Method and system for digital audio broadcasting with frequency modulation (fm) type "in band on channel"

 

The invention provides a method of broadcasting, comprising the steps of placing broadcast signal in a Central frequency band of an FM radio channel, placement of the first set of subcarriers in the upper side band) FM radio, host the second set of subcarriers in the lower side band FM radio channel, the modulation of the first groups of the first and second sets of subcarriers using coded additional perforated convolutional code version of the program material, transmission of the broadcast signal, the first groups of the first and second sets of subcarriers. In a fully digital implementation of the invention, the Central frequency band may include a number of subcarriers transmitted at a lower power level than the subcarriers in the upper and lower side bands. These additional subcarriers can be used for the transmission of additional data. The proposed transmitters and receivers that use this method. 3 C. and 10 C.p. f-crystals, 7 Il.

The technical field to which the invention relates 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 is I, using such modulation formats.

"Digital audio broadcasting" is a framework for providing digital audio quality exceeding the existing analog radio formats. Digital audio broadcasting with frequency modulation in the channel strip existing stations may be implemented in a hybrid format, where the digitally modulated signal coexists with the current transmitted analog signal frequency modulation (FM). Broadcasting in the channel strip of the existing stations will not require new allocations of spectrum, as each signal of the digital audio broadcasting simultaneously transmitted within the spectral mask of an existing distribution FM channels. Broadcasting in the channel strip existing plants help conserve spectrum, at the same time allowing broadcast stations to provide digital audio quality to existing their audience. Used broadcasting system with frequency modulation bandwidth channel radio stations are disclosed in U.S. patents 5465396; 5315583; 5278844 and 5278826.

The advantages of digital transmission of audio information include better signal quality with less noise and a wider dynamic range is to allow existing receivers continue to receive analog FM signal and at the same time to allow new IBOC receivers to decode the digital signal. Digital audio broadcasting hybrid format is described in the following publications: kreger (Choedak) and other "Robust modem and coding technologies for hybrid systems digital audio broadcasting with frequency modulation in the channel strip of the existing stations. Works on broadcasting IEEE (Institute of Electrical and Electronics Engineers Institute of electrical engineers and electronics), vol 43, 4 December 1997; Kruger and other "Compatibility of the hybrid system digital audio broadcasting with frequency modulation, operating in the channel strip of the existing stations. Proceedings of the IEEE on broadcasting, vol 43, 4 December 1997; Kruger and other "noise-tolerant IBOC DAB AM (amplitude modulation - amplitude modulation) and FM technology for digital audio broadcasting", 51st Annual conference on technology of broadcasting (NAB) National Association of Broadcasters national Association of broadcasters), April 1997; and published PCT patent application WO 9749207 A. sometime in the future, when IBOC DAB receivers will become ubiquitous, broadcasters will be able to choose to send a fully digital format. System for digital sound broadcasting in a fully digital format is described in the publication Coupeau (Cupo) and other System fully quency division multiplexing), using RAS (perceptual audio coding - coding of perceived audio) - encoder. Proceedings of the IEEE on broadcasting, vol 44, 1, March 1998. The purpose of hybrid IBOC DAB with frequency modulation is the provision of a stereo digital audio (plus data) as a virtual CD-ROM with the simultaneous transfer of an existing FM signal. The aim of fully digital IBOC DAB with frequency modulation is providing stereo audio as a virtual CD-ROM together with a data channel with a capacity of approximately 200 Kbps depending on the interference situation for the particular station.

It can be assumed that there will be a transition from hybrid to all-digital formats of broadcasting IBOC DAB, and it would be desirable to create a modulation format that could be used both systems, resulting in the mentioned transition could be implemented with minimal changes in the transmitting equipment.

Summary of the invention the Invention provides a method of broadcasting, comprising stages: placement of the first set of subcarriers in the upper side band FM radio channel, and the upper sideband has a range of approximately +100 is olose FM radio, moreover, the lower sideband has a range from about -100 kHz to -200 kHz from the center frequency of the radio channel; modulation of the first group of the first set of subcarriers using the previous digital processing an encrypted version of the program material, which must be transmitted; and modulation of the first group of the second set of subcarriers using the previous digital processing version of the program material, which must be transmitted; and this method differs in that it includes the steps of placing a third set of subcarriers in a Central frequency band of an FM radio channel, where the spectral power density of the third set of subcarriers is less than the spectral power density of subcarriers in the upper and lower side bands; modulation of the third set of subcarriers additional data; and transmitting the first group of the first set of subcarriers of the first group of the second set of subcarriers, and the third set of subcarriers.

When working in a hybrid format modulation signal Central frequency band contains a carrier modulated in frequency analog software signal. When working in a fully digital format modulation signal Central frequency band of aderinola power, less than the subcarriers of the upper sideband and the lower sideband.

The invention also includes transmitters and receivers that use the above method.

A brief description of the drawings Fig. 1 is a schematic representation of the frequency distribution and relative spectral power density components of the signal for FM IBOC DAB signal hybrid format.

Fig. 2 is a schematic representation of the frequency distribution and relative spectral power density components of the signal for FM IBOC DAB signal is completely digital format in accordance with the present invention.

Fig.3 is a schematic representation of the frequency distribution and relative spectral power density of the signal components for the upper sideband FM IBOC DAB signal in accordance with the present invention.

Fig.4 is a schematic representation of the frequency distribution and relative spectral power density of the signal components for the lower sideband of the FM IBOC DAB signal in accordance with the present invention.

Fig. 5 illustrates a potential interference between the transmission channel in accordance with this invention and the left first SOS is a function of the channel in accordance with this invention and the left first adjacent IBOC DAB channel IBOC DAB system.

Fig. 7 is a simplified block diagram of a broadcasting system that can use the modulation method of the present invention.

Description of the preferred variants of the invention of Fig. 1 is a schematic representation of the distribution of frequencies (spectral location) and relative spectral power density components of the signal for FM IBOC DAB signal 10 hybrid format in accordance with the present invention. The hybrid format includes a conventional modulated frequency stereo analog signal 12 having a power spectral density, represented by triangular profile 14, which is located in the Central part (or center frequency) 16 channel. The spectral power density of a typical analog FM signal broadcast is roughly triangular with a slope of about 0.35 dB/kHz from the center frequency. Many of the past digital modulation evenly distributed subcarriers are located on each side of the analog FM signal, at the top side 18 and bottom side 20, and this set is transmitted simultaneously with the analog FM signal. All carriers are transmitted at a power level that is preelectoral density peak power rather than a more common characteristic of the spectral density average power. In this case, the total power of the DAB signal with a single side-band 25 dB below the power of the FM carrier, while the ratio of spectral peak capacity is much greater. Short-range broadcasting in the FM format is more "EcoObraz" than the short range broadcasting in DAB format, when both are considered in the band of 1 kHz. As will become apparent from the following description, held digital modulation portion of the hybrid signal is a subgroup of the full digital DAB signal, which is transmitted in a fully digital IBOC DAB.

The center of signals from adjacent FM channel (i.e., the first adjacent FM signals), if such a channel exists, will be located at a distance of 200 kHz from the centre of the considered channel. In a hybrid format FM IBOC modulation on each side of the main analog FM signal are 95 evenly distributed subcarriers modulated with the division on orthogonal frequency (OFDM) and occupying a range at a distance of from about 129 kHz to 198 kHz from the Central frequency of the main FM signal, as illustrated by the upper lateral stripe 18 and the lower side band 20 of Fig.1. In the hybrid system the total power of the DAB signal for mo is yavlyaetsya at the value of about -25 dB relative to the power of its main analog FM signal.

The spectral placement and relative levels of power density digital signal subcarriers are modulated using OFDM, one of the options for implementing the present invention, which is hereinafter referred to as "fully digital FM DAB format, illustrated by element number 24, is shown in Fig.2. In this implementation variant of the invention the analog FM signal is replaced with the possible additional band OFDM-modulated subcarriers, hereafter referred to as "advanced fully digital signal 26, and located in the center of the band 28. Here also in the upper side band 30 and the lower side band 32 are evenly distributed OFDM-modulated subcarriers. The side bands are fully digital format in Fig.2 are wider than the sidebands in Fig. 1. In addition, the spectral power density of the side bands of all-digital IBOC signal is set to approximately 10 dB above are valid for the lateral bands of the hybrid IBOC signal. It provides all-digital IBOC signal a significant advantage in performance. Moreover, the spectral power density of the fully extended cyfrowy fixes the problem for neighboring hybrid or fully digital IBOC signals, at the same time providing additional capacity for other digital services.

It is recommended that the extended data subcarriers installed on the relative level of approximately 15 dB below the level of other major carriers. This represents a compromise between the robustness of these extended subcarriers and interference effects on key subcarriers of the first adjacent signal. To assess the potential interference situation, assume that the maximum relative level of the first adjacent fully digital station is -6 dB in the protected circuit 54 dBu (signal interference is undesirable). This is for a pair of first adjacent stations, which correspond to the directives of the Federal communications Commission of the USA, although there are exceptions, characterized by a closer distance. Subcarriers extended data will interfere with the main carriers of the first neighbor on the relative level of -21 dB (-6 dB -15 dB). This level of interference includes some margin for fading and should not lead to significant deterioration of the main signal. However, extended data subcarriers will be affected, if the first adjacent interference source rasshirennykh data. To subcarriers extended data should be applied coding with direct error correction (FEC - forward error control), the result may be a valid one first adjacent interference source. If it is assumed that the extended data are more valuable than specified provided the protection, then it is assumed increasing levels of subcarriers for the extended data to -10 dB instead of -15 dB.

Fig. 3 is a schematic representation of the placement and relative spectral power density of the signal components for the upper sideband FM IBOC DAB signal in accordance with the present invention. In Fig.3 and Fig.4 the position of a potential subcarriers indexed (numbered) and vary in the range from zero at the center frequency of the FM signal to plus or minus 273 at the edges of the band width of 400 kHz, with a positive value are the carrier frequency above the center frequency of the channel and negative numbers have frequencies below the center frequency of the channel. Designation of subcarriers is shown in parentheses above the frequency scale in Fig.3, include all possible subcarriers in the upper side band as hybrid and all-digital system. In preferred embodiments of istoselida phase shift keying) and orthogonal distributed at a frequency of approximately 726,7456055 Hz (44100135/8192) after applying pulse shaping (the last square root cosine clock pulse with 7/128 excessive time functions as a guard time interval). On the frequency scale shows the difference frequency from the Central frequency of the channel.

The upper sideband is shown in Fig.3, consists of information subcarriers with non-140-272 corresponding to frequency subcarriers 101,744 Hz-197,675 Hz. Subcarriers 273 is a possible reference subcarrier. As shown, the upper side band is divided into several groups 34, 36, 38 and 40. Group 34 represents the main channel and contains subcarriers 178-253. Subcarriers of the main channel used to transmit program material is broadcast in the form of data bits of the encoding algorithm at a speed of at least 96 thousand bits per second (Kbps). The main channel may include auxiliary and backup data. The second group of bearing 36, occupying the position of subcarriers 254-272, is used for the transmission of parity bits. The third group of bearing can be used for bearing version of program material with a delay of 24 Kbit/s for the purposes of configuration and backup. As will be discussed later, these under the closer to the center of the channel. The most extensible code bits are placed on the external OFDM-modulated subcarriers. Extensible bits have the lowest possible impact on the free distance or the coding efficiency combined code, and they are the least important from the point of view of error correction code. Therefore, to carry these extensible bits are used most vulnerable subcarriers.

Another group of subcarriers 38 is used in a fully digital implementation of the invention for carrying parity bits or possible data. Group 40 subcarriers includes provisions subcarriers 140-158 and is used in fully digital form for transmission delay backup version of program material at a lower data rate, such as 24 Kbit/s. In a fully digital version of the subcarriers of the group 40 provide data that can be used in case of loss of the signal transmitted through the main channel. Subcarriers in position 273 is a possible reference signal 42. This signal can be used, if necessary, for the purposes of entering into synchronism.

The lower sideband, as shown in Fig.4, is mirroring the format of the upper lateral positions from -178 to -253 used to transmit the same program material, which is transmitted through the main channel of the upper sideband. Subcarriers in groups 46, 48 and 50 are used in the same way as sub-groups 36, 38 and 40 of the upper sideband. Subcarriers in position -273 can be used to transfer the potential of the reference signal. Subcarriers in both side bands use orthogonal frequency seal and have been coding with direct error correction using additional perforated convolutional codes (CPC-Complementary Punctured Convolution). CPC codes are known in the art, see S. Kallel (S. Kallel) "Additional perforated convolutional codes and their applications". Proceedings of the IEEE on communications, vol 43, 6, pp. 2005-2009, June 1995.

Reference subcarriers, if used, are located in positions plus or minus 273 with the Central frequency plus or minus 198,402 Hz. Reference subcarriers modulated with the same phase of the symbol, which is used to modulate the subcarrier 272 for the time of the previous symbol. This gives the receiver the possibility of differential detection of the occurrence frequency using the reference subcarrier or differential detection of the occurrence frequency using otlichayuschij using the reference subcarrier performance may improve. However, it may be advantageous to remove the reference subcarriers with the aim of minimizing potential interference from the second neighboring DAB signal.

The main RACES-coded channel with a speed of 96 Kbit/s takes subcarriers 178-253. This main channel is encoded on both side bands of the digital audio broadcast with additional perforated convolutional codes, leading to the creation of additional perforated convolutional code with rate 1/2. The reference pilot subcarriers can be modulated with a periodic sequence to help to enter the synchronism frequency and the characters and their tracking. The preferred embodiment of the present invention uses an encoding algorithm of the perceived audio signal. The encoding algorithms of the perceived audio signal are disclosed, for example, in U.S. patents 5481614; 5285498 and 5040217. However, it should be understood that the present invention is not limited to the use of coding algorithms perceived audio.

Subcarriers 254-272 (upper and lower sidebands) are any additional parity bits for additional perforated convolutional code or data. Here, the transmission b is Oh sidebar independently. In the presence of interference from adjacent channel FM signal these external OFDM-modulated subcarriers are most susceptible to destruction and interference on the upper and lower side bands is independent. Since the power spectral density of the signal FM broadcast distribution has approximately the shape of a triangle, the interference increases as the OFDM-modulated subcarriers close to the frequency of the first adjacent signal. When the transmitted parity bits, in order to cope with this heterogeneous interference, can be applied specially developed coding and interleaving, resulting in the transfer of information will become robust.

Subcarriers 159-177 in the group 38 of the upper sideband and carrier from -159 to -177 in the group 48 of the lower sideband can carry any additional parity bits for additional perforated convolutional code or data. Here, the transmission of parity bits increases the speed of transmission of the code forward error correction on the main channel with R=1/2 to R=2/5 or R=4/5 on each independent side band digital audio broadcasting. If the parity bits are transmitted in both areas 159-177 and 254-272 (and corresponding padnes audible broadcast.

IBOC DAB system will transmit all digital audio on each side band digital audio broadcasting (upper or lower) FM channel. Although to allow transmission of all bits code rate 1/3 code forward error correction can be used for more subcarriers outside the base system, the base system uses the speed code 2/5. Each sideband can be detected and decoded independently coding efficiency, direct correction of errors dealt with by a convolutional code with rate 4/5 (maybe 2/3). This redundancy allows you to work on one side, while the other is destroyed. However, usually both sides are combined to provide additional power signal and the encoding efficiency commensurate code with rate 2/5 (perhaps 1/3). In addition, for demodulation and separation strong first adjacent sources of interference can be used special technology, resulting in a "restored" sideband digital sound broadcasting can complement the opposite sideband to improve coding efficiency and power of the signal at any one of the side Polynesia from -140 to -158 bottom sidebar for bearing version data of the main channel low speed data transmission, for example, sub-RACES-code with a data rate of 24 Kbps. These backup data with a lower transfer rate latency to improve performance, using a temporary separation. These backup data is fully digital systems replace analog FM-composition hybrid system, which is described in co-owned, concurrently pending application "System and method for suppressing periodic interrupts in the system radio audio", registered on 9 October 1997, serial 08/947902. When the data in the main channel is destroyed, the backup data can fill audiosegment. As backup data consist of nested subgroups of data bits of the main channel, redundancy can make possible additional protection against errors for the main channel.

In a fully digital implementation of the present invention subcarriers with indexes from -139 to 139, which are located in the Central frequency band 28 in Fig.2, can be used as an opportunity for increasing system capacity digital sound broadcasting. The speed of transmission of bits over the channel in this "expanded" strip no coding is about 384 Kbit/s. Because half of the applied technology coding using additional convolutional perforated code and forward error correction, i.e., subcarriers 1 through 139 must carry the same information, and that subcarriers with -1 on -139. Then, if either half is destroyed, the remaining half will still contain additional code with rate 2/3. In this case, the information capacity after coding with rate 1/3 is about 128 Kbit/s.

Advanced fully digital strip is exposed to the interference only from the first neighboring hybrid or fully digital interference source. Under the existing directives on the protected contour of the maximum level of the first adjacent interference source is -6 dB relative to the main station. If this first adjacent interference source is the all-digital IBOC signal, then the interference source can be up to 14 dB above the level of this half of the extended runway. Extended band begins to have a positive impact on the coding efficiency when the spectral density of the interference source is approximately the same level as the signal of the extended runway. This implies that a fully digital first adjacent interference source must be at least 20 dB below consider the i.i.d. data would be possible, when both the first neighbor are at the level of -20 dB; however, a stable reception when the freeze will probably require at least one first neighbor was at a level of -30 dB or below.

Consider increasing the level of the extended strip to levels of lateral stripes hybrid DAB system. The interference impact of the expanded strip adjacent to the first hybrid will be then only -6 dB at circuit 54 dBu. In the same conditions, the interference effect on the first fully digital neighboring signal is -16 dB. At that time, when the service area and interference immunity extended area are not as good as for a fully digital side bands, acceptable levels of performance should be achievable within the normal secure circuit with the exception of areas where both the first adjacent signal are significant. Possible applications advanced fully digital band is "surround sound" (surround-sound), video with low frequency sweep, the data broadcast (datacasting is derived from data broadcasting). These additional services may be accepted where they are available.

The interference impact of the first neighboring canalside impact can be obtained from the correlation of neighboring signals, shown in the graph of Fig.5. In Fig.5 shows a hybrid DAB signal 54 with the signal 56 of the Central band and the top 58 and bottom 60 of the side strips and shows normal first neighboring left channel 62. FM stations have such a geographical location that the nominal received power unwanted adjacent channel is at least 6 dB below the power of the desired station on the edge of its service area. Then the ratio D/U (desired power to undesirable power in dB) is at least 6 dB. Knowledge is power ratio DAB signal of each station relative to its main FM signal allows to estimate the interference effect of the first neighbor on the digital audio broadcasting. Similarly the interference effect of the first neighboring DAB signal 64 (signal 66 of the Central band and the upper 68 and lower 70 side bars) on the main FM signal can be estimated from the relation shown in Fig.6. In this example, the main signal is shown with an offset of 200 kHz from the interference source.

Can also be traced the interference impact of the second neighboring DAB signal in the kHz from the frequency of its main carrier to prevent aliasing.

The analysis of the interference effects DAB signal on its first neighbor on the edge of the service area has shown that the total power of the DAB signal should be set at approximately -21 to -25 dB relative to the power of its host FM signal. This reduces the degree of interference impact neighboring DAB signal on an FM signal with approximately -24 dB to approximately range from -31 to -34 dB, assuming that the ratio of D/U at the edge of the service area is 6 dB.

Although in some countries the FM channels are located at a distance of 100 kHz, these first neighbors geographically separated so that the FM signal does not deteriorate within the service area. Therefore, it is not an issue for FM IBOC system. Interference DAB signal DAB signal at a distance of 300 kHz can affect features on one side, but the additional convolutional code is designed in such a way that allows for this condition.

The following describes the technology of orthogonal frequency sealing system for IBOC DAB. OFDM signal consists of orthogonal posted by carrying, all of which is modulated at a total symbol rate. The distance between the frequencies of characters rectangular Impala phase shift keying), 8PSK (vosmipolosnoy phase shift keying) or QAM (a quadrature amplitude modulation is quadrature amplitude modulation) is equal to the transmission speed of the character. For transmission in the channel strip existing stations FM/DAB signals excessive band OFDM-modulated subcarriers is approximately in the range from 100 kHz to 200 kHz on each side of the coexisting spectrum FM channel. The power of the DAB signal (upper or lower band) is approximately -25 dB relative to the FM signal. The level and filling the spectrum DAB signal is set so as to limit interference effects on the main FM signal and at the same time to provide a satisfactory signal-to-noise (SNR - signal-to-noise ratio) for DAB subcarriers. The first adjacent signals are located at a distance of200 kHz from the FM carrier, can destroy the DAB signal. However, in any particular location within the service area of the station is almost incredible that the first two neighbor will significantly interfere with the DAB signal. Therefore, the upper and lower side band digital audio broadcasting are the same redundant information, resulting in only one sideband is required to transmit referencei and resistance to short-term non-Gaussian noise or failures due to selective fading. Relatively long periods insert characters lead to "gaussianization" these short-term deterioration.

Fig. 7 is a greatly simplified block diagram of a system for digital audio broadcasting, developed in accordance with this invention. The transmitter 72 has an input line 74 and 76 for receiving the left and right channels of program material. For additional data signal has a private entrance for data 78, particularly for use with all digital modulation format according to this invention. The transmitter includes an analog FM processor 80 and set the FM generator 82, which are known as the processors and generators in order to generate a signal analog FM broadcasting on line 84. The input lines 74 and 76 also go to codereuse processor 86, which converts the program material signal and encoded additional perforated convolutional code, which are the correction of errors in the block 88 and fed to the modulator 90 which places the coded signals on the multiple subcarriers using orthogonal frequency seal. The output signal 92 of the modulator is summed with the signal on the line 84 in the adder 94 and is sent to the antenna of the program material and associated data, if they are enabled. The audio information is sent to the loudspeaker 104 and the additional data, if any, served on output line 106, which may be connected to the display or other device, which may further process the data.

The present invention provides a modulation format for all digital systems digital audio broadcasting with frequency modulation in the channel strip of the existing plants. The modulation format all-digital IBOC signal compatible with hybrid IBOC system with frequency modulation. An embodiment of the present invention with a fully digital format makes it possible to substantially increase the capacity for data transmission. The modulation formats make it possible for broadcasters and listeners compliance with compatibility to make the transition to the sound quality at the level of the virtual CD-ROM provided by the digital signal, and at the same time also propose a new data environment.

The format modulation IBOC DAB of the present invention uses a version of the program material obtained by encoding with additional perforated convolutional code, the two lateral is different independent sources of interference with independent fading. If one sideband is completely destroyed a strong first adjacent FM signal existing in the vicinity of the receiver, the opposite sideband must be able to independently decoded in the receiver. Therefore, each sideband must be encoded using independently decoded code quick bug fixes. However, if both sidebands contain useful information, which is not completely destroyed by the interference source, the CPC codes provide additional coding efficiency over that which is achieved by combining the capacities of the two side bands.

Although the present invention is described using the preferred options for its implementation, it is necessary to understand that in the described method and system can be manufactured in various modifications without going beyond the scope of the invention defined by the attached claims. For example, although the above preferred embodiment of the invention illustrates the use of QPSK modulation with application of CPC codes can be applied to various other modulation formats and types of codes, such as 8PSK-modulation using a lattice code is the shadow

1. Way radio, containing the steps of placing the first set of subcarriers in the upper side band (30) radio frequency modulation (FM radio), and the upper sideband is located at a distance in the range from about +100 to +200 kHz from the center frequency of the radio channel, placement of a second set of subcarriers in the lower side band (32) FM radio channel, and the lower sideband is located at a distance in the range from about -100 to -200 kHz from the center frequency of the radio channel, the modulation of the first group (34) of the first set of subcarriers using an encrypted digital version of program material, which must be passed, and the modulation of the first group (44) of the second set of subcarriers using the encoded digital version of the program material, which must be transmitted, characterized in that place the third set of subcarriers in the Central band (28) FM radio, with power spectral density of the third set of subcarriers is less than the spectral power density of subcarriers in the upper and lower side bands, modulate the third set of subcarriers additional data on multiple subcarriers.

2. The method according to p. 1, characterized in that modulate the second group (40) of the first set of subcarriers using an encrypted digital version of program material, having a delay, and modulate the second group (50) of the second set of subcarriers using an encrypted digital version of program material, with the delay.

3. The method according to p. 2, characterized in that the second group of the first set of subcarriers come closer to the center of the FM radio channel than the first group of the first set of subcarriers and a second group of the second set of subcarriers features closer to the center of the FM radio channel than the first group of the second set of subcarriers.

4. The method according to p. 2, wherein the subcarriers in the upper side band, located at the greatest distance from the center of the FM radio channel is the reference subcarrier, and subcarriers at the bottom side, located at the greatest distance from the center of the FM radio channel is the reference subcarrier.

5. The method according to p. 2, characterized in that modulate the third group (36) of the first set of subcarriers bits parity for encoded digital version of program material, and modulate the third group (46) of the second set is on p. 5, characterized in that modulate the fourth group (38) of the first set of subcarriers using an encrypted digital way of additional information, and modulate the fourth group (48) of the second set of subcarriers using encoded digitally for more information.

7. The method according to p. 5, characterized in that modulate the fourth group (38) of the first set of subcarriers additional bits parity for encoded digital version of program material, and modulate the fourth group (48) of the second set of subcarriers additional bits parity for encoded digital version of program material.

8. The method according to p. 5, characterized in that a third group of the first set of subcarriers further from the center of the FM radio channel than the first group of the first set of subcarriers and a third group of the second set of subcarriers further from the center of the FM radio channel than the first group of the second set of subcarriers.

9. The method according to p. 1, wherein the encoded digital version of the program material contains additional convolutional code, and the first part of the additional convolutional code transmitted from the first group of the second set of subcarriers, are independently decoded.

10. Transmitter (72) for transmission of digital audio signals transmitted in the channel strip of the existing stations, characterized in that it contains means (82) to generate a first set of subcarriers in the upper side band FM radio channel, and the upper sideband lying within a frequency band extending in the range from about +100 kHz to about +200 kHz from the center frequency of the radio channel, create a second set of subcarriers in the lower side band FM radio channel, and the lower sideband lying within a frequency band, stretching in the range from about -100 kHz to about -200 kHz from the center frequency of the radio channel, and the third set of subcarriers in a Central frequency band of an FM radio channel, where the third set of subcarriers has a power spectral density lower than that of the first and second sets of subcarriers means (90) for modulation of the first group of the first set of subcarriers coded version of the program material, means (90) for modulation of the first group of the second set of subcarriers coded version of the program material, means (90) for modulation of the third mnozhestvennoi group of the second set of subcarriers, and the third set of subcarriers.

11. The transmitter under item 10, wherein the subcarriers in the upper side band, located at the greatest distance from the center of the FM radio channel is the reference subcarrier, and subcarriers at the bottom side, located at the greatest distance from the center of the FM radio channel is the reference subcarrier.

12. Receiver (98) for receiving digital audio signals transmitted in the channel strip of the existing stations, characterized in that it contains means (100) for receiving the first set of subcarriers in the upper side band FM radio channel, and the upper sideband lying within a frequency band extending in the range from about +100 kHz to about +200 kHz from the center frequency of the radio channel, and a first set of subcarriers is modulated using an encrypted version of the program material, also held the additional coding perforated convolutional code, receiving the second set of subcarriers in the lower side band FM signal, moreover, the lower sideband lying within a frequency band extending in the range from about -100 kHz to about -200 kHz from the center frequency of the radio channel, and the second set of subcarriers is modulated with inspirowane convolutional code, and receiving a third set of subcarriers, and the third set of subcarriers is modulated additional data having a lower spectral power density than the first and second sets of subcarriers means (102) for demodulation of the first group of the first set of subcarriers of the first group of the second set of subcarriers, and the third set of subcarriers and a means (104, 106) for displaying program material obtained by demodulation of the first group of the first set of subcarriers and the second set of subcarriers, and additional data obtained by demodulation of the third set of subcarriers.

13. The receiver under item 12, wherein the subcarriers in the upper side band, located at the greatest distance from the center of the FM radio channel is the reference subcarrier, and subcarriers at the bottom side, located at the greatest distance from the center of the FM radio channel is the reference subcarrier, and the receiver further comprises a means for differential detection of the reference subcarrier in the upper side band, and means for differential detection of the reference subcarrier in the lower side band.

 

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