JP2012156736A - Compression-coded signal transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system for transmitting a piecewise compression-coded signal which implements improved transmission quality of a low level signal.SOLUTION: The compression-coded signal transmission system for signal transmission/reception through conversion from an analog signal to a digital signal with a linear characteristic and conversion from the digital signal with the linear characteristic to a piecewise compressed code includes: companding sections 15, 18 for conversion between the digital signal with the linear characteristic and the piecewise compression-coded signal including a one-bit polarity bit, three-bit segment bits and seven-bit step bits; and means for transmitting/receiving the piecewise compression-coded signal. The companding sections are configured to have a conversion characteristic of associating a low level range of the digital signal inclusive of zero covering the range of 0 to ±1 with patterns of the step bits of the piecewise compression-coded signal with all "1" segment bits.

Description

  The present invention relates to a compression-encoded signal transmission system that transmits a signal having linear characteristics after being subjected to polygonal line compression encoding and can improve low-level signal quality.

  In a radio broadcast system, for example, a broadcast signal is transmitted from a key station to a single or a plurality of local stations. In this case, a system that converts an analog signal into a digital signal and transmits it is applied. ing. In this case, the digital signal is a ITU-T (International Telecommunication Union-Telecommunication Standardization Sector) recommended J.P. The polygonal line compression encoding by 41 is applied. This broken line compression encoding method includes a variant A and variant B. In Japan, variant B is applied to various places as A-law. According to this Variant B polygonal line compression encoding method, an analog signal is converted into, for example, a 24-bit digital signal having a linear characteristic of 384 kbps, and the low-order bits of the 24-bit linear characteristic digital signal are deleted to form a 14-bit structure. This is converted into an 11-bit broken line compression code consisting of 1 polarity bit, 3 segment bits, and 7 step bits, and a parity bit of even parity is added for a total of 12 bits It is to be configured.

  FIG. 4 shows the above-mentioned ITU-T J.P. 41 is an explanatory diagram of a polygonal line compression encoding according to No. 41, (A) shows a polygonal line compression encoding curve, (B) shows the name of each bit, the vertical axis in FIG. 4 (A) is the signal level, and the horizontal axis Indicates a segment name, and a digital signal having a linear characteristic of +8192 to 0-8192 is defined as a sixth segment with a range of −256 to −128 to 0 to +128 to +256 as a single broken line centered on the 0 level. The above-described range of ± 256 to ± 8192 is defined as the first to fifth broken lines, and the digital signal having a 14-bit linear characteristic is converted into a broken line compression code having a total of 11 bits. Also, as shown in FIG. 5B, a 12-bit broken line compression encoded signal in which a parity bit is added to an 11-bit broken line compressed code includes a 1-bit polarity bit S and a 3-bit segment. Bits X to Z, step bits A to G having a 7-bit configuration, and parity bits P having a 1-bit configuration are illustrated, and the arrangement of each bit is “SFABZEXYCGDP” as illustrated.

  FIG. 5 shows the code relationship on the positive polarity side of the polygonal line compression encoding. The input level range, the output standard value, the step size Δi, the segment No. And the 11-bit compression code “SXYZABCDEFG”, showing the first to fifth segments and the sixth segment on the positive polarity side of the polygonal line compression coding curve shown in FIG. Δi = 32, second segment Δi = 16, third segment Δi = 8, fourth segment Δi = 4, fifth segment Δi = 2, and sixth segment Δi = 1 . In the range of the input level 0 to ± 8192, the sixth segment is encoded with the step size Δi = 1 within the range of the input level 0 to ± 256.

  FIG. 6 shows a schematic flowchart of the received signal processing. When the current received signal Xn is normally received, the receiving process is sequentially repeated with Yn = Xn (S1). When an error occurrence is detected in the received signal Xn, that is, when an error occurrence is detected using the parity bit P, or when an error is displayed with the segment bit XYZ set to “111”, the received signal Xn− before the current received signal Xn is displayed. 1 is processed as a received signal instead of the current received signal Xn (Yn = Xn-1) (S2). If there are two consecutive errors, that is, errors in the received signals Xn−1 and Xn, Yn = Yn−1 and the received signal one sample before is repeated and processed as a received signal (S3). If such an error occurs three times, that is, if there are three consecutive errors of Xn, Xn-1, and Xn-2, reception processing is performed as Yn = 0.9 * Yn-1 (S4). This indicates that, in the case of three consecutive errors, the output level is reduced by 10% to suppress an abnormal level increase in the received / reproduced analog signal, and reception when an abnormal transmission occurs in the analog audio signal transmission / reception system. Means are applied to avoid an abnormal increase in the reproduced audio signal level due to an abnormal increase in level.

  FIG. 7 is a schematic explanatory diagram of a conventional broadcast signal transmission system, showing an outline in the case of transmission as the above-mentioned broken line compression encoded signal. The key station 100, an existing local station 101, and a newly installed local station 102 are shown. , 103 is a demultiplexing unit, 104 is a multiplexing unit, 110 is an A / D conversion unit, 111 is a transmission broadcast processing unit, 112 is a D / A conversion unit, and 113 is a reception selection processing unit. The local stations 101 and 102 show only functional parts of the D / A converter and the A / D converter, and the A / D converter and the D / A converter are respectively J.A. 41 includes compression encoding and decoding functions. The broadcast audio signal is converted into a digital signal by AD conversion and polygonal line compression encoding in the A / D conversion unit 110 of the key station 100, and is copied to the local stations 101 and 102 by the transmission broadcast processing unit 111. Then, it inserts into successive time slots as shown by # 2, # 3, performs multiplexing processing and transmits. The time-multiplexed digital signals are separated by the separation unit 103 corresponding to the time slots and transmitted to the local stations 101 and 102, respectively. The local stations 101 and 102 are connected to J.I. 41. A digital signal that has been compression-encoded is received, decoded into a linearly encoded signal by the D / A converters 115 and 117, converted into an analog signal, and broadcast as an audio signal for broadcasting by a transmission means (not shown). Transmit from the antenna. Also, the relay signals collected or created in the local stations 101 and 102 are converted into digital signals by the A / D converters 116 and 118, are subjected to polygonal line compression coding, and sent to the key station 100 via the multiplexing unit 104. Send. The key station 100 selects a digital signal from one of the local stations 101 and 102 received and processed by the reception selection processing unit 113, decodes it into a linearly encoded signal by the D / A conversion unit 112, and converts it into an analog signal. It is converted into a relay signal and transmitted to the broadcast or another local station.

  In a system for multiplexing and transmitting a plurality of systems of digital broadcasting signals from the key station to the local station, when the digital broadcasting signal is an image signal compressed and encoded by predictive encoding, the system is switched A means for enabling smooth switching on the reception and reproduction side has been proposed (see, for example, Patent Document 1). J. When audio signals are transmitted by applying 41 compression encoding, the lower 10 bits of a 24-bit digital signal by A / D conversion are discarded, and a linear code digital signal of 1-bit code bit and 13-bit is obtained. J. When converting to a 11-bit broken line code according to the 41 compression encoding method, means for adding a noise component as a digital signal or an analog signal in advance in order to eliminate the influence of the noise component due to the change of the least significant bit. It has been proposed (see, for example, Patent Document 2). As quantization means, there are a Mid-rise type and a Mid-tread type, and a Mid-rise type quantizer has the characteristics that the output does not include 0, ± 1, ± 3,... , Mid-tread type quantizers have characteristics such that the output includes 0 and becomes ± 2, ± 4,..., Combining them to form a feedback circuit, and the noise of the analog processing circuit Means for shaving has been proposed (see, for example, Patent Document 3).

JP 2003-284074 A JP 2009-296696 A JP 2010-74652 A

  J. The 41 compression coding is applied to a broadcasting signal transmission system and the like, which digitizes an analog signal and further performs line compression coding to improve the transmission efficiency. As in J. The 41 encoding method converts an analog signal into a digital signal by 14-bit linear encoding, and further performs 11-bit broken line encoding, and converts 16,384 signals into 2,048 signals. By assigning to, compression encoding is performed. In this case, the sample value in the range of +255.5 to 0-255.5 centered on 0 is a value corresponding to the uncompressed region, but includes quantization noise when decoded into an analog audio signal. In many cases, the high-quality sound reproduction apparatus has a problem that the reception reproduction sound includes noise.

  In addition, as means for improving signal quality by suppressing noise components, the Mid-rise type and Mid-tread type quantizers disclosed in Patent Document 3 above are combined, and noise component suppression is performed by feedback control. The means for achieving this has a complicated circuit configuration based on feedback control, converts the signal fed back via the noise shaping circuit into an analog signal, and subtracts it from the input analog signal. It is impossible to achieve a low level of quality improvement. In addition to the improvement in the characteristics of the audio signal reproducing apparatus including the radio broadcast receiving apparatus, the characteristics of the broadcasting facilities of the new local station or the existing local station are improved. However, the broadcast signal transmitted from the key station side to each local station is, as described above, J.P. It is compression-encoded by the 41 encoding method, and is sent out as a 12-bit configuration including parity bits. Before compression, the analog signal is converted into a digital signal having a 14-bit configuration, so the minimum amplitude in that case is −73 dBm It is usually a level that can be heard slightly. Thus, within the range corresponding to the sixth segment, this corresponds to a case where a 14-bit digital signal is uncompressed, and there is a problem that quantization noise is reproduced due to the improvement of the characteristics of the audio signal reproducing device.

  The present invention aims to solve the above-mentioned problems of the conventional example, and it has a conventional reception characteristic for the existing transmission / reception station, and low for the new transmission / reception station and the characteristic improvement equipment introduction station. It is possible to improve the level signal quality.

  The compression-coded signal transmission system of the present invention is a compression-coded signal transmission system that converts an analog signal into a digital signal having a linear characteristic, and transmits / receives a signal obtained by converting the digital signal into a polygonal line compression code. A companding unit for converting a digital signal, a 1-bit polarity bit, a 3-bit segment bit, and a 7-bit step-bit encoded signal, and a transmission / reception unit for the bent-line compression-coded signal; The companding unit associates the low-level range including 0 in the range of 0 to ± 1 of the digital signal with the step bit pattern by setting all the segment bits of the polygonal line compression encoded signal to “1”. The configuration including the conversion characteristics.

  The companding unit has a function of performing a conversion process between a digital signal having a linear characteristic and a polygonal line compression encoded signal, the digital signal having the linear characteristic is associated with 0 of the polygonal line compression encoded signal, It has a conversion characteristic in which a range of 0 to ± 1 of a linear characteristic digital signal is associated with the step bit pattern of the broken line compression encoded signal, and the segment bits are all “1”.

  The transmission / reception means includes means for time-division-multiplexing and transmitting the polygonal line compression encoded signal corresponding to a plurality of reception sides of the polygonal line compression-encoded signal by the companding unit; And a means for receiving an encoded signal by time division processing.

  In signal transmission systems such as broadcast signals, in response to the improvement in reception and reproduction characteristics, a polygonal line compression coding is applied to improve transmission efficiency, and a low-level signal is transmitted almost accurately, It is possible to improve the reproduction quality.

It is explanatory drawing of Example 1 of this invention. It is explanatory drawing of the polygonal line compression encoding signal of the low level signal of Example 1 of this invention. It is principal part explanatory drawing of the transmission system of Example 1 of this invention. It is explanatory drawing of the segment structure of a broken line compression coding signal. It is explanatory drawing of the code | cord | chord relationship by the side of the positive polarity of broken line compression encoding. It is a schematic flowchart of a received signal process. It is outline | summary explanatory drawing of the broadcast signal transmission system of a prior art example.

  The compressed encoded signal transmission system of the present invention will be described with reference to FIG. 1. A compressed encoded signal for converting an analog signal into a digital signal having a linear characteristic and transmitting / receiving a signal obtained by converting the digital signal into a polygonal line compression code. A companding unit 15 for converting a linear digital signal, a polarity bit of 1 bit, a segment bit of 3 bits, and a polygonal line compression encoded signal including 7 step bits; 18 and a transmission / reception means for the polygonal line compression encoded signal, and the companding unit includes all of the low level range including 0 in the range of 0 to ± 1 of the digital signal and the segment bit of the polygonal line compression encoded signal. 1 ″ includes a configuration including conversion characteristics corresponding to the step bit pattern.

  FIG. 1 is an explanatory diagram of Embodiment 1 of the present invention, where 1 is an input / output unit, 2a and 2b are 0-system and 1-system code conversion function units, 3 is an optical interface unit, and 4 is a supervisory control function unit Reference numeral 5 denotes a power supply unit, and 6 and 7 denote monitor signal branching units. Reference numeral 11 denotes an analog input unit, 12 denotes an analog output unit, 13 denotes an A / D conversion unit, and 14 denotes a D / A conversion unit. Left (L) and right (R) (right) for stereo application , 15 and 18 are companding sections, 16 and 17 are branch sections, 19 is an HSD (High Super Digital) section, and the HSD section 19 includes a photoelectric conversion function and an electro-optic conversion function section. The optical switch of the optical interface unit 3 is used to switch the transmission optical signal between the 0-system and the 1-system, and the received optical signal is branched by the optical coupler to the H-system unit 19 of the 0-system and the 1-system. input. In addition, the power supply unit 5 includes a power supply having a dual configuration of the 0 system and the 1 system, and includes a super capacitor that is constantly charged to cope with a power failure of the AC power supply unit. The monitoring control function unit 4 includes an audio monitor unit, and can monitor the audio input signal and the audio output signal branched by the monitor signal branching units 6 and 7. Since the 0-system and 1-system code conversion function sections 2a and 2b have the same function, the internal function portions are denoted by the same reference numerals.

  Further, when there are a plurality of receiving sides, the branching unit 16 of the code conversion function units 2a and 2b can receive, for example, a 12-bit broken line compression encoded signal shown in FIG. 4B corresponding to a plurality of receiving sides. Each slot is inserted and time multiplexed, and transmitted via the HSD unit 19 and the optical interface unit 3, and the branch unit 17 multiplexes the signal from the transmission side in the selected time slot in the received multiplexed signal. The separated signal is input to the D / A converter 14 and converted into an analog signal. The companding units 15 and 18 include a conventional broken line compression encoding / decoding unit and a broken line compression encoding / decoding unit for improving the quality of a low-level signal, which will be described later. In accordance with the reception processing function of the conventional example, there is provided means for time-multiplexing the conventional polygonal line compression encoded signal and the low-level signal high-quality polygonal line compression encoded signal in units of time slots as described above. It is a waste. If reception side capable of receiving and decoding a polygonal line compression encoded signal for improving the quality of a low level signal becomes widespread, the conventional polygonal line compression encoding means will attempt to improve the quality of all the low level signals. The configuration is a polyline compression encoding / decoding unit.

  2A and 2B are explanatory diagrams of a polygonal line compression encoded signal for improving the quality of a low level signal according to the first embodiment of the present invention. FIG. 2A is an input / output characteristic curve diagram, and FIG. 2B is a polarity bit S and a segment. An example of bit XYZ, step bits A to G, and input / output values is shown. When the input signal level is a value close to 0, the compression encoding is set to +0.5 for positive polarity and -0.5 for negative polarity, and a mid-rise system that does not include 0 in the output signal, It is known that the signal level is in the range of −0.5 to +0.5, the Mid-tread method is 0, −0.5 or less is −1, +0.5 or more is +1, and (A) The input / output curve shown in FIG. 4 is configured based on the Mid-tread method including the case where the output is 0. When the input signal level is in the range of −0.125 to 0 to +0.125, the output signal level is , 0, polarity bit S = "1", segment bit XYZ = "111", and step bits A to G = "1111111". When the input signal level is +0.125 to +0.375, the polarity bit S = “1”, the segment bit XYZ = “111”, and the step bits = A to G = “1111110”. When the input signal level is −0.125 to −0.375, the polarity bit S = “1”, the segment bit XYZ = “111”, and the step bits = A to G = “1111101”. Conventionally, the segment bit XYZ = “111” indicates the occurrence of an error, and the step bits A to G in this case are ignored, but in the present invention, as described above, the segment bit XYZ = In the case of “111”, the compression code of the low level signal is set by the step bits A to G.

  In the case shown in FIG. 2, the polarity bit S = "1" and the segment bit XYZ = "111" indicate the polarity depending on the contents of the segment bits A to G. For example, the polarity bit S = "" “1” indicates a positive polarity, S = “0” indicates a negative polarity, and when the segment bit XYZ = “111”, the step bits A to G are set to “1111110”, the signal level is 0, and the step bits A to Assuming that G is “1111101”, signal level 0.125 of signal levels 0 to 1 and step bits A to G are “1111110”, signal level 0.375 can be indicated. The level range from 0.375 to 1.0 can also be indicated by step bits A to G. In this case, it is also possible to display the occurrence of an error in the same manner as in the conventional example by setting the segment bits XYZ to all “1” and the step bits A to G to all “1”.

  FIG. 3 is an explanatory diagram of the transmission system of the embodiment of the present invention, and is a schematic explanatory diagram when applied to a broadcast signal transmission system. In this figure, 31 is a key station, 32 is an existing local station, 33 is a new local station including means for improving the quality of low level signals, 34 is a demultiplexing unit, 35 is a multiplexing unit, and 40 is an A / D. Conversion unit, 41 is a transmission broadcast processing unit, 42 is a D / A conversion unit, 43 is a reception selection processing unit, 44 is a pattern recognition unit, 51 is a D / A conversion unit, 52 is an A / D conversion unit, and 53 is A transmission / reception processing unit, 54 is a pattern selection unit, 55 is an A / D conversion unit, 56 is a D / A conversion unit, and 57 is a pattern recognition unit. The broadcasting audio signal is converted into a digital signal by the A / D conversion unit 40 of the key station 31, and J.I. As described with reference to FIG. 2, the segment bit XYZ is set to “111”, and the segment bits XYZ including the low level signal are subjected to the polygonal line compression encoding. Means for generating a high-quality B pattern in parallel is included.

  The transmission broadcast processing unit 41 is a J.M. In order to transmit the A pattern signal # 2 of the broken line compression encoded signal according to the 41 encoding method and the B pattern signal # 3 obtained by improving the quality of the low level signal to the newly installed local station and the existing local station. Includes, for example, means for time-multiplexing transmission processing corresponding to the time slot, and the separation unit 34 separates the A pattern signal # 2 and the B pattern signal # 3, so that the local station 32 having the transmission / reception function of the conventional example is provided. On the other hand, the A pattern signal # 2 is transmitted, and the D / A converter 51 receives and decodes the A pattern signal # 2 subjected to the polygonal line compression encoding from the key station 31, and converts it into an analog signal. The audio signal for broadcasting is used. Also, the relay signal and the like are converted into a digital signal by the A / D converter 52, and the J.P. The A pattern signal # 2 subjected to polygonal line compression encoding according to the 41 encoding method is transmitted to the key station 31 via the multiplexing unit 35.

  The new local station 33 receives the B pattern signal # 3 from the key station 31 via the separation unit 34, and the pattern recognition unit 57 uses the B pattern signal # 3 to improve the quality of the low level signal. When the segment bit XYZ is “111”, the D / A conversion unit 56 converts the low level signal by the step bits A to G into a low level analog signal to obtain a broadcast audio signal. For the relay signal and the like, the A / D conversion unit 55 performs A and B pattern polygonal line compression encoding processing, and the transmission processing unit 53 selects according to the processing function on the reception side. By the recognizing unit 57, the key station 31 recognizes the transmission by the B pattern by the pattern recognizing unit 57 and notifies the transmission processing unit 53 of the information, so that the pattern selecting unit 54 of the transmission processing unit 53 The B pattern signal # 3 is selected and transmitted to the key station 31 via the multiplexing unit 35. The key station 31 determines that it is the B pattern signal # 3 by the pattern recognition unit 44 of the reception selection processing unit 43, and relays the high quality signal by the decoding process including the low level signal in the D / A conversion unit 42. Send out as a signal.

  As described above, transmission signals from the key station 31 to a plurality of local stations are generally managed in units of time slots and in association with the transmission order and local station numbers. Also, the key station 31 transmits and receives the polygonal line compression encoded signals from a plurality of local stations, for example, by time division multiplexing for each time slot, and manages the time slot number and the local station number in association with each other. As a result, the B pattern signal # 3 is received from the newly established local station 33, for example, by the pattern recognition unit 44 of the reception selection processing unit 43 of the key station 31 without transmitting / receiving the information on the existing or newly installed segment bit. When XYZ is “111” and, for example, a continuous line compression code is performed three or more times continuously, the reception selection processing unit 43 determines that the local station 33 has a new facility, and the transmission broadcast processing unit 41. To notify. Based on this, the key station 31 transmits a transmission signal for the local station 33 as a B pattern signal # 3. As a result, the key station 31 and the plurality of local stations 32 and 33 can respectively determine whether or not high-quality signal transmission is possible. It is possible to transmit the level signal and contribute to the improvement of the quality of the transmission signal.

DESCRIPTION OF SYMBOLS 1 Input / output part 2a, 2b Code conversion function part of 0 system and 1 system 3 Optical interface part 4 Supervisory control function part 5 Power supply part 6,7 Monitor signal branch part 11 Analog input part 12 Analog output part 13 A / D conversion Unit 14 D / A conversion unit 15, 18 Rolling unit 16, 17 Branch unit 19 HSD unit

Claims (3)

In a compression encoded signal transmission system that converts an analog signal into a digital signal having a linear characteristic, and transmits and receives a signal obtained by converting the digital signal into a polygonal line compression code.
A companding unit for converting the digital signal having the linear characteristics, the polygonal line compression encoded signal including one polarity bit, 3 segment bits, and 7 step bits; and the polygonal line compression encoded signal Transmission / reception means,
The companding unit associates the low-level range including 0 in the range of 0 to ± 1 of the digital signal with the step bit pattern by setting all the segment bits of the broken line compression encoded signal to “1”. A compressed encoded signal transmission system comprising a configuration including the converted conversion characteristics.   The companding unit has a function of performing a conversion process between a digital signal having a linear characteristic and a polygonal line compression encoded signal, the digital signal having the linear characteristic is associated with 0 of the polygonal line compression encoded signal, A conversion characteristic in which a range of 0 to ± 1 of a digital signal having a linear characteristic is associated with a pattern of the step bit of the broken line compression encoded signal and the segment bit is all “1” is provided. The compression-coded signal transmission system according to claim 1.   The transmission / reception means includes means for time-division-multiplexing and transmitting the polygonal line compression encoded signal corresponding to a plurality of reception sides of the polygonal line compression-encoded signal by the companding unit; 3. The compressed encoded signal transmission system according to claim 1, further comprising means for receiving the encoded signal and receiving the encoded signal by time division processing.

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