JP2007282159A - Uplink confluent noise eliminating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate confluent noise without complicated adjustment work, without affecting the transmission of an uplink signal. <P>SOLUTION: In an uplink signal path 24 for transmitting an uplink signal in a two-way community reception device, a level controller 26 constituted of an equalizer 28 and a variable attenuator 30 is provided. The level of an uplink noise signal on the uplink signal path 24 is detected by a detector 40, and an uplink noise level detecting signal is generated. The uplink noise level detecting signal is supplied to a control unit 36, and the control unit 36 controls the equalizer 28 and the variable attenuator 30 or only the variable attenuator 30 so that the uplink noise level detecting signal becomes a reference value or lower. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus for removing upstream inflow noise transmitted to a center apparatus side in a bidirectional joint receiving apparatus.

  One of the problems in the bidirectional joint receiver is inflow noise. Ingot noise is a phenomenon in which noise is concentrated on the trunk line in a bidirectional joint receiver. Inflow noise occurs in upstream communication from the terminal device of each home to the center device of the bidirectional joint reception device, and hinders a service with directionality such as an Internet connection service.

  Patent Document 1 discloses a technique for removing this inflow noise. In the technique of Patent Document 1, a variable attenuator is provided for each of a plurality of terminals that supply an uplink signal from each terminal device to an uplink amplifier of a bidirectional amplifier. The variable attenuator can transmit the upstream signal to the center device side in the non-attenuated state, but can substantially prevent the first attenuation state larger than the non-attenuated state and transmission of the upstream signal to the center device side. The second attenuation state having a large attenuation amount can be switched to a selected one. In this technique, each variable attenuator is set to the first attenuation state one by one, and the center device detects which infusion noise is reduced when which variable attenuator is in the first state. By identifying the terminal where the noise that most affects the noise is generated and setting the variable attenuation means connected to the terminal to the second attenuation state, the infusion noise is transmitted to the center device. Blocking.

JP 2003-111043 A

  However, in the above technique, a worker is arranged on the center device side and each bidirectional amplifier, the worker operates the variable attenuation means in order, the result is checked on the center device side, and the check result is again displayed on both sides. It is necessary to contact a worker on the side of the amplifier and to operate the variable attenuation means of the bidirectional amplifier, which requires a lot of time for adjustment work. In addition, since many bidirectional amplifiers are used in the joint receiving apparatus, it takes a lot of time to perform such adjustment for all the bidirectional amplifiers. In addition, an upstream signal supplied to a terminal having a high noise level cannot be transmitted to the center device side.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an infusion noise removing apparatus capable of removing infusion noise without affecting uplink signal transmission and without troublesome adjustment work.

  In the infusion noise eliminating apparatus according to one aspect of the present invention, the upstream noise level adjusting means is interposed in the upstream signal path through which the upstream signal is transmitted in the bidirectional joint receiver. This upstream signal path can be formed, for example, in various devices such as bidirectional amplification means interposed in the line of the bidirectional joint receiver. As the upstream noise level adjusting means, one capable of adjusting the level by supplying a control signal can be used. Upstream noise level detection means generates an upstream noise level detection signal by detecting the level of upstream noise in the upstream signal path. Detection of the level of upstream noise can be performed on the input side or output side of the upstream signal path. The control means controls the upstream noise level adjustment means so that the upstream noise level detection signal is not more than a reference value.

  In the infusion noise eliminating apparatus configured as described above, the upstream noise level adjusting means is automatically adjusted by the control means so that the upstream noise level detection signal is equal to or less than the reference value. There is no problem, and there is no problem in transmitting the upstream signal itself to the center apparatus side. Note that the control by the control means can be performed continuously.

  Further, the upstream signal may have an upstream frequency band that is a predetermined frequency band. In this case, the level detecting means detects a frequency characteristic of the upstream noise signal in the upstream frequency band. That is, the upstream noise level detection signal represents each noise level from the lower limit frequency to the upper limit frequency of the upstream frequency band. It is also possible to detect the noise level at appropriate intervals instead of the noise level at all frequencies from the lower limit frequency to the upper limit frequency. In order to detect the frequency characteristics of the noise, it is desirable that the upstream noise level detecting means includes a receiving means capable of receiving an upstream frequency band signal. The level adjusting means is controlled by the control means so that the peak level in the upstream frequency band detected by the upstream signal level detecting means is not more than the reference value. It should be noted that the detection of the upstream noise level by the upstream noise level detecting means is desirably performed in the absence of the upstream signal.

  With this configuration, it is possible to automatically adjust the noise peak level in the frequency band of the upstream signal to a reference value or less, and to reduce the influence of the peak level noise that most affects the infusion noise.

  Furthermore, the level adjusting means may include an equalizer that changes a frequency characteristic of the upstream noise signal and a level attenuating means that attenuates the level of the upstream noise signal.

  With this configuration, the frequency characteristics of the noise signal can be adjusted by the equalizer so as to lower the peak level, and then the level of the upstream noise signal can be attenuated by the noise level attenuation means. It can be easily adjusted. It is also possible to adjust the frequency characteristic using an equalizer after the level of the upstream signal is attenuated by the level attenuation means.

  The control means determines whether the frequency characteristics of the upstream noise level detection signal correspond to a plurality of patterns having different peak level frequencies, and the equalizer and the noise level attenuation means according to the determined pattern or The noise level attenuation means can be adjusted. The control unit includes a pattern determination unit that determines which of a plurality of patterns having different peak level frequencies, and an adjustment unit that adjusts the equalizer and the noise level adjustment unit or the noise level adjustment unit according to the pattern determination result. It is desirable to have.

  With this configuration, for example, when there is a peak on the lower limit side of the upstream frequency band, when there is a peak near the center, or when there is a peak on the upper limit side, the state corresponding to the position where the noise peak is present The equalizer and level adjusting means can be adjusted quickly.

  The uplink frequency band may be composed of a plurality of different frequency bands. In this case, the noise level adjusting means is adjusted in a frequency band selected from different frequency bands. The level adjustment unit can adjust the level by supplying the upstream noise signal input to the level detection unit to a signal extraction unit, for example, a filter, and extracting the upstream noise signal of each frequency band.

  If comprised in this way, a noise peak level can be appropriately adjusted to below a reference value with respect to each frequency band from which an upstream signal differs.

  As described above, according to the present invention, the level of the upstream noise signal can be automatically reduced below the reference value without affecting the transmission of the upstream signal to the center device side.

  The upstream inflow noise canceling apparatus according to the first embodiment of the present invention is provided in a bidirectional amplifier used in a bidirectional joint receiving apparatus as shown in FIG. It has been. The bidirectional joint reception device includes a center device (not shown), the center device includes a head end device, and the head end device is a downstream signal, for example, a terrestrial television broadcast signal, a satellite broadcast signal, a satellite communication signal, or the like. Is output. This downlink signal is transmitted to a plurality of terminal devices via a transmission path. In this embodiment, this transmission path includes a trunk line 4 and a plurality of branch lines 6... Are not shown, but also has a plurality of branch lines on the downstream side of the trunk line 4. That is, the transmission path is branched into a plurality of parts. There are various forms of transmission lines other than those shown in the drawings, and any of these forms can be used.

  A bi-directional branch amplifier 2 is provided at a branch point between the main line 4 and the branch line 6. The bi-directional branch amplifier 2 amplifies the downstream signal transmitted from the center apparatus and attenuated during transmission through the main line 4 and supplies it to each branch line 6 and further to the bi-directional branch amplifier (not shown) on the downstream side of the main line 4. . Each branch line 6 has a branching means, for example, a plurality of bidirectional four branching devices 8..., And a terminal device (not shown) provided in the detached house or the apartment 10 from these four branching devices 8. Is provided with a downstream signal.

  An upstream signal, for example, an Internet communication signal is transmitted from each terminal device, and is supplied to the bidirectional branching amplifier 2 via the bidirectional four branching devices 8... And amplified here, and the trunk line 4 is directed upstream. Transmitted to the center device. The center device appropriately processes the upstream signal and enables, for example, Internet communication. The upstream signal is a signal in an upstream frequency band, which is a frequency band different from the downstream signal, for example, a frequency band of 10 to 50 MHz, and is composed of n channels.

  When an uplink signal is transmitted from each terminal device and supplied to the bidirectional branch amplifier 2, noise may also be transmitted from the terminal device side. When noise is supplied to the main line 4 from each terminal device, and these are joined together and transmitted to the center device, the upstream signal is buried in the noise joined from many branch lines 6, and Internet communication based on the upstream signal May become impossible.

  Such noise is generated from various terminal devices, but there is a terminal device that generates a large level of noise among them. By suppressing this large level of noise, inflow noise can be reduced.

  Therefore, the bidirectional branch amplifier 2 is configured as shown in FIG. The bi-directional branch amplifier 2 has an input / output terminal 12, to which the downstream signal as described above is supplied from the center device side. This downstream signal is supplied to the downstream path 16 via the demultiplexer / mixer 14. Although not shown, the downstream path 16 is provided with a downstream amplification stage, whereby the downstream signal is amplified and supplied to the input / output terminal 20 via the demultiplexer / mixer 18. An amplified downlink signal is supplied from the input / output terminal 20 to a branching unit (not shown), for example, a four-branch, which is branched to each branch line 6 and transmitted to the downstream side of the trunk line 4.

  Upstream signals from the downstream sides of the branch lines and the main line 4 are supplied from the four branching units to the input / output terminal 20. This upstream signal is supplied to a distributing means, for example, a two distributor 22 through a distributor / mixer 18. The two distributors 22 distribute the upstream signal, and one of them is supplied to the upstream signal path 24. The upstream signal path 24 communicates with the demultiplexer / mixer 14 and has an upstream amplification stage (not shown). The upstream amplification stage amplifies the upstream signal.

  Noise level adjusting means, for example, a level adjuster 26 is provided on the input side or output side of the upstream amplification stage. The level adjuster 26 includes frequency characteristic adjusting means such as an equalizer 28 and level attenuating means such as a variable attenuator 30, which are connected in cascade.

  The equalizer 28 is capable of adjusting frequency characteristics at least in the upstream frequency band in accordance with the control signal supplied from the D / A converter 32. For example, the equalizer 28 is configured to lower the level in the upper frequency band of the upstream frequency band. A first tilt characteristic that is greater than the level in the frequency band, and conversely, a second tilt characteristic in which the level in the upper frequency band of the upstream frequency band is smaller than the level in the lower frequency band; In addition, the tilt can be adjusted in the first and second tilt characteristics.

  The variable attenuator 30 attenuates the level in the entire upstream frequency band in accordance with the control signal supplied from the D / A converter 34.

  The D / A converters 32 and 34 supply a control signal to the equalizer 28 and the variable attenuator 30 in accordance with a command from a control unit 36 constituted by control means, for example, a CPU, a memory and the like. In order to give such a command, the control unit 36 includes receiving means, for example, a tuner 38, detecting means, for example, a detector 40 and an A / D converter 42.

  An upstream signal is supplied from the two distributor 22 to the tuner 38. The tuner 38 is configured to be able to individually receive n channels of uplink signals according to instructions from the control unit 36. The reception signal of each channel is supplied to the detector 40, where the reception level is detected and a reception level detection signal is generated. The reception level detection signal is converted into a digital reception level detection signal by the A / D converter 42 and supplied to the control unit 36. When there is no uplink signal, that is, when there is no carrier, each reception level detection signal represents a noise level in each channel.

  As shown in FIG. 3, the control unit 36 stores the reception level and the presence / absence of the carrier in the detection voltage storage memory in the control unit 36 for each channel. As described above, when there is no carrier, each reception level represents a noise level.

  The control unit 36 determines the frequency characteristics of noise based on the noise level for each channel obtained in this way. For example, as indicated by reference signs a1 to e1 in FIGS. 4A to 4E, noise frequency characteristics are determined. In this case, the frequency characteristics are determined excluding the reception level of the channel in which the carrier exists.

  The noise frequency characteristic indicated by reference sign a1 in FIG. 4A has a noise peak at a low frequency in the upstream frequency band, and the noise frequency characteristic indicated by reference sign b1 in FIG. 4 has a noise peak, and the noise frequency characteristic indicated by reference numeral c1 in FIG. 4C has a noise peak at almost the center frequency of the upstream frequency band. FIG. The frequency characteristic of noise indicated by reference sign d1 has noise peaks at low and high frequencies in the upstream frequency band. The frequency characteristic of noise indicated by reference sign e1 in FIG. The band noise is almost the same value.

  By setting the peak noise level in these noise frequency characteristics to be equal to or less than a predetermined reference value rf indicated by a broken line in FIGS. 4A to 4E, inflow noise on the center device side can be reduced. . In order to make the reference value rf or less, the control unit 36 determines what pattern the determined noise frequency characteristic belongs to, and controls the equalizer 28 and the variable attenuator 30 according to the determination result.

  For example, when there is a noise peak at a low frequency as indicated by reference sign a1 in FIG. 4A, the equalizer 28 makes the frequency characteristic substantially flat as indicated by reference sign a2 (with the level in the entire upstream frequency band being substantially constant). Then, the variable attenuator 30 lowers all levels below the reference value rf as indicated by reference numeral a3. When there is a noise peak at a high frequency as indicated by reference numeral b1 in FIG. 4B, the equalizer 28 makes the frequency characteristic substantially flat as indicated by reference numeral b2, and the variable attenuator 30 as shown by reference numeral b3. Reduce all levels below the value rf. When there is a noise peak at the center as indicated by reference numeral c1 in FIG. 4C, and when there is a noise peak between a low frequency and a high frequency as indicated by reference numeral d1 in FIG. When the noise level of the entire area is substantially constant as indicated by reference numeral e1 in e), the variable attenuator 30 lowers the level below the reference value rf as indicated by reference numerals c2, d2, and e2.

  And the control part 36 performs such control continuously.

  The control of the control unit 36 is first initialized as shown in FIG. 5 (step S2). In initialization, the equalizer 28 and the variable attenuator 30 are adjusted so as to have the minimum attenuation. Next, the memory for storing the detected voltage in the control unit 36 is cleared (step S4). Then, the first channel of the upstream frequency band to be received by the tuner 38 is set (step S6). Next, the tuner 38 is controlled so that the tuner 38 receives the set channel (step S8).

  In this reception state, a value obtained by A / D converting the reception level detection signal of the detector 40 by the A / D converter 42 is stored in the memory for storing the detection voltage (step S10). Next, it is checked whether or not there is a carrier in the reception channel, and the result is stored in the memory for storing the detected voltage (step S12). Then, it is determined whether or not the processing of steps S10 and S12 has been performed for all channels (step S14). If the answer to this determination is no, the next channel is set (step S16) and the process is executed again from step S8.

  If the answer to the determination in step S14 is yes, that is, if the processing of steps S10 and S12 is executed for all channels, the noise level in the upstream frequency band is stored in the memory, and the noise frequency characteristic is determined.

  If the answer to the determination in step S14 is yes, it is determined whether the frequency characteristic stored in the detection voltage storage memory is a frequency characteristic as indicated by reference numeral a1 in FIG. 4A (step S18). If the answer to this determination is yes, adjustment 1 of the equalizer and variable attenuator is performed (step S20), and the process is executed again from step S4. If the answer to the determination in step S18 is no, it is determined whether or not the frequency characteristic stored in the detection voltage storage memory is a frequency characteristic as indicated by reference numeral b1 in FIG. 4B (step S22). If the answer to this determination is yes, the equalizer and variable attenuator adjustment 2 is performed (step S24). If the answer to this determination is no, the equalizer and variable attenuator adjustment 3 is performed (step S26). Then, following step S24 or S26, the process is executed again from step S4.

  In the adjustment 1 of the equalizer and the variable attenuator, as shown in FIG. 6A, each reception level is read from the memory and the inclination of the frequency characteristic is checked (step S28). Next, the equalizer 28 is adjusted so that the inclination is substantially flat (step S30). Then, the attenuation amount of the variable attenuator 30 is adjusted so that the overall noise level is equal to or less than the reference value rf (step S32).

  Also in the adjustment 2 of the equalizer and the variable attenuator, as shown in FIG. 6B, each reception level is read from the memory, and the slope of the frequency characteristic is checked (step S34). Next, the equalizer 28 is adjusted so that the inclination is substantially flat (step S36). Then, the attenuation amount of the variable attenuator 30 is adjusted so that the overall noise level is equal to or less than the reference value rf (step S38).

  In the adjustment 3 of the equalizer and the variable attenuator, as shown in FIG. 6C, the attenuation amount of the variable attenuator 30 is adjusted so that the peak noise level is equal to or less than the reference value rf (step S40).

  By performing control in this way, the upstream noise signal from this bidirectional amplifier is maintained below the reference value rf, and inflow noise can be reduced. In addition, since this control is continuously performed, even if the frequency characteristic of the upstream noise signal changes due to a change in the environment or the like, the peak level of the upstream noise signal is set to the reference value rf or less in response to the change. Can be maintained.

  FIG. 7 shows a bidirectional amplifier 2a according to the second embodiment of the present invention. In the bidirectional amplifier 2 a, frequency selection means, for example, a variable band pass filter 44 is provided between one distribution side of the two distributor 22 and the equalizer 28. The pass band of the band pass filter 44 is changed by a control signal from the control unit 36. Therefore, for example, when the upstream frequency band is composed of a plurality of frequency bands, for example, two frequency bands separated from each other, and only the upstream signal of one of the frequency bands is used in the bidirectional joint receiving device, Only the noise signal of the used upstream frequency band is supplied to the equalizer 28. Noise suppression in this frequency band is performed in the same manner as in the first embodiment. Even when one frequency band is used as an upstream frequency band, when this bidirectional joint reception apparatus uses only a specific frequency band, only noise in the used frequency band is transmitted to the equalizer 28. It is also possible to adjust the passband of the filter 44 to be supplied.

  The adjustment of the pass band of the filter 44 is performed by the control unit 36 in accordance with an instruction from the center device. In order to receive an instruction from the center device, a one branching device 46 is provided in the downstream path 16. The downlink signal from the center device branched by the one branching device 46 is supplied to downlink receiving means, for example, a downlink FSK receiver 48. The FSK receiver 48 receives and demodulates an instruction from the center apparatus transmitted from the center apparatus using the FSK signal, and supplies the received instruction to the control unit 36. The controller 36 adjusts the pass band of the filter 44 based on the received demodulated signal from the FSK receiver 48.

  In both the above-described embodiments, the level adjuster 26 is configured by the equalizer 28 and the variable attenuator 30, but may be configured by only the variable attenuator 30, for example. In this case, the variable attenuator 30 is adjusted so that the peak level of the frequency characteristic of the noise signal is equal to or less than the reference value rf. In both the above embodiments, the frequency characteristic of the upstream signal indicating which reception level is in which frequency in the upstream frequency band is detected. For example, an average reception level in the entire upstream frequency band is detected, and this is detected. The variable attenuator 30 can also be controlled by the control unit 36 so as to be equal to or less than the reference value rf. In this case, the equalizer 28 is unnecessary. In both of the above-described embodiments, the inflow noise elimination apparatus according to the present invention is provided in the bidirectional branch amplifier. However, the present invention is not limited to this, and an arbitrary position of the bidirectional line in the bidirectional joint receiving apparatus. Can be provided.

1 is a block diagram of a bi-directional branch amplifier provided with an infusion noise elimination apparatus according to a first embodiment of the present invention. It is a block diagram of the bidirectional | two-way joint receiving apparatus in which the bidirectional | two-way branch amplifier of FIG. 1 is used. FIG. 2 is a diagram illustrating a schematic configuration of a detection voltage storage memory provided in a control unit of the bidirectional branch amplifier of FIG. 1. FIGS. 4A to 4E are explanatory diagrams of adjustment by the variable attenuator and the equalizer according to the frequency characteristics of various noises detected by the bidirectional branch amplifier of FIG. It is a flowchart of the process which the control part of the bidirectional | two-way branch amplifier of FIG. 1 performs. 6 is a detailed flowchart of processing of the variable attenuator and equalizer adjustments 1 to 3 in FIG. 5. It is a block diagram of the bidirectional | two-way branch amplifier which provided the inflow noise removal apparatus of the 2nd Embodiment of this invention.

Explanation of symbols

24 Up-path 26 Level adjuster (level adjuster)
28 Equalizer 30 Variable attenuator (level attenuation means)
36 Control part (control means)
38 Tuner (Receiving means)
40 Detector (Reception level detection means)

Claims (5)

An upstream level adjusting means interposed in an upstream signal path through which the upstream signal is transmitted in the bidirectional joint receiver;
An upstream noise level detecting means for detecting an upstream noise signal level in the upstream signal path and generating an upstream noise level detection signal;
Control means for controlling the upstream level adjusting means so that the upstream noise level detection signal is equal to or lower than a reference value;
An upstream inflow noise removing apparatus.   2. The upstream inflow noise removal apparatus according to claim 1, wherein the upstream signal has an upstream frequency band that is a predetermined frequency band, and the level detection means detects a frequency characteristic of the upstream noise signal in the upstream frequency band. And the upstream level adjusting means is controlled by the control means so that a noise peak level in the upstream frequency band detected by the upstream noise level detecting means is equal to or lower than the reference value. .   The uplink inflow noise removing apparatus according to claim 2, wherein the uplink level adjusting means includes an equalizer that changes a frequency characteristic of the uplink noise signal, and a level attenuating means that attenuates the level of the uplink noise signal. Infusion noise elimination device.   4. The upstream inflow noise removing apparatus according to claim 3, wherein the control means determines whether the frequency characteristic of the upstream noise level detection signal corresponds to a plurality of patterns having different peak level frequencies. An upstream inflow noise removal apparatus that adjusts the equalizer and the level attenuation unit or the level attenuation unit according to a pattern. The upstream inflow noise removal apparatus according to claim 2, wherein the upstream frequency band is composed of a plurality of different frequency bands, and the noise level adjusting means is adjusted in the frequency band extracted from the different frequency bands. Noise removal device.

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