JP6309865B2 - Optical receiver, image reproducing device, and noise signal elimination method - Google Patents

Description

  The present invention relates to an optical receiver, an image reproducing device, and a noise signal removal method in the optical receiver.

  In a general optical receiver, radio waves are shielded by covering an internal circuit with a metal casing, a shield part, or the like. As a general optical receiver, for example, an optical receiver disclosed in Patent Document 1 can be applied. Although these radio wave shielding structures can suppress the invasion of radio waves to the inside of the device to some extent, it is difficult to completely seal the internal circuit because there are gaps in the metal housing, openings of the optical cable outlet, etc. It is difficult to perform complete radio wave shielding. Although a radio wave shielding effect can be improved if a double structure in which a case and a shield are further added from above a metal case and a shield part, the cost of the apparatus increases due to an increase in the number of parts.

  Even when a radio wave shielding structure is used, when a wireless LAN (Local Area Network) device or a mobile phone is used in the immediate vicinity of the light receiving device, the intensity of the radio wave received by the light receiving device is large, and the radio wave shielding structure alone is wireless. The influence of the signal on the internal circuit cannot be prevented. When a radio wave that has entered the optical receiver is picked up by an internal circuit, a radio frequency (RF) multiplexed electrical signal that is a TV broadcast signal and a radio signal are superimposed. When the radio signal frequency and the frequency of the RF multiplexed electrical signal are the same, the radio signal becomes noise and affects the TV image.

  Techniques for removing wireless noise mixed in the apparatus are disclosed in, for example, Patent Documents 2 to 4. Patent Document 1 discloses that noise signals are removed by adjusting the phase and amplitude of a noise signal that has entered the apparatus and combining it with a signal received by an antenna. In Patent Document 2, an external antenna and a noise signal receiving antenna are arranged, and the phase of the signal received by the noise signal receiving antenna is inverted and combined with the signal received by the external antenna. The removal is disclosed. Further, Patent Document 3 discloses that a noise is removed by arranging a dummy preamplifier and canceling the output from the preamplifier and the output from the dummy preamplifier by a differential input amplifier.

JP 2012-205003 A JP 2013-098767 A JP 2010-004451 A JP-A-8-139342

  However, the techniques of Patent Documents 2 and 3 are noise removal techniques for a device that receives a radio signal, and cannot be applied to an optical receiver as it is. Moreover, the technique of patent document 4 is a technique in an optical component with a simple function, and cannot be applied as it is to a high-function optical receiver in which a plurality of circuits are arranged.

  The present invention has been made in view of the above problems, and an optical receiver capable of removing a noise signal mixed into the optical receiver with high accuracy on the circuit in a high-performance optical receiver in which a plurality of circuits are arranged. An object of the present invention is to provide an image reproducing device in which the optical receiver is arranged and a noise signal elimination method in the optical receiver.

  In order to achieve the above object, an optical receiving apparatus according to the present invention includes a photoelectric conversion unit that converts an input optical signal into an RF electric signal and outputs the first optical signal, and a first that adjusts the amplitude of the output RF electric signal. An amplitude adjustment unit; a delay unit that adds a predetermined delay amount to the output RF electrical signal; a radio signal detection unit that detects a radio signal mixed in the optical receiver and outputs it as a noise signal; By performing processing equivalent to that of the amplitude means, the second amplitude adjustment means for adjusting the amplitude of the output noise signal, the phase inversion means for inverting the phase of the output noise signal, and the amplitude are adjusted. And a combining means for combining and outputting the RF electric signal to which the delay amount is added and the noise signal whose amplitude is adjusted and whose phase is inverted.

  In order to achieve the above object, an image reproduction apparatus according to the present invention displays the image by demodulating the output RF electric signal and the optical receiving apparatus that outputs the RF electric signal based on the input optical signal. An image display device.

  In order to achieve the above object, a noise signal elimination method according to the present invention detects noise by detecting a radio signal mixed in a photoelectric conversion means for converting an input optical signal into an RF electrical signal and outputting it, and an optical receiver. A method of removing a noise signal in an optical receiving device including a wireless signal detection unit that outputs a signal, adjusts the amplitude of an output RF electric signal, adds a predetermined delay amount to the output RF electric signal, and performs RF An RF electrical signal in which the amplitude of the output noise signal is adjusted and the phase of the output noise signal is inverted by performing processing equivalent to that for the electrical signal, and the amplitude is adjusted and a delay amount is added. The noise signal whose amplitude is adjusted and whose phase is inverted is combined and output.

  According to the above-described aspect of the present invention, in a high-function optical receiver in which a plurality of circuits are arranged, a noise signal mixed into the optical receiver can be removed with high accuracy on the circuit.

It is a block block diagram of the optical receiver 10 which concerns on 1st Embodiment. (A) The block block diagram of optical receiver 10B which concerns on the modification of 1st Embodiment, (b) The block block diagram of another optical receiver 10C which concerns on the modification of 1st Embodiment. It is a block block diagram of the optical receiver which concerns on 2nd Embodiment. FIG. 10 is an operation flowchart when the optical receiving device 100 according to the second embodiment sets the attenuation amount of the variable attenuation unit 340. It is an operation | movement flowchart in case the optical receiver 100 which concerns on 2nd Embodiment performs AGC control. It is a block block diagram of the optical receiver 100B which concerns on the modification of 2nd Embodiment. It is a block block diagram of the optical receiver 100C which concerns on 3rd Embodiment. It is an operation | movement flowchart when the optical receiver 100C which concerns on 3rd Embodiment sets the filter circuit 430C. It is a system configuration figure of CATV service system 500 concerning a 4th embodiment.

<First Embodiment>
A first embodiment according to the present invention will be described. FIG. 1 shows a block diagram of the optical receiver according to the present embodiment. In FIG. 1, the optical receiver 10 includes a photoelectric conversion unit 21, a first amplitude adjustment unit 22, a delay unit 23, a radio signal detection unit 31, a second amplitude adjustment unit 32, a phase inversion unit 33, and a multiplexing unit 40. Is provided.

  The photoelectric conversion unit 21 converts the optical signal input to the optical receiver 10 into an RF electrical signal and outputs the RF electrical signal to the first amplitude adjustment unit 22. The first amplitude adjusting unit 22 adjusts the amplitude of the input RF electric signal and outputs the adjusted signal to the delay unit 23. The delay means 23 adds a predetermined delay amount to the input RF electrical signal and outputs the result to the multiplexing means 40. The delay means 23 according to this embodiment adds a time equivalent to the time required for a noise signal, which will be described later, to pass through the phase inversion means 33 as a delay amount. Here, the radio signal mixed in the optical receiver 10 is also superimposed on the RF electrical signal.

  The radio signal detection unit 31 detects a radio signal mixed in the optical receiver 10 and outputs it as a noise signal to the second amplitude adjustment unit 32. The second amplitude adjusting unit 32 adjusts the amplitude of the input noise signal by performing the same process as the first amplitude adjusting unit 22 and outputs it to the phase inverting unit 33. The phase inverting means 33 inverts the phase of the input noise signal and outputs it to the multiplexing means 40.

  The combining means 40 includes an RF electric signal in which the amplitude input from the delay means 23 is adjusted and a delay amount is added, and a noise in which the amplitude input from the phase inversion means 33 is adjusted and the phase is inverted. The signal is combined and output.

  Since the RF multiplexed electrical signal output from the delay unit 23 and the noise signal output from the phase inversion unit 33 are adjusted to have the same amplitude, the phases are opposite to each other. By combining the two, the noise signal superimposed on the RF multiple electrical signal, that is, the radio signal superimposed on the RF multiple electrical signal is canceled.

  As described above, the optical receiver 10 according to the present embodiment can remove the mixed radio signal with high accuracy on the circuit.

<Modification of First Embodiment>
An optical receiver according to a modification of the first embodiment will be described. In a general optical receiver, the intensity of the RF multiplexed electric signal is changed according to the optical intensity of the optical signal input to the optical receiver. In the present embodiment, the processes in the first amplitude adjusting unit 22 and the second amplitude adjusting unit 32 are adjusted in accordance with the change in the light intensity of the input optical signal. FIG. 2A shows a block configuration diagram of the optical receiving apparatus according to the present embodiment. The optical receiver 10B shown in FIG. 2A is formed by arranging the light intensity detector 50B in the optical receiver 10 shown in FIG.

  The light intensity detection means 50B measures the light intensity of the optical signal input to the photoelectric conversion means 21, and outputs it to the first amplitude adjustment means 22B and the second amplitude adjustment means 32B.

  The first amplitude adjusting unit 22B adjusts the amplitude of the input RF electric signal by following the input light intensity. On the other hand, the second amplitude adjusting unit 32B adjusts the amplitude of the input noise signal so as to follow the input light intensity, thereby performing the same processing as the first amplitude adjusting unit 22B.

  The first amplitude adjusting unit 22B and the second amplitude adjusting unit 32B adjust the amplitude based on the light intensity of the optical signal input to the photoelectric conversion unit 21 detected by the light intensity detecting unit 50B, thereby receiving the optical signal. Even when the optical intensity of the optical signal input to the device 10B changes, the radio signal superimposed on the RF multiplexed electrical signal can be removed with high accuracy.

  Next, another optical receiver according to a modification of the first embodiment will be described. FIG. 2B shows a block configuration diagram of the optical receiving apparatus according to the present embodiment. The optical receiver 10C in FIG. 2B is formed by disposing the power control means 61C and the signal level detector 62C in the optical receiver 10B in FIG.

  The power supply control means 61C performs ON / OFF control of the power supply of the photoelectric conversion means 21. When the power of the photoelectric conversion means 21 is turned off, the RF multiplexed electric signal is not output from the photoelectric conversion means 21, and only the radio signal mixed in the optical receiver 10 is input to the first amplitude adjustment means 22B. The

  The signal level detection means 62C detects the signal level of the signal output from the multiplexing means 40 and outputs it to the second amplitude adjusting means 32C.

  The second amplitude adjusting unit 32C is configured to reduce the amplitude of the input noise signal so that the signal level input from the signal level detecting unit 62C is minimized when the power control unit 61C turns off the power of the photoelectric conversion unit 21. Adjust. Then, after the amplitude of the noise signal is adjusted so that the signal level output from the signal level detection means 62C is minimized, the power supply control means 61C turns on the power supply of the photoelectric conversion means 21, thereby the second amplitude adjustment. The means 32C adjusts the amplitude of the input noise signal by following the light intensity input from the light intensity detection means 50B with reference to the amplitude adjusted when the power supply is OFF.

  When the photoelectric conversion means 21 is OFF, the radio signal to which the amplitude is adjusted and the delay is added is input to the multiplexing means 40 from the delay means 23, the amplitude is adjusted, and the phase is inverted. The received noise signal is input from the phase inverting means 33. Therefore, the second amplitude adjusting unit 32C adjusts the amplitude of the noise signal so that the signal level of the signal output from the multiplexing unit 40 is minimized when the photoelectric conversion unit 21 is OFF, thereby the RF multiplexed electric signal. The radio signal superimposed on the signal can be removed with higher accuracy.

<Second Embodiment>
A second embodiment will be described. FIG. 3 shows a block diagram of the optical receiver according to the present embodiment. In FIG. 3, the optical receiving device 100 includes an RF signal output unit 200, a radio signal processing unit 300, and an attenuation adjustment control unit 400.

  The RF signal output unit 200 includes an optical connector 210, a photoelectric conversion unit 220, an amplifier 230, a received light power detection unit 240, a gain control unit 250, a variable attenuation unit 260, an amplifier 270, and an output terminal 280, and is input to the optical receiver 100. An RF multiple electrical signal based on the optical signal thus generated is generated and output.

  An optical cable (not shown) is connected to the optical connector 210. An optical signal is input to the optical receiver 100 via the optical cable and the optical connector 210.

  The photoelectric conversion unit 220 converts the optical signal input to the optical receiver 100 into an RF multiplexed electrical signal and outputs the RF multiplexed electrical signal to the amplifier 230. The photoelectric conversion unit 220 according to this embodiment employs a pigtail type light receiving element in which an optical cable and a light receiving element photodiode are integrated. The photoelectric conversion unit 220 receives a light signal, outputs a photocurrent superimposed with an RF multiple electrical signal, converts the photocurrent into a voltage signal using a resistive load, and outputs the voltage signal as an RF multiple electrical signal. .

  The amplifier 230 amplifies the input RF multiplexed electrical signal to a desired level and outputs the amplified signal to the variable attenuation unit 260. It is desirable that the amplifier 230 has excellent low noise and gain frequency characteristics in the frequency range used for the RF multiplexed electrical signal.

  The received light power detection unit 240 detects the received light power of the optical signal received by the photoelectric conversion unit 220 and outputs it to the gain control unit 250 and a gain control unit 330 described later. The received light power detection unit 240 according to the present embodiment converts the direct current component of the photocurrent output from the photoelectric conversion unit 220 into a voltage corresponding to the received light power using a resistive load, and receives the light received by the photoelectric conversion unit 220 based on this voltage level. Detect power.

  The gain control unit 250 performs signal attenuation according to the light reception power level input from the light reception power detection unit 240. The gain control unit 250 according to the present embodiment sets the signal attenuation amount of the variable attenuation unit 260 so that the signal level of the RF multiplexed electrical signal output from the output terminal 280 becomes the device specification level.

  The variable attenuating unit 260 adjusts the signal level of the RF multiplexed electrical signal input from the amplifier 230 under the control of the gain control unit 250 and outputs the signal level to the signal delay unit 360 described later. By adjusting the signal level by the variable attenuating unit 260, the signal level of the RF multiplexed electric signal output from the output terminal 280 becomes the device specification level.

  The amplifier 270 amplifies the amplitude of the RF multiplexed electrical signal input from the multiplexing unit 370 described later, from which the radio signal is removed, to a desired level and outputs the amplified signal to the output terminal 280.

  The output terminal 280 is an RF terminal for connecting a coaxial cable, and outputs an input RF multiplexed electric signal to the connected coaxial cable. For example, when a coaxial cable is connected to the output terminal 280, the optical receiving device 100 and a video reproduction device (not shown) are connected via the coaxial cable.

  Here, since the signal level of the RF multiplexed electrical signal output from the output terminal 280 is required to be a constant value of about 80 dBμV, even when the light receiving power of the optical signal input to the optical receiver 100 changes. AGC (Auto Gain Control) control is performed to control the RF multiple electrical signal level to a constant value. In the present embodiment, the received light power detector 240, the gain controller 250, and the variable attenuator 260 adjust the signal level of the RF multiplexed electrical signal following the change in received light power to constitute an AGC circuit. When the attenuation amount of the variable attenuation unit 260 is changed by AGC control due to the change in the received light power, the radio signal picked up in the RF multiplex electric signal circuit also passes through the same circuit as the RF multiplex electric signal. The signal level also changes.

  The radio signal processing unit 300 includes a radio signal receiving circuit 310, an amplifier 320, a gain control unit 330, a variable attenuation unit 340, a phase control unit 350, a signal delay unit 360, and a multiplexing unit 370, and is superimposed on the RF multiplexed electrical signal. A radio signal having the same level and opposite phase as the radio signal is generated, and the generated radio signal is combined with the RF multiplexed electric signal.

  The radio signal receiving circuit 310 detects a radio signal mixed in the optical receiving device 100 and outputs the detected radio signal to the amplifier 320. The radio signal receiving circuit 310 can be configured by a radio wave receiving antenna, a circuit pattern antenna, a circuit pattern in which components similar to the photoelectric conversion unit 220 are not mounted, or the like. Here, since the radio signal picked up at the output terminal of the photoelectric conversion unit 220 passes through all the amplifiers 230 and 270 in the subsequent stage, the noise level is amplified, the radio signal reception circuit 310 includes the photoelectric conversion unit 220. It is preferable to arrange in the vicinity.

  The amplifier 320 amplifies the level of the radio signal detected by the radio signal receiving circuit 310 to a desired level and outputs the amplified signal.

  The gain control unit 330 uses the information from the received light power detection unit 240 and the information from the RF detector 420 to be described later in the signal level of the radio signal superimposed on the RF multiplexed electric signal and the radio signal reception circuit 310. The attenuation amount set in the variable attenuation unit 340 is adjusted so that the signal level of the detected radio signal is the same. The gain controller 330 further realizes a noise removal operation that follows the change in received light power by performing signal attenuation according to the received light power detected by the received light power detector 240.

  The variable attenuating unit 340 adjusts the signal level of the radio signal input from the amplifier 320 under the control of the gain control unit 330 and outputs it to the phase control unit 350. By adjusting the signal level in variable attenuation section 340, the signal level of the radio signal becomes the same as the signal level of the radio signal superimposed on the RF multiplexed electrical signal.

  The phase control unit 350 changes the phase of the input radio signal by 180 degrees, and outputs the radio signal having the opposite phase to the multiplexing unit 370.

  For example, the signal delay unit 360 extends the propagation time by setting the signal line length to be long. The radio signal detected by the radio signal receiving circuit 310 is phase-converted by the phase control unit 350. However, a signal delay occurs more than the radio signal superimposed on the RF multiplexed electric signal due to the addition of the phase conversion time. The signal delay unit 360 delays the RF multiplexed electric signal input from the variable attenuating unit 260 by the same time as the time generated when the radio signal passes through the phase control unit 350 and outputs the delayed signal to the multiplexing unit 370.

  The multiplexing unit 370 combines the RF multiplexed electrical signal input from the signal delay unit 360 with the radio signal having the opposite phase input from the phase control unit 350 and outputs the resultant signal. The RF multiplexed electric signal input from the signal delay unit 360 and the radio signal input from the phase control unit 350 have the amplitudes adjusted to be equal and have opposite phases. Since the radio signal superimposed on the RF multiplexed electrical signal input from the signal delay unit 360 and the radio signal input from the phase control unit 350 have the same amplitude, the RF output from the signal delay unit 360 is output. The radio signal superimposed on the RF multiplexed electrical signal is canceled by combining the multiplexed electrical signal with the radio signal of the opposite phase output from the phase control unit 350.

  The attenuation adjustment control unit 400 includes a voltage control circuit 410 and an RF detector 420, and uses the output from the RF detector 420 when the power of the photoelectric conversion unit 220 is turned off to set attenuation in the variable attenuation unit 340. Adjust the amount.

  The voltage control circuit 410 performs power ON / OFF control of the photoelectric conversion unit 220. When the power source of the photoelectric conversion unit 220 is turned off, the RF multiplexed electric signal is not output from the photoelectric conversion unit 220 even when the optical signal is emitted to the optical connector 210. When the power of the photoelectric conversion unit 220 is turned off, only the wireless signal picked up by the optical receiving device 100 is input to the amplifier 230.

  The RF detector 420 measures the level of the radio signal output from the multiplexing unit 370 in a state where the power source of the photoelectric conversion unit 220 is turned off by the voltage control circuit 410. As described above, when the power of the photoelectric conversion unit 220 is turned off, the radio signal picked up by the optical receiving device 100 is transmitted from the signal delay unit 360 to the multiplexing unit 370 via the amplifier 230 and the variable attenuation unit 260. input. On the other hand, from the phase control unit 350 to the multiplexing unit 370, the wireless signal mixed in the optical receiving device 100 detected by the wireless signal receiving circuit 310 without being affected by ON / OFF of the power supply of the photoelectric conversion unit 220 is This is input via the amplifier 320 and the variable attenuation unit 340. A radio signal that cannot be removed by the multiplexing unit 370 when the power of the photoelectric conversion unit 220 is turned off is detected by the RF detector 420. Therefore, the variable attenuation unit 340 is set so that the radio signal level detected at this time is minimized. Adjust the amount of attenuation.

  A detailed operation procedure when the optical receiver 100 configured as described above sets the attenuation amount of the variable attenuation unit 340 will be described with reference to FIG. When setting the attenuation amount of the variable attenuation unit 340, first, the voltage control circuit 410 turns on the power of the photoelectric conversion unit 220 (S101).

  The photoelectric conversion unit 220 converts an optical signal input from the optical cable via the optical connector 210 into an RF multiplexed electrical signal and outputs the RF multiplexed electrical signal. The RF multiple electrical signal is amplified to a desired level by the amplifier 230 and input to the variable attenuation unit 260 (S102).

  On the other hand, the wireless signal receiving circuit 310 detects a wireless signal mixed in the optical receiving device 100. The detected radio signal is amplified to a desired level by the amplifier 320 and input to the variable attenuation unit 340 (S103).

  The received light power detection unit 240 detects the received light power of the optical signal received by the photoelectric conversion unit 220 and outputs it to the gain control unit 250 and the gain control unit 330 (S104).

  Based on the received light power input from the received light power detector 240, the gain controller 250 sets the attenuation amount of the variable attenuator 260 so that the RF multiplexed electrical signal level becomes a specified value in the apparatus specification. The variable attenuating unit 260 adjusts the power of the RF multiplexed electrical signal input from the amplifier 230 according to the amount of attenuation set by the gain control unit 250 and outputs the adjusted signal to the signal delay unit 360. The signal delay unit 360 adds a delay amount equivalent to that passing through the phase control unit 350 to the input RF multiplexed electrical signal and outputs it to the multiplexing unit 370 (S105).

  On the other hand, the gain control unit 330 sets the attenuation amount of the variable attenuation unit 340 based on the received light power input from the received light power detection unit 240. As a result, the variable attenuation unit 340 is set to an attenuation amount equivalent to the attenuation amount set in the variable attenuation unit 260 by the gain control unit 250. The variable attenuating unit 340 adjusts the power of the radio signal input from the amplifier 320 according to the amount of attenuation set by the gain control unit 330 and outputs the adjusted signal to the phase control unit 350. Then, the phase control unit 350 inverts the phase of the input radio signal and outputs it to the multiplexing unit 370 (S106).

  The voltage control circuit 410 turns off the power supply of the photoelectric conversion unit 220 while maintaining the setting of the attenuation amount of the variable attenuation unit 260 by the gain control unit 250 (S107). When the power source of the photoelectric conversion unit 220 is turned off, the output of the RF multiplexed electric signal from the photoelectric conversion unit 220 is stopped. As a result, only the radio signal picked up by the RF multiplex electric signal circuit is input to the multiplexing unit 370 via the amplifier 230, the variable attenuation unit 260 and the signal delay unit 360. On the other hand, the wireless signal receiving circuit 310 detects a wireless signal mixed in the optical receiving device 100 without being affected by the power-off of the photoelectric conversion unit 220. The radio signal detected by radio signal receiving circuit 310 is output to multiplexing unit 370 via amplifier 320, variable attenuation unit 340, and phase control unit 350.

  The multiplexing unit 370 is configured to detect a radio signal input from the signal delay unit 360 (a radio signal picked up by the RF multiplex electric signal circuit) and a radio signal input from the phase control unit 350 (detected by the radio signal receiving circuit 310). Are combined and output (S108).

  The RF detector 420 measures the level of the radio signal output from the multiplexing unit 370 and outputs it to the gain control unit 330. The gain control unit 330 sets the attenuation amount of the variable attenuation unit 340 so that the measurement value input from the RF detector 420 is minimized when the power of the photoelectric conversion unit 220 is turned off (S109). By adjusting the attenuation amount of the gain control unit 330 so that the level of the radio signal output from the multiplexing unit 370 is minimized when the power of the photoelectric conversion unit 220 is turned off, the RF multiplex electric signal circuit The picked-up radio signal is canceled by the multiplexing unit 370.

  The optical receiving apparatus 100 according to the present embodiment sets the attenuation amount of the variable attenuation unit 340 by the above-described procedure, and then turns on the power of the photoelectric conversion unit 220 again. When the power source of the photoelectric conversion unit 220 is turned on again, the output of the RF multiplexed electric signal from the photoelectric conversion unit 220 is resumed, and the operation is the same as a general optical receiver. That is, AGC control according to the received light power level detected by the received light power detection unit 240 is started, and the RF multiplexed electric signal obtained by canceling the radio signal picked up by the RF multiplexed electric signal circuit in the multiplexing unit 370 is The signal is amplified to a predetermined level by the amplifier 270 and output from the output terminal 280 to an external device such as a video reproduction device.

  Next, an operation procedure when the optical receiver 100 according to the present embodiment performs AGC control will be described with reference to FIG. When the light receiving power of the photoelectric conversion unit 220 changes (S201), AGC control is performed. That is, based on the light reception power level detected by the light reception power detection unit 240, the variable attenuating unit 260 is configured such that the signal level of the RF multiplexed electrical signal output from the output terminal 280 by the gain control unit 250 is within the device specifications. The setting is changed (S202). On the other hand, the gain control unit 330 sets an attenuation amount equivalent to the attenuation amount set in the variable attenuation unit 260 by the gain control unit 250 in the variable attenuation unit 340 based on the received light power level detected by the received light power detection unit 240. (S203).

  In the multiplexing unit 370, the RF multiplexed electrical signal from the signal delay unit 360 and the radio signal from the phase control unit 350, which are adjusted based on the detected light reception power level and have an opposite phase, are combined. (S204). The gain control unit 330 changes the setting of the variable attenuation unit 340 based on the received light power level detected by the received light power detection unit 240, so that processing similar to the AGC control in the gain control unit 250 is also performed on the radio signal. Is done. Accordingly, an RF multiplexed electrical signal in which the radio signal picked up by the RF multiplexed electrical signal circuit is canceled is output from the output terminal 280.

  As described above, the optical receiving device 100 according to the present embodiment adjusts the radio signal level following the change in the received light power even when the received light power of the optical signal changes, and wirelessly transmits the signal from the RF multiplexed electrical signal. Signal noise is stably removed.

  Even when a radio signal is picked up from the surrounding environment, an RF multiplexed electric signal from which the radio signal has been removed can be output, so that the optical receiving device 100 according to the present embodiment can be used in an environment where the radio signal is strong. . For example, a wireless LAN device can be installed in the vicinity of the optical receiving device 100, and a device combining the optical receiving device 100 and the wireless LAN device can be provided.

  Further, since the radio signal is removed inside the circuit, the metal casing and shield parts arranged in the optical receiver 100 can be simplified and reduced, and the parts and manufacturing costs can be reduced.

<Modification of Second Embodiment>
A modification of the second embodiment will be described. The optical receiver according to the present embodiment is applied when the radio signal level picked up by the RF multiplex electric signal circuit is known. When the radio signal level picked up by the RF multiplex electric signal circuit is known by design or inspection, the necessary antiphase radio signal level is also known, and the optimum value (fixed value) of attenuation is preset in the gain controller 330. Can be kept. In this case, the attenuation adjustment control unit 400 can be deleted.

  FIG. 6 shows a block diagram of the optical receiver according to the present embodiment. The optical receiver 100B of FIG. 6 is formed by deleting the attenuation adjustment controller 400 (the voltage control circuit 410 and the RF detector 420) from the optical receiver 100 of FIG. 3 described in the second embodiment. . By omitting the attenuation adjustment control unit 400, the cost of the optical receiving device 100B is reduced.

  Similarly to the optical receiver 100 in FIG. 3, the optical receiver 100B configured as described above also has a function of a general optical receiver that outputs an RF multiplexed electrical signal and a radio that is superimposed on the RF multiplexed electrical signal. And a function of removing a signal.

  In other words, the optical receiving device 100B converts the optical signal input in the photoelectric conversion unit 220B into an RF multiplexed electric signal, amplifies it to a desired level in the amplifier 230B and the amplifier 270B, and then transmits the RF multiplexed electric signal from the output terminal 280B. Output.

  On the other hand, the optical receiving device 100B detects a radio signal in the radio signal receiving circuit 310B, amplifies the detected radio signal in the amplifier 320B, adds a predetermined attenuation amount in the variable attenuating unit 340B, and a phase in the phase control unit 350B. Is output to the multiplexing unit 370B. Since the level of the radio signal picked up by the RF multiplex electric signal circuit is known, the necessary antiphase radio signal level is also known, and the gain control unit 330B sets the optimum attenuation amount which is a fixed setting value in the variable attenuation unit 340B. To do.

  Then, in the multiplexing unit 370B, the RF multiplexed electrical signal and the radio signal having the same amplitude and having opposite phases are combined to cancel the radio signal superimposed on the RF multiplexed electrical signal.

  Furthermore, in the optical receiving device 100B according to the present embodiment, noise removal is continued by performing signal attenuation according to the received light power detected by the received light power detector 240B by the gain controller 250B and the gain controller 330B. That is, gain control section 250B changes the amount of attenuation set to variable attenuation section 260B so that the signal level of the RF multiplexed electrical signal output from output terminal 280B is within the device specifications. On the other hand, the gain control unit 330B sets an attenuation amount in the variable attenuation unit 340B by adding the amount of fluctuation of the received light power detected by the received light power detection unit 240B to the fixed set value (initial value) of the attenuation amount. As a result, even when the light receiving power of the photoelectric conversion unit 220B changes, the optical receiving device 100B adjusts the radio signal level following the change in the light receiving power, and the radio signal noise is stably generated from the RF multiplexed electric signal. Removed.

<Third Embodiment>
A third embodiment will be described. The optical receiving apparatus according to the present embodiment is affected by the radio signal when the radio signal superimposed on the RF multiplexed electrical signal cannot be sufficiently removed even if the radio signal whose amplitude is adjusted and the phase is inverted is multiplexed. By blocking an RF multiplexed electrical signal in a large frequency band, an excessive radio signal noise is suppressed from being output from the optical receiver.

  FIG. 7 shows a block diagram of the optical receiver according to the present embodiment. In FIG. 7, the optical receiving device 100C includes an RF signal output unit 200C, a radio signal processing unit 300C, and an attenuation adjustment control unit 400C. The RF signal output unit 200C and the radio signal processing unit 300C are the same as the RF signal output unit 200 and the radio signal processing unit 300 of FIG. 3 described in the second embodiment. The attenuation adjustment control unit 400C according to this embodiment includes a voltage control circuit 410C, an RF detector 420C, and a filter circuit 430C.

  The voltage control circuit 410C performs power ON / OFF control of the photoelectric conversion unit 220C in the same manner as the voltage control circuit 410 of FIG. 3 described in the second embodiment.

  The RF detector 420C measures the level of the radio signal output from the multiplexing unit 370C in a state where the power source of the photoelectric conversion unit 220C is turned off by the voltage control circuit 410C, and the measured radio signal level is minimized. The gain controller 330C is controlled. The RF detector 420C according to the present embodiment further controls the transmission frequency band and the cutoff frequency band of the filter circuit 430C. A method in which the RF detector 420C sets transmission / cutoff for each frequency band to the filter circuit 430C will be described later.

  The filter circuit 430C is a frequency filter whose operating frequency band is variable. In the filter circuit 430C, transmission / cutoff of the signal is set with high accuracy for each frequency band divided in the frequency band of 70 MHz to 2.6 GHz by the RF detector 420C. By blocking the signal in the frequency band having a high radio signal level in the filter circuit 430C, it is possible to suppress the radio signal from being excessively output from the output terminal 280C.

  The optical receiving device 100C configured as described above also has a function of a general optical receiving device that outputs an RF multiplexed electrical signal and a radio that is superimposed on the RF multiplexed electrical signal, like the optical receiving device 100 of FIG. And a function of removing a signal.

  That is, the optical receiving device 100C converts the optical signal input in the photoelectric conversion unit 220C into an RF multiplexed electrical signal, amplifies it to a desired level in the amplifier 230C and the amplifier 270C, and then transmits the RF multiplexed electrical signal from the output terminal 280C. Output. Here, in the optical receiving device 100C according to the present embodiment, an RF multiplexed electric signal from which a signal in a frequency band in which the influence of the radio signal is large is removed in advance by the filter circuit 430C is output from the output terminal 280C.

  When the frequency band limitation of the filter circuit 430C is in the OFF state, the RF multiplexed electric signal in the frequency band of 70 MHz to 2.6 GHz is transmitted without loss from the filter circuit 430C, and the light of FIG. 3 described in the second embodiment is used. Similar to the receiving apparatus 100.

  On the other hand, the optical receiving device 100C detects a radio signal in the radio signal receiving circuit 310C, amplifies the detected radio signal in the amplifier 320C, adds a predetermined attenuation amount in the variable attenuation unit 340C, and a phase in the phase control unit 350C. Is output to the multiplexing unit 370C. Then, by combining the RF multiplexed electrical signal and the radio signal, whose amplitudes are adjusted equally and whose phases are inverted with each other, in the multiplexing unit 370C, the radio signal superimposed on the RF multiplexed electrical signal is canceled. Furthermore, a noise removal operation following the change in received light power is realized by performing signal attenuation according to the received light power detected by the received light power detecting unit 240C by the gain controller 250C and the gain controller 330C (AGC control).

  Next, in the optical receiving device 100C according to the present embodiment, an operation procedure when the RF detector 420C sets signal transmission / cutoff in the filter circuit 430C for each frequency band will be described. When setting transmission / cut-off of a signal for each frequency band in the filter circuit 430C, the optical receiving device 100C first performs steps S301 to S309 similar to steps S101 to S109 in the operation flow of FIG. 4 described in the second embodiment. Perform the action. That is, in the state where the power of the photoelectric conversion unit 220C is turned on, the gain control unit 250C causes the signal attenuation of the variable attenuation unit 260C so that the signal level of the RF multiplexed electric signal output from the output terminal 280C becomes the device specification level. The amount is set, and the gain control unit 330C sets an attenuation amount equivalent to the attenuation amount set to the variable attenuation unit 260C by the gain control unit 250C to the variable attenuation unit 340C (S301 to S306). Thereafter, the power of the photoelectric conversion unit 220C is turned off, and the attenuation amount of the variable attenuation unit 340C is set so that the measurement value at the RF detector 420C is minimized while the attenuation amount of the variable attenuation unit 260C is maintained. (S307 to S309). The operation procedure after S310 of the optical receiving device 100C will be described with reference to FIG.

  After the attenuation amount of the variable attenuation unit 340C is set so that the measurement value in the RF detector 420C is minimized when the power of the photoelectric conversion unit 220C is OFF, the RF detector 420C controls the filter circuit 430C, Only the signal of the first frequency band (for example, 70 MHz to 450 MHz) is transmitted (S310). Thereby, in the RF detector 420C, the noise level of the radio signal in the 70 MHz to 450 MHz band is measured. The RF detector 420C determines whether or not the noise level of the wireless signal in the 70 MHz to 450 MHz band is a level that makes it difficult to demodulate the RF multiplexed electrical signal, and based on the determination result, the first frequency band (for example, 70 MHz). The transmission / cutoff of the signal (˜450 MHz) is set in the filter circuit 430C (S311).

  For example, when the noise level of the radio signal in the 70 MHz to 450 MHz band is smaller than a predetermined threshold, the RF detector 420C performs setting for transmitting the signal in the frequency band of 70 MHz to 450 MHz to the filter circuit 430C. On the other hand, when the noise level of the radio signal in the 70 MHz to 450 MHz band is larger than a predetermined threshold, the RF detector 420C sets the filter circuit 430C to set the filter circuit 430C to block the signal in the first frequency band (for example, 70 MHz to 450 MHz). Apply.

  The RF detector 420C sets the transmission / cutoff of the signal in the first frequency band (70 MHz to 450 MHz) in the filter circuit 430C, and then transmits the signal in the second frequency band (for example, 450 MHz to 900 MHz). The filter circuit 430C is controlled (S312). At this time, when the first frequency band is set to be transparent, the filter circuit 430C transmits signals of the first and second frequency bands (70 MHz to 900 MHz). On the other hand, when the first frequency band is set to cut off, the filter circuit 430C transmits only the signal in the second frequency band (450 MHz to 900 MHz).

  The RF detector 420C controls the filter circuit 430C so that the signal in the second frequency band is transmitted, and whether the measured noise level of the radio signal is a level that makes it difficult to demodulate the RF multiplexed electric signal. Judge whether or not. Then, similarly to S311, the transmission / cutoff of the signal in the second frequency band (450 MHz to 900 MHz) is set in the filter circuit 430C based on the determination result (S313).

  The RF detector 420C repeats S312 and S313 for each divided frequency band. When signal transmission / cutoff is set to the filter circuit 430C for the entire frequency band (70 MHz to 2.6 GHz) by the RF detector 420C (YES in S314), the power source of the photoelectric conversion unit 220C is turned on again (S315). . When the power source of the photoelectric conversion unit 220C is turned on again, the output of the RF multiplexed electric signal from the photoelectric conversion unit 220C is resumed.

  In the optical receiver 100C according to the present embodiment, the frequency band in which the noise level of the radio signal affects the RF multiplexed electrical signal is blocked by the filter circuit 430C. Thereby, it is suppressed that excessive radio signal noise is output from the optical receiving device 100C.

<Fourth Embodiment>
A fourth embodiment will be described. In recent years, as optical cables are drawn to subscribers (FTTH: Fiber To The Home), optical cables are used as means for transmitting digital terrestrial broadcast signals and satellite digital broadcast signals in cable television (CATV) services and joint reception systems. It has become common to be used. In a CATV service that converts a terrestrial digital broadcast signal or a BS / CS satellite digital broadcast signal into an optical signal and transmits the optical signal to a service contractor, the above-described optical receivers 100, 100B, and 100C may be arranged in the residence of the service contractor. it can.

  FIG. 9 shows a system configuration diagram of the CATV service system according to the present embodiment. In FIG. 9, a CATV service system 500 receives a plurality of signals output from a CATV service provider's station 600, a plurality of CATV service contractor's residences 800A, 800B, 800C,. The optical signal propagation unit 700 propagates to the residence 800 of the CATV service contractor.

  At the station 600 of the CATV service provider, radio waves of terrestrial digital broadcasting and BS / CS satellite digital broadcasting are received using the terrestrial digital broadcasting receiving antenna 630 and the BS / CS satellite broadcasting receiving antenna 640.

  The head end device 610 adjusts the signal power of the received terrestrial digital broadcast signal and BS / CS satellite digital broadcast signal, converts the signal power into a frequency / modulation method suitable for CATV service, and the like, and transmits the optical transmitter 620 as an RF signal. Output to.

  The optical transmitter 620 modulates the optical signal using the input RF signal, and transmits the optical signal on which the terrestrial digital broadcast signal and the BS / CS satellite digital broadcast signal are superimposed via the optical signal propagation unit 700 to the CATV. It transmits to the residence 800 of the service contractor.

  The optical signal propagation unit 700 includes an optical cable 710, an optical amplifier 720, and an optical multiplexer / demultiplexer 730. The optical signal propagated by the optical cable 710 is amplified to a desired level by the optical amplifier 720 and distributed to the residences 800A, 800B, 800C,... Of a plurality of CATV service subscribers by the optical multiplexer / demultiplexer 730.

  Optical receivers 810A, 810B, and 810C and video playback devices 820A, 820B, and 820C are arranged in the residences 800A, 800B, 800C,. Hereinafter, when it is not necessary to distinguish between them, they are simply referred to as a residence 800, an optical receiver 810, and a video reproducing device 820.

  In the residence 800 of the CATV service contractor, the optical signal input from the optical multiplexer / demultiplexer 730 is input to the optical receiver 810. The optical receiver 810 converts the input optical signal into an RF multiplexed electrical signal and outputs it to the video playback device 820. The video playback device 820 demodulates the input RF multiplexed electrical signal and displays it as an image.

  Here, the optical receiver 810 is installed indoors or on the outer wall of a house. Outdoors, WIMAX (Worldwide Interoperability for Microwave Access) and mobile phone base stations are installed, and radio signals are output from transmission / reception antennas. Indoors, wireless signals are output from wireless LAN devices and mobile phones. In the case of a CATV service using the same frequency pass-through method as a transmission method of a TV signal, a signal having a channel frequency of 70 MHz to 770 MHz used in CATV and a BS / after conversion at an intermediate frequency are used from the RF output terminal of the optical receiver 810. An RF signal of about 1 GHz to 2.6 GHz used in CS satellite digital broadcasting (BS / CS-IF signal) is output.

  The wireless LAN mainly uses a 2.4 GHz band radio frequency, and the mobile phone uses 700 MHz, 1.5 GHz, 1.7 GHz, 2 GHz band, and the like. These frequency bands overlap with the frequency band of the RF multiplexed electrical signal output from the optical receiver 810. Although the optical receiver 810 does not include an antenna for receiving a radio signal, the optical receiver 810 picks up the radio signal as noise because a large number of amplifiers for amplifying the RF signal are mounted in the internal circuit. In the case of the radio signal, the radio signal is amplified in the same manner as the RF multiplexed electrical signal, and is output to the video reproduction device 820 together with the RF multiplexed electrical signal. In this case, the quality of the RF multiplexed electric signal deteriorates due to the influence of the radio signal, and noise appears in the TV video or it cannot be viewed. Therefore, in the CATV service system 500 according to the present embodiment, any one of the optical receiving devices 100, 100B, and 100C described in the above-described embodiments is applied to the optical receiving device 810.

  That is, the optical receiver 810 is provided with an optical connector for connecting the optical cable 710. The optical signal is converted into an electric signal by the built-in photoelectric conversion circuit and amplification circuit, and the terrestrial digital broadcast signal and BS / CS satellite are converted. A digital broadcast signal is output from the RF output terminal. By transmitting this signal to a video playback device 820 such as an STB (Set Top BOX) or a digital broadcast compatible TV, the video playback device 820 can view digital terrestrial broadcasts and BS / CS satellite digital broadcasts.

  The optical receiving apparatus 810 according to the present embodiment converts the optical signal input in the photoelectric conversion unit into an RF multiplexed electric signal, amplifies it to a desired level by an amplifier, and then outputs the RF multiplexed electric signal to the video reproduction apparatus 820. To do. As described in the above embodiment, the optical receiver 810 further detects a radio signal mixed in the optical receiver 810 in the radio signal receiver circuit, and amplifies and inverts the detected radio signal. Then, a high-quality RF multiplexed electric signal from which the superimposed radio signal is removed by combining the RF multiplexed electric signal and the radio signal having the same amplitude and having opposite phases at the multiplexing unit in the image is displayed. The data is output to the playback device 820.

  The present invention is not limited to the above-described embodiment, and design changes and the like within a range not departing from the gist of the present invention are included in the present invention.

10, 10B, 10C Optical receiver 21 Photoelectric conversion means 22, 22B First amplitude adjustment means 23 Delay means 31 Radio signal detection means 32, 32B, 32C Second amplitude adjustment means 33 Phase inversion means 40 Multiplexing means 50B Light Intensity detection means 61C Power supply control means 62C Signal level detection means 100 Optical receiver 200 RF signal output section 210 Optical connector 220 Photoelectric conversion section 230 Amplifier 240 Light reception power detection section 250 Gain control section 260 Variable attenuation section 270 Amplifier 280 Output terminal 300 Wireless Signal processing unit 310 Radio signal receiving circuit 320 Amplifier 330 Gain control unit 340 Variable attenuation unit 350 Phase control unit 360 Signal delay unit 370 Multiplexing unit 400 Attenuation adjustment control unit 410 Voltage control circuit 420 RF detector 500 CATV service system 600 CA TV service provider's station 610 Head-end device 620 Optical transmitter 630 Terrestrial digital broadcasting receiving antenna 640 BS / CS satellite broadcasting receiving antenna 700 Optical signal propagation unit 710 Optical cable 720 Optical amplifier 730 Optical multiplexer / demultiplexer 800 Residence of CATV service contractor 810 Optical receiver 820 Video playback device

Claims (7)

Photoelectric conversion means for converting an input optical signal into an RF electric signal and outputting the RF signal;
First amplitude adjusting means for adjusting the amplitude of the output RF electrical signal;
Delay means for adding a predetermined delay amount to the output RF electrical signal;
Radio signal detection means for detecting a radio signal mixed in the optical receiver and outputting it as a noise signal;
Second amplitude adjusting means for adjusting the amplitude of the output noise signal by performing processing equivalent to that of the first amplitude adjusting means;
Phase inversion means for inverting the phase of the output noise signal;
A combining means for combining and outputting the RF electric signal with the amplitude adjusted and the delay amount added, and the noise signal with the amplitude adjusted and the phase inverted;
A light receiving device comprising: a light intensity detecting means for measuring a light intensity of an optical signal input to the photoelectric conversion means and outputting the light intensity to the first amplitude adjusting means and the second amplitude adjusting means;
The first amplitude adjusting means adjusts the amplitude of the output RF electric signal based on the input light intensity,
The second amplitude adjusting unit is an optical receiver that performs processing equivalent to the first amplitude adjusting unit by adjusting the amplitude of the output noise signal based on the input light intensity. The first amplitude adjusting means includes
First variable attenuation means for adjusting the amplitude by adding a set attenuation amount to the output RF electrical signal;
First gain control means for setting an attenuation amount to the first variable attenuation means based on the output light intensity,
The second amplitude adjusting means includes
Second variable attenuation means for adjusting the amplitude by adding a set attenuation amount to the output noise signal;
Second gain control means for setting an attenuation amount to the second variable attenuation means based on the output light intensity,
The optical receiver according to claim 1. Power control means for controlling the power of the photoelectric conversion means ON or OFF;
Signal level detection means for detecting and outputting the signal level of the signal output from the multiplexing means, and further comprising:
The second gain control means adjusts the attenuation so that the output signal level is minimized when the power supply of the photoelectric conversion means is OFF, and is output when the power supply of the photoelectric conversion means is ON. Setting an attenuation amount to the second variable attenuation means based on the light intensity and the adjusted attenuation amount,
The optical receiver according to claim 2. A filter unit disposed between the multiplexing unit and the signal level detection unit, for removing a signal in a predetermined frequency band;
When the frequency band of the RF electrical signal is divided into a plurality of frequencies and the output signal level in the divided frequency band when the power of the photoelectric conversion means is OFF is larger than a predetermined threshold, the divided frequency band is Frequency setting means for setting the frequency band to be removed by the filter means;
The optical receiver according to claim 3, further comprising: First amplification means for amplifying the amplitude of the RF electrical signal output from the photoelectric conversion means to a predetermined level and outputting the amplified signal;
A second amplifying means for amplifying the amplitude of the noise signal output from the wireless signal detecting means to a predetermined level and outputting it;
A third amplifying means for amplifying the amplitude of the signal output from the multiplexing means to a predetermined level and outputting it;
The optical receiver according to any one of claims 1 to 4, further comprising: The optical receiver according to any one of claims 1 to 5, which outputs an RF electrical signal based on an input optical signal;
An image display device that demodulates the output RF electrical signal and displays an image;
An image reproducing apparatus comprising: Photoelectric conversion means for converting an input optical signal into an RF electric signal and outputting the RF signal;
Wireless signal detection means for detecting a wireless signal mixed in the optical receiver and outputting it as a noise signal;
First amplitude adjusting means for adjusting the amplitude of the output RF electrical signal;
Delay means for adding a predetermined delay amount to the output RF electrical signal;
Second amplitude adjusting means for adjusting the amplitude of the output noise signal by performing processing equivalent to that of the first amplitude adjusting means;
Phase inversion means for inverting the phase of the output noise signal;
A combining means for combining and outputting the RF electric signal with the amplitude adjusted and the delay amount added, and the noise signal with the amplitude adjusted and the phase inverted;
A light receiving method using a light receiving device comprising a light intensity detecting means,
The light intensity detection means measures the light intensity of the optical signal input to the photoelectric conversion means and outputs the light intensity to the first amplitude adjustment means and the second amplitude adjustment means;
The first amplitude adjusting means adjusts the amplitude of the output RF electric signal based on the input light intensity,
The second amplitude adjusting unit uses an optical receiver that performs processing equivalent to that of the first amplitude adjusting unit by adjusting the amplitude of the output noise signal based on the input light intensity. The optical reception method that was.

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