JP2009049683A - Gate device and uplink streamed noise removal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove uplink streamed noise without generating an insertion loss to a downlink signal. <P>SOLUTION: A high-pass filter 8 which passes the downlink signal transmitted in a bidirectional common reception system and low-pass filters 10, 16 which passes an uplink signal are connected in parallel. A gate 12 is interposed between the low-pass filters 10 and 16 to pass or attenuate the uplink signal according to a supplied control signal. A CPU 18 supplies the control signal to the gate 12. The downlink signal including the control signal is supplied from an external input terminal 20 to an FSK demodulation part 24, a gate control information signal included in the downlink signal is demodulated here and supplied to the CPU 18. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an upstream inflow noise removal apparatus for removing upstream inflow noise in a bidirectional joint reception system, and a gate apparatus used in the apparatus.

  In the bidirectional joint reception system, the transmission path branches from the head end side to the trunk line and the branch line, the branch line further branches, and a terminal device is arranged at each end. Downstream signals are transmitted from the head end side of the transmission path toward each terminal device, and upstream signals are transmitted from each terminal device toward the head end side. These upstream signals join at the connection point between the branch line and the branch line, and join at the connection point between each branch line and the trunk line. Infusion noise is generated due to mismatch of these connection points or noise generated from the terminal device. In order to prevent the inflow noise from being transmitted to the head end side, a gate device is provided. An example of this gate device is shown in FIG.

JP 2005-20343 A

  The gate device is opened and closed by a control signal included in a downstream signal from the head end. Therefore, although not disclosed in Patent Document 1, in the gate device, a downlink signal is branched by a branching device, and a control signal is extracted from the branched downlink signal.

  However, when the branching device is used as described above, an insertion loss occurs, and the downstream signal transmitted downstream from the gate device is attenuated. Such a loss is undesirable because it greatly affects the operating level of the joint reception system.

  It is an object of the present invention to provide a gate device that reduces the insertion loss of a downstream signal and a merging noise elimination device that uses this gate device.

  The gate device according to one aspect of the present invention includes a downlink signal transmission path that is transmitted through the bidirectional joint reception system, and an uplink signal transmission path that is connected in parallel to the downlink signal transmission path. . Gate means is interposed in the transmission path of the upstream signal, and the upstream signal is passed, attenuated or cut according to the supplied control signal. The control means supplies the control signal to the gate means. At least the downstream signal is supplied to the external input terminal. The control means generates the control signal based on the downlink signal supplied from the external input terminal.

  In the gate device configured as described above, a downstream signal necessary for controlling the gate means is supplied from the outside of the gate device. Therefore, it is not necessary to provide a branching device or the like in the gate device, loss in the gate device can be reduced, and a decrease in the level of the downstream signal transmitted downstream can be reduced.

  Furthermore, selection means can be provided for supplying a selected one of the downlink signal from the downlink signal transmission path and the downlink signal supplied from the external input terminal to the control signal. When a downstream signal can be input from the outside, the downstream signal from the external input terminal is input by the selection means. When the down signal cannot be input from the outside because the booster is not installed in the vicinity of the gate device, the down signal is supplied from the inside of the gate device to the control unit by the selection unit. By comprising in this way, a gate apparatus can be controlled according to the condition where this gate apparatus was installed.

  According to another aspect of the present invention, there is provided an upstream inflow noise canceling apparatus including any one of the gate devices described above and a bidirectional amplifier disposed in a bidirectional joint reception system upstream or downstream of the gate device. ing. The bidirectional amplifier has a monitor terminal, and the monitor terminal is connected to the external input terminal of the gate device. As the monitor terminal, either an input-side monitor terminal or an output-side monitor terminal can be used.

  In general, such an upstream inflow noise removal apparatus is often installed when the bidirectional joint reception system is operated and is affected by upstream upstream noise. In the actual operation state, the bidirectional amplifier is not monitored using the monitor terminal. Therefore, by supplying the downstream signal generated at the monitor terminal to the external input terminal of the gate device, it is possible to eliminate the influence of upstream inflow noise without giving insertion loss to the downstream signal.

  As described above, according to the present invention, upstream inflow noise can be removed with almost no decrease in downstream signal level due to insertion loss.

  The gate device 2 according to the first embodiment of the present invention has terminals 4 and 6 as shown in FIG. The terminal 4 is supplied with a downstream signal transmitted from the upstream head end of the joint reception system. A downstream signal path is provided between the terminal 4 and the terminal 6, and a high-pass filter 8 having a cutoff frequency selected so as to pass the downstream signal is disposed in the downstream signal path. The terminal 6 is connected to a line for transmitting a downlink signal to each terminal device on the downstream side of the joint reception system.

  The terminal 6 is also supplied with an upstream signal from each terminal device. An upstream signal path is formed between the terminals 4 and 6 in parallel with the downstream signal path. In this upstream signal path, a low-pass filter 10, a gate unit, for example, a gate 12, a mixing unit, for example, a mixer 14 and a low-pass filter 16 are arranged in order from the terminal 6 side to the terminal 4 side.

  In the low-pass filters 10 and 16, the cutoff frequency is selected so as to pass the upstream signal. Note that the upstream signal uses a lower frequency than the downstream signal.

  The gate 12 can be switched between a state in which an upstream signal is passed without being attenuated and a state in which it is attenuated, for example, 6 dB, in accordance with a control signal supplied thereto, for example, a gate control signal. It is also possible to provide a state in which the upstream signal is further cut.

  This gate is controlled by a control means, for example, the CPU 18. The CPU 18 performs this control based on the gate control information signal transmitted by the head end included in the downstream signal. The gate control information signal is extracted from the downstream signal supplied from the external input terminal 20 by the band pass filter 22. Since this gate control information signal is, for example, FSK modulated and transmitted from the head end, it is demodulated by a demodulating means, for example, the FSK demodulator 24 and supplied to the CPU 18. Further, the upstream signal that needs to be transmitted from the CPU 18 to the head end side is PSK modulated by the modulation means, for example, the PSK modulator 26, and is mixed with the upstream upstream signal that has passed through the gate 12 in the mixer 14. 16, and transmitted to the head end side via the terminal 4.

  Thus, in this gate device, a gate control information signal for controlling the gate 12 is obtained from the external input terminal 20. Therefore, it is not necessary to provide a branching device for branching the downstream signal on the terminal 6 side in the gate device 2 in order to supply the gate control information signal to the band pass filter 22. Since no branching device is provided, the downstream signal supplied to the terminal 6 is not subjected to the insertion loss of the branching device, and the downstream signal level does not decrease downstream.

  As shown in FIG. 2, a downstream signal is supplied to the external input terminal 20 from a monitor terminal 28 a on the input side or output side of the bidirectional amplifier 28 installed on the downstream side of the gate device 2. The gate device 2 is installed at a predetermined position of the bidirectional joint reception system when the upstream joint noise is large in a state where the bidirectional joint reception system is operated. In that case, the probability that a bidirectional amplifier such as the bidirectional amplifier 28 is arranged downstream is very high. The bidirectional amplifier 28 is supplied with a downstream signal from the gate device 2. In a state where the bidirectional joint reception system is actually operated, the monitor terminal of the bidirectional amplifier is often not used, and the downstream signal is supplied to the gate device 2 using this monitor terminal. In the bidirectional amplifier 28, a branching unit or the like is provided to output a monitor output to the monitor terminal. An insertion loss occurs in the bidirectional amplifier 28. Since the gain of the bidirectional amplifier 28 is adjusted so as not to affect the operation level of the joint reception system, even if the downstream signal is supplied from the monitor terminal to the gate device 2, the operation level is not affected.

  Note that reference numeral 30 shown in FIG. 2 denotes distribution means, for example, four distributors, and branch lines are connected to these distribution terminals, respectively. As described above, the gate device 2 and the bidirectional amplifier 28 constitute an infusion noise removing device.

  FIG. 3 shows a gate device 2a according to the second embodiment of the present invention. In the gate device 2a of this embodiment, the selection means, for example, the changeover switch 30 is provided between the junction point of the downstream signal path and the upstream signal path and the terminal 6, and the gate device 2 of the first embodiment. And different. Since the other configuration is the same as that of the gate device 2, the same reference numerals are given to the equivalent parts, and the description thereof is omitted.

  The changeover switch 30 has a contact point 30a, and the contact point 30a is connected to a junction of the downstream signal path and the upstream signal path. The contact 30a can contact either the contact 30b or 30c. Similarly, the changeover switch 30 has a contact 30 d, and this contact 30 d is connected to the terminal 6. The contact 30d can contact either the contact 30e or 30f. Moreover, when the contact 30a is in contact with the contact 30b, the contact 30d is in contact with the contact 30e, and when the contact 30a is in contact with the contact 30c, the contact 30g is in contact with the contact 30f. It is configured.

  The contacts 30b and 30e are connected. Further, the contact 30 c is connected to the input side of the one branching device 32, and the contact 30 f is connected to the output side of the one branching device 32. The branch side of the one branching device 32 is connected to the external input terminal 20.

  When a bidirectional amplifier is present downstream of the installation position of the gate device 2a, the monitor terminal of the bidirectional amplifier is connected to the terminal 20 in the same manner as shown in FIG. Then, the contact 30a is switched so that the contacts 30a and 30b are connected and the contacts 30d and 30e are connected. Thus, the operation is the same as that of the gate device 2 of the first embodiment.

  On the other hand, there may be no bidirectional amplifier downstream of the installation position of the gate device 2a. In such a case, the change-over switch 30 switches the contact 30g so that the contacts 30a and 30c are connected and the contacts 30d and 30f are connected. As a result, the downstream signal is supplied to the one branching device 32 from the confluence of the upstream route and the downstream route, supplied from the output side to the terminal 6, and transmitted downstream. At the same time, the downlink signal branched from the branch side of the one branching device 32 is supplied to the bandpass filter 22, and the gate control information signal is extracted from the downlink signal in the same manner as described in relation to the gate device 2, The signal is demodulated by the FSK demodulator 24 and supplied to the CPU 18. The upstream signal supplied from the terminal 6 is supplied from the output side of the one branching device 32 to the low-pass filter 10 via the input side. This gate device is often retrofitted to a point where inflow noise occurs after the system is constructed. Therefore, it may be installed in the vicinity of the booster or in a place away from the booster.

  In the above-described two embodiments, the mixer 14 is provided. At that time, the PSK modulator 26 is also unnecessary. In the above-described embodiment, the gate 12 that can be switched between non-attenuation and 6 dB is used. However, for example, a switch can be used as the gate to switch between the conductive state and the non-conductive state. Alternatively, the gate 12 can be switched to three stages of no attenuation, 6 dB attenuation, and cutoff, or can be switched to three stages of no attenuation, 6 dB attenuation, and 3 dB attenuation. In the second embodiment, the down signal is supplied from the monitor terminal of the booster provided near the downstream of the gate device, but the down signal may be supplied from the monitor terminal of the booster provided near the upstream.

It is a block diagram of the gate apparatus of the 1st Embodiment of this invention. It is a block diagram of the upstream inflow noise removal apparatus comprised using the gate apparatus of FIG. It is a block diagram of the gate apparatus of the 2nd Embodiment of this invention.

Explanation of symbols

2 2a Gate device 4, 6 Terminal 12 Gate (gate means)
18 CPU (control means)

Claims (3)

Downstream signal transmission path transmitted through the bidirectional joint reception system,
An uplink signal transmission path connected in parallel with the downlink signal transmission path and transmitted through the bidirectional joint reception system;
Gate means interposed in the transmission path of the upstream signal and passing or attenuating the upstream signal according to the supplied control signal;
Control means for supplying the control signal to the gate means;
At least an external input terminal to which the downstream signal is supplied,
And a gate device that generates the control signal based on the downlink signal supplied from the external input terminal.   2. The gate device according to claim 1, further comprising: a selection unit configured to supply a selected signal to the control signal among the downlink signal from the downlink signal transmission path and the downlink signal supplied from the external input terminal. Having a gate device.   A gate device according to claim 1 or 2, and a bidirectional amplifier disposed upstream or downstream of the gate device in the bidirectional joint reception system, the bidirectional amplifier having a monitor terminal The upstream inflow noise removing device, wherein the monitor terminal is connected to the external input terminal of the gate device.

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