Method and device for detecting mode of transmission and synchronization of audio broadcast digital signal

FIELD: control data transmission in audio broadcast.

SUBSTANCE: proposed method includes transmission phases for transferring set of control bits in each of set of control frames, first control bit sequence presenting transmission mode and second one, control data synchronizing word. Set of control bits may include in addition third sequence of bits presenting interleaver synchronizing word. Method for detecting mode of transmission and synchronization of audio broadcast signal implemented in radio receiver is also proposed. This method includes reception phases for set of interleaver frames incorporating digital information, each of interleaver frames incorporating set of control frames. Control frames include set of control bits; first sequence of control bits presents transmission mode and second one, control data synchronizing word. Set of control bits may include in addition third bit sequence presenting interleaver synchronization word. First sequence of control bits is processed for definite transmission mode, second one, for detecting control data synchronization, and third sequence of control bits, for determining interleaver boundaries. Radio-frequency transmitters and receivers using above-described methods are also given in description of invention.

EFFECT: reduced cross-talk noise with respect to analog amplitude-modulated signal.

12 cl, 5 dwg

 

The level of technology

The present invention relates to transmission and reception of radio frequency signals and, more specifically, to methods and apparatus for transmitting and receiving control information in a signal of the digital audio broadcasts.

There is a growing interest in the possibility of broadcasting using the digitally encoded audio signals to provide superior quality playback of audio signals. It was suggested several approaches. One such approach, formulated in U.S. patent No. 5588022, discloses a method for the simultaneous broadcast of analog and digital signals in a standard channel, AM broadcast. Transmitted amplitude-modulated (AM) RF signal having the first frequency spectrum. Amplitude-modulated radio frequency signal includes a first carrier frequency modulated analog signal program. At the same time, within the band, which encompasses the first frequency spectrum, passed many signals of carrier frequencies modulated in digital form. Each of the modulated digital signals of carrier frequencies modulated digital signal broadcasting program. The first group of signals of carrier frequencies modulated in digital form, is within the first frequency spectrum and are modulated in quadrature on attributed the th to the first signal carrier frequency. The second and third group of signals of carrier frequencies modulated in digital form, are outside of the first frequency spectrum and are modulated both in-phase and quadrature relative to the first signal carrier frequency.

The shape of the signal in the digital audio broadcasts that are compatible with the AM signal, described in U.S. patent No. 5588022, was chosen to provide sufficient data throughput for digital signal while avoiding crosstalk compared to analog AM channel. Many of the carrier frequencies used for transfer of information transmitted by multiplexing orthogonal frequency division (MOCR).

In a digital system audio broadcasts that are compatible with the AM signal, the digitally encoded audio information is transmitted simultaneously with the existing analog AM signal. Digital information is encoded and transmitted using modulation MOCR. Digital audio broadcasts can transmit digital information using different coding rate, audio and variable-speed forward error correction to ensure that the broadcasting system is a compromise between audio quality for the service area and the resistance to deterioration of the channel.

In the patent application great Britain GB 2320871 And rusk is it communication system, using the carrier frequency, multiplexed with orthogonal frequency division (MOCR, including many of the carrier frequencies of the pilot signals used to transfer parameters of the signal and provides the transmission of the synchronization information frame. U.S. patent No. 5748686 discloses a digital audio broadcasts, which uses the synchronization algorithm for matching a predefined configuration of symbols with the received signal to determine the synchronization of the frame.

The present invention provides a method for determining the transmission mode and the data synchronization signal digital audio broadcasts, with an analog modulated carrier frequency, and set of modulated digital carrier frequency.

The invention

The present invention provides a method for signal transmission of digital audio broadcasts, and the said signal includes modulated in analog form the carrier frequency and the multiple modulated digital carrier frequencies MOCR in the same channel as modulated analog carrier frequency different stages:

delay modulated in an analog form of the carrier frequency relative to the modulated digital carrier frequencies MOCR,

modulation of complementary pairs of moduleref is the R in digital form subcarriers frequencies MOCR with one bit of control in each of the multiple frames of characters MOCR, moreover, sequential mentioned control bits mentioned in sequential frames of characters MOCR form a control frame, the control frame includes the first sequence of bits of the control, representing a transmission mode, the second bit sequence control, representing the word synchronization data management, and a third sequence of bits of the control, representing the word synchronization of the interleaver, these complementary pair of carrier frequencies, comprising first and second carrier frequencies, is related to the modulated analog carrier frequency, and said first and second carrier frequencies have a greater amplitude than the other subcarriers frequency, and

transmission modulated in an analog form of the carrier frequency and the multiple modulated digital carrier frequencies MOOR.

The invention also provides a system of digital audio broadcasts to transmit a signal including modulated in analog form the carrier frequency and the multiple modulated digital carrier frequencies MOCR in the same channel as modulated analog carrier frequency, characterized in that it contains:

means for delaying the modulated into the analog form of the carrier frequency relative to egulirovannyh digital subcarriers frequencies MOCR,

means for modulation of complementary pairs of modulated digital carrier frequencies MOCR with one bit of control in each of the many characters personnel MOCR, and mentioned serial control bits in successive frames of the characters MOCR form a control frame, the control frame includes the first sequence of bits of the control, representing a transmission mode, the second bit sequence control, representing the word synchronization data management, and a third sequence of bits of the control, representing the word synchronization of the interleaver, and a complementary pair of carrier frequencies, comprising first and second carrier frequencies, is related to the modulated analog carrier frequency, and the first and second of these carrier frequencies have a greater amplitude than the other subcarriers frequency, and

means for transmitting modulated in an analog form of the carrier frequency and the multiple modulated digital carrier frequencies MOOR.

Brief description of drawings

The invention is further explained in the description of specific variants of its implementation with reference to the drawings, which represent the following:

figure 1 - schematic representation of the composite analog AM signal and the signal of the digital broadcasting, to the that can be used in the process according to the present invention,

figure 2 - block diagram of the transmitter, which may be made of the method of signal processing according to the present invention,

figure 3 - block diagram of the receiver which can be carried out a method of signal processing according to the present invention,

4 is a more detailed block diagram of the receiver in figure 3, and

5 is a schematic representation of a frame of data management, which can be processed in accordance with the present invention.

A detailed description of the preferred embodiments

The present invention provides a method for determining the transmission mode and the sync signal of the digital audio broadcasts. Method broadcasts a digital signal on the same channel as the analog AM signal is defined as broadcast "channel strip". This radio is implemented by transmission of digital waveforms using multiple carrier frequencies, multiplexed with orthogonal frequency division (MOCR), some of which is modulated in quadrature with the analog AM signal and are located within a spectral region in which the standard signal of the AM radio has significant energy. The remaining digital carrier frequencies are modulated both in-phase and quadrature analog AM signal and are located in the same channel as obtained the new S-signal, but in the spectral regions in which the analog AM signal has no significant energy. In the United States of radiation of AM radio stations limited to the requirements of the Federal communications Commission so that they were within the mask signal can be defined as follows: radiation, remote from the analog carrier frequency of 10.2 kHz - 20 kHz shall be attenuated at least 25 dB below the unmodulated analog carrier frequency, radiation, remote from the analog carrier frequency of 20 kHz to 30 kHz shall be attenuated at least 35 dB below the unmodulated analog carrier frequency; and radiation remote from the analog carrier frequency 30 kHz - 60 kHz must be attenuated by at least [35 dB + 1 dB/kHz] below the level of the unmodulated analog carrier frequency.

Figure 1 depicts the spectrum of the AM signal digital audio broadcasts of this type, which can be used when implementing the present invention. Curve 10 represents the amplitude spectrum of the standard broadcasting amplitude-modulated signal in which the carrier has a frequency f0. Mask of radiation allowed by the Federal communications Commission designated position 12. Waveform with MOCR consists of a number of carrier frequencies of the data posted to the f1= 59,535•106/(131072), or p is blithedale 454 Hz. The first group of twenty-four modulated digital carrier frequency is within the frequency band (f0- 12f1) to (f0+ 12f1), as illustrated envelope 14 in figure 1. Most of these signals by 39.4 dB below the carrier frequency, non-modulated signal AM - carrier in order to minimize crosstalk with respect to the analog AM signal. Crosstalk is additionally reduced by this encoding digital information in a way that guarantees orthogonality with analog S-shape signal. This type of encoding is called complementary coding (i.e. complementary dip phase shift keying (Dpfm), complementary quadrature phase shift keying (Kfmn) or complementary 32-point quadrature amplitude modulation (32 QAM)), and it is described in more detail in U.S. patent No. 5859876. Complementary Dpfm modulation is used for the innermost pair of digital carrier frequencies f0± f1to transmit the management information. These carrier frequencies are at the level of -28 d (average sound pressure in decibels on scale of a sound level meter). All other carrier frequencies in the first group have a level -39,4 d and modulated using complementary 32 QAM speeds is tiravanija 48 and 32 KB/s Complementary 8-position phase shift keying (8 QPSK) is used for carrier frequencies lying in the range from (f0- 11f1) to (f0- 2f1), and from (f0+ 2f1) to (f0+ 11f1), with the encoding speed 16 KB/s For all three velocity encoding carrier frequencies (f0- 12f1) and (f0+ 12f1) bear the additional data may be modulated using complementary 32 QAM.

Additional groups of digital carrier frequencies are located outside of the first group. The need for these digital waveforms to be in quadrature with respect to the analog signal is eliminated by limiting the frequency band of the analog AM signal. Carrier frequencies in the second and third groups, shows the envelopes 16 and 18, respectively, can be modulated using, for example, 32 QAM with rate coding 48 and 32 KB/s and 8 FMN at the encoded bit rate of 16 KB/s Carrier frequency is set at -30 d for all output encoding.

Figure 2 depicts a block diagram of the transmitter corresponding to the present invention. Analog signal broadcasting program (in this example, includes right and left side of a stereo signal), which should be transferred, is fed to the input conclusions 28 and 28'. The left and right channels are combined in a summing point 29, and then serves the Xia through the processor 30, the analog audio signal, to increase the average analog amplitude modulation, which significantly expands the service area. Such processors are conventional analog AM broadcasting radio stations around the world. The analog signal is passed through the filter 31 of the lower frequencies, with a steep characteristic slice get in line 32 filtered monophonic analog signal broadcasts. The filter 31 may be, for example, the cutoff frequency of 5 kHz and an attenuation of 40 dB, and outside of 5.5 kHz. Additionally, the effect of filtering by the filter 31 can be achieved by processing the audio signal in an analog processor 30 audio.

For those applications in which to transmit the same program material should be used in analog and digital part of the signal being transmitted, the digital encoder 34 of the source, which can realize an encoding algorithm that converts the analog signals of the right and left channels of programs in the digital signal in line 36. Forward error correction scheme and 38 of the interleaver improves data integrity in the channels distorted by impulse noise and mutual interference, producing a digital signal in line 40. For those cases in which the transmitted digital signal is a digital version of the analog signal broadcasting program, for reception of digital is ignal provides a data port 42. For those cases, in which the digital version of the analog signal broadcasting program or the digital signal supplied to the port 42, it should be supplemented by the inclusion of additional data, also provides a source 44 of additional and ancillary data. Some of the auxiliary data may be input into a digital encoder 34 source. Encoder source may reserve a portion of output bits for transmission of auxiliary data. Also, if the audio source does not require full speed encoding the source coder, for example, during a simple musical passages, the encoder can be made available on the elemental basis to transmit auxiliary data. When the encoder source does not require full speed encoding and can transmit auxiliary information in addition to the reserve auxiliary data, the encoder source could indicate this condition to the source of auxiliary data, sending to the source of auxiliary data signal, which indicates the amount of additional data that can be transferred. Auxiliary data could be used to transmit signals such as emergency information, stock market quotes, weather forecasts, or information relating to the program material audio broadcasts, such as song name.

The analyzer 46 data etc which receives the digital data and generates multiple output signals in lines 48. Additional data that is used for carrier frequencies (f0- 12f1) and (f0+ 12f1), are entered in the line 43. The signals in pairs of lines 48 from the analyzer 46 data form the complex coefficients, which, in turn, are used in the algorithm of the inverse fast Fourier transform (OBPF) in block 50, which produces in-phase (I) and quadrature (Q) components of the data signals of the frequency bands in the lines 52 and 54, respectively. The processor 53 to the output OBPF adds a guard interval. When the output OBPF consist of 128 samples per operation OBPF, guard interval consists of 7 samples. Guard interval is added by a periodic extension of the output OBPF, or in other words, by taking samples 1 through 7 and copy them respectively as samples from 129 to 135. After the guard interval is applied to the data window (finite weighing function). Finite weighing function reduces interference with the second and third adjacent stations, reducing the side lobes in the transmitted spectrum.

Periodically, instead of the transmission of the coded data of the broadcasting program or the auxiliary data are sent to the test sequence, also known as the pilot signal, which are known D. is installed. Test sequence enables the processor in the receiver, EQ type, to quickly detect the signal and to track the rapidly changing state of the channel. The test sequence can be stored in the device 55, or may be generated by the device 55, and periodically selected as the transmitted waveform, for example every tenth frame. Alternatively, the information for the test sequence could be stored in the frequency domain and fed to the input device OBPF. However, saving the information in the time domain reduces the number of required operations OBPF. Although the known data are sent every tenth frame, carrier frequencies allocated for the transmission of additional data (f0- 12f1) and (f0+ 12f1)are not known to transmit data every tenth frame. In this case, additional data for transmission in every tenth frame are input to the generator waveform of the test sequence, and the contribution of carrier frequencies allocated for additional data, is added to the known data. The difference between the additional data and the auxiliary data is that the processing of additional data is completely independent of source coding, forward error correction and operations alternation to the e used for processing encoded in digital form information of the broadcasting program.

The processed analog AM signal baseband is converted into a digital signal by analog-to-digital Converter 60 and is delayed by the device 61 delay. The delay of the analog signal in the transmitter provides a separation in time between analogue and digital signals in the channel. The passing of time allows secure coupling between analog and digital signals. The delayed analog signal is combined with the in-phase part of the digital waveform digital audio broadcasts (TSAV) at the summing point 62 to generate a composite signal in line 64. The composite signal on the line 64 is converted to an analog signal by digital to analog Converter 66 is filtered by the low pass filter 68 and supplied to the mixer 70, where it is multiplied by with the radio frequency signal generated in the line 72 local oscillator 74. Quadrature signal line 57 is converted into an analog signal by digital to analog Converter 76 and filtered by the low pass filter 78 to obtain a filtered signal, which is multiplied by the second mixer 80 with the signal in line 82. The signal in line 72 is shifted in phase, as illustrated in block 84, to receive the signal in line 82. The output signals of the mixers 70 and 80 are fed via lines 86 and 88 to a point sum is investing 90 to generate a composite waveform in line 92. Spurious mixing products are attenuated bandpass filter 94, and the resulting TSAV signal is subsequently amplified by the amplifier 96 power supply to the transmitting antenna 98.

Information system control is transferred by a pair of carrier frequencies MOCR that is closest in frequency to the AM carrier. These carrier frequencies, one below the frequency of the AM carrier, and the other located on the same value for a higher frequency AM-carrier is modulated using a modulation Dpmn. Dpfm carrier frequencies are a complementary pair, which means that when Dpfm carrier frequencies are summed, then their resultant is in quadrature to the AM carrier frequency. Dpfm carrier frequencies become complementary due to the choice of modulation on one carrier frequency so that it was negatively associated with the modulation on another carrier frequency. This means that although there are two Dpfm carrier frequencies, information about the carrier frequency is not independent, and the carrier frequency is passed only 1 bit of information management frame MOCR. The speed at which characters are sent to preferred variant implementation of digital audio broadcasts that are compatible with the AM signal, is approximately 430,66 bps, which means that per second transmitted 430,66 bits of information upravleniyami. The carrier frequency, the closest to the AM carrier frequency is transmitted with higher power than the other carrier frequencies MOCR. Because they are closest to the center of the channel, the equalizer in the receiver should be less to adapt to these carrier frequencies than the carrier frequencies located farther from the center channel, since the phase reference for digital signal normalized with respect to the phase at the center of the channel, and the amplitude of the digital signal normalized with respect to the received power Dpfm carrier frequencies. In addition, since Dpfm carrier frequencies are complementary, increasing the signal-to-noise ratio due to the assignment of carrier frequencies in the receiver. In addition, carrier frequencies, which are closest to the center of the channel, the least sensitive to errors in the schemes of synchronization symbols, or restore baud (data transfer speed). These factors together contribute to the reliability of management information.

In addition, according to the invention, as shown in figure 2, control bits are generated by the generator 100 sequence control mode and data synchronization. This generator may include a storage device that stores the specified sequence. The signal in line 102 from the CPU 38 PIO and the interleaver is used to synchronize control the ia mode and sequence data synchronization for sampling data of the interleaver. Digital encoder source sends a signal on line 104 in the sequence generator mode control and synchronization data, to transmit the current value of the coding rate, the audio signals. The sequence mode control and synchronization data is supplied via line 106 to the device OBPF. The device OBPF uses data received on line 106 as an input for a digital carrier frequencies that transmit sequence control mode and data synchronization. In one of the preferred embodiments the processor PIO and the interleaver contains external code PIO, followed by the outer interleaver followed by internal ID PIO with subsequent internal interleaver. The length of the sequence control mode and data synchronization can be established such that the sequence provides the data for the number of bps, which is equal to the number of bps that can be transferred using the data in the internal interleaver. This procedure allows to determine the boundaries of the inner interleaver in the receiver, through appropriate processing sequence control mode and data synchronization.

In one of the preferred embodiments has 400 frames MOCR transmitted on each frame of internal displacement is Italia, where the frame of the inner interleaver refers to the data required to populate the internal interleaver. As one bit of information management falls on the frame of the interleaver, there is 400 bits of control information transmitted in the frame of the interleaver. Therefore, if the sequence mode control and synchronization data has a length of 400 bits, the sequence will be repeated for each frame of the inner interleaver. These 400 bits are divided into 10 segments of 40 bits, in which each segment length of 40 bits is called a frame control. Figure 5 presents the format of 40 bits, containing the frame 184 of the control.

Figure 3 depicts a block diagram of a receiver configured to receive the composite digital and analog signals, as shown in figure 1. The antenna 110 receives a composite signal containing digital and analog signals, and sends the signal to the normal input of the cascades 112, which may include RF preselector, amplifier, mixer and local oscillator. The intermediate frequency signal generated by the input cascades in line 114. This intermediate frequency signal passes through the circuit 116 automatic gain control (AGC) in the generator 118 inphase/quadrature signal. Generator inphase/quadrature signal, generates an in-phase signal in line 120 and wattorney signal in line 122. The output signal of the inphase channel line 120 is input to an analog-to-digital Converter 124. Similarly, the output signal of the quadrature channel by line 122 is supplied to the input of another analog-to-digital Converter 126. The feedback signals in lines 120 and 122 are used to control circuit 116 for automatic adjustment of the amplification. The signal in line 120 includes an analog AM signal, which, as illustrated, is highlighted by the block 140 and is held at the output stage 142 and then to the loudspeaker 144 or other output device.

To exclude energy analog AM signal and outputting a filtered signal on line 148 can be used an additional filter 146 of the upper frequency to filter the in-phase components in the line 128. If the high-pass filter is not used, the signal on line 148 is the same as in line 128. The demodulator 150 receives digital signals on lines 148 and 130 and generates output signals in lines 154. These output signals are fed into the equalizer 156, and the output signal EQ is supplied to the switch 158. The output signal of the switch is fed into the circuit 164 facing the interleaver and decoder for forward error correction to improve data integrity. The output signal of the circuit converts the interleaver/forward error correction is supplied to the decoder 166 East is cnica. The output signal of the decoder source is delayed by circuit 168 to compensate for the delay of the analog signal at the transmitter and equalization at the time of analogue and digital signals in the receiver. The output signal of the delay circuits 168 is converted into an analog signal by digital to analog Converter 160 for receiving the signal line 162, which leads to the output stage 142.

Figure 4 depicts a detailed functional block diagram, which additionally illustrates the operation of the invention. As in-phase (I)and quadrature (Q) signals are provided in the lines 148 and 130 as input signals for the circuit 170 weighing using compactly supported functions (formation of the window) and remove guard interval. These signals can be produced using elements of the transducer with decreasing frequency, similar to that shown in figure 3. Finite weighing function should be applied to the digital carrier frequencies remained orthogonal, or at least the lack of orthogonality between the digital carrier frequency would be small enough not to affect the performance of the system. In-phase (I) and quadrature (Q) signals are synchronized with the transmitted badovini intervals, and each baud is used as input signal for the circuit 172 rapid transformation f is Riez (FFT). In some cases, it may be advantageous to perform weighting using compactly supported functions and remove guard interval to be processed by the filter 146 of the upper frequencies. Output signals from the circuit 170 weighing using compactly supported functions and remove guard interval are input signals for the circuit 172 of the fast Fourier transform. To obtain higher signal-to-noise ratio for complementary carrier frequencies, the output signals of the FFT for complementary pairs of carrier frequencies are combined. The output signals of the FFT are fed into the multiplier 174 coefficients on lines 154. The multiplier coefficients adjusts the amplitude and phase data for each digital carrier frequency to compensate for the effects of channel filtering in the transmitter and receiver and other factors that may affect the amplitude and phase of the received digital information. The output signal of the multiplier coefficients used for making character decisions that define the data corresponding point of the point groups that have been transferred. The processor 176 determines which of the pixels of the group of points of the frequency domain was transferred. These decisions, along with pre-adjusted points of the point group and the previous values of the coefficients of the equalizer are used to update to the rates of the equalizer, as illustrated by block 178. To update the equalizer coefficients in the block 178 may be used a known algorithm such as the least squares algorithm or a recursive least squares algorithm.

For demodulation of the data accordingly, the receiver must identify when passed test baud. When receiving the test baud output signal of the equalizer is not entered in the processor character recognition (including PIO and converted premarital), since the information of the test body is not used to receive encoded digital signal program audio broadcasts. Thus, when receiving the test frame, the equalizer uses a different multiplier convergence or constant adaptation. In addition, when receiving the test baud, the data entered in the procedure of estimating the noise power, are handled differently. Thus, the block 176 symbolic solution/apriori data gives the ideal data corresponding to the test body when taken test baud, and character decisions, when taken normal baud. As shown in figure 4, the output signal of the multiplier coefficients are entered in the processor 165, which determines the timing of normal and test signals.

As shown in figure 3 and 4, the flow of data from the multiplier on the cylinder the patients entered in the processor 163 to control and synchronize data. This processor uses only the data sequence mode control and data synchronization. The processor 163 mode control and data synchronization processes information management and determines the encoding rate of the audio signal, as well as the borders of the inner interleaver. The signal is sent via line 167 to the circuit 164 facing the interleaver and FEC to specify the boundaries of the inner interleaver. This leads to data synchronization in the receiver with respect to the boundaries of the internal interleaver and helps to ensure the proper functioning of the circuit 164 facing the interleaver and FEC. Also the signal is transmitted to indicate to the decoder the source transmission rate encoded audio information.

The present invention provides a transfer format and method of reception of system information management system digital audio broadcasts that are compatible with the AM signal. Transmitted data includes the transmission mode, the interleaver synchronization and timing information management data. In a preferred embodiment of the invention, information is transmitted on carrier frequencies MOCR that are closest to the carrier frequency of the AM signal. To ensure high performance in presence of noise and interference, the use of the format modulation Dpmn. Synchronizing sequence, described below, is chosen to produce low levels of side maxima of the autocorrelation.

Figure 5 illustrates the full frame 184 data management. As shown in figure 5, it is necessary to determine the first 12 bits indicated by the position 186, and use them as needed for the modernization of future systems. The following 4 bits indicated by the position 188, are bits of information transfer mode. These bits indicate the encoding rate of the audio signal and the speed of forward error correction used in the convolutional encoder. In the preferred in the present embodiment, digital AM-audio broadcasts has 3 modes set for the program, including the encoding of an audio signal with a speed of 48 kbps, rate convolutional encoder 3/5; encoding the audio signal with a speed of 32 KB/s, speed convolutional encoder 2/5; and encoding the audio signal with a speed of 36 KB/s, the speed of the convolutional encoder is 1/3. In order to have the maximum number of bits that have been selected 4-bit code information transfer mode.

In the receiver information of the transmission mode is not required until such time until it is passed the full frame of the interleaver. Therefore, to determine the mode of transmission to the receiver, it is advantageous to use information from 10 frames control in AC is resident. One way to determine the mode of transmission would be to count the number of bits in the transmission mode, which is taken as 1. With bit codes illustrated in figure 4, the bits should give the amount of 0, 20 and 40 for speeds code 3/5, 2/5 and 1/3, respectively. In order to determine which mode of transmission is made, can be used the ideal value, the closest to the total value. The simulation of this algorithm to determine the mode of transmission has shown that it is practical and reliable, because if the bits transfer mode cannot be restored from Dpfm carrier frequencies, it is very unlikely that data for other carrier frequencies, which use more complex modulation formats can be recovered. Alternatively, one could correlate bits transfer mode from all possible codes transfer mode. The correlation that provides the largest output signal can be selected as defining the transmission mode. The correlation result can be filtered by the lowpass filter, and to reduce the effects of noise can also be taken into account hysteresis. Correlation can be implemented using a logical operation "exclusive OR" (XOR) for received bits and possible code transmission mode. The bits resulting from the exclusive OR operation to the ka, the Dogo code transmission mode, can be summed to represent the correlation values.

The following four bits 190 are part of the 40 bits that contain the word 194 synchronization of the interleaver. 40 bit word synchronization of the interleaver is transmitted once in each frame of the interleaver, 4 bits transmitted during each of the 10 administrative personnel, which are transmitted during each frame of the interleaver. The receiver processes the information synchronization of the interleaver to define the boundaries of the frame of the interleaver. The unique word of the interleaver was chosen in such a way as to have a high autocorrelation main peak with side peaks, to ensure a reliable determination of the boundaries of the interleaver.

In particular, we used the bit configuration 1100111010111000101111010100100000100100 that when aligning the sequence has the autocorrelation equal to 40, and when the sequence is not aligned, has a maximum level of spurious maxima equal to +/- 4. Note that the autocorrelation is determined by correlation of the sequence with respect to the periodic extension of her, and these numbers are obtained using values of 1 for a bit equal to 1 and -1 for bit 0. As the frame of the interleaver is processed by the receiver, can be collected given the full word synchronization of the interleaver by combining sequences of four bits in each of the ten administrative personnel. To define the boundaries of the interleaver is possible to correlate a received word synchronization of the interleaver with the known transmitted word of the interleaver. In particular, whenever taken full control frame, it is possible to correlate the last 40 received synchronization bits of the interleaver with a known combination. To determine the interleaver synchronization of the correlation result can be compared with the threshold.

In order to achieve good correlation, it is first necessary to provide synchronization for Dpfm frame control. As shown in figure 5, the last 20 bits (192) control frame consists of unique words Dpfm synchronization. The purpose of this sequence of bits is to allow the receiver to synchronize with the bit configuration of the control frame so that he could choose the proper bits for transmission mode and the synchronization information of the interleaver. Like the word synchronization of the interleaver, the word chosen in such a way as to ensure high autocorrelation peak and side peaks. In particular, it was used a bit combination 11111011001010110001, which has the autocorrelation is equal to 20, when the sequence is aligned, and the maximum level of spurious maxima equal to +/- 4, when the sequence is not aligned. These bits can Exec Lisovets known transmitted combination, to correlate adopted by the bit pattern of the control word to the receiver. Because the other 20 bits of the control word could randomly generate a high correlation with the unique word Dpfm synchronization and reduce the influence of noise can individually be filtered by the lowpass filter output signal correlations for each of the possible positions of the correlation within the control frame. The output signal of low-pass filters, or the signal correlations, if the lowpass filter is not used, can be compared with a threshold to determine when it reaches Dpfm synchronization.

The control frame may be processed to identify the bits of the control, representing the word synchronization data management, by performing the correlation of the bits of the second bit sequence control with the specified word data and comparison of results correlation with a given threshold.

Control bits in the frame control representing the transmission mode, to one of the many frames of the interleaver can be summed to obtain the total value. And then the total value is compared to one of many predefined values of a variety of transmission modes, and selects the transmission mode corresponding to the pre definitely is the value which is closest to the total value.

The present invention provides a method and apparatus for transmitting and receiving control information in an AM compatible digital audio broadcasts. In the description set forth certain preferred methods and embodiments of the present invention, however, it should be borne in mind that the invention can be implemented in other ways within the scope of the claims.

1. The method of signal transmission of digital audio broadcasts, in which the said signal includes the carrier frequency of the analog amplitude-modulated (AM) signal and a set of carrier frequencies of the signal is digitally modulated, multiplexed with orthogonal frequency division (MOCR) in the same channel as the carrier frequency of the analog AM signal, characterized in that it includes the stages of the delay of the carrier frequency of the analog AM signal relative to the carrier frequencies MOCR signals with digital modulation, modulation of complementary pairs of carrier frequencies MOCR signals digitally modulated with one bit of control in each character frame MOCR, with complementary pair of bearing frequency MOCR signals with digital modulation includes first and second carrier frequencies from the set of carrier frequencies MOCR signals with digital modulation, which are BL is closer to the carrier frequency of the analog AM signal, to transmit control bits, in addition, the serial control bits in each character frame MOCR constitute a control frame that includes the first sequence of bits of the control, representing a transmission mode, the second bit sequence control, representing the word synchronization data management, and a third sequence of bits of the control, representing the word synchronization of the interleaver, the transmission carrier frequency of the analog AM signal and the number of carrier frequency signals with digital modulation.

2. The method according to claim 1, characterized in that a lot of the mentioned character frames MOCR constitute the frame of the interleaver.

3. The method according to claim 1, characterized in that it further comprises the processing steps of the control frame identification bits control representing the word synchronization data management, by performing the correlation of the bits of the second bit sequence control with the specified word data and comparison of results correlation with a given threshold.

4. The method according to claim 1, characterized in that the complementary pair of carrier frequencies of the signal in digital form modulate using the dip phase manipulation.

5. The method according to claim 1, characterized in that it further includes the steps of receiving the carrier frequency analogue of the first AM signal and the number of carrier frequency signal with digital modulation and processing control frame identification bits control representing the word synchronization data management.

6. The method according to claim 1, characterized in that it further includes the steps of summing the bits of the control in the first bit sequence control representing the transmission mode, to one of the many frames of the interleaver to obtain a total value, comparing the total value with one of multiple predefined values of a variety of transmission modes, and select the transmission mode corresponding to a predefined value, which is closest to the total value.

7. Digital audio broadcasts for radio broadcast signal comprising a carrier frequency of the analog amplitude-modulated (AM) signal and a set of carrier frequencies of the signal is digitally modulated, multiplexed with orthogonal frequency division (MOCR) in the same channel as the carrier frequency of the analog AM signal, characterized in that it contains means for delaying the carrier frequency of the analog AM signal relative to the carrier frequencies MOCR signals with digital modulation means to modulate the complementary pairs of carrier frequencies MOCR signals digitally modulated with one bit of control in each character frame MOCR, with complementary pair of bearing frequency MOCR signals from a digital m is dulala includes first and second carrier frequencies from the set of carrier frequencies MOCR signals with digital modulation, which are the closest to the carrier frequency of the analog AM signal, to transmit control bits, in addition, the serial control bits in each character frame MOCR constitute a control frame that includes the first sequence of bits of the control, representing a transmission mode, the second bit sequence control, representing the word synchronization data management, and a third sequence of bits of the control, representing the word synchronization of the interleaver, and a means for transmitting the carrier frequency of the analog AM signal and the number of carrier frequency signals with digital modulation.

8. Digital audio broadcasts according to claim 7, characterized in that a lot of the mentioned character frames MOCR is the frame of the interleaver.

9. Digital audio broadcasts according to claim 7, characterized in that it further comprises means for processing the control frame identification bits control representing the word synchronization data management, and the means for processing is configured to perform correlation of the bits of the second bit sequence control with predefined data word, and for comparison of results correlation with a pre-defined threshold.

10. Digital audio broadcasts pop, characterized in that the means for modulation of complementary pairs of carrier frequencies of the signal in digital form is made with the possibility of modulation using a two-position phase manipulation.

11. Digital audio broadcasts according to claim 7, characterized in that it further comprises means for receiving the carrier frequency of the analog AM signal and the number of carrier frequency signal with digital modulation and the means for processing control frame identification bits control representing the word synchronization data management.

12. Digital audio broadcasts according to claim 7, characterized in that it further comprises means for summing the bits of the control in the first bit sequence control representing the transmission mode, to one of the many frames of the interleaver to obtain a total value, for comparing the total value with one of multiple predefined values that characterize the variety of transmission modes, and to select a transmission mode corresponding to a predefined value, which is closest to the total value.



 

Same patents:

FIELD: methods and devices for processing composite audio broadcast signal.

SUBSTANCE: proposed method includes following procedures: analog-modulated part of audio broadcast signal is separated from digital-modulated part of audio broadcast signal; data from analog component of broadcast signal is separated from its digital component to produce mixed output audio signal. Method is also proposed for transferring composite audio broadcast signal that has analog part and digital part to suppress irregular interruptions in reception of mentioned audio broadcast signal by adding modem frames with analog part of broadcast signal which incorporate audio frames presenting digital part of audio broadcast signal.

EFFECT: provision for suppressing irregular interruptions in reception of audio broadcast signal.

25 cl, 4 dwg

The invention relates to a wired broadcasting and can be used to selectively enable the speaker or the operator of the radio station off speakers

The invention relates to the field of transmission and reception of digital data for use in digital broadcasting systems

The invention relates to electronic signal processing, in particular to the signal processing to reduce the ratio of maximum power to the average radio signals
The invention relates to the field of quality control of the radio medium wave and shortwave bands

The invention relates to telecommunications, and particularly to data transmission systems and to methods for assessing the quality of their functioning

The invention relates to radio broadcasting and can be used for demodulation and signal correction in the receiver that is designed to work in the system broadcast a digital signal that is compatible with the amplitude-modulated signal

The invention relates to radio broadcasting and can be used for correction of the demodulated signal at the receiver is designed to work in the system broadcast a digital signal that is compatible with the amplitude-modulated signal

The invention relates to radio broadcasting and, in particular, to the modulation formats for digital audio broadcasting (DAB) digital audio broadcasting with frequency modulation type "in band on channel" existing (operating) stations (IBOC-In-Band-On-Channel) and to the broadcasting systems using such modulation formats

The invention relates to receivers for receiving signals digital audio broadcasting

FIELD: methods and devices for processing composite audio broadcast signal.

SUBSTANCE: proposed method includes following procedures: analog-modulated part of audio broadcast signal is separated from digital-modulated part of audio broadcast signal; data from analog component of broadcast signal is separated from its digital component to produce mixed output audio signal. Method is also proposed for transferring composite audio broadcast signal that has analog part and digital part to suppress irregular interruptions in reception of mentioned audio broadcast signal by adding modem frames with analog part of broadcast signal which incorporate audio frames presenting digital part of audio broadcast signal.

EFFECT: provision for suppressing irregular interruptions in reception of audio broadcast signal.

25 cl, 4 dwg

FIELD: control data transmission in audio broadcast.

SUBSTANCE: proposed method includes transmission phases for transferring set of control bits in each of set of control frames, first control bit sequence presenting transmission mode and second one, control data synchronizing word. Set of control bits may include in addition third sequence of bits presenting interleaver synchronizing word. Method for detecting mode of transmission and synchronization of audio broadcast signal implemented in radio receiver is also proposed. This method includes reception phases for set of interleaver frames incorporating digital information, each of interleaver frames incorporating set of control frames. Control frames include set of control bits; first sequence of control bits presents transmission mode and second one, control data synchronizing word. Set of control bits may include in addition third bit sequence presenting interleaver synchronization word. First sequence of control bits is processed for definite transmission mode, second one, for detecting control data synchronization, and third sequence of control bits, for determining interleaver boundaries. Radio-frequency transmitters and receivers using above-described methods are also given in description of invention.

EFFECT: reduced cross-talk noise with respect to analog amplitude-modulated signal.

12 cl, 5 dwg

FIELD: encoding technologies.

SUBSTANCE: method includes generating digital information, characterizing sound signal, estimating number of bits, distributed for digital information in modem frame, encoding digital information in estimated number of bits to produce encoded information, selected bits are deleted from encoded information, bits, appropriate for digital messages, are added to encoded information for generation of composition modem frame, bits of said composition modem frame are formatted to produce formatted bits of composition modem frame and said formatted bits of composition modem frame are transmitted.

EFFECT: higher efficiency of sound frames encoding.

2 cl, 14 dwg

FIELD: audio signals processing technologies.

SUBSTANCE: multiple users are presented with opportunity to adjust relation voice/sound effects by receiving on first decoder of voice signal and audio effect signal and concurrent receipt in second decoder of voice signal and sound effect signal, while receiving signals for voice and sound effects is performed separately, and in each decoder voice and audio effects signals received separately are adjusted separately.

EFFECT: broader functional capabilities, higher efficiency.

2 cl, 28 dwg

FIELD: generation of analog and digital signals for.

SUBSTANCE: method for generating signal of weakened amplitude for simultaneous transfer, meant for simultaneous transfer of digital radio broadcast and analog radio broadcast signal, contains stages of generation of primary error signal, generation on basis of primary weakened signals of final signal for simultaneous transmission. Generator of weakened amplitude signal for simultaneous transmission, meant for simultaneous transfer of digital and analog radio broadcast signals contains final signal generator for simultaneous transmission, advance weakening cascade, containing primary signal generator for simultaneous transfer, meant for generation, on basis of aforementioned digital and analog broadcast signals, of primary error signal and primary amplitude weakening block, meant for weakening of at least one of aforementioned radio broadcast signals.

EFFECT: generation of stable signal for simultaneous transfer with maximal level of signal for analog and digital transferred signals, allowing to increase primary service area for analog and digital system.

2 cl, 4 dwg

FIELD: communications engineering, in particular, systems for communication inside vehicles or in close proximity of vehicles.

SUBSTANCE: in accordance to one of variants, system for transferring information from first position inside or in close proximity of a vehicle to second position inside a vehicle, where vehicle has a conductive metallic structure, containing a remote block, containing first communication equipment, provided with sensor, exciter block, containing second communication equipment and excitation means, connected due to conductivity to metallic structure of vehicle, while first communication equipment receives information in first position, realizes modulation of signal using this information, receives electromagnetic field in metallic structure of vehicle through sensor, excitation device performs extraction of current at the expense of conductivity from metallic structure of vehicle and production of current signal, second communication equipment receives that signal, demodulates and transfers information to second position, in such a way realizing transfer of information from first position to second position by wireless communication method.

EFFECT: creation of excitation system and excitation methods for providing communication inside or in close proximity of vehicles.

8 cl, 18 dwg

FIELD: methods for identification of changed in repeatedly broadcasted database.

SUBSTANCE: in accordance to the method data is produced in fragments, document is received which contains information about fragments, information is analyzed, and fragments are received repeatedly in accordance to aforementioned information.

EFFECT: possible listening of repeated broadcasting with minimal processing of data, detection of change of any data element and determining of location where the change is described.

4 cl, 2 dwg

FIELD: technology for receiving audio broadcasting signals.

SUBSTANCE: method for receiving frequency-modulated signal of digital audio broadcasting, including first and second sets of sub-carriers respectively in upper and lower side band of radio channel, contains steps of mixing of digital audio broadcasting signal with heterodyne signal, letting through of intermediate frequency signal through band filter, determining presence of distortion of upper or lower side band of digital audio broadcasting signal, application of frequency shift to heterodyne signal for ensuring change of frequency of signal of intermediate frequency, at which band filter removes sub-carriers in distorted upper or lower side band. The receiver realizes the method.

EFFECT: minimized influence of first neighboring interferences in received signals.

2 cl, 5 dwg

FIELD: communications engineering.

SUBSTANCE: in accordance to the invention, ground-based digital video-broadcasting network contains content provider and three transmitters. Integrated receiver/decoder (IRD) moves in a zone near transmitters. By transmitting service information as a part of network information table at data level, transmitters provide transmission parameter information in their output signals as data for signaling transmission parameters (TPS) at physical level. Aforementioned TPS information includes one bit, which defines to which type of network the signal is related, and information, which denotes whether the signal contains data flows, quantized in time. That information is used by (IRD) both in scanning a signal or (IRD) initialization by parameters, required for detection of service at 1-2 levels of open systems (OSI), and for canceling selection of signals as candidates for relay service transfer. Because transmission parameter information is transmitted more often and at lower OSI level compared to network information table, (IRD) may efficiently make decisions: whether the signal is fitting for relay service transfer, or whether it is a signal of interest.

EFFECT: reduction of energy consumption in mobile receiver.

5 cl, 5 dwg, 11 tbl

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