JPS6212222A - Wavelength multiplex optical transmitter - Google Patents

Abstract

PURPOSE:To control other O/E depending on the content of a signal by providing plural electrooptic converters (E/O) outputting lights whose wavelengths differ from each other, a photocoupler applying wavelength multiplex transmission to the optical output, an optical fiber and a demultiplexer and >=2 O/E converters in a receiver. CONSTITUTION:A signal being a result of a modulated video signal (S1) multiplexed by a reception code and an O/E2 control signal (C) is inputted to a transmission side E/O1 111 and modulated video signals (S2-S4) are inputted respectively to E/O2-E/D4 respectively. The E/O 111-114 apply directly the intensity modulating the light having 4 different wavelengths lambda1-lambda4 by using an electric signal, and the result is subject to wavelength multiplex transmission by a photocoupler 115 and an optical fiber 120. A, O/E2 control signal extracting section 144 extracts separately the signal C multiplexed with the signals S1, S2 from the output electric signal of the O/E1 142, the converter O/E2 is turned on/off by the O/E2 control section 145 according to the signal C to change number of channels to be viewed into two ways of in total 4- channel of the S1-S4 and 2 channels of the S1, S2 only.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a wavelength division multiplexing optical transmission device used for 0ATV and the like.

Conventional technology Conventional 0ATVs mostly use coaxial cables, but there is a movement to use low-loss, broadband, and small-diameter optical fiber cables instead of coaxial cables to achieve long relay distances and space savings. There is.

Currently, between reception points and headends, independent program relay points and CA
Optical fibers are first being used for trunk lines between TV centers and the like. On the other hand, the use of optical fibers in the distribution (subscriber) system is considered to be relatively easy to implement, for example, in a star distribution system configured by providing a hub as shown in FIG. 5(&). A coaxial cable or optical fiber cable is used for the main line 3a from the center 1 to the hub 2 to transmit all broadcast channels, and an optical fiber cable is used for the distribution system 4 as shown in Figure 6(b). A star hub 2-subscriber 6 distribution system is constructed.

Here, a switch 7 for switching a transmission signal to a requested video signal channel is a downstream optical fiber that transmits the signal to the subscriber, a keyboard 8 is used by the viewer to select a channel, and 9 is an upstream optical fiber that transmits the signal. It is.

In the hub 2 - subscriber 5 star distribution system configured as described above, the maximum number of channels that subscriber 5 can view is transmitted to the optical frame 3, but the maximum number of channels that subscriber 5 can watch is transmitted to the downlink optical fiber It is only necessary to select and transmit only the signal of one channel selected by 5 using the keyboard 8 by switching the switch 6. (Reference: Optical communication technology and 0ATV, Kichi 1
) Susumu.

Kyodo Publishing Company).

On the other hand, wavelength division multiplexing optical transmission is considered as one method of transmitting multiple channels using a small number of optical fiber cables.

A conventional one-way wavelength division multiplexing optical transmission device generally has a configuration shown in FIG. (For example, Optical Communication Handbook, Breakfast Shoten, p. 491) In FIG. 6, 10 to 13 are electrical-to-optical conversions, while in conventional wavelength multiplexed optical transmission,
A single optical fiber can transmit as many channels as there are wavelengths, but normally Elo outputs a wavelength of 0/
There is a one-to-one correspondence with l, and Elo and O/ require the same number of wavelengths, that is, the same number of channels. In addition, the O/Es are independent of each other, and the idea is to control other O/Es by the signal received by one O/K. Therefore, in the present invention, multiple O/Es that output light with different wavelengths are used. Elo, an optical coupler, an optical fiber, an optical demultiplexer for wavelength-multiplexing transmission of the optical output, and two or more O/Xs in one receiver, and the O/E Some of them are wavelength division multiplexing optical transmission devices that have a function of controlling other O/Ls depending on the received signal content.

Effect of the present invention With the above-described configuration, the optical signals output from a plurality of Ilo's are received by at least two O/Es in the same receiver after wavelength multiplexing transmission, and some of the O/Es receive the optical signals. The number of channels that can be viewed can be increased or decreased by turning on/off other O/Es or limiting the transmission band depending on the signal content.

Embodiment FIG. 1 shows 1104 pieces in the first embodiment of the present invention,
FIG. 2 is a block diagram of a wavelength division multiplexing optical transmission device when two O/Es are used. In FIG. 1, 110 is the transmitting side, that is, the center, and 111 to 114 are the wavelengths λ and λ, respectively.
Outputs light of 2 λ3 λ4! Air-light converter 1! :
10. ．． E10. Elo, K104°, and 115 is an optical multiplexer or optical combiner for wavelength multiplexing the optical outputs of the four Elos 111 to 114. 120 is an optical fiber for transmitting wavelength-multiplexed optical signals, and 130 is an optical fiber for transmitting optical signals to each receiver 14o.

Each receiver has the same configuration. In the following explanation, only one will be explained. 141
The branched wavelength multiplexed optical signal is divided into wavelengths λ1.
λ2. λ5. Optical multiplexer for splitting into two sets of λ4, 142
, 143 is an optical-to-electrical converter (0/1!:, O/E2) that converts each optical signal split into two sets into an electrical signal.
, 144 is O/E from the output electrical signal of O/IC, 142
146 is an 07E2 control unit that controls 0/E2143 according to the 0/E2 control signal control contents extracted by the 0/E2 control signal control ratio section 144. be. In FIG. 1 and FIG. 4, which will be described later, a single line connecting each block is an optical system line made of an optical fiber or the like, and a double line is an electrical system line made of a coaxial cable or the like.

The operation of the wavelength division multiplexing optical transmission apparatus of this embodiment configured as described above will be described below. K70 on the sending side,
111 includes a modulated video signal (hereinafter referred to as S), a receiver code and 0/E2 control signal (hereinafter referred to as control signal C).
The K10□E105E104 receives a modulated video signal (5283, respectively).
84) is input. Here finally the same 0/E
The signals converted are electrically multiplexed sounds, and the frequencies are shifted to prevent interference. For example, as shown in FIG. 2, S, , S2 . C have different frequencies, and similarly S5.C received by KO/E2. S
4 also have different frequencies. IC1 with these electrical signals
Four different wavelengths λ4 at 0111 to 114
．． λ2. λ3. The light of λ4 is directly intensity modulated, and the optical coupler 1
15. Wavelength multiplexing transmission is performed using the optical fiber 120. receiver 1
40, the wavelength-multiplexed optical signal branched by the optical branching device 130 is divided into wavelengths λ, λ2, . λ5 and λ
Divided into two sets of 4, each O/E, 142.
It is converted back into an electrical signal by O/E2143.

Here, the output electrical signal of 0/E is that Sl, C, and 82 are 0
The output electrical signal of /E2 is S.

and S4 become frequency multiplexed signals. And 0/E
2 control signal control ratio section 144 separates and extracts C, which was multiplexed with Sl and S2, from the output electrical signal of O/E, 142,
The 0/E2 control unit 146 turns 0/E2 on and off according to C, and the number of channels that can be viewed is set to s in this case.
, s, s3. A total of 4 channels of s4 and SL,
Changes are made in two ways: 2 channels of S2 only.

As described above, according to this embodiment, by providing two O/Es in one receiver for 2104 channels, the maximum number of channels that a viewer can watch with one receiver is 4.
Becomes a channel. Also, unlike conventional star distribution systems, the signals of all channels that can be viewed (4 channels in this example) are transmitted to the receiver, so there is no need to tell the viewer which channel they have selected. It doesn't have to be bidirectional. In addition, the downlink optical fiber between center receivers can be branched and distributed to other receivers, and by branching the received wave, even if there are multiple Tvs, it is not necessary to provide as many optical fiber lead-in lines as there are. do not have. And unlike normal wavelength multiplexed optical transmission, O/
E requires fewer numbers than E/O.

On the other hand, when conducting paid broadcasting such as pay TV, SL and 8
2 is a free broadcast program, and S5 and 84 are pay broadcast programs, and when it is sent, it is called O if you are a pay TV subscriber.
If you turn on /FC, you can watch 4 channels for free and 2 channels for paid TV subscribers, but if you are not a paid TV subscriber, you can turn off 0/E2 and watch only 2 channels of free programs, 81 and 82. You can make it impossible. In this embodiment, signals for four channels can be received with one received word, no scrambler is required on the transmitting side, and the receiving R
Eavesdropping can be prevented by equipping the G with a device that is simpler than a descrambler, and since no manipulation is applied to the signal itself, a high-quality screen can be obtained.

Next, a second embodiment of the present invention will be described.

The second embodiment is O/E in the first embodiment.

The C received by 142 only turned O/E2143 on and off, but the C received by 07IC5
This is intended to increase or decrease the number of channels that the receiver can view by changing the transmission band of 143.

For example, in pay TV, when the output signal of o/E2 is a 4-channel frequency multiplexed signal as shown in Figure 3 (IL), a certain subscriber pays only a small amount of viewing fee, so the transmission band of O/E2143 is Figure 3 (b
) so that, for example, only 2 out of 4 channels can be viewed. However, since other subscribers pay high viewing fees, the transmission band of the O/E 2143 is widened, as shown in FIG. 3(C), so that all four channels can be viewed.

In this way, in this embodiment, subscribers can watch paid programs on various channels depending on the viewing fee they are paying, in addition to the free broadcast programs they receive on O/E.

Next, in the third embodiment, for example, when there are two O/Es, 0/
E, 142, O/E2143 output electrical signal is the second
If you create a frequency-multiplexed signal as shown in the figure (IL) and transmit the corresponding signals of each channel at the same frequency, the switching after O/E as shown in Figure 4 will occur. A switch 146 is provided to connect 0/E1 and O/
By simply switching the electrical signal output of E2, you can mix programs output from 0/E and O on one channel of a general TV.
You can easily watch both of the two programs output from /E2. In this way, one television channel can be used for two programs without having to re-modulate the RF signal in accordance with the frequency of the television channel.

In addition, when there are two O/Es, one is an O/X that is sensitive only to short wavelengths and the other is only sensitive to long wavelengths, and multiple E10s are divided into a set that emits light at long wavelengths and a set that emits light at short wavelengths. Divide, 1 for each
If the signals input to 0 are selected so that they do not interfere within the same group, a wavelength division multiplexing optical transmission device can be realized by using a cheaper optical branching device instead of the optical branching filter 141.

In the example, the signals input to Elo were selected so that the output signals from each 0/E would be frequency multiplexed signals.
The output numbers from 0/E may be selected to be time division multiplexed. Also, the number of Elo and O/E is 2 as above.
The combination is not limited to 104 pieces, 0712 pieces, etc.

As described in detail, according to the present invention, it is possible to transmit several times the number of channels in one direction compared to the conventional star distribution system using optical fibers, and all channels can be transmitted to the receiver. , it is possible to branch in the distribution system, and pay television can be realized without using a scrambler or descrambler, that is, with a high-quality screen.

By appropriately selecting the input signal and output wavelength of the O/O, it is possible to use TV channels for several programs, and it is possible to realize wavelength multiplexed optical transmission using an optical splitter.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a wavelength division multiplexing optical transmission device according to a first embodiment of the present invention, FIG. 2 is a frequency characteristic diagram of the input signal to each E10, and FIG. /E
2. Frequency characteristic diagram of electric power and transmission band, Figure 4 is a block diagram of a receiver equipped with a changeover switch, Figure 6 is a block diagram of a star distribution system using conventional optical fibers, FIG. 6 is a block diagram of a conventional wavelength division multiplexing optical transmission device. 110... Sending side (center), 111-11
4...Elo, 116...Optical multiplexer or optical coupler, 120...Optical fiber, 130
. . . Optical splitter, 140 . . . Receiver 1.
141... Optical demultiplexer, 142...0/
E1.143...0/E2.144...
・O/E2 control signal extraction section, 145...0/E
2 control unit, 146...changeover switch. Name of agent: Patent attorney Toshio Nakao and one other person Kasumi 2
Figure 3 (b) h fz fs f4
Frequency f, f, f3 f4 p4
Wave 11 (÷ Mensa Figure 5)

Claims (5)

[Claims] (1) A plurality of electrical-to-optical converters that output light of different wavelengths, an optical coupler/multiplexer for wavelength-multiplexing the output light, and an optical fiber for transmitting the wavelength-multiplexed light. and the wavelength of the transmitted light is at least 2
A single receiver is equipped with a plurality of optical demultiplexers for dividing into groups and optical-to-electrical converters for converting each demultiplexed light into electricity, and one or more optical-to-electrical converters are provided. A wavelength multiplexing optical transmission device that controls one or more other optical-to-electrical converters according to the signal content received by the converter. (2) Claim 1 in which one or more optical-to-electrical converters have a function of restricting the receivable transmission band of one or more other optical-to-electrical converters depending on the received signal content. The wavelength division multiplexing optical transmission device as described in 2. (3) Claim 1 having the function of turning on/off one or more other optical-to-electrical converters depending on the signal content received by one or more optical-to-electrical converters.
The wavelength division multiplexing optical transmission device as described in 2. (4) The output from multiple optical-to-electrical converters is a frequency multiplexed signal, and the frequency of one or more multiplexed channels is one or more of the frequencies output from one or more other optical-to-electrical converters. The frequency of the plurality of channels is the same, and the frequency is the same as that of the plurality of channels, and includes a changeover switch for outputting one of the outputs of each optical-to-electrical converter. Wavelength multiplexing optical transmission equipment. (5) A single receiver is equipped with an optical-to-electrical converter that is sensitive only to short wavelength light and an optical-to-electrical converter that is sensitive only to long wavelength light, and converts wavelength-multiplexed light into two optical-to-electrical converters. A wavelength division multiplexing optical transmission device according to any one of claims 1 to 3, comprising an optical branching device for branching to a converter.