JPH0465930A - CATV optical transmission equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is a CATV optical transmission system! In particular, the present invention relates to a gain control device suitable for transmitting downlink signals.

BACKGROUND OF THE INVENTION In recent years, demand for optical transmission equipment as the main line of CATV systems has increased, taking advantage of the advantages of low cost and long-distance transmission. The signal transmitted from the head end is converted into an optical signal by a laser diode (hereinafter referred to as LD), and this optical signal is transmitted via an optical transmission line to the relay point of the CATV system, and is then transmitted to a photodiode (hereinafter referred to as PD). The optical signal is converted into an electrical signal again and transmitted to the receiving terminal.

The conventional optical transmission equipment described above with reference to the drawings below! An example will be explained.

FIG. 3 is a block diagram showing the configuration of a conventional CATV two-way optical transmission device. In FIG. 3, 1 is a head end, 2 is a mixer/brancher connected to head end 1, and 3 is a head end.
, 4 are a downstream optical transmitter and an upstream optical receiver connected to the mixer/demultiplexer 2, respectively, and 3 and 4 are housed in the same housing. 5 is a downstream optical transmission line, and 6 is an upstream optical transmission line. 7 is a downstream optical receiver connected to the downstream optical transmission line 5, 8 is an upstream optical transmitter connected to the upstream optical transmission line 6, and 7.8 is housed in the same enclosure. There is. 9 is a mixer/demultiplexer connected to the downstream optical receiver 7 and the uplink optical transmitter 8; 10 is a trunk amplifier connected to the mixer/demultiplexer 9; and 11 is a receiving terminal. 12 is a signal attenuator, and 13 is a downlink LD, which is built into the downlink optical transmitter 3. 14 is a signal amplifier, 15 is a DC component removal capacitor, 16 is an uplink PD, and 17 is a current-voltage conversion resistor, which are built into the uplink optical receiver 4. 18 is a downlink PD, 19 is a current-voltage conversion resistor, 20 is a DC component removal capacitor, and 21 is a signal amplifier, which is built into the downlink optical receiver 7. 22 is the uplink LD, 23
is a signal attenuator, which is built into the uplink optical transmitter 8.

Next, an example of the operation of the system with the above configuration will be described. The signal carried out from the head end 1 is input to the mixer/demultiplexer 2 and separated into downstream signals, which are input to the signal attenuator 12 of the downstream optical transmitter 3. In the downlink optical transmitter 3, the downlink LD 13 converts this input signal into an optical signal, and this optical signal is transmitted to the downlink PD 18 of the downlink optical receiver 7 via the downlink optical transmission path 5. Downlink optical receiver 7
Then, the downstream PD 18 converts this optical signal into an electrical signal, and the converted signal is amplified by the signal amplifier 21.
The signal is input to the main amplifier 10 via the mixer/brancher 9 and transmitted to the receiving terminal 11.

The signal output from the receiving terminal 11 and the signal input from any trunk amplifier are mixed/mixed via the trunk amplifier 10.
The signal is input to the demultiplexer 9, separated into uplink signals, and input to the signal attenuator 23 of the uplink optical transmitter 8. In the uplink optical transmitter 8, the uplink LD 22 converts the input signal into an optical signal, and this optical signal is transmitted to the uplink PD 16 of the uplink optical receiver 4 via the uplink optical transmission line 6. Uplink optical receiver 4
Then, the uplink PD 16 converts this optical signal into an electrical signal, and the converted signal is amplified by the signal amplifier 14 and transmitted to the head end 1 via the mixer/demultiplexer 2.

Problems to be Solved by the Invention However, in the above configuration, the downlink optical transmitter 3
The LD input signal level is adjusted locally to a signal level that corresponds to the system of each CATV station and the performance of each individual LD, and the downlink optical receiver 7 side checks whether the signal level is the optimal value. After making the determination, it is necessary to adjust the output signal level of the downlink optical receiver 7, so in CATV optical transmission equipment where the optical receivers are installed far apart, the adjustment of the optical transmitter and optical receiver is necessary. This has the problem of being time consuming and complicated.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a CATV optical transmission device that allows adjustment of an optical transmitter and an optical receiver only on the optical receiving side.

Means for Solving the Problems In order to solve the above problems, the CATV optical transmission device of the present invention is provided with a control signal generation section on the optical reception side, and transmits an optical signal output from the control signal generation section on the optical transmission side. A signal level adjuster control unit that outputs a signal level adjuster control signal corresponding to a control signal transmitted by a signal transmission line or an electric signal transmission line, and an LD input signal level adjuster are provided, and this LD input signal level adjuster is an optical receiver. This makes it possible to adjust the LD input signal to an arbitrary signal level using a control signal set by a control signal generator on the side.

According to the above-described configuration, the present invention allows the adjuster of the optical transmission device to set the control signal output from the control signal generator, and the set control signal to be transmitted via the optical signal transmission line or the electrical signal transmission line. The signal level adjuster controller applies a control signal to the LD input signal level adjuster on the optical transmitting side according to the control signal, and adjusts the LD input signal level. therefore,
The adjuster can adjust the LD input signal level to the optimum value using the control signal generated from the control signal generator while checking the image quality on a TV monitor or the like on the optical receiving side.

Embodiment Hereinafter, a CATV optical transmission apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a CAT ■ 2-way optical transmission device in the first embodiment of the present invention. The same reference numerals as in FIG. 3 indicate the same members, and detailed explanation thereof will be omitted. .

In FIG. 1, 24 is connected to the mixer/brancher 2,
An LD input signal level adjuster 25 adjusts the level of the downlink signal, and a signal level adjuster 25 detects a part of the output signal of the signal amplifier 14 of the uplink optical receiver 4 and controls the LD input signal level adjuster 24. Both control units are built into the downlink optical transmitter 3, and the output of the LD input signal level adjuster 24 is input to the downlink LD 13. 26 is LD22 for upstream,
The control signal generator is built into the uplink optical transmitter 8 together with the signal attenuator 23, and its output signal is input to the signal attenuator 23 together with the uplink signal.

Next, the operation of the above configuration will be explained. The control signal output from the control signal generator 26 is mixed with the upstream signal and input to the upstream LD 22 via the signal attenuator 23. The uplink LD 22 converts the uplink signal into an optical signal, and this optical signal is transmitted to the uplink PD 16 via the uplink optical transmission line 6. The uplink PD 16 converts this optical signal into an electrical signal, and the control signal generator 2 included in a part of the output signal
The control signal No. 6 is input to the signal level adjuster control section 25. The signal level adjuster control section 25 outputs a signal level adjuster control signal corresponding to this control signal to the LD input signal level adjuster 24. The LD input signal level adjuster 24 receives the downlink signal and the signal level adjuster control signal, and adjusts the downlink signal to the optimal LD in response to the signal level adjuster control signal.
Adjust to input signal level. The downlink LD 13 converts the signal output from the LD input signal level adjuster 24 into an optical signal, and this optical signal is sent to the downlink P via the downlink optical transmission line 5.
It is transmitted to D18. The optical signal is converted into an electrical signal by the downstream PD 18, amplified by the signal amplifier 21, and mixed/mixed.
The signal is output to the receiving terminal 11 via the demultiplexer 9 and the main amplifier 10.

As described above, according to this embodiment, the control signal generator 26 is provided in the uplink optical transmitter 8, and this control signal is transmitted to the uplink optical receiver 4 along with the uplink signal through the uplink optical transmission line 6. do. This control signal is input to the signal level adjuster control unit 25, and by providing the LD input signal level adjuster 24 controlled by the signal level adjuster control unit 25 in the LD input signal system, the optical It becomes possible to adjust the signal levels of both the transmitter and the optical receiver.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a CA showing a second embodiment of the present invention.
FIG. 2 is a block diagram showing the configuration of a TVI way optical transmission device. In FIG. 2, a control signal generation section 26 is built in the downlink optical receiver 7, and the control signal generation section 26 and the signal level adjuster control section 25 built in the downlink optical transmitter 3 are connected to each other via a metal wire 27. The difference from the configuration shown in FIG. 1 is that this is a one-way optical transmission device in which the metal wire 27 is provided in the same cable as the downlink optical transmission line 5.

The operation of the CATV optical transmission equipment configured as described above will now be described. The control signal output from the control signal generator 26 is input to the signal level adjuster controller 25 via the metal wire 27. Signal level adjuster control section 25
outputs a signal level adjuster control signal corresponding to this control signal to the LD input signal level adjuster 24. The LD input signal level adjuster 24 receives the downstream signal and the signal level adjuster control signal output from the signal level adjuster control section 25, and adjusts the LD input signal level in accordance with the signal level adjuster control signal. The downlink LD 13 converts the signal output from the LD input signal level adjuster 24 into an optical signal, and this optical signal is transmitted to the downlink PD via the downlink optical transmission line 5.
18. The optical signal is converted into an electrical signal by the downlink PD 18, amplified by the signal amplifier 21, and output to the receiving terminal 11 via the trunk amplifier 10.

As described above, according to this embodiment, in the CATVI way optical transmission device, the control signal generator 26 is provided in the downlink optical receiver 7, and the metal wire 27 is provided in the same cable as the downlink optical transmission line. The control signal is transmitted to the signal level adjuster control unit 25 in the downlink optical transmitter 3. By providing the LD input signal level adjuster 24 controlled by the signal level adjuster control section 25 in the LD input signal system, it is possible to adjust the signal levels of both the optical transmitter and the optical receiver only on the optical receiving side. Become. In this embodiment, the control signal transmission path is a metal wire, but other transmission paths such as a telephone line may also be used.

Effects of the Invention As described above, according to the present invention, the control signal output from the control signal generation section provided on the optical reception side and the signal level adjuster control section provided on the optical transmission side are used to control the signal output from the control signal generation section provided on the optical transmission side. By controlling the LD input signal level adjuster, the transmission signal can be adjusted to the optimal LD input signal level on the optical receiving side, and the signal level of both the optical transmitter and the first receiver can be adjusted only on the optical receiving side. It becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a CAT 2-way optical transmission device in the first embodiment of the present invention, Fig. 2 is a block diagram of a CATVI-way optical transmission device in the second embodiment of the invention, and Fig. 3 is FIG. 1 is a configuration diagram of a conventional CATV two-way optical transmission device. 1...Head end, 2...Mixer/brancher, 3...
- Optical transmitter for downlink, 4... Optical receiver for uplink, 5...
Downlink optical transmission line, 6... Uplink optical transmission line, 7... Downlink optical receiver, 8... Uplink optical transmitter, 9... Mixer/demultiplexer, 10... Main line amplifier, 11... Receiving terminal, 13... Downlink LD, 14... Signal amplifier, 16
...PD for uplink, 18...PD for downlink, 21...
Signal amplifier, 22... LD for upstream, 23... Signal attenuator, 24... LD input signal level adjuster, 25...
- Signal level adjuster control section, 26... Control signal generation section, 27... Metal wire. Agent Yoshihiro Morimoto

Claims (1)

[Claims] 1. The transmission signal in CATV is converted into an optical signal by a laser diode on the optical transmitting side, transmitted to the optical receiving side via an optical transmission line, and the optical signal is converted into an electrical signal by a photodiode on the optical receiving side and output. An optical transmission device that
A control signal generating section is provided on the optical receiving side, and an input signal level adjuster for adjusting the level of the input signal to the laser diode is provided on the optical transmitting side, and the input signal level adjusting device is controlled by the control signal from the control signal generating section. A CATV optical transmission device comprising a signal level adjuster control unit.