Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04H—BROADCAST COMMUNICATION
  • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
  • H04H20/12—Arrangements for observation, testing or troubleshooting

Definitions

• the invention relates to the adaptation of a transmission chain to the 5 transmission conditions.
• the broadcasters plan according to the time of the year, the time of day and the solar activity, when it is foreseeable, different frequencies in order to optimize the reception.
• the present invention overcomes or, at the very least, reduces these drawbacks by optimizing various elements of the transmission chain to the propagation conditions, in particular by adapting the transmitter power and channel coding parameters. This guarantees the best possible quality of service at all times for a given frequency in a defined reception area. 25
• the invention relates to a device intended to optimize a transmitter, characterized in that it comprises:
• an additional object of the invention is a transmission system comprising at least one transmitter, at least one receiver, and an optimization device connected to a communication network, receiving at least one quality indicator from the receiver making it possible to deliver at least one optimized parameter and transmit it to the transmitter.
• a variant of the invention is a transmission system comprising at least:
• a transmitter receiving optimized parameters coming to adjust the parameters of at least one element of its transmission chain and transmitting a signal comprising at least one program and the configuration of its transmission chain,
• a receiver for example a consumer receiver, receiving the signal transmitted by said transmitter and reproducing at least one program contained in said received signal
• a reference receiver receiving the signal transmitted by said transmitter and delivering a signal containing at least one quality indicator
• each receiver allowing the reproduction of the program received can also deliver at least one quality indicator
• either the receiver and the reference receiver are two separate devices, the first allowing the reproduction of the received program and the second is a signal sensor capable of delivering at least one quality indicator.
• FIG. 1 an example of a representation of the broadcasting system according to the invention
• FIG. 2 an exemplary embodiment of the broadcasting system with optimization of the program according to the invention
• FIG. 3 an exemplary embodiment of a reference receiver according to the invention
• Figure 1 shows that broadcasters have target areas for broadcasting their programs. Indeed, the transmitter E of the broadcaster transmits in the direction of a predetermined target area. All the receivers (R ⁇ ... R m , Rfi ... R f n) in this zone receive the programs broadcast by the transmitter with more or less good quality. So-called reference receivers (Rfi ... Rf n ) are deployed in this area. They are able to analyze the received signal and the integrity of its content.
• the reference receivers (R i ... Rf n ) transmit this pre-analysis to an optimization device A comprising at least one signal processing system.
• This optimization device A can be located at a greater or lesser distance from the transmitter E, or even included in the transmitter E - this latter configuration is not shown in the figure -.
• the optimization device A collects the information produced by the receiver (s) R f . Then, he draws up a summary of the measurements carried out. By applying set points, it remote controls the adjustment parameters of the transmitter E, in particular of the transmission chain.
• the transmission of the measurements from the reference receivers R f to the optimization device A and, if necessary, the transmission of the optimized parameters from the optimization device A to the transmitter E can be carried out, for example, on a wired network. (telephone, ethemet ...) or wireless (telephone, satellite .).
• FIG. 3 shows an exemplary embodiment of a reference receiver R f adapted to receive the broadcast signal, that is to say that it comprises at least the elements (for example, demodulator and / or decoder and / or interleaver ...) necessary to recover the program or programs transmitted in the broadcast signal.
• the reference receiver Rf therefore makes it possible to demodulate the multicarrier constellation, to perform channel decoding, to demultiplex the beam (for example of the DRM, Digital Radio World type), to decode the audio and data beams and to perform a real-time analysis using appropriate means C (shown in dotted line in FIG. 3) delivering measurements M. During this analysis, various measurements can be made all along the reception chain.
• the broadcast signal is received on the antenna R f 11 of the reception device R f 1 of the receiver R f .
• the signal then passes through an R f 12 module called RF Front End (or HF head in French).
• a first measurement M11 can be performed on the level of the received signal.
• the signal then passes through a filter bringing it back to base band R f 13.
• a second measurement M12 can be envisaged, such as, for example, on the frequency mask or a spectral analysis.
• this chain comprises in series a demodulator R f 21, a descrambling R f 22, a deinterleaver R f 23, a channel decoder R f 24, a demultiplexer R f 25, a source decoder R f 26 optionally comprising an audio decoder R f 26a, and one or more program reproduction devices (such as for example a loudspeaker R f 27 for audio and / or data programs, and / or a screen not shown to display the data ).
• a demodulator R f 21 a descrambling R f 22, a deinterleaver R f 23, a channel decoder R f 24, a demultiplexer R f 25, a source decoder R f 26 optionally comprising an audio decoder R f 26a, and one or more program reproduction devices (such as for example a loudspeaker R f 27 for audio and / or data programs, and / or a screen not shown to display the data .
• the R f 21 demodulator and / or the R f 22 descrambling measurements on the constellation M21, on the SNR signal-to-noise ratio M22, statistics (average and or distribution on the constellations, the SNR, the paths, by example) M23, and / or measurements on the paths (numbers, amplitudes, positions ...) M24 can be carried out.
• the error rates M25 such as the MER (Mean error rate or average error rate in French) and or the rate of bit errors error BER (bit error rate, BER) M26 can be measured.
• the analysis can deliver a measurement of the audio quality M27 if it is an audio program or data quality more generally ...
• the reference receiver R f has one or more of the following functions: - the indication of the received signal level,
• the various possible uses of the reference receiver R f are, for example: - listening and / or displaying the received signal, locally or remotely (monitoring in English),
• the optimization device A receives the measurements M carried out by the various reference receivers of the target area of the transmitter E to which it is associated. It performs a synthesis of these results, for example, by comparing the values received with minimum and / or maximum thresholds fixed by the radio broadcaster according to the desired minimum reception quality. For example, when the minimum threshold is exceeded, the optimization device A can react by increasing the channel coding. When one or more minimum thresholds are crossed, the channel coding is then reduced.
• the different thresholds (set points) can be either predefined or set by the operator of the transmission network).
• the measurements received can, for example, be one or more of the following measurements:
• the signal-to-noise ratio at several levels of the reception chain (means, distribution, etc.)
• the impulse response of the channel (amplitudes, position, number of paths, Doppler effect, etc.)
• FIG. 4 presents, by way of example, a flow diagram implementing the optimization method of the optimization device A.
• one of the measurements received by the optimization device A here the audio quality , is examined first.
• the optimization device can, for example:
• the different parameters can have different weights, which allows the optimization device to examine them in the order of their weight. For example, if the transmitted power parameter P1 has a weight greater than that of the channel coding P2, the optimization device first checks whether the transmitted power P1 is at its default value. If this is not the case, it modifies the transmitted power parameter P1. And, if the power emitted is the default, it examines the following parameter P2 ... It can be envisaged to examine several parameters to which an identical weight is assigned together.
• the optimization device envisages a certain number of hypotheses as to the origin of the degradation of the audio quality. For example, it will examine the behavior of a number of measures in a dependent or independent manner. The order of examination of the different measures can be given by assigning, here again, a weight to each measure. In the case presented in the flow diagram of FIG. 4, it examines the behavior of a first measurement with respect to a threshold fixed by the broadcaster. For example, the level of the signal received M11 with respect to a minimum threshold. In case 1, i.e.
• the parameter concerning the transmitted power is increased and / or the direction of emission (the azimuth, the orientation of the transmitting antenna ) is changed.
• a second measurement is examined. For example, the bit error rate M25 is compared to a maximum threshold.
• the parameter P2 concerning the channel coding is modified so that a more powerful channel coding is used.
• the optimization of the settings by the optimization device A can, for example, be such that: - the loss of audio quality results in the modification of the channel coding and / or of the modulation and / or of the multiplexing (by example, suppression of certain programs) used with interaction on the source coding because of the useful bit rate, - the degradation observed on the impulse response or on the signal to noise ratio leads to the modification of the channel coding and / or of the mode (Ground , SKYWAVE, Robust) used with interaction on the source coding because of the useful bit rate.
• the optimization device can make it possible to optimize the adjustment of the parameters of transmitted power, transmission frequency and direction of the transmission antenna ...
• the optimization device A includes at least one means of synchronizing all the measurements received from the different reference receivers Rf.
• the modification of certain parameters can generate the obligation to adapt other parameters of the transmitter E.
• the modification of parameter causes the change of the useful bit rate, when the signals are extremely protected
• the optimization device To whom the slave E transmits also acts on the adjustment of the audio coder (s) in order to adapt the bit rate delivered to the useful bit rate available at this instant.
• the useful bit rate is of the order of 25 kbits / s with 64 QAM modulation. If the propagation conditions deteriorate: reduction in the signal to noise ratio and / or increase in the bit error rate, the transmission mode can be changed to better protect the useful content, switching from Ground mode to SKYWAVE mode (These are modes defining the structure OFDM - Orthogonal Frequency Division Multiplexing, ie Multiplexing with orthogonal frequency division - specific to DRM). The useful speed is then reduced to 19 kbits / s. The source coding is reparametered to change the bit rate from 25 to 19 kbits / s. Optimization device A sends the optimized parameters to the transmission chain which will apply them to the source coder, the channel coder and the modulator.
• optimization device will control the switch to 16QAM without a Reed Solomon (RS) encoder.
• the useful bit rate is then around 18 kbits / s and the source coder will be optimized accordingly.
• Optimization device A can also control the transition to robust mode with a useful bit rate of 16kbits / s, etc.
• the source encoder is reparametered in order to provide the useful bit rate adapted to the protection obtained by optimizing the parameters of the transmission chain thanks to the optimization device A.
• the parameters thus optimized are transmitted to the transmitter E to adjust the various adjustable parameters, in particular the parameters of the transmission chain but also, if necessary, the parameters of the transmission device as shown in FIG. 5.
• a source encoding E11 of the audio and / or data programs is carried out, comprising at least one compression E11b of the digital signal.
• the source encoder used E11 is determined by the parameters transmitted by the optimization device A.
• the different programs are multiplexed E12 according to the multiplexing parameter also determined by the optimization device A.
• the signal obtained is subjected E13 channel coding, E14 interleaving, E15 packetization and E16 modulation.
• Each of these functions is configured by the optimized parameters delivered by the optimization device A.
• the parameters of the transmission device E2 are adjusted by parameters also optimized by the optimization device A. This makes it possible to modify the synthesizer E21 used (transmission frequency ), the power transmitted thanks to the device E22 and / or the direction of the transmitting antenna E23.
• the modulations envisaged may, for example, be a QAM (Quadrature Amplitude Modulation) modulation in French, 8, 16, 64 state amplitude to quadrature modulation or a QPSK (Quadrature Phase Shift Keing) modulation, in French phase shift modulation in quadrature).
• the channel coding envisaged can, for example, be an MLC coding (Multi Level Coding or coding at multiple level in French) and / or a Reed Solomon (RS) coding.
• the audio source coding envisaged may be, for example, MPEG-4 AAC (Advanced Audio Coding, in French advanced audio coding) or MPEG-4 AAC and SBR (Spectral Band Replication, in French reproduction of spectral band) or MPEG-4 AAC and PAT (Perceptual Audio Transposition, in French perceptual audio transposition) or G729 (CCETT) or CELP or MPEG 2 layer 3.
• MPEG-4 AAC Advanced Audio Coding, in French advanced audio coding
• MPEG-4 AAC and SBR Spectral Band Replication, in French reproduction of spectral band
• MPEG-4 AAC and PAT Perceptual Audio Transposition, in French perceptual audio transposition
• G729 CETT
• CELP MPEG 2 layer 3.
• the receiver R f receives information on the setting of the transmitter in the received broadcast signal and adapts automatically.
• the signal comprises one or more audio programs and / or one or more data programs.
• the signal can also comprise, alone or in addition to one or more of the preceding programs, one or more programs containing still images.
• This system can be used within the framework of broadcasting according to the DRM standard, as well as more generally within the framework of broadcasting according to the standard UIT217-1 / 10 / Union Internationale des Telecommunications).
• the use of this transmission system or at least one of the devices composing it must not be limited to the AM bands but can also be, for example, used for the FM bands ...
• the optimization device A receives one or more signals, each comprising one or more measurements indicating the quality of the signal received in a broadcasting system and coming from one or more several R receptors.
• These R receptors can be specific receptors, called Rf reference receptors.
• the signals comprising the measurements or quality indicators are transmitted either via a wired network (telephone or ethernet network, etc.) or via a wireless network (mobile telephone network, satellite, etc.). These signals can, for example, be transmitted on request from the optimization device A or periodically at times defined for each reference receiver R f .
• the optimization device A can consider one or more measures to modify one or more parameters. It thus allows the maintenance of a fixed reception quality when the transmission conditions deteriorate and the use by the transmitter E of less powerful device (lower transmitted power, less powerful channel coding ...) when the transmission conditions are satisfactory.
• the parameters of the transmitter E thus optimized by the optimization device A adjust the various elements of the transmitter E, in particular of the transmission chain so that they adapt to the transmission conditions.
• the device A can carry out an analysis either on an event generated by a reference receiver, or on the basis of cyclic analysis whose periodicity can be predetermined or fixed by the operator.
• the device A thus makes it possible to control the adjustment either only of the elements of the emission chain E1, or only of the elements of the emission device E2, or jointly of the elements of the emission chain E1 and of the emission device E2 .
• the setting of the transmitter E is transmitted with the programs in the broadcast signal.
• the receivers are able to reparameter their devices (OFDM modes, demodulator, demultiplexer, channel decoder, source decoder ...) accordingly.

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• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Transmitters (AREA)
• Inspection Of Paper Currency And Valuable Securities (AREA)
• Monitoring And Testing Of Transmission In General (AREA)

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• 2000
  • 2000-11-21 FR FR0015017A patent/FR2817092B1/fr not_active Expired - Fee Related
• 2001
  • 2001-11-20 AU AU2002221997A patent/AU2002221997B2/en not_active Ceased
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  • 2001-11-20 US US10/432,284 patent/US20040053576A1/en not_active Abandoned
  • 2001-11-20 WO PCT/FR2001/003644 patent/WO2002043289A1/fr active Application Filing
• 2003
  • 2003-05-21 HR HRP20030411AA patent/HRP20030411B1/xx not_active IP Right Cessation
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