EP0847157A2 - Vorrichtung für die wirtschaftliche Nutzung vom Frequenzspektrum durch die Zeitmultiplizierung von stereophonischen Übertragungen - Google Patents

Vorrichtung für die wirtschaftliche Nutzung vom Frequenzspektrum durch die Zeitmultiplizierung von stereophonischen Übertragungen Download PDF

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Publication number
EP0847157A2
EP0847157A2 EP19970121048 EP97121048A EP0847157A2 EP 0847157 A2 EP0847157 A2 EP 0847157A2 EP 19970121048 EP19970121048 EP 19970121048 EP 97121048 A EP97121048 A EP 97121048A EP 0847157 A2 EP0847157 A2 EP 0847157A2
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EP
European Patent Office
Prior art keywords
hand
channels
khz
frequency
arrangement according
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Application number
EP19970121048
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English (en)
French (fr)
Inventor
Juan José Maria Lago
Emilio Oscar Caime
Julio Miguel Di Giusto
Néstor Rogelio Orlando
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Individual
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/86—Arrangements characterised by the broadcast information itself
    • H04H20/88—Stereophonic broadcast systems

Definitions

  • the present invention refers to an arrangement for optimizing the utilization of the frequencies by means of time-division multiplexing of stereophonic broadcastings, to the main purpose of obtaining an improved distribution of the spectrum of the frequencies that are used during stereophonic broadcasting so as to increase the number of available channels.
  • the main purpose of the present invention is to provide a new electronic arrangement that enables two or more monophonic or, preferably, stereophonic frequency-modulated music channels to be broadcast either on the air or by means of any two-wire installation that may or may not carry energy, such as for instance a point-to-point telephone link, without interfering with the related service.
  • Such an aim according to the present invention is reached in the utilization of modulated frequency, owing basically to its widely known property of being immune from the noises that may be generated by contiguous lines, industrial power generators, nearby machinery, atmospheric disturbances and the like, so that it actually proves to be ideal in view of being used in connection with the above mentioned broadcasting applications.
  • the frequency band selected to reach the aim according to the present invention is preferably the one which ranges from 100 kHz to 450 kHz.
  • the above cited arrangement is time-division multiplexed and essentially consists of a kind of electronic key that alternatingly commutates two distinct signals.
  • the transmission of information is a stereophonic music broadcast, by which the left-hand channel and the right-hand channel are sent by leaving on a side the monophonic signal of the standard large-band transmission used in regular broadcasting, to the extent that the width of the stereophonic channels to be transmitted is reduced to 50 kHz, which corresponds to the fourth part of the above mentioned standard values.
  • the signals of each one of the channels will keep within 15 kHz with a maximum deviation of 50 kHz.
  • the arrangement is supplied with a signal issued by a modulated-frequency generator of a conventional type. Audio signals can be converted in digital form and compressed in any appropriate manner in the multiplexing arrangement according to the present invention.
  • Modems used to transmit data through a telephone line are generally known to convert such data into digital sound pulses ranging between 1500 and 2700 kHz, which means that they practically cannot exceed the passband of telephone exchanges, which is comprised between 300 and 3500 kHz.
  • the width of the above mentioned band can be left out of consideration, since a frequency-modulated radio-frequency signal is sent through the telephone means, in a spectrum that actually enables the bandwidth to be extended, thereby obtaining a greater transmission and reception speed.
  • the arrangement frequency-modulates the spectrum ranging from 100 to 450 kHz, wherein it reserves the space comprised between 100 and 200 kHz to the transmission of commands and the space comprised between 250 and 450 kHz to the reception or return, whereas the intermediate sector from 200 to 250 kHz, which is not modulated, serves the purpose of avoiding intermodulations between transmission and reception and to this end makes use of low-pass and high-pass filters.
  • Bandwidths of 60 kHz are in this way attained, instead of the usual 200 kHz, so that the modulator multiplexes by time division the stereo signals in the baseband by means of an electronic key that alternatingly commutates the transmission of the signals corresponding to the right-hand channel with those corresponding to the left-hand channel, thereby modulating up to 70% of the signal.
  • the applied decoder unit is provided, as this will be described in a more detailed manner further on, with a transmission sequence inverter block.
  • a 19-kHz subcarrier and a commutation time divided into spaces of 13 microseconds each have been used.
  • Such a commutation time cannot be perceived by the human ear and for this reason the signals turn actually out to be audibly continuous and fully separate from each other in both channels.
  • the invention will then enable a greater coverage area to be obtained for on-air broadcasts with a power equal to the usual one, or else the same coverage area to be obtained with a broadcast of lower power and energy usage.
  • the features of the invention are such as to make it compatible with conventional receivers currently available and used on the market.
  • the aims according to the present invention are reached in the frequency or amplitude modulation of either stereophonic or monophonic signals transmitted in a time-division multiplexed form with a 100% separation between channels in stereophonic transmission and reception, along with a smaller occupation of the RF badwidth.
  • the arrangement that is described below comprises essentially an installation which is provided for the transmission of six channels and is essentially constituted by a modulated-frequency generator, a multiplexor generator and a multiplexor coder, which channels, starting from a multiple transmission head pass through a mixer to the telephone line and, following the distribution route of the existing telephone network, reach the users, each one of them being provided with his/her own receiver apparatus comprising a low-pass input filter, a tuner from which, after a new filtration, they reach the demodulator and the decoder from which each channel is then amplified.
  • the telephone line used to this purpose remains operationally separated.
  • the electronic configuration of the station providing the telephone service is again left out of consideration, so that no limits are actually set to the transmission speed which, as this has already been stated above, will basically depend on the modems installed at both its ends. It comprises a modulated-frequency carrier wave modulator/demodulator connected between the telephone line and a computer modem.
  • Said modulator/demodulator comprises an emitter stage including a voltage-controlled oscillator and a FM-baseband generator with RF-pass filters, and connected to a separator stage exciting an output transistor having its collector connected to a telephone-line coupling transformer, whereas the receiver stage comprises an input stage with respective high-pass and low-pass filters according to the extremities, tuned on the frequency of the carrier wave and connected to a phase-locked oscillator with the output thereof directly connected to the computer modem.
  • the decoder for otpimizing the utilization of frequencies by means of time-division multiplexing of broadcast transmissions is substantially and preferredly formed by a time-division multiplexor processing block for each one of the channels, starting from the block constituted by the audio source, the channels of which integrate the transmission baseband of 10 to 15 kHz and a subcarrier having a frequency in the order of 19 kHz for controlling both left-hand and right-hand channels that are sequentially suppressed in an alternate manner, and are connected to the RF transmission block
  • the radio receiver includes, at the output of the demodulator block, a decoder block inverting the alternating sequence imposed to said right-hand and left-hand channels, said decoder block comprising a level-boosting transistor, after which they are input in a commutator IC, the circuit of which includes a divider IC and a phase-comparator IC, the latter being controlled by a master oscillator, and a second conditioning transistor of a divider
  • Various arrangements are known in the art which are set up to provide a music broadcasting service transmitted by a radio station emitting in frequency modulation with a pair of channels that can be selected according to the type of music that one desires to listen to, whereas the user must install a receiver with an appropriate decoder if he/she wants to be admitted to the service.
  • the broadcast music is monophonic.
  • a further service is known which, supplied by the radio in amplitude-modulated form, enables half a dozen channels to be acceded to, each one of them transmitting a well-determined kind of music, whereas transmissions are in all cases amplitude-modulated monophonic ones.
  • Said service can as well be recived through the telephone line, wherein it maintains the peculiarity of being monophonic.
  • the described multiplexor generator can be noticed to be constituted by a first 456-kHz oscillator block conditioned electronically to divide by six said frequency, which therefore gives a result of 76 kHz.
  • a frequency is then sent to a divider-by-2 block which reduces it to 38 kHz, such a frequency being in turn processed in another divider-by-2 block and is at the same time supplied to a multiplexor block jointly with the left-hand and right-hand audio-frequency channels.
  • a ceramic filter From such multiplexor block, and passing through a ceramic filter, it enters the mixer block along with the 19-kHz signal resulting from the division by six of the oscillator frequency, from the block of which the output of the muitiplexor is obtained.
  • FIG. 2 is a block diagram of the user receiver apparatus.
  • the low-pass filter block followed by the tuner block.
  • the resulting signal is sent to a ceramic filter that is followed immediately first by the demodulator block and then by the decoder block to which the amplifier blocks corresponding to the left-hand and right-hand channels are connected.
  • the conventional sound reproducing system may be a compact disc, a hard disc, a magnetic tape, satellite signals picked up by a receiver, etc.
  • Said receiver apparatus includes a microprocessor-based automatic sequencer of music themes.
  • Figure 3 illustrates an embodiment of the transmission head unit of the arrangement, which accomodates, in this case, a plurality of six analogue channels that are formed sequentially by a first sound reproducer block D linked to a second microprocessor-based automatic music-theme sequencer block C, which is followed by a third block A representing an audio processor, from which each modulator block M and, from there, an adder block S is supplied From the latter block, the signals are then input in the telephone network RT for transmission.
  • Figure 4 completes the transmission block diagram starting from the last adder block.
  • the signal enters the input telephone exchange, or block CTA, from which it then can take the appropriate route to other peripheral telephone companies CTP. From each such company the signal then continues to travel along the respective telephone lines LT until it reaches either the private user UD or commercial users UC, such as offices, hotels, trading centers and the like.
  • the line remains on one side available for telephone communications T, while it on the oher side inputs in the RF-receiver block R, which will described in greater detail separately, and from the latter in the speaker network P or the respective audio equipment EA, from which the so received music is diffused appropriately.
  • FIG. 5 illustrates in detail the construction of a multiplexor coder circuit according to the present invention.
  • Said circuit is formed essentially by a 456-kHz oscillator that includes a ceramic filter FC and a field-effect triode FET whose output is connected to a divider-by-six represented by the integrated circuit IC1.
  • the integrated circuits IC2 and IC3 accomodate a pair of dividers.
  • the integrated circuit IC2 consists of a divider by two and by four, wheras the integrated circuit IC3 is a divider by three.
  • a divider-by-two can easily be obtained by connecting the output QA to the input D and applying the frequency to be divided to the clock input. Both dividers are used in the above mentioned schematics.
  • an electronic commutator switch an integrated circuit IC4 is used, which has been appropriately selected in view of its characteristics of switching speed and channel separation.
  • the terminal 13 is used for the right-hand channel and the terminal 3 for the left-hand channel.
  • a variable-amplitude pilot signal may possibly be aggregated at the input of the operational adder IC5.
  • two frequency-limiting operational elements IC7 ie. e right-hand and a left-hand one, which contain a frequency-limiter network to limit frequency to 15 kHz, and whose respective outputs lead to two equalizer operational elements IC6, which are equalized with a pre-emphasis of 50 microseconds to the purpose of improving the signal-to-noise ratio.
  • the radio-frequency generator illustrated in Figure 6 comprises a coil with a frequency of 456 kHz and a VCO element electrically associated to a pair of appropriately biased transistors to obtain the desired oscillations.
  • the decoder circuit of Figure 7 is a simple one and is based on an integrated circuit IC11 that contains a phase-locked loop PPL to regenerate either a pilot signal or a signal of its own in view of achieving the separation of the two channels. It also includes an indicator consisting of a LED device.
  • Figure 8 which represents the spectrum of frequencies used for six channels, shows the width of the band comprised between 100 and 450 kHz, wherein each one of the channels is distributed at 140, 190, 240, 290, 340, 390 and390 kHz with an available aplitude of 50 kHz for a stereo signal of 15 and 15 kHz.
  • Figure 9 illustrates the composite stereo signal, wheras following distributions can be compared in it.
  • Monophonic 100% 75 kHz Deviation
  • the signal received at the telephone input is filtered in the corresponding input filter which consists of determined band-pass filters. After passing through the demodulator, the signal is sent to the modem which is connected to the data processor.
  • the signal received by the modem is received in the FM-generator and, once it has been filtered in the output filter, which also consists of determined band-pass filters, it is returned to the input telephone line.
  • both the demodulator and the modulator receive their power supply from the mains to which they are connected through a line filter.
  • Figure 12 illustrates how the various PC computer units of each user are connected with the central unit, or "server”, through their respective modems and the above described units, on the telephone lines.
  • Figure 13 illustrates the electronic circuit which, for the transmission of the data, has an integrated circuit IC1 of the VCO type (voltage-controlled oscillator) which, connected to the modem, generates the baseband for the FM, whose output is connected through the variable excitation-adjustment capacitor C1 to the base of the RF-exciting transistor T1, said base being biased by means of the resistor R1.
  • the emitter of said transistor T1 is connected to ground through the biasing resistor R2 in parallel with the capacitor C2, whereas the collector thereof is connected to the tuned load L1 which is in series with the RF choke L2.
  • the collector of the transistor T1 is in turn connected through the capacitor C4 to the base of the output transistor T2, said base being biased by means of the resistor R3 in parallel with the capacitor C5, whereas the emitter thereof is biased by means of the resitor R4 in parallel with the capacitor C6.
  • the collector of the output transistor T2 is connected to the RF output transformer LT1 which in turn is connected to the telephone line TEL. Said transformer is in series with the RF choke L3 and the capacitor C7 is grounded.
  • the telephone line supplies the signal to the input filter F1, which is a low-pass filter in "server” and a high-pass filter in user and whose output supplies the integrated circuit IC2 of the Pll type (phase-locked loop) which has its output connected to the modem of the computer of the user.
  • the input filter F1 which is a low-pass filter in "server” and a high-pass filter in user and whose output supplies the integrated circuit IC2 of the Pll type (phase-locked loop) which has its output connected to the modem of the computer of the user.
  • the source-filter capacitors C7 and C8 are connected in the circuit supply.
  • the block 1 represents the audio source with its left-hand channel L and right-hand channel R that will be processed in the baseband multiplexor processor block 2, the signals of which are then sent to the transmission RF generator block 3.
  • the emitted processed signals are received by the radio receiver block 4 that includes the decoder block 5 which in this case supplies the channels L and R in audio frequency.
  • Figure 15 illustrates the carrier without modulation P represented by a simple axis.
  • a carrier with monophonic modulation M is then joined thereto, followed by the carrier with stereo modulation S.
  • the contiguous diagram shows the multiplex modulation according to the invention, with the left-hand channel L and the right-hand channel R, the electronic switching key C and the result of the sequence to be transmitted.
  • Figure 16 illustrates a possible embodiment of the electronic circuit corresponding to the decoder that is incorporated in the receiver apparatus, the basic component parts of which are identified in the circuit diagram.
  • Such component parts include the integrated circuits the basic characteristics of which are: IC1 is an electronic comparator and IC2 is an electronic commutator; the circuit includes the transistors T1, T2 and T3.
  • the reference E is used to indicate the already demodulated signal; SL is used to indicate the output of the left-hand channel and SR the output of the right-hand channel.
  • the demodulated signal E is sent to the integrated circuits IC1 and IC2, to the integrated comparator IC1 through the resitor R2 and the capacitor C1, which is connected to the base of the transistor T1, which is biased by means of the resistors R1 and R2 and is channelled to the integrated circuit IC1 by its collector through the capacitor C2, wheras its emitter is connected to ground.
  • the above mentioned signal E also reaches the IC2 directly.
  • Said IC comprises a LED indicator, connected at its pin 6, and the resistor R3 in series with the variable resistor R4 adjusting the VCO value fof the voltage-controlled oscillator thereof, which acts as the FM baseband generator.
  • the therein illustrated arrangement generates a radio frequency (RF) that is appropriately divided to a value which is approximately six times smaller than the one that is normally used in radio transmission.
  • RF radio frequency
  • Such a frequency is obtained through integrated frequency dividers.
  • the stereophonic information to be transmitted through the telephone line is input , appropriately filtered, in a multiplexor block and the radio-frequency is modulated by means of an integrated electronic commutator adapted to alternate, in the form of pulses with a duration of 13 microseconds each, the signals corresponding to the left-hand and the right-hand channels.
  • the whole combination of various analogue channels which are in the number of six in the above described example of embodiment, are introduced in an integrated adder, appropriately equalized and adjusted to the desired frequency by means of respective integrated operational circuits.
  • the information is then conveyed by the telephone network, and the from time to time involved telephone exchange units, up to the destination thereof, where it is then filtered, tuned and demodulated, after which, as soon as the left-hand and right-hand channels are duly decoded and separated, the latter are amplified and sent to the places or rooms that have been planned.
  • the so separated telephone line remains capable of being normally used for telephone communications with no interference at all.
  • transducers ie. the loudspeakers or the audio equipment as the case may be, are installed, can be in private household, residential dwellings, offices and trading centers, shops and the like.
  • the time-division multiplexed signal emitted in the above indicated manner is received in a receiver of a conventional kind to which, in this case, the decoder according to the present invention has however been added.
  • Said decoder operated in an inverted manner with respect to the afore described signal multiplexing process. It is in fact this decoder that is given the task of reconstituting the received information into two fully separated audio channels, so that there will be obtained the same 100% separation between the laft-hand channel and the right-hand one as in the above described case.
  • the decoder is applied to the receivers at the output of the demodulated signal.
  • the latter is sent to a transistor T1 which boosts the level thereof.
  • the integrated circuit IC1 compares the received signal which it puts in phase with the generated signal, so that the signal is restored to the exact form in which it had been emitted.
  • Such an arrangement can also be applied to amplitude-modulation transmissions, which would enable a stereophinc signal to practically occupy the same space that is currently occupied by broadcasting stations transmitting in the AM spectrum.
  • the same decoder arrangement would be used as the one described for the FM transmissions. This practically means that, adding the decoder arrangement according to the invention to a conventional receiver, the latter will be enabled to receive FM stereo, AM stereo and FM/AM monophonic transmissions as well.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Stereo-Broadcasting Methods (AREA)
  • Transmitters (AREA)
EP19970121048 1996-12-04 1997-12-01 Vorrichtung für die wirtschaftliche Nutzung vom Frequenzspektrum durch die Zeitmultiplizierung von stereophonischen Übertragungen Withdrawn EP0847157A2 (de)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
AR10548396 1996-12-04
AR9605483 1996-12-04
AR10617297 1997-01-17
AR9706172 1997-01-17
AR10515597 1997-11-05
AR9705155 1997-11-05

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EP0847157A2 true EP0847157A2 (de) 1998-06-10

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EP19970121048 Withdrawn EP0847157A2 (de) 1996-12-04 1997-12-01 Vorrichtung für die wirtschaftliche Nutzung vom Frequenzspektrum durch die Zeitmultiplizierung von stereophonischen Übertragungen

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EP (1) EP0847157A2 (de)
BR (1) BR9705938A (de)
ES (1) ES2140326B1 (de)
IT (1) IT1297568B1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113676820A (zh) * 2021-09-18 2021-11-19 合肥中感微电子有限公司 无线多声道音频传输方法、装置和电子设备

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5299264A (en) * 1991-08-21 1994-03-29 L. S. Research, Inc. System for short-range transmission of signals over the air using a high frequency carrier
US5343534A (en) * 1992-12-07 1994-08-30 Dorrough Michael L Sequential audio switcher

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113676820A (zh) * 2021-09-18 2021-11-19 合肥中感微电子有限公司 无线多声道音频传输方法、装置和电子设备

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BR9705938A (pt) 1999-04-06
ITUD970223A1 (it) 1999-06-02
ES2140326B1 (es) 2000-10-16
IT1297568B1 (it) 1999-12-17
ES2140326A1 (es) 2000-02-16

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