drawings, wherein:
`
`1. Field of the Invention
`This invention pertains to a common-wave broadcasting
`network wherein additional carrier frequencies which differ
`from each other from region to region are emitted in order
`to make transmitter or regional identification possible.
`Reception of these additionally carrier frequencies make it
`possible to select at the receiver specialized regional news. 15
`2. Description of the Prior Art
`Analog VHF radio transmission is not able to match the
`quality standard offered by digital recording media (such as
`compact discs or Digital Audio Tape
`'DAT'). Further,
`mobilc reception in a motor vehicle or with portable devices
`results in further degradation of thc reception. Field intensity
`fluctuations and multipath reception result in signal distor(cid:173)
`tions, whose effects can be reduced only partially by alter(cid:173)
`nating strategies to alternative reception frequencies (for
`example, in conjunction with the radio data systems).
`Digital radio transmission for mobile reception with the
`aid of satellites is not presently feasible as it is necessary to
`usc receiver antennas with distinct directional effects in view
`of the relatively low transmission efficiency. Therefore,
`work has been in progress for a few years to develop a 30
`standard for a new terrestrial digital transmission system
`known as DAB (Digital Audio Broadcasting), see "Funk(cid:173)
`sehau-Spezial", "Digitaler Ton-Von HGrfunk bis Mobiltele(cid:173)
`[on", 1990, pages 9-18).
`One of the specifics of the planned transmission network
`is the common wave operation of the transmitting station
`within a country-wide program offering. This means that in
`a defined region all transmitting stations simultaneously
`broadcast with the same modulation on the same transmis(cid:173)
`sion frequency or the same carrier frequency.
`The COFDM (coded orthogonal frequency division mul(cid:173)
`tiplex) transmission procedure is provided wherein within a
`region, for example the transmission area of a European
`country, a broadcasting station simultaneously transmits
`about five or six stereo programs by using a carrier fre(cid:173)
`quency bandwidth of, for example, 1.5 megahertz (in addi(cid:173)
`tion to the program related and program independent data).
`Within the available channel bandwidth, a plurality of
`individual carriers (for example, 448 carrier frequencies
`equidistant on the frequency axis) are generated with a
`4-DPSK (differential phase shift keying) modulation. By
`scrambling the digital program data in the time sequence and
`in the allocation to the individual carrier frequencies, trans(cid:173)
`mission errors due to field intensity fluctuation do not extend
`over longer time connected signal segments and can there(cid:173)
`fore be more easily corrected.
`A detailed explanation of the principal transmission and
`coding procedure can be found in the article "Digital Sound
`Broadcasting to Mobile Receivers" in the "IEEE Transac(cid:173)
`tions on Consumer Electronics", Vol. 35, No.3, August
`1989, pages 493-503).
`To establish an overlapping transmission network for an
`area the size of a European country (or equivalently, a U.S.
`state), it is necessary to provide a minimum of four different 65
`transmission channels of a defined bandwidth B, so that the
`different programs of the different transmission regions do
`
`45
`
`5
`
`

`
`5,544,198
`
`3
`FIG. 1a is the schematic of the carrier frequency configu(cid:173)
`ration of the present invention for a region (Le., European
`country or similar size) related common-wave network.
`FIG. 1b is a schematic of the carrier frequency configu(cid:173)
`ration of the present invention in accordance with FIG. la, 5
`including an additional transmitter or region identification.
`FIG. 2 is a schematic of the frequency distribution in the
`form of a four-cluster as used in the present invention.
`FIG. 3 is a flowchart of an aspect of the apparatus of the 10
`present invention.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`
`20
`
`30
`
`4
`identification if the news is important throughout a wider
`geographic range. To recognize which specific transmitting
`station within the regional common-wave network is closest
`to the receiver, the field intensity and/or the number or
`timing sequence of the received echo of the receiving signal,
`which is provided with a special identification, may be
`evaluated.
`In accordance with FIG. 1b, the identification may be
`performed via n non-modulated carrier frequencies (dash dot
`lines; n-3 .. n) which are additionally transmitted to the
`carrier frequencies 1 ... m used for the program transmis(cid:173)
`sion in accordance with FIG. 1a. These additional n carriers
`may be inside or outside of the frequency band required for
`the program transmission at any given location, but only
`within the predetermined frequency raster. In any case, the
`bandwidth to be transmitted is enlarged from B to B'. The
`configuration of the additional carrier frequencies in the
`frequency range to be transmitted permits mUltiple varia(cid:173)
`tions in the identification.
`The additional carrier frequencies required for station
`identification result in a considerable widening of the trans(cid:173)
`mitting frequency bandwidth B' with a great number of
`transmitting stations within a transmission region. This
`disadvantage can be eliminated if one or a plurality of these
`25 additional carriers are modulated with a specific identifica(cid:173)
`tion signal. In order not to interfere with the common-wave
`broadcasting, at least four groups of additional carriers may
`be provided, analogous to the configuration disclosed in
`FIG. 2, whose local use is planned so that no common
`influence occurs. The identification signals are modulated on
`the additional carriers in the same manner as the aforemen(cid:173)
`tioned COFDM-procedure.
`By the modulation of the additional carriers with identi-
`fication signals, any number of sub-common-wave net(cid:173)
`works, in relation to the additional carriers, may be formed
`within large area common-wave broadcasting networks. For
`transmission of regionally independent data, the additional
`carriers may be modulated, for example, with switch or
`40 synchronous signals. Since there is sufficient time for evalu(cid:173)
`ating the additional signals or enough redundancy for the
`prevention of errors within the transmission capacity of
`individual additional carriers, the additional frequency
`requirement may be limited to one additional carrier in most
`45 cases, instead of to an entire group.
`With the aid of transmission or regional identification, it
`is also possible to identify the change into an adjoining
`transmission region with a deviating program selection in a
`timely manner during the mobile reception in border cross-
`ing traffic. The orientation is performed by comparing the
`perceived identification with one, stored in the internal
`memory of the receiver, based on the identification list for
`the entire transmission area. Thus the receiver may be
`adjusted manually or automatically to the carrier frequency
`55 group of the new transmission region as soon as the quality
`of the hitherto transmission signal as received is no longer
`adequate.
`Thus the several aforementioned objects and advantages
`are most effectively attained. Although a single preferred
`embodiment of the invention has been disclosed and
`described in detail herein, it should be understood that this
`invention is in no sense limited thereby and its scope is to be
`determined by that of the appended claims.
`What is claimed is:
`1. A method for radio transmission of digital signals
`through a broadcasting network operating in the common(cid:173)
`wave frequency comprising the steps of:
`
`Referring now to the drawings in detail wherein like 15
`numerals refer to like elements throughout the several
`views, one sees that in FIG. la, the method includes the
`transmission of m carrier frequencies (for example, 448)
`with equidistant frequency distance M within the bandwidth
`B.
`The individual carriers are each modulated with a portion
`of the digital data, whereby the modulation contents of the
`individual carriers for all transmitting stations are identical
`for a transmission region. If the procedure and method are
`performed in time multiplex operation, the data of the
`different programs are transmitted in timely sequence within
`a data packet, so that for a program change within the
`program selection of a particular broadcasting station, no
`change of the tuning frequencies in the receiver has to be
`performed, but only a switching-over of the timely associ(cid:173)
`ated decoding of the data packets. The data content of a
`program is not limited to audio signals, but may additionally
`include information and control data (for example, video
`transmission or traffic guidance data).
`Outside of the transmission region (typically the size of a
`European country or a U.S. state) of a broadcast station with
`the carrier frequency range B I the same carrier frequencies
`naturally may not be used by a station with a different
`program selection, because otherwise no clear program
`decoding would be possible in the overlapping area of both
`transmission regions. Therefore, a separate carrier frequency
`range B2 must be assigned to this adjoining transmission
`region. It can be seen from FIG. 2 that by using at least four
`separate frequency ranges, BI, B2, B3, B4, a frequency
`allocation may be provided wherein the regions with the
`same carrier frequency range do not adjoin each other
`(analogous to the theorem that no more than four colors are
`required in a two-dimensional map to avoid any adjoining
`regions of the same color).
`However, within a transmission region, locally limited
`stations can be embedded with another program selection, if
`the remaining three cluster-frequencies are assigned thereto
`and if it is assured that their transmission does not overlap
`into adjacent transmission regions having the same carrier
`frequency range.
`In order to assure an interference-free common wave
`operation within a transmission region, all carrier frequen(cid:173)
`cies used for program and data transmission must be gen(cid:173)
`erated with an identical modulation content, that is, regional 60
`or station specific identification is not possible within the
`program information. However, to receive a specific selec(cid:173)
`tion from the region-wide traffic news, for example, or to
`receive regional alerts or emergency broadcasts, it is nec(cid:173)
`essary to provide a coarse local orientation for the receiver 65
`by means of a specific station identification. In this manner,
`all stations of a given region may be provided with the same
`
`35
`
`50
`
`6
`
`

`
`5,544,198
`
`5
`simultaneously transmitting a plurality of different carrier
`frequencies for each of a plurality of transmitting
`stations within the broadcasting network, said different
`carricr frequencies being equidistantly arranged in a
`frequency axis of a defined transmission frequency
`band;
`modulating each of said plurality of different carrier
`frequencies only with portions of a bit sequence rep(cid:173)
`resenting said digital signals, whereby modulation
`results of said different carrier frequencies are identical
`for each of said plurality of transmitting stations of a
`transmitting region;
`identifying at least one transmitting station in a transmit(cid:173)
`ting region by way of simultaneously transmitting at
`least one unmodulated additional carrier frequency
`corresponding to a unique transmitter or region from at
`least one transmitting station, receiving said unmodu(cid:173)
`latcd additional carrier frequencies and evaluating the
`prcscnce and frequency of said unmodulatcd additional
`carrier frequencies in a frequency raster for identifica(cid:173)
`tion of said unique transmitter or region, wherein said
`unmodulated additional carrier frequencies do not
`interfere with transmission of said digital signals in
`common-wave operation within overlapping transmis(cid:173)
`sion areas of each of said plurality of transmitting
`stations, due to the processing of said signals separately
`from modulation of said digital signals.
`
`10
`
`6
`2. The method of claim 1 further including the steps of
`separating said at least one unmodulated additional carrier
`frequency which is added to the individual transmitting
`stations or regions in the broadcasting network into at least
`four groups, whereby identical frequencies are simulta(cid:173)
`neously used in transmitting regions substantially separated
`from each other; and modulating said at least one unmodu(cid:173)
`lated additional carrier frequency with at least one specific
`identification signal for identification.
`3. The method of claim 2 further comprising the steps
`providing COFDM modulation in said common wave net(cid:173)
`works and modulating said at least one specific identification
`signals using COFDM modulation.
`4. The method of claim 2 wherein the step of modulating
`15 said at least one unmodulated additional carrier frequency
`includes one and only one unmodulated additional carrier
`frequency per group.
`5. The method of claim 4 further including the step of
`modulating said at least one unmodulated carrier additional
`frequency with additional data.
`6. The method of claim 5 further including the step of
`forming sub-common-wave networks within the common(cid:173)
`wave broadcasting network which is separated in the form of
`clusters by including at least one identification carrier per
`25 cluster.
`
`20
`
`* * * * *
`
`7