CN102186066A - Optical fiber wired television super-trunk line transmission system - Google Patents
Optical fiber wired television super-trunk line transmission system Download PDFInfo
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Abstract
The invention discloses an optical fiber wired television super-trunk line transmission system. The signal transferring relationship among modules of the system is as follows: a radio frequency television signal is modulated into a first-path optical signal and a second-path optical signal through a front end module 1; the first-path optical signal is transferred via a first sub-front end module 2, a second sub-front end module 3, a third sub-front end module 4, a fourth sub-front end module 5, a fifth sub-front end module 6 and a sixth sub-front end module 7 in sequence through a forward optical fiber 8; and the second-path optical signal is transferred via the sixth sub-front end module 7, the fifth sub-front end module 6, the fourth sub-front end module 5, the third sub-front end module 4, the second sub-front end module 3 and the first sub-front end module 2 in sequence through a reverse optical fiber 9, therefore, digital signal transmission with high quality transmission within a super-long distance is realized. The system has the advantages that the system reliability can be improved; composite second order intermodulation indexes can be compensated so as to improve the compensation effect; and the carrier noise ratio (CNR) index can be improved by adopting a Raman amplifier.
Description
Technical field
What the present invention relates to is the super trunk transmission system of a kind of optical fiber cable TV, the long distance that is used for subcarrier multiplexing optical fiber cable TV net is networking project on a large scale, and the networking on a large scale of broadcasting and TV cable television network is integrated and simulated television has important function to the translation of Digital Television.
Background technology
The super trunk transmission system of optical fiber cable TV adopts the 1550nm wavelength, conventional monomode fiber at the dispersion constant (DC) of 1550nm wavelength up to 17ps/km.nm.Optical fiber combines with the strong chromatic dispersion of optical fiber on long distance at high-power self phase modulation down, the conversion of the spurious phase modulation of light wave electric field to parasitic amplitude modulation takes place, non-linear index-combination the second order inter-modulation that causes the subcarrier multiplexing fiber optic transmission system is deterioration greatly, and carrier-to-noise ratio is restricted simultaneously.Making up the combined effect of second order inter-modulation and carrier-to-noise ratio, determined the Modulation Error Rate of Digital Television, how to alleviate the deterioration of combination second order inter-modulation and carrier-to-noise ratio, is the ultimate challenge of realizing the super trunk transmission system of optical fiber cable TV.
One of the way that overcomes of combination second order inter-modulation deterioration is that optical fiber is carried out dispersion compensation.Owing to will just can be converted into extra light wave intensity modulated by optical fiber dispersion from phase modulated in the optical fiber, people wish to overcome from the angle of control optical fiber dispersion the influence of nonlinear fiber.Dispersion compensation can be with dispersion compensating fiber or realization.The advantage of dispersion compensating fiber is that bandwidth is big, delay character good linearity (the time delay ripple is little), to the position of compensator not as the chirped fiber grating sensitivity.Shortcoming is that the insertion loss is bigger, non-linear also bigger.
The super trunk transmission system of optical fiber cable TV requires to use the erbium-doped fiber amplifier chain, the incident optical power that the fiber span in the chain between adjacent two EDFA is tolerated by system index and the input optical power decision of back one erbium-doped fiber amplifier.Incident optical power is limited by stimulated Brillouin scattering thresholding and system in combination second order inter-modulation index, generally is no more than 16dBm in super mains system.The input optical power of erbium-doped fiber amplifier then is limited by system's carrier-to-noise ratio index.Because the existence of amplified spont-aneous emission noise (ASE), system's output carrier-to-noise ratio damage that erbium-doped fiber amplifier causes depends on its input optical power, and input optical power is big more, and carrier-to-noise ratio is fallen few more.
The super trunk transmission system of original optical fiber cable TV as shown in Figure 1, form by optical sender (31), multistage optical fiber and a plurality of erbium-doped fiber amplifier (32,33,34,35) cascade, and at suitable place insertion dispersion compensating fiber (36), the length of dispersion compensating fiber is pressed D*L=D
d* L
dCalculate, D is dispersion constant (DC), the D of Transmission Fibers
dBe the chromatic dispersion of dispersion compensating fiber, L is for needing the Transmission Fibers length of compensation, L
dFor the length of dispersion compensating fiber.
There is following problem in this system:
1, the dispersion compensating fiber length calculation has only been considered the influence of chromatic dispersion, does not consider the influence of the self phase modulation that big launched power causes, and makes the compensation inaccuracy, need adjust repeatedly in engineering.
2, when the overlength span optical relay section that exists greater than 100km, because the input optical power of back level erbium-doped fiber amplifier is less, make the serious deterioration of system's carrier-to-noise ratio index,, under some condition, can be subjected to condition restriction such as power supply, environment if increase the optical relay point in the centre.
3, because the super trunk transmission system coverage of optical fiber cable TV is big, and the user is many, if equipment fault or fibercuts a bit take place, can cause rating interruption on a large scale, and repair time is longer at Fig. 1, this is that broadcasting and TV safety Broadcast Control institute is unallowed.
Owing to above reason, the examination method of gathering is substantially all adopted in domestic in recent years experiment and the engineering practice to the super trunk transmission system of optical fiber cable TV, lacks theoretical direction, so that experimental result differs greatly, and effect is also undesirable.Need repeatedly various device and parameter to be debugged on engineering, make long construction period, performance is also unstable.
Summary of the invention
The object of the present invention is to provide the super trunk transmission system of a kind of optical fiber cable TV, this system not only can improve the super primary transmission reliability of TV, also can reduce the debug time of trunk transmission system.
For achieving the above object, the present invention adopts following technical proposals:
The super trunk transmission system of a kind of optical fiber cable TV of the present invention, this system comprises front-end module 1, the first sub-headend module 2, the second sub-headend module 3, the 3rd sub-headend module 4, the 4th sub-headend module 5, the 5th sub-headend module 6, the 6th sub-headend module 7, forward optical fiber 8, reverse optical fiber 9, wherein:
Front-end module is used for radio television signal is modulated into the first via light signal and the second road light signal;
The described first sub-headend module 2, the second sub-headend module 3, the 3rd sub-headend module 4, the 4th sub-headend module 5, the 5th sub-headend module 6, the 6th sub-headend module 7, each module are respectively applied for dispersion compensation, amplifying optical signals, light signal are carried out shunt, selective light signal, distribute the power of luminous power, compensated optical signal.
Signal transitive relation between above-mentioned each module is: radio television signal is modulated into the first via light signal and the second road light signal through front-end module 1, first via light signal passes through forward optical fiber 8 successively through the first sub-headend module 2, the second sub-headend module 3, the 3rd sub-headend module 4, the 4th sub-headend module 5, the 5th sub-headend module 6, the 6th sub-headend module 7 is transmitted, the reverse optical fiber 9 of the second road light signal is successively through the 6th sub-headend module 7, the 5th sub-headend module 6, the 4th sub-headend module 5, the 3rd sub-headend module 4, the second sub-headend module 3, the first sub-headend module 2 is transmitted, and realizes transmitting digital data transmission on the extra long distance.
Described front-end module 1 comprises forward optical sender 11, backlight transmitter 12, forward switches light switch 13, reverse switches light switch 14, forward erbium-doped fiber amplifier 15, reverse erbium-doped fiber amplifier 16, wherein:,
Forward optical sender 11, backlight transmitter 12 are modulated to radio television signal two defeated light-emitting windows respectively;
Forward switches light switch 13 is used to switch and the forward light signal, and normally closed port connects first defeated light-emitting window of described optical sender 17, first defeated light-emitting window of the described optical sender 18 of normal ported connection, and public port is connected with erbium-doped fiber amplifier 21;
Reverse switches light switch 14 is used to switch and reverse optical signal, and normally closed port is connected with second defeated light-emitting window of described optical sender 17, second of ported described optical sender 18 defeated light-emitting window connection often, and public port is connected with erbium-doped fiber amplifier 22;
Forward erbium-doped fiber amplifier 15 is used to amplify the forward light signal, and exports forward optical fiber 8 to;
Oppositely erbium-doped fiber amplifier 16 is used to amplify reverse optical signal, and exports reverse optical fiber 9 to.
The above-mentioned first sub-headend module 2, the second sub-headend module 3, the 3rd sub-headend module 4, the 4th sub-headend module 5, the 5th sub-headend module 6, the 6th sub-headend module 7, wherein,
The described first sub-headend module 2, the second sub-headend module 3, the 3rd sub-headend module 4, the 4th sub-headend module 5, the 5th sub-headend module 6, the 6th sub-headend module 7 comprise respectively:
Forward dispersion compensation module 21 is used for forward optical fiber 8 is carried out dispersion compensation, and its output is connected with forward erbium-doped fiber amplifier 23;
Reverse dispersion compensating module 22 is used for the last hop of reverse optical fiber 9 is carried out dispersion compensation, and its output connects erbium-doped fiber amplifier 24 and connects;
Forward erbium-doped fiber amplifier 23 is used to amplify the forward light signal, and its output is connected with forward optical branching device 25;
Oppositely erbium-doped fiber amplifier 24 is used to amplify reverse optical signal, and its output is connected with backlight splitter 26;
Forward optical branching device 25 is used for the forward light signal is carried out shunt, and one tunnel output is connected with forward optical fiber, and another road output is connected with the normally closed port of light selector switch 27;
Backlight splitter 26 is used for reverse optical signal is carried out shunt, and one tunnel output is connected with the next hop of reverse optical fiber 9, and normal ported connection the with selective light switch 27 exported on another road;
Light selector switch 27 is used to select light signal forward or backwards, and output is connected with distributing erbium-doped fiber amplifier 28;
Distribute erbium-doped fiber amplifier 28, be used for providing enough luminous powers to the optical distribution network after the sub-headend module;
Forward pumping raman amplifier 29 when the length of the last fiber segment of forward optical fiber 8 surpasses 100km, is used to compensate the power of forward light signal, and output connects forward dispersion compensation module 21;
Backward pumping raman amplifier 30 when the length of the last hop of reverse optical fiber 9 surpasses 100km, is used to compensate the power of reverse optical signal, and output connects reverse dispersion compensating module 22.
Above-mentioned forward dispersion compensation module 21 comprises erbium-doped fiber amplifier 201 and dispersion compensating fiber 202, and reverse dispersion compensating module 22 comprises erbium-doped fiber amplifier 203 and dispersion compensating fiber 204, wherein:
Erbium-doped fiber amplifier 201 is used for the loss of compensation of dispersion compensated fiber, output and be connected to dispersion compensating fiber;
In the formula,
Be the dispersion constant (DC) of DCF, D is the dispersion constant (DC) of Transmission Fibers,
Be incident optical power,
Be the non linear coefficient of Transmission Fibers, L is the fiber lengths of compensator section,
Be the input optical power of dispersion compensating fiber,
Be the non linear coefficient of dispersion compensating fiber,
Length for dispersion compensating fiber.α is the dissipation constant of Transmission Fibers,
Dissipation constant for DCF.
Described forward dispersion compensation module 21, reverse dispersion compensating module 22, it comprises small-power erbium-doped fiber amplifier, dispersion compensating fiber respectively.
The super trunk transmission system of a kind of optical fiber cable TV of the present invention has following outstanding substantive distinguishing features and remarkable advantage compared with prior art:
1, this system adopts the two fine transmitted in both directions structures of dual transmitter, and signal is carried out redundancy backup, makes system recovery time foreshorten to the switching time of light selector switch, reaches Millisecond, has improved system reliability;
2, dispersion compensating fiber length is calculated in advance according to the incident optical power of compensator section, fiber lengths etc. by this system, the tailored dispension compensator, thus can make compensation effect better to combination second order inter-modulation index fine compensation;
3, this system adopts raman amplifier to solve the signal high-quality transmission problem that the above overlength span of 100km does not have optical relay, has improved the input optical power of back grade of EDFA, has improved the CNR index.
Description of drawings
Fig. 1 is the structural representation of the super trunk transmission system of existing optical fiber cable TV;
Fig. 2 is the structural representation of the super trunk transmission system of a kind of optical fiber cable TV of the present invention;
Fig. 3 is the schematic diagram of the forward fibre circuit configuration of the embodiment of the invention.
Embodiment
The present invention is described in further detail below in conjunction with the drawings and specific embodiments.As shown in Figure 2, the super trunk transmission system of a kind of optical fiber cable TV of the present invention, this system comprises front-end module (1), the first sub-headend module (2), the second sub-headend module (3), the 3rd sub-headend module (4), the 4th sub-headend module (5), the 5th sub-headend module (6), the 6th sub-headend module (7), forward optical fiber (8), reverse optical fiber (9), wherein:
Front-end module is used for radio television signal is modulated into the first via light signal and the second road light signal,
The described first sub-headend module (2), the second sub-headend module (3), the 3rd sub-headend module (4), the 4th sub-headend module (5), the 5th sub-headend module (6), the 6th sub-headend module (7), each module are respectively applied for being used for dispersion compensation, amplifying optical signals, light signal being carried out shunt, selective light signal, distributes the power of luminous power, compensated optical signal;
Signal transitive relation between above-mentioned each module is: radio television signal is modulated into the first via light signal and the second road light signal through front-end module (1), first via light signal passes through forward optical fiber (8) successively through the first sub-headend module (2), the second sub-headend module (3), the 3rd sub-headend module (4), the 4th sub-headend module (5), the 5th sub-headend module (6), the 6th sub-headend module (7) is transmitted, the reverse optical fiber of the second road light signal (9) is successively through the 6th sub-headend module (7), the 5th sub-headend module (6), the 4th sub-headend module (5), the 3rd sub-headend module (4), the second sub-headend module (3), the first sub-headend module (2) is transmitted, and realizes transmitting digital data transmission on the extra long distance.
Described front-end module (1) comprising: forward optical sender (11), backlight transmitter (12), forward switches light switch (13), reverse switches light switch (14), forward erbium-doped fiber amplifier (15), reverse erbium-doped fiber amplifier (16), wherein:,
Forward optical sender (11), backlight transmitter (12) are modulated to radio television signal two defeated light-emitting windows respectively;
Forward switches light switch (13), be used to switch and the forward light signal, normally closed port connects first defeated light-emitting window of described optical sender (17), first defeated light-emitting window of the described optical sender of normal ported connection (18), and public port is connected with erbium-doped fiber amplifier (21);
Reverse switches light switch (14), be used to switch and reverse optical signal, normally closed port is connected with second defeated light-emitting window of described optical sender (17), and second defeated light-emitting window of normal ported described optical sender (18) connects, and public port is connected with erbium-doped fiber amplifier (22);
Forward erbium-doped fiber amplifier (15) is used to amplify the forward light signal, and exports forward optical fiber (8) to;
Oppositely erbium-doped fiber amplifier (16) is used to amplify reverse optical signal, and exports reverse optical fiber (9) to;
The described first sub-headend module (2), the second sub-headend module (3), the 3rd sub-headend module (4), the 4th sub-headend module (5), the 5th sub-headend module (6), the 6th sub-headend module (7),
The described first sub-headend module (2), the second sub-headend module (3), the 3rd sub-headend module (4), the 4th sub-headend module (5), the 5th sub-headend module (6), the 6th sub-headend module (7) comprise respectively:
Forward dispersion compensation module (21) is used for forward optical fiber (8) is carried out dispersion compensation, and its output is connected with forward erbium-doped fiber amplifier (23);
Reverse dispersion compensating module (22) is used for the last hop of reverse optical fiber (9) is carried out dispersion compensation, and its output connects erbium-doped fiber amplifier (24) and connects;
Forward erbium-doped fiber amplifier (23) is used to amplify the forward light signal, and its output is connected with forward optical branching device (25);
Oppositely erbium-doped fiber amplifier (24) is used to amplify reverse optical signal, and its output backlight splitter (26) connects;
Forward optical branching device (25) is used for the forward light signal is carried out shunt, and one tunnel output is connected with forward optical fiber, and another road output is connected with the normally closed port of light selector switch (27);
Backlight splitter (26) is used for reverse optical signal is carried out shunt, and one tunnel output is connected with the next hop of reverse optical fiber (9), and normal ported connection the with light selector switch (27) exported on another road;
Light selector switch (27) is used to select light signal forward or backwards, and output is connected with distributing erbium-doped fiber amplifier (28);
Distribute erbium-doped fiber amplifier (28), be used for providing enough luminous powers to the optical distribution network after the sub-headend module;
Forward pumping raman amplifier (29) when the length of the last fiber segment of forward optical fiber (8) surpasses 100km, is used to compensate the power of forward light signal, and output connects forward dispersion compensation module (21);
Backward pumping raman amplifier (30) when the length of the last hop of reverse optical fiber (9) surpasses 100km, is used to compensate the power of reverse optical signal, and output connects reverse dispersion compensating module (22).
Above-mentioned forward dispersion compensation module (21) comprises erbium-doped fiber amplifier (201) and dispersion compensating fiber (202), reverse dispersion compensating module (22) comprises erbium-doped fiber amplifier (203) and dispersion compensating fiber (204), wherein: erbium-doped fiber amplifier (201) (203), be used for the loss of compensation of dispersion compensated fiber, output is connected with dispersion compensating fiber; Dispersion compensating fiber (202) (204) is used to improve by optical fiber dispersion and the system in combination second order inter-modulation index that causes from phase modulated, the length of dispersion compensating fiber
By following calculating formula, its calculating formula:
In the formula,
Be the dispersion constant (DC) of DCF, D is the dispersion constant (DC) of Transmission Fibers,
Be incident optical power,
Be the non linear coefficient of Transmission Fibers, L is the fiber lengths of compensator section,
Be the input optical power of dispersion compensating fiber,
Be the non linear coefficient of dispersion compensating fiber,
Length for dispersion compensating fiber.α is the dissipation constant of Transmission Fibers,
Dissipation constant for DCF.
Described forward dispersion compensation module (21), reverse dispersion compensating module (22), it comprises respectively: small-power erbium-doped fiber amplifier, dispersion compensating fiber.
The protection handoff procedure of the super trunk transmission system of a kind of optical fiber cable TV of the present invention is described as follows:
The handoff procedure of the front-end module in the said system (1):
Optical sender (11) is identical with the radiofrequency signal of optical sender (12) input in the front-end module in the said system (1).During the system operate as normal, the light signal of optical sender (11) output enters the normally closed port of optical switch (13), is connected to erbium-doped fiber amplifier (15) through optical switch (13), inputs to forward optical fiber after amplifying.The light signal of optical sender (12) output enters the normally closed port of optical switch (14), is connected to erbium-doped fiber amplifier (16) through optical switch (14), inputs to reverse optical fiber after amplifying.
When optical sender (11) damages, during unglazed output, optical switch (13) detects the unglazed input of normally closed port, then switches to often ported, be communicated with optical sender (12) and erbium-doped fiber amplifier (15), recover descending forward light signal, when optical sender (12) damages, during unglazed output, optical switch (14) detects the unglazed input of normally closed port, then switch to often portedly, be communicated with optical sender (11) and erbium-doped fiber amplifier (16), recover descending reverse optical signal.Thereby having guaranteed to have a transmitter job certainly, just can produce forward and reverse optical signal.
The handoff procedure of the second sub-headend module (3) in the said system:
During the said system operate as normal, the forward light signal input backward pumping raman amplifier (29) that a last fiber segment of forward optical fiber (8) is come, behind erbium-doped fiber amplifier (201), input dispersion compensating fiber (202), again through forward erbium-doped fiber amplifier (23) input optical branching device (25), optical branching device (25) one tunnel outputs connect next forward fiber segment, another road output connects the normally closed port of light selector switch (27), exports optical distribution network to again after distributing erbium-doped fiber amplifier (28).Oppositely the next reverse optical signal of a last fiber segment of optical fiber (9) is imported backward pumping raman amplifier (30), behind erbium-doped fiber amplifier (203), input dispersion compensating fiber (204), again through erbium-doped fiber amplifier (24) input optical branching device (26), (26) one tunnel outputs of backlight splitter connect next backlight hop, and it is often ported that another road output connects light selector switch (27).
When a certain equipment breaks down on forward fibercuts or the forward fiber path, light selector switch (27) detects the unglazed input of normally closed port, then switch to often ported, be communicated with backlight splitter (26) and distribute er-doped image intensifer (28), reverse optical path is communicated with optical distribution network, recovers light signal.
For the transmission reliability of verifying the super trunk transmission system of optical fiber cable TV of the present invention and the debug time of trunk transmission system carry out validation test to dispersion compensating fiber length, carrier-to-noise ratio, the Modulation Error Rate index of this system:
As shown in Figure 3, the allocation plan of the forward fibre circuit in the transmission system of the present invention, the total line length of this allocation plan is 560km, has omitted light selector switch and optical branching device that system index is not exerted an influence among the figure.
In fiber segment (61), fiber segment (62), fiber segment (63), fiber segment (64), fiber segment (65) is provided with dispersion compensating fiber (39 respectively, 42,46,49,52), fiber segment (60) does not adopt dispersion compensation, adopt erbium-doped fiber amplifier (41), erbium-doped fiber amplifier (45), erbium-doped fiber amplifier (48), erbium-doped fiber amplifier (51) is the decay of compensation of dispersion compensated fiber respectively, in overlength span section (61), overlength span section (63) adopts 14dB backward pumping raman amplifier (38), backward pumping raman amplifier (44), to improve power output, improve system's carrier-to-noise ratio.
Calculate best dispersion compensating fiber length by above-mentioned formula (1)
, the DCF parameter of employing is:
,
,
,
Adopt the decay of the small-power erbium-doped fiber amplifier compensation of dispersion compensated fiber of 7dBm output, the dispersion compensating fiber length such as the table 1 that calculate:
Table 1 dispersion compensating fiber length
| The dispersion compensating fiber numbering | Length (km) |
| 39 | 13 |
| 42 | 7 |
| 46 | 11 |
| 49 | 6 |
| 52 | 7 |
As shown in Figure 3, according to the configuration of the forward fibre circuit among the figure system of the present invention is tested, the index that obtains is carrier-to-noise ratio CNR〉40dB, combination second order inter-modulation index CSO〉55dB, Digital Television Modulation Error Rate MER〉35dB, satisfied the transmission requirement of high-quality transmission Digital Television on extra long distance.
By above narration as can be seen, the super trunk transmission system of a kind of optical fiber cable TV of the present invention adopts the two fine bidirectional redundancy transmission structures of dual transmitter can improve system reliability, the dispersion compensation effect of the length by calculating dispersion compensating fiber has been improved combination second order inter-modulation index; Adopt the backward pumping distributed raman amplifier to solve the signal high-quality transmission problem that overlength span does not have optical relay, improved the carrier-to-noise ratio index.And provided the computational methods of system index, can carry out the transmission equipment configuration according to real topology at system design stage, thereby shorten the engineering debug time.
Claims (5)
1. super trunk transmission system of optical fiber cable TV, it is characterized in that, this system comprises front-end module (1), the first sub-headend module (2), the second sub-headend module (3), the 3rd sub-headend module (4), the 4th sub-headend module (5), the 5th sub-headend module (6), the 6th sub-headend module (7), forward optical fiber (8), reverse optical fiber (9), wherein:
Front-end module is used for radio television signal is modulated into the first via light signal and the second road light signal;
The described first sub-headend module (2), the second sub-headend module (3), the 3rd sub-headend module (4), the 4th sub-headend module (5), the 5th sub-headend module (6), the 6th sub-headend module (7), each module are respectively applied for dispersion compensation, amplifying optical signals, light signal are carried out shunt, selective light signal, distribute the power of luminous power, compensated optical signal;
Signal transitive relation between above-mentioned each module is: radio television signal is modulated into the first via light signal and the second road light signal through front-end module (1), first via light signal passes through forward optical fiber (8) successively through the first sub-headend module (2), the second sub-headend module (3), the 3rd sub-headend module (4), the 4th sub-headend module (5), the 5th sub-headend module (6), the 6th sub-headend module (7) is transmitted, the reverse optical fiber of the second road light signal (9) is successively through the 6th sub-headend module (7), the 5th sub-headend module (6), the 4th sub-headend module (5), the 3rd sub-headend module (4), the second sub-headend module (3), the first sub-headend module (2) is transmitted, and realizes transmitting digital data transmission on the extra long distance.
2. according to the super trunk transmission system of the described a kind of optical fiber cable TV of claim (1), it is characterized in that: above-mentioned front-end module, described front-end module (1) comprises forward optical sender (11), backlight transmitter (12), forward diverter switch (13), reverse switches light switch (14), forward erbium-doped fiber amplifier (15), reverse erbium-doped fiber amplifier (16), wherein:
Forward optical sender (11), backlight transmitter (12) are modulated to radio television signal two defeated light-emitting windows respectively;
Forward switches light switch (13), be used to switch and the forward light signal, normally closed port connects first defeated light-emitting window of described optical sender (11), first defeated light-emitting window of the described optical sender of normal ported connection (12), and public port is connected with erbium-doped fiber amplifier (15);
Reverse switches light switch (14), be used to switch and reverse optical signal, normally closed port is connected with second defeated light-emitting window of described optical sender (12), and second defeated light-emitting window of normal ported and described optical sender (11) is connected, and public port is connected with erbium-doped fiber amplifier (16);
Forward erbium-doped fiber amplifier (15) is used to amplify the forward light signal, and exports forward optical fiber (8) to;
Oppositely erbium-doped fiber amplifier (16) is used to amplify reverse optical signal, and exports reverse optical fiber (9) to.
3. according to the super trunk transmission system of the described a kind of optical fiber cable TV of claim (1), it is characterized in that: the first above-mentioned sub-headend module (2), the second sub-headend module (3), the 3rd sub-headend module (4), the 4th sub-headend module (5), the 5th sub-headend module (6), the 6th sub-headend module (7), wherein
The described first sub-headend module (2), the second sub-headend module (3), the 3rd sub-headend module (4), the 4th sub-headend module (5), the 5th sub-headend module (6), the 6th sub-headend module (7) comprise respectively:
Forward dispersion compensation module (21) is used for forward optical fiber (8) is carried out dispersion compensation, and its output is connected with forward erbium-doped fiber amplifier (23);
Reverse dispersion compensating module (22) is used for the last hop of reverse optical fiber (9) is carried out dispersion compensation, and its output connects erbium-doped fiber amplifier (24) and connects;
Forward erbium-doped fiber amplifier (23) is used to amplify the forward light signal, and its output is connected with forward optical branching device (25);
Oppositely erbium-doped fiber amplifier (24) is used to amplify reverse optical signal, and its output is connected with backlight splitter (26);
Forward optical branching device (25) is used for the forward light signal is carried out shunt, and one tunnel output is connected with forward optical fiber, and another road output is connected with the normally closed port of optical switch (27);
Backlight splitter (26) is used for reverse optical signal is carried out shunt, and one tunnel output is connected with the next hop of reverse optical fiber (9), and normal ported connection the with optical switch (27) exported on another road;
Optical switch (27) is used to select light signal forward or backwards, and output is connected with distributing erbium-doped fiber amplifier (28);
Distribute erbium-doped fiber amplifier (28), be used for providing enough luminous powers to the optical distribution network after the sub-headend module;
Forward pumping raman amplifier (29) when the length of the last fiber segment of forward optical fiber (8) surpasses 100km, is used to compensate the power of forward light signal, and output connects forward dispersion compensation module (21);
Backward pumping raman amplifier (30) when the length of the last hop of reverse optical fiber (9) surpasses 100km, is used to compensate the power of reverse optical signal, and output connects reverse dispersion compensating module (22).
4. according to the super trunk transmission system of the described a kind of optical fiber cable TV of claim (1), it is characterized in that: above-mentioned forward dispersion compensation module (21) comprises erbium-doped fiber amplifier (201) and dispersion compensating fiber (202), reverse dispersion compensating module (22) comprises erbium-doped fiber amplifier (203) and dispersion compensating fiber (204), wherein:
Erbium-doped fiber amplifier (201) (203) is used for the loss of compensation of dispersion compensated fiber, and output is connected with dispersion compensating fiber;
Dispersion compensating fiber (202) (204) is used to improve by optical fiber dispersion and the system in combination second order inter-modulation index that causes from phase modulated, the length of dispersion compensating fiber
By following calculating formula, its calculating formula:
In the formula,
Be the dispersion constant (DC) of DCF, D is the dispersion constant (DC) of Transmission Fibers,
Be incident optical power,
Be the non linear coefficient of Transmission Fibers, L is the fiber lengths of compensator section,
Be the input optical power of dispersion compensating fiber,
Be the non linear coefficient of dispersion compensating fiber,
Be the length of dispersion compensating fiber, α is the dissipation constant of Transmission Fibers,
Dissipation constant for DCF.
5. according to the super trunk transmission system of the described a kind of optical fiber cable TV of claim (1), it is characterized in that: described forward dispersion compensation module (21), reverse dispersion compensating module (22), it comprises erbium-doped fiber amplifier, dispersion compensating fiber respectively.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110087696 CN102186066A (en) | 2011-04-08 | 2011-04-08 | Optical fiber wired television super-trunk line transmission system |
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| CN 201110087696 CN102186066A (en) | 2011-04-08 | 2011-04-08 | Optical fiber wired television super-trunk line transmission system |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109412694A (en) * | 2017-08-17 | 2019-03-01 | 上海长弋通信技术有限公司 | A kind of 1550nm extra long distance DTV fibre-optic transmission system (FOTS) |
| CN110336605A (en) * | 2019-07-25 | 2019-10-15 | 广东复安科技发展有限公司 | A kind of fiber optic interferometric sensing positioning system of long range pinpoint accuracy |
| CN111404612A (en) * | 2020-03-25 | 2020-07-10 | 武汉光谷信息光电子创新中心有限公司 | Optical signal amplifying device and transmission system |
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| CN1452328A (en) * | 2002-04-18 | 2003-10-29 | 华为技术有限公司 | Erbium doped optical fibre light amplifier |
| CN1783757A (en) * | 2004-11-30 | 2006-06-07 | 中兴通讯股份有限公司 | Dispersion compensator of dense wave division multiplex system |
| CN201541049U (en) * | 2009-10-26 | 2010-08-04 | 福州高意通讯有限公司 | Two-way transmission optical amplifier |
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| CN1452328A (en) * | 2002-04-18 | 2003-10-29 | 华为技术有限公司 | Erbium doped optical fibre light amplifier |
| CN1783757A (en) * | 2004-11-30 | 2006-06-07 | 中兴通讯股份有限公司 | Dispersion compensator of dense wave division multiplex system |
| CN201541049U (en) * | 2009-10-26 | 2010-08-04 | 福州高意通讯有限公司 | Two-way transmission optical amplifier |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109412694A (en) * | 2017-08-17 | 2019-03-01 | 上海长弋通信技术有限公司 | A kind of 1550nm extra long distance DTV fibre-optic transmission system (FOTS) |
| CN110336605A (en) * | 2019-07-25 | 2019-10-15 | 广东复安科技发展有限公司 | A kind of fiber optic interferometric sensing positioning system of long range pinpoint accuracy |
| CN111404612A (en) * | 2020-03-25 | 2020-07-10 | 武汉光谷信息光电子创新中心有限公司 | Optical signal amplifying device and transmission system |
| CN111404612B (en) * | 2020-03-25 | 2021-05-11 | 武汉光谷信息光电子创新中心有限公司 | Optical signal amplifying device and transmission system |
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