The way terrestrial transmission of digital signals

 

(57) Abstract:

The invention relates to radio communications, in particular to the transmission of digital radio broadcasting, or television signals. The way terrestrial transmission of digital signals is characterized by the fact that at least one digital signal transmit at least one channel adjacent at least one occupied or unoccupied channel for transmission of analog broadcasting signal, with a dynamic range of at least one digital signal is less than the specified value, which is significantly less than the dynamic range of the analog broadcasting signal and/or the amplitude spectrum of the at least one digital signal is less than the specified value, which is significantly less than the carrier amplitude image of the analog broadcasting signal. Technical result achieved - reducing mutual and cross-modulation. 11 C.p. f-crystals, 6 ill.

Prior art

The invention relates to a method according restrictive part of the main claim.

At ground distribution of television signals due to topographic conditions, but glauc be very large differences in field strength. Constantly limited selectivity and linearity in the input stage of the receiver with the occupation of all theoretically possible television channels, in particular during the occupation of the adjacent television channels analog-modulated television programs, noise may occur due to too large differences between the levels used ("useful") and adjacent channels, and cross and cross modulation. Attempts to limit this interference can be reduced to the fact that avoid activities adjacent channels. Not used in this manner, the adjacent channels are often called forbidden channels. This leads to the fact that in the two-dimensional serviced areas and the consequent overlapping of different transmitters for a particular area, not all of the possible terrestrial television channels can be employed. The resulting shortage of frequencies is aggravated by the fact that even for the two transmitters transmitting the same program, it is necessary to provide in the area of overlapping of different frequencies, because otherwise, as a rule, there are co-channel interference, such as, for example, re-image as a result of differences in lying inventions

Compared with the prototype of the advantage of the proposed method, which is characterized by distinctive features of the main claim, is that not used illicit channels may be occupied by digital signals, such as digital broadcasting and/or television signals, without giving effect to significant mutual and cross-modulation other digital signals and analog signals already busy channels. Thus, you can use a much larger number of channels for terrestrial transmission of signals.

Preferred embodiments of the method specified in the main claim, given in the dependent claims.

To reduce mutual and cross-modulation is mainly used modulation of digital signals on I want-method (code orthogonal frequency seal) according to p. 2 claims.

According to p. 3 and 4 formulas of the invention, it is preferable to transmit at least one digital signal with the relatively low levels. Due to this more pomekhoustoichivye in comparison with digital signals analog signals in restricted izbiratelnata data according to p. 5 claims is that in the restricted channels can be placed the maximum number of programs and/or information services.

Due to the fact that the frequency range of at least one digital signal and at least one adjacent channel provides a protective frequency spacing (the spacing in frequency) significantly increases immunity at a constant and limited selectivity input stages of the receiver and the decoding device.

According to p. 7 for the formula of the invention preferably use the same frequency in the same channel for transmission of programs or information services for different transmitters. This maximizes the number of programs for terrestrial distribution of the signal within a specified frequency range.

According to p. 8 claims preferred protecting multiple digital information, broadcasting and/or television signals from a mutual influence upon reception through the use of protective frequency spacing.

Brief description of drawings

Below the invention is explained more on the embodiments thereof with reference to the drawings. In Fig. 1 shows the in, in Fig. 2 and 3 shows an example of the lessons of the three adjacent channels, respectively, of analog and digital spectra of the signals in Fig. 4 shows a device for receiving terrestrial transmitted digital signals in Fig. 5 shows the spectrum of the digital signal, and Fig. 6 shows the occupation of the channel for transmitting signals of digital broadcasting.

In Fig. 1 item 10 marked the multiplexer, through first, second and third encoders 1, 2 and 3 are served by a single digital broadcast signal, and a fourth-ninth encoders 4-9 serves one broadcasting signal. The multiplexer 10 is connected through a modulator 15 and the amplifier 20 to the transmitting antenna 25 for terrestrial radiation digital broadcasting and television signals.

Encoders 1-9 reduce the amount of data of the digital broadcast signals and digital broadcast signals, which is implemented by limiting the frequency spectra of digital signals. To reduce the amount of data is suitable, for example, such data compression algorithms like MPEG 1, MPEG 2 or MPEG 4 (developed by the expert group standards on methods of video compression, transmitting movement).

EXOR 10 through encoders 1-9 digital signals are combined in the multiplexer 10 with frequency seal into a digital signal with subsequent modulation in the modulator 15, for example, preferably I want-a method of modulation (orthogonal frequency seal), if necessary also by FMN-method (phase shift keying) or the Stones-method (quadrature amplitude modulation with suppressed carrier. One purpose of this is to implement frequency spectrum 41 of the digital signal according to Fig. 5 with a dynamic range of 100 below the setpoint to reduce mutual and cross-modulation other digital signals or analog signals. Another objective of this is to limit the amplitude of the frequency spectrum 41 of the digital signal to a set value and to convert the digital signal in accordance with frequency of channel 31, which side lower and side higher frequencies coexist two channels 30 and 32 according to Fig. 2. The level of the modulated digital signal is then set by means of the amplifier 20 to a value that, as a rule, can be significantly lower than the peak level of the analog broadcast signals, and emit this signal via the transmitting antenna 25.

In Fig. 2 shows an example of classes of channel 31 to a digital signal, the adjacent side of the lower frequencies ka is the train for analog broadcasting signal. In the diagram according to Fig. 2 amplitude And corresponding frequency spectrum caused by the frequency f. Below analog channel 30 adjacent to the channel 31 from a lower frequency is called the first channel, channel 31 to a digital signal is called a second channel, and the channel 32 adjacent to the channel 31 from the side of higher frequencies, called the third channel. The first channel 30 is limited to the lower limit frequency f1and the upper limit frequency f2and contains a range of 35 first analog TV signal with the image carrier with frequency fT1. The third channel 32 is limited to the lower limit frequency3and the upper limit frequency f4and contains a range of 36 of the second analog broadcast signal from the image carrier with frequency fT2. The second channel 31 to a digital signal is limited to the upper limit frequency f3the first channel 30 and the lower limit frequency f3the third channel 32. The second channel 31 as adjacent to two analog channels 30 and 32 is a so-called forbidden channel.

The spectrum of the digital signal is divided into four blocks 40, respectively, separated from one another protective frequency spacing 50 SiGe channel 30, accordingly, the lower limit frequency f3the third channel 32 has a security frequency range 45 to the width of the frequency band fS1. When bandwidth is about 7 MHz of the second channel 31 this second channel 31 can be divided into four blocks, each about 1.5 MHz, and the remaining approximately 1 MHz can be used for protective frequency spacing 50 between the individual blocks 40 and the protective frequency spacing 45 between the spectrum 41 of the digital signal and the upper limit frequency f2the first channel 30, respectively, the lower limit frequency f3the third channel 32.

When bandwidth of about 8 MHz for the second channel 31 this second channel 31 can also be divided into four blocks, each about 1.5 MHz, and the remaining approximately 2 MHz can be used for protective frequency spacing 50 between the individual blocks 40 and the protective frequency spacing 45 between the spectrum 41 of the digital signal and the upper limit frequency f2the first channel 30, respectively, the lower limit frequency f3the third channel 32. Due to the modulation in the modulator 15 range 41 of the digital signal is limited to a specified value that creatures. In addition, due to the modulation dynamic range 100 and the amplitude spectrum 41 of the digital signal are limited to a set value, which is significantly less dynamic range, respectively, the carrier amplitude image resolution spectra 35 and 36 of the analog signals of the first and third channels 30 and 32.

Thus, there is only a small mutual and cross-modulation of digital signals between themselves and with the digital signals of the first and third channels 30 and 32. Use one of the above methods of modulation and digital signal levels that are significantly below the levels of the analog signals makes it possible to avoid the peak levels in the digital signal. Due to this and due to the protective frequency spacing 45 between the spectrum 41 of the digital signal and the upper limit frequency 2the first channel 30, respectively, the lower limit frequency f3the third channel 32 to decrease the interference of analog television signals in the receiver with limited selectivity.

Protective frequency spacing 50 between separate blocks of spectrum 40 41 digital signal are used to explode the blocks 40 contained therein cyfrowa. The effect on digital signals in the receiver by entering and accepting a parallel analog broadcast signals is negligible due to the high noise immunity when the selected transmission and signal processing in digital form and, if necessary, when using block methods of error correction, seals pulse signals and/or external protection against errors, for example, by the method of reed-Solomon.

In each of the four blocks 40 according to Fig. 2 can be placed at least six stereo radio for data compression according to the standard ISO 11172 MPEG Layer 2 or the transferred at least one TV program for data compression standard MPEG 1 or 2. ISO 11172 MPEG Layer 3 on one of the 1.5 MHz to the first block 40 can extend from six to twelve sound radio at the transmission rate of 128 kbps for audio broadcast standard MPEG-4 allows for the expansion of the number of television programmes in the 1,5 MHz to the first block until at least two. In the second channel 31 to a digital signal separately or blocks can be transferred to other digital additional signals or other signal information. These include, for example, such information services as Pei is the case, stock data, transport timetables, etc.

For classes of prohibited channels in the ultra high frequency (UHF) range can also be used in the digital broadcasting signals [(DTV signals (digital video broadcasting)], which is currently defined only for 8 MHz of the first field. When sizing 7 MHz-new fields for DTV signals it is possible to provide the lesson of forbidden bands in the range of very high (VHF) frequencies. Moreover, according to Fig. 6 in the second channel 31 is passed closed the encoded block 40 frequency with protective frequency spacing 45 on the borders with the neighboring channels 30 and 32.

Additional lesson forbidden channels on the territory of the standard PAL B/G can be quantified as follows:

Band 1 (VHF): additional 7 MHz-a new channel, if TV programmes busy channel E2, having a carrier frequency image 48,25 MHz, and channel E4, having a carrier frequency image 62,25 MHz, two additional 7 MHz output channel, if only busy channel E3 having a frequency 55,25 MHz carrier image.

Band III (VHF): four additional 7 MHz output channel or more, depending on the classes of analog-to-modelirovanie from the analog-modulated TV programs.

The V band (UHF): fourteen additional 8 MHz o channels or more, depending on the classes of analog-modulated TV programs.

In yet another exemplary embodiment according to Fig. 3 implemented the lesson of the first channel 30 and the third channel 32 range of analog broadcasting signal 35, 36 respectively, as in Fig. 2. However, the range of 41 digital signal in the second channel 31 is divided into three blocks 40, spaced apart from one another protective frequency spacing of 50 with bandwidth fS2and separated from the upper limit frequency f2the first channel 30 and the lower limit frequency f3the third channel 32, respectively, protective frequency spacing 45 with bandwidth fS1. This implementation is suitable when using 6 MHz of the first field and the width of the block is approximately 1.5 MHz. The remaining approximately 1.5 MHz are used for protective frequency spacing 50 between the individual blocks 40 and the protective frequency spacing 45 between the spectrum 41 of the digital signal and the upper limit frequency f2the first channel 30, respectively, the lower limit frequency f3the third channel 32.

Then there is a possibility instead of 1.5 MHz-o select blocks and also other W is Anenii I want-modulation method you can use, by broadcasting on a General wave in the service area of a television station, one and the same frequency in the same channel for the same program transmitted by different transmitters.

In Fig. 4 position 55 designated receiver with a receiving antenna 60, which is connected through a band-pass filter 65 and the demodulator 70 with the demultiplexer 75. The receiver 55 contains, in addition, the decoding device 80 for digital broadcasting signals and a decoding device 81 for digital broadcasting signals. In the decoding device 80 for digital television signals are digital television signals from the demultiplexer 75, and a decoding device 81 for digital broadcasting signals are digital broadcasting signals, which are also received from the demultiplexer 75. The decoded digital broadcast signals are fed to the digital input 86 telepresence 85, and dekodirovaniya digital broadcasting signals are fed through the amplifier 90 to the speaker 95.

Adopted by the receiver 55 through the receiving antenna 60 a signal contains digital broadcast signals and digital broadcast signals, ground radiated scheme Oterom passed this digital signal. Selectively the digital signal is then fed to the demodulator 70 and it is demodulated. And, finally, the demodulated digital signal is separated in the demultiplexer 75 on two digital signal, and a digital signal contains digital TV programs, and other digital signal contains digital audio broadcasting program. In conclusion, in a decoding device 80 for digital TV programs and a decoding device 81 for digital audio broadcasting digital broadcasting, respectively, of the digital broadcasting signals are expanded. Advanced digital signal, a digital broadcasting signals are then fed to the digital input 86 of the television receiver 85, split it into individual TV programs, is subjected to digital-analog conversion and finally reproduced in the image and the sound. Advanced digital signal, a digital broadcasting signals, is fed to the amplifier 90, split it into separate audio broadcasting program, is subjected to digital-analog conversion, amplified and fed to the loudspeaker 95 for audio playback.

In other embodiments, the method sogi specified value, in some embodiments, the execution of the invention is only a restriction of the amplitude of the digital spectrum 41 the specified value. Usually in these cases there is a wider protective frequency spacing 45 on the borders with the neighboring channels 30 and 32, or apply the input stages of the receiver with a higher selectivity.

1. The way land transfer at least one digital signal, such as digital broadcasting or television signal, characterized in that it transmits at least one digital signal in at least one channel (31) adjacent at least one occupied or unoccupied channel (30,32) for transmission of analog broadcasting signal, while the dynamic range (100) spectrum (41) at least one digital signal is less than the specified value, which is significantly less than the dynamic range of the spectrum (up RUB 35.36) analog broadcast signal, and/or the amplitude spectrum (41) at least one digital signal is less than the specified value, which is significantly less than the amplitude of the carrier image analog broadcast signal.

2. The method according to p. 1, characterized in that the at least one digital signal PE is S="ptx2">

3. The method according to p. 1 or 2, characterized in that at least one of the transmitted digital signal does not exceed the given value, which is significantly less than the peak level of the analog broadcast signal.

4. The method according to any of paragraphs.1 to 3, characterized in that the at least one received digital signal is below the peak level of the analog broadcasting signal by an amount approximately 20 dB.

5. The method according to any of paragraphs.1 to 4, characterized in that the amount of data of at least one digital signal is reduced by encoding.

6. The method according to any of paragraphs.1 to 5, characterized in that the frequency range of the at least one digital signal during transmission of the at least one channel (31) is separated protective frequency spacing (45) from at least one adjacent occupied or unoccupied channel (30,32).

7. The method according to any of paragraphs.1 - 6, characterized in that the digital modulated I want-method signals of the same content are transmitted in the same service area different transmitters on the same frequency and in the frequency range of at least one channel (31).

8. The method according to any of paragraphs.1 - 7, is distinguished by the same channel (31) frequency bands of at least two digital signals are separated from one another protective frequency spacing (50).

9. The method according to any of paragraphs.1 to 8, characterized in that at least one channel (31) when the channel width of approximately 6 MHz is divided into three blocks (40) approximately 1.5 MHz each, and the remaining approximately 1.5 MHz is used as a protective frequency spacing (50) between the individual blocks (40) and as a protective frequency spacing (45) between the frequency range of the digital spectrum (41) and the upper and lower adjacent channels (32) and (30).

10. The method according to any of paragraphs.1 to 8, characterized in that at least one channel (31) when the channel width of about 7 MHz is divided into four blocks (40) approximately 1.5 MHz each, and the remaining approximately 1 MHz is used as a protective frequency spacing (50) between the individual blocks (40) and as a protective frequency spacing (45) between the frequency range of the digital spectrum (41) and the upper and lower adjacent channels (32) and (30).

11. The method according to any of paragraphs.1 to 8, characterized in that at least one channel (31) when the channel width of approximately 8 MHz divided into four blocks (40) approximately 1.5 MHz each, and the remaining approximately 2 MHz is used as a protective frequency spacing (50) between the individual blocks (40) and as a protective frequency spacing (45) between often is the Bohm PP.1 - 8, wherein the at least one channel (31) transfer closed encoded, in particular containing signals of a digital television broadcasting (DTV signals), block (40) frequencies with a protective frequency spacing (45) on the borders with the neighboring channels (30) and (32).

 

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