JP2023179167A - optical receiver - Google Patents

Abstract

To provide an optical receiver which outputs a high-frequency signal from the same terminal as when power is being supplied even when power is not being supplied, and in which a circuit is housed in a drip-proof case that is without fear of deterioration of sealing material or packing material.SOLUTION: An optical receiver used in an access optical communication network configuration that draws an optical fiber directly into a general individual home as a transmission path includes a signal processing unit that has a light-receiving instrument that receives an optical signal from the optical fiber and converts it into an RF signal, a processing circuit that processes the RF signal, and an RF switch that switches the transmission path of the RF signal depending on a power feeding state. When power feeding to the optical receiver is stopped, the RF signal is output to an RF output terminal without amplifying it by the RF switch.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to an optical receiver used in the construction of an access optical communication network, in which an optical fiber is used as a transmission path directly into a private residence.

Various types of optical receivers used in access optical communication network configurations have been developed and disclosed. For example, an optical receiving terminal device aimed at power saving is disclosed in Patent Document 1.

Further, Patent Document 2 discloses an optical receiving device that operates in an emergency when power is not supplied.

Since an optical receiver used in an access optical communication network installed outdoors requires a drip-proof structure, Patent Document 3 discloses a waterproof case in which a cable can go in and out.

JP2009-135880A Japanese Patent Application Publication No. 2010-136018 Japanese Patent Application Publication No. 2006-351905

However, although the invention disclosed in Patent Document 1 saves power, it does not deal with a non-power supply state.

In the invention described in Patent Document 2, when the commercial power supply is interrupted and there is no power supply, a high frequency signal is output from the non-power supply output terminal instead of the power supply output terminal that is always used, so the terminal can be switched depending on the power supply state. , which complicates the high-frequency signal acceptance circuit.

The invention described in Patent Document 3 uses outer packing that is sandwiched between a base that houses a circuit and a cover that covers the base in order to achieve a drip-proof function, and there remains a concern that the waterproof function may deteriorate due to deterioration of the packing. .

The purpose of this invention was made in view of the above-mentioned circumstances.It is an object of the present invention to output a high-frequency signal from the same terminal when power is not supplied as it is when power is supplied, and to house the circuit in a drip-proof case that prevents the sealing material and packing material from deteriorating. The object of the present invention is to provide an optical receiver that is

The optical receiver 100 of the present invention is an optical receiver used in an access optical communication network structure in which an optical fiber is brought directly into a general private home as a transmission line, and receives an optical signal from an optical fiber and converts it into an RF signal. A signal processing unit including an optical receiver for conversion, a processing circuit for processing the RF signal, and an RF switch that switches the transmission path of the RF signal depending on the power supply state, and when power supply to the optical receiver is stopped. The optical receiver is characterized in that the RF switch outputs the RF signal to the RF output terminal without amplifying the RF signal.

A signal processing unit including a light receiver that receives an optical signal from an optical fiber and converts it into an RF signal, a processing circuit that processes the RF signal, and an RF switch that switches the transmission path of the RF signal depending on the power supply state, When the power supply to the optical receiver is stopped, the RF switch outputs the RF signal to the RF output terminal without amplifying it, so the user can use the RF output of the device when power is being supplied and when no power is being supplied. This eliminates the need to switch input circuits.

The invention described in claim 2 is characterized in that the signal processing section includes a first RF switch connected to the light receiver and a second RF switch connected to the RF output terminal. It is an optical receiver.

Since the signal processing section includes the first RF switch connected to the light receiver and the second RF switch connected to the RF output terminal, reliability of operation during no power supply can be improved.

The invention described in claim 3 is the optical receiver according to claim 2, wherein the first RF switch forms a closed circuit having an inductor between it and the light receiver when no power is supplied. .

Since the first RF switch forms a closed circuit with an inductor between it and the light receiver when no power is supplied, an RF signal can be effectively obtained from the light receiver.

The invention described in claim 4 is characterized in that the circuit switching operation of the first RF switch and the second RF terminal switch when no power is supplied is based on a fail-safe mode. It is an optical receiver.

Since the circuit switching operation of the first RF switch and the second RF terminal switch when no power is supplied is based on the fail-safe mode, the reliability of the operation when no power is supplied can be improved.

The invention described in claim 5 is characterized in that the signal processing section is housed in a drip-proof case configured without using a sealing material or a packing material. It is an optical receiver.

Since the signal processing section is housed in a drip-proof case constructed without using a sealing material or packing material, there is no concern that the sealing material or packing material will deteriorate over time, and manufacturing costs can be reduced.

FIG. 3 is an external view of the optical receiver housed in a drip-proof case. FIG. 3 is an explanatory diagram of the arrangement of optical input/output terminals and RF output terminals. (A) A block diagram of a processing circuit, and (B) an explanatory diagram of connections when power is not supplied. It is an explanatory view of (A) a main body case, and (B) a lid.

The present invention is an optical receiver used in the construction of an access optical communication network that connects optical fibers directly into private homes as transmission lines, and includes an optical receiver that receives optical signals from the optical fibers and converts them into RF signals; A signal processing unit includes a processing circuit that processes the RF signal, and an RF switch that switches the transmission path of the RF signal depending on the power supply state, and when the power supply to the optical receiver is stopped, the RF switch Since the RF signal is output to the RF output terminal without being amplified, the user is freed from concerns about failure of the power supply to the optical receiver.

FIG. 1 shows an external view of an optical receiver (VONU) according to the present invention. When installing the VONU outdoors, attach it to the wall of a building with the terminals visible at the bottom of Figure 1 facing down. Since the VONU is provided with a lid 201 to cover a main body case 200, which will be described later, it becomes a JIS class 4 drip-proof case that is not easily affected by rainwater.

What is shown in FIG. 2(A) is the input/output portion of the VONU. In addition to the optical cable input/output terminals 10 and 5 and the RF output terminal 7, LED lamps 8 and 9 indicating the presence or absence of power and optical input are attached to the terminal mounting surface 204 of the main body case. The portion of the lid 201 that extends over the terminal mounting surface covers only the upper part of the main body case, and the input/output terminals 10 and 5 of the optical cable are cut out.

FIG. 3(A) shows a block diagram from the optical input to the RF output of the VONU. At the left end of FIG. 3A, a photodiode 300, which is a light receiver, photoelectrically converts the optical output from the optical fiber into a high frequency signal (RF signal). The voltage converter 305 converts the voltage of a DC power source superimposed from the outside, which the RF output terminal receives, into a voltage suitable for the processing circuit, and supplies power to the processing circuit.

When power is being supplied, the photodiode 300 is separated from the parasitic circuit by the first RF switch, and the RF signal is sent to the equalizer amplifier 303 via the relay. The RF signal is adjusted in magnitude to an appropriate level by an automatic amplifier control circuit (AGC) 302.

Thereafter, the RF signal is sent to a power amplifier 304 to obtain an external output and is amplified to a signal level compatible with external equipment. The amplified signal is sent to the RF output terminal 309 through a switch and an attenuator, and is supplied to external equipment.

FIG. 3(B) shows a block diagram illustrating the operation when no power is supplied. The circuit for when power is not supplied includes two RF switches that perform circuit switching operations. As shown in this block diagram, when no power is being supplied, the photodiode 300 is connected to the parasitic circuit by the first RF switch 306, and the photodiode 300 and the inductor 301 form a closed circuit. It has been confirmed through experiments that the level of the RF signal from the photodiode 300 is improved by connecting the inductor 301 to the photodiode. In this configuration, the inductor 301 was preferably 820 nH. Further, since both the first RF switch and the second RF switch are configured so that the circuit switching operation when no power is supplied is in a fail-safe mode, the operation when no power is supplied is reliable.

The RF signal from the photodiode 300 is transmitted to the second RF switch 307 through a waveguide such as a microstrip circuit. The second RF switch 307 switches between the RF signal from the AMP during power supply and the RF signal from the first RF switch 306 during no power supply, depending on the power supply state, and outputs the RF signal to the RF output terminal 309. By using two RF switches, sufficient high-frequency signals can be supplied to external equipment even when no power is being supplied, without adversely affecting the circuit during power supply.

Figure 4 shows the outer casing of the VONU. 4(A) shows the main body case 200, and FIG. 4(B) shows the lid 201. The processing circuit is housed in a main body case 200, and optical input/output terminals and RF output terminals are attached to a terminal mounting surface 204 of the main body case. The terminal mounting surface 204 is also displayed with an LED lamp indicating the energized state and an LED lamp indicating the presence or absence of optical input.

The lid 201 completely covers the bottom surface of the main body case and the parts other than the terminal mounting surface 204, and the terminal mounting surface 204 is provided with an eaves 205 in which the optical input/output terminals and the RF output terminals are cut out. The main case 200 and the lid 201 were tightly assembled without using any sealing material or packing material between them to form a JIS class 4 drip-proof case.

Use of the optical receiver (VONU) of the present invention eliminates concerns about signal interruption due to power failure and helps improve the reliability of optical fiber lines, so it has great economic effects in the communications industry.

100 Optical receiver (VONU)
200 Main body case 201 Lid 204 Terminal mounting surface 205 Eaves 300 Light receiver (photodiode)
301 Inductor 302 AGC amplifier 303 Equalizer amplifier 304 Power amplifier 305 Voltage converter 306 First RF switch 307 Second RF switch 309 RF output terminal

Claims (5)

An optical receiver used in the construction of an access optical communication network that connects optical fiber directly to private homes as a transmission line,
A signal processing unit including a light receiver that receives an optical signal from an optical fiber and converts it into an RF signal, a processing circuit that processes the RF signal, and an RF switch that switches the transmission path of the RF signal depending on the power supply state,
An optical receiver characterized in that when power supply to the optical receiver is stopped, the RF switch outputs the RF signal to an RF output terminal without amplifying the RF signal. The optical receiver according to claim 1, wherein the signal processing section includes a first RF switch connected to the light receiver and a second RF switch connected to the RF output terminal. 3. The optical receiver according to claim 2, wherein the first RF switch forms a closed circuit with an inductor between the first RF switch and the optical receiver when no power is supplied. 4. The optical receiver according to claim 2, wherein the circuit switching operation of the first RF switch and the second RF switch when no power is supplied is in a fail-safe mode. 4. The optical receiver according to claim 1, wherein the signal processing section is housed in a drip-proof case configured without using a sealing material or packing material.

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