CN1439226A

CN1439226A - Twoway calbe system with noise-free return path

Info

Publication number: CN1439226A
Application number: CN 01811662
Authority: CN
Inventors: A－K·拉哈尼
Original assignee: Advanced Interactive Inc USA
Current assignee: Advanced Interactive Inc USA
Priority date: 2000-04-25
Filing date: 2001-04-25
Publication date: 2003-08-27
Also published as: EP1287693A2; NZ522452A; AU2001252082A1; WO2001082618A9; CA2407321A1; WO2001082618A3; WO2001082618A2

Abstract

The return path for a signal in a cable system uses a portion of the 50-750 MHz frequency band to send signals from each set-top box therein to a receiver at the feeder line end. A band stop filter is placed in each auxiliary feeder line to prevent the return signal from set-top boxes being received by more than one feeder line end. The feeder line end has a receiver for the signal from set-top boxes and a means to transmit the signal back to the headend via various mediums. The size of the return path is operator selectable. Further more this system eliminates virtually all ingress noise picked up by the collection of set-top boxes, home wiring and drop wiring entering the cable system.

Description

Two-way cable system with noiseless return path

MULTIPLE-BLADE

The application is the patent application serial numbers No.09/541 that the application's applicant applied on April 3rd, 2000,187 subsequent application.

Technical field

The present invention relates to cable system, and especially relate to and have enough noiseless return paths, send the such system of family that travels to and fro between to support high-bandwidth bi-directional broadband, content of multimedia.

Background technology

As everyone knows, the return path in cable system is noisy, and often is called as " noise funnel ".There are three main above-mentioned noise sources: heat, optical fiber link and ingress.In each active parts (amplifier and receiver), all can produce thermal noise.This optical fiber link noise produces in return laser light, optical fiber and front end receiver.Noise occurs entering via local distribution and wiring, and constitute main noise source.The comprehensive argumentation of return path and noise characteristic is by Donald Raskin and Dean Stoneback, write in 1998, " send-back system that is used for the hybrid fiber/coaxial cable TV network " of Prentice Hall company (Return Systems for Hybrid Fiber/Coax Cable TV Networks, byDonald Raskin and Dean Stoneback, 1998 Prentice Hall provide in Inc.).

Traditional cable system has a main line from front end to set-top box with the direction that forward is launched along its signal, and this set-top box is arranged in family or the commercial undertaking that is connected to this feeder line.By providing set-top box to be connected to feeder line through each set-top box of tap to this feeder line.In the common structure of cable system, exist many set-top box to be connected to each feeder line.In addition, each feeder line and/or main line comprise two-way amplifier, and it transmits signal with forward (passing down) direction in high frequency band, and transmits signal to return (uploading) direction in low-frequency band, and this is fine understanding in this area.Signal begins in set-top box in low-frequency band, and is used to upload direction and is communicated to front end.

Because the problem of the present return path in cable system comes across such fact, promptly the characteristics of the tap (house wiring and lead-in) are from set-top box to feeder line, a unacceptable noise level (entering) is picked up in the low-frequency band of set-top box emission by in local distribution and lead-in cable.In addition, low separate do not have in the cable system other frequency band (relatively not having the above-mentioned noise that enters) for from this locality to the emission of front end be available.Present low separation cable system is launched with high frequency band from the cable front end, and launches with low-frequency band from set-top box.

Yet financial quarters's expectation is two-way, broad-band channel is so strong via the cable system transmission, so that very big resource is endeavouring to enter in return path towards solution the direction of noise problem.Current means to save the situation is expensive, makes to cause system's instability by system closing, need to repeat service call and give subscriber equipment, and frequent this locality and lead-in rewires or special trap circuit is installed.In addition, along with the erosion and the degeneration of lead and connector, existing needs the cable operator high likelihood of maintenance continuously.

In the past ten years, cable industry is its cable foundation structure of retrofit, to allow two-way communication on cable line.This relates to and start return path in the sector, and this return path is in the 5-40 mhz band.The design of this return path was rebuild since the later stage seventies.In the later stage of the eighties, the coverage that a lot of cable companies begins to cut apart them is less group, is called " node ", and under many circumstances, change their relay system, from only using coaxial cable and relay amplifier to hybrid fiber/coaxial system (HFC).Active being replaced simultaneously with passive device, in downstream direction, to increase frequency spectrum, from 50-350 megahertz performance index to the 50-750 megahertz, sometimes up to 850 megahertzes.The outbound frequency band of this increase allows cable companies to remove to provide the channel of more video communication service.The bandwidth of this increase also can be used for the digital service at forward.In addition, start this return path by now, two-way business such as impromptu pay-per-use, interactively TV, cable modem, telephone service and supplementary service can be provided.

In the activation of return path, find by most of cable companies, the 5-40 mhz band, especially the 5-15 mhz spectrum is very noisy.Owing to there is this noise, available most of business are digital services at present in lower frequency band, and it often can be worked with the low carrier of noise signal level.But because this noise is inconsistent, business is seriously weakened sometimes.Therefore, a lot of present finding methods of cable companies remove to reduce this noise in the 5-40 mhz band.Most methods has reduced the number that is connected to each node family, thereby is reduced in the noise of total gathering that each segmentation of node gathers.The method that also has comprises installs 5-50 megahertz blocking filter, and the noise that goes to reduce in the 5-50 mhz band from inactive user's family enters this trunk cable distributed network.Current the best way is that this cable system of decomposition is many nodes, and it is 15 home services seldom, and in fact the home system of a very little grouping is provided, and each family is directly connected to this node.

Summary of the invention

The part (being the 50-750 megahertz) that the present invention is based on the frequency band that can use the downstream is to a certain extent gone to transmit this return path signal from a set-top box and is realized.This frequency band part is used for providing TV signal and digital signal to family from front end at present.But this frequency band part can not be used to transmit the return path signal at present.

According to principle of the present invention, picking up and send to the noise of respective nodes in the feeder line in family expenses utensil, lead-in, connector or the like can avoid by reconfiguring set-top box, go in high frequency band, to launch, rather than in the low-frequency band that most of noises take place, launch.This signal begins to feeder terminal with downstream direction from this set-top box, and this feeder terminal is equipped with a receiver (optical sender) and the optical fiber getting back to node or directly arrive front end in addition.The result is that set-top box is propagated to feeder terminal in forward direction transmission, and they are received and send (optical sender) through an optical fiber and give node or front end here.Owing to can not use the lower frequency frequency band, great majority enter noise and are positioned at wherein in this lower frequency frequency band, and this noise (local to the feeder line tap) is avoided.In this respect, each feeder terminal has terminal, and this receiver (that is, optical sender) adds that optical fiber link can just be placed on after the final amplifier terminal in feeder line, and separates to the different line terminals at feeder line.Feeder line part between the position of final amplifier (terminal) and feeder line separation line terminal is called as feeder terminal herein.

Specifically, the applicant increases to the relatively inexpensive equipment of this cable system herein, and it allows this set-top box to the feeder terminal of return path partly to play forward path.In one embodiment, this is by provide an optical sender and optical fiber link to finish at each feeder terminal.This optical sender receives this signal at highband part, and launches this signal through an optical fiber link and get back to this node or front end.The characteristic of native system is that in fact it eliminate from house wiring and this lead-in and enter noise, and it is schematically illustrated on 57 of the publication of note pages in the above.It further provides advantage, allows this Systems Operator to go to select to return the size and the position of frequency band within the 50-750 mhz spectrum.

In another embodiment, each feeder terminal comprises a receiver and demodulator go the to decode data of this reception.The data of this decoding are used to modulate a new signal then.This newborn signal does not comprise the noise in the signal that is included in this reception.It is actually a muting signal.Optical sender sends this signal to node or front end through optical fiber then.

Therefore, according to principle of the present invention, provide a kind of and be used for from the equipment of house wiring, family and from the lead-in of importing this cable system, eliminated the method that enters noise in low-frequency band by not using great majority to enter the lower frequency frequency band that noise is positioned at.Each forward direction amplifier has had a high pass filter, hinders this low-frequency band and is exaggerated at forward.This higher frequency band is used to transmit this inverse signal from the feeder terminal to the node or front end.Because actual noise lowers, and can adopt many higher modulation schemes, such as QAM-16, QAM-32, QAM-64, QAM-256 or the like.It is more reliable that current modulation scheme also becomes, and have the much lower error rate.This feedback signal is not limited to modulated signal.Various signals (that is, vision signal, radio signal) can derive from this customer location.Generally speaking, it is more convenient to use that it makes this return path in cable system.Along with higher reliability result, have user's requested service still less probably, and higher customer satisfaction.The size of return path is flexibly fully, and this Systems Operator can select virtually any size and position to be used for this feedback signal in frequency band.In addition, because the return path that is used for each feeder terminal can be taken back respectively to front end, be used for the size that the effective dimensions of this return path of whole system can allow greater than existing systems substantially.

Illustrative ground, the present invention utilizes the part of 50-750 mhz band rather than 5-40 mhz spectrum to go to transmit feedback signal from customer location.But this feedback signal at first is launched and is transferred to this feeder terminal, and here it is picked and recover to give the cable front end.End at each feeder line is a receiver, illustrative ground its be operated in that the 50-750 mhz band goes to receive should " returning " signal.For example, this 300-350 mhz band can be used for delivering this feedback signal " forwarding " to this feeder terminal.Signal in this frequency band is received by the receiver (that is optical sender) at the end of this feeder line.This signal is sent to this node or this cable front end through an optical fiber link then.Owing to do not use lower frequency band, this in this lower frequency band enters noise and thoroughly eliminated.This system does not need sign-changing amplifier yet, thereby and also avoided necessary adjustment sign-changing amplifier signal level, adjusting the sign-changing amplifier signal level is work time-consuming and effort.

Description of drawings

Fig. 1 is the schematic diagram of the cable system of an expression prior art, and this cable system comprises cable front end, main line, node and illustrative set-top box position;

Fig. 2 is the figure that an expression is used for the frequency band part of cable front end, set-top box and two-way amplifier work at the prior art cable system at present;

Fig. 3 is one and is illustrated in the figure that the typical case who is used to launch in the low-frequency band of Fig. 2 enters noise level;

Fig. 4 is the schematic diagram of an expression according to the cable system of principle of the present invention;

Fig. 5 A-5D represents to be used for the figure of the frequency band part of front end, set-top box, two-way amplifier and optical sender that Fig. 4 arranges;

Fig. 6 A-6E and 7A-7E represent that signal processing scheme and expression are used at the figure according to the frequency band part correlation of the feeder terminal of the cable system of the principle of the invention;

Fig. 8 illustrates one group of signal level figure more relevant with frequency ratio that is used for according to cable front end, set-top box, amplifier and the optical sender of the cable system of principle of the present invention;

Fig. 9 illustrates and enters noise and according to the figure of the portions of the spectrum of principle set-top box of the present invention emission;

Figure 10 represents the schematic diagram of the embodiment that a present invention replaces;

Figure 11 is one group of signal level figure more relevant with frequency ratio that is used for respectively according to cable front end, set-top box, amplifier and the optical sender of the cable system of principle of the present invention;

Figure 12 is the figure of an expression for the band pass filter of embodiments of the invention use; With

Figure 13,14 and 15 is the set-top box of a prior art of expression and the schematic diagram of useful in an embodiment of the present invention selective set-top box.

Embodiment

Fig. 1 illustrates a description that is used for the illustrative embodiment of the present invention, goes to set up the schematic block diagram of the prior art cable system of a reference point and term.Specifically, Fig. 1 illustrates a cable system 10 that has cable front end 11 and main line 12.Main line 12 typically comprises a coaxial cable and is connected to node or hub 13.Node 13 is connected to this cable front end through optical fiber (perhaps coaxial cable) 14, and (for the former) comprise an optical sender, is used for providing inverse signal to this cable front end from a subscriber computer top box.

This main line comprises a plurality of two-way amplifiers, and illustrative ground is with 17 and 18 expressions.This main line also comprises two-way bridge amplifier 20 and 21, and as expression, feeder line 22,23 and 24 is connected to it.Also show an auxiliary feeder 26 and tap 28, auxiliary feeder 26 also comprises two-way amplifier (with 27 expressions), and the branch cable 29 to set-top box is connected to tap 28.

A trunk cable end terminals comes across the end of main line 12, as representing with 30.The end of feeder line 24 has line terminal 31 and 32.

Fig. 2 illustrates one group for the prior art cable system, respectively for the signal level chart more relevant with frequency ratio of front end, set-top box and two-way amplifier.In the prior art system, this cable front end illustrative ground is in 5-40 mhz band received signal, and illustrative ground is launched on whole 50-750 mhz band.This set-top box is just in time worked in opposite mode.Specifically, this set-top box is launched in the 5-40 mhz band, and in the 50-750 mhz band received signal.

This two-way amplifier forwards signal (leaving this front end) in the 50-750 mhz band, and transmits in the 5-40 mhz band and return (towards the direction of this front end) signal.Therefore, major part just in time occurring from the signal of set-top box in the 5-40 mhz band enters noise and takes place.Fig. 3 illustrates one and is illustrated in the characteristic curve that enters noise 33 that has the gathering of the maximum value of entering in the 5-40 mhz band.Clearly, the efficient of present return path may be entered noise and seriously limited.

Fig. 4 is a block diagram according to the cable system of principle of the present invention.This system 40 comprises a front end 41 that is connected to node (perhaps hub) 42 by optical fiber (perhaps coaxial cable) cable 43.This node comprises one or more back light transmitters (being used for fibre system).This system also comprises a main line 45 that has amplifier 47 and 48 (having more amplifier and them to be positioned at the 500-1500 foot usually there usually), bridge amplifier 50 and 52 with being separated by.In one embodiment, a feeder line 56 is shown, it is connected to bridge amplifier 50 and leading-out terminal terminal 58.A high pass filter 59 and an optical sender 60 are located between final amplifier (terminal) 57 and the feed line terminals 58.This optical sender injection fibre 91, it enters into node 42.It may be routed directly to cable front end 41, and principle of the present invention will stand good.The frequency spectrum of modulating this optical sender 60 is shown in Fig. 5 A.

In another embodiment, a feeder line 61 has feeder terminal at terminal 62 and 65.A band pass filter 63 and an optical sender 64 are located at after the final amplifier 53, and before terminal 62 and 65.This band pass filter only by the signal in the 300-350 mhz band, launch in this frequency band by this set-top box.This optical sender 64 signal of feeding enters optical fiber 92, so that enter into node 42.The frequency spectrum of modulating this optical sender 64 is shown in Fig. 5 B.

Another embodiment is described, feeder line 66 has a feeder line end terminal 69, and it comprises a band pass filter 67, demodulator 70, a modulator 71 and an optical sender 68.This band pass filter only by the signal in the 300-350 mhz band, launch in this frequency band by this set-top box.For illustrative purpose, a demodulator only is shown in Fig. 4.Can there be a plurality of demodulators and modulator right, in the frequency spectrum of all independence on the 300-350 mhz band.The output of modulator combination may be higher than all frequency spectrums.In the illustrative embodiment of Fig. 4, these modulator 71 outputs are on the 140-190 mhz spectrum.The frequency spectrum of modulating this optical sender 68 is shown in Fig. 5 C.In another embodiment, feeder line 110 has a feed end 80, and it comprises 81, one frequency band block converter 83 of a band pass filter, and its converted band 300 to 350 megahertz modules are 50 to 100 megahertzes, and an optical sender 82.Equally, this band pass filter only by the signal in the 300-350 mhz band, launch in this frequency band by this set-top box.The frequency spectrum of modulating this optical sender 82 is shown in Fig. 5 D.The use of block converter allows different frequency band ranges to be used for communication and gets back to this node, be used for here the various signals of this feeder terminal combined together become single, but at this frequency band signal independently, and send back to this cable front end.

In Fig. 4, the optical fiber 92 that illustrates is connected to node 42.Do not have the additional process of signal at node 42, this optical fiber may be routed directly to front end.Then, the whole spectrum 50-750 megahertz may be received at front end.This will provide the Systems Operator to check that the signal quality that sends adds the ability of this received signal that is sent it back by set-top box on network.

Fig. 6 A illustrates an embodiment in the possible signal processing of the node 42 of Fig. 4.Under this particular case, be combined into a signal at node 42 from all signals that feeder terminal receives, and this composite signal is transported to this front end through single optical cable.Fig. 6 A illustrates the light that optical receiver 151 is advanced in an input.The input of giving optical receiver 151 can be the signal of emission on the optical fiber 92 of Fig. 4.Fig. 6 B illustrates the frequency spectrum output of optical receiver 151.The output signal of this optical receiver 151 is fed to synthesizer 155.Optical receiver 152,153 and 154 similar output also are fed to synthesizer 155.Fig. 6 C illustrates the frequency spectrum of optical receiver 152.Fig. 6 D illustrates the frequency spectrum of optical receiver 153 outputs.Fig. 6 E illustrates the frequency spectrum output of optical receiver 154.The output spectrum of synthesizer 155 illustrates at Fig. 6 A.Optical receiver 151,152,153 and 154 frequency spectrum are synthesized in the frequency output spectrum of synthesizer 155 and superpose.Under this particular case, only a set-top box is simultaneously with special frequency emission.The time division multiplexing of the output of each set-top box is effective.Fig. 6 A only illustrates that four light return, but principle is identical, and in fact the number of back light may be more.The output of synthesizer 155 is fed to optical sender 156.The output of optical sender 156 is optical cables of getting back to this front end.Be similar to those of prior art systems in the signal processing of this front end.Tabulation 1 illustrates different types of equipment and medium, and it can replace optical sender and at the optical fiber of this feeder terminal, and the signal that still obtains to obtain from the set-top box at this feeder terminal this reception is got back to the identical result of this front end.It will be understood by those skilled in the art that if this equipment and medium are changed at this feeder terminal, will need a receiver to remove to receive this signal with this medium and transmitter apparatus compatibility at this cable front end.Can also carry out the conversion of any desired signal at this feeder line.

Fig. 7 A illustrates another embodiment in the signal processing of the node 42 of Fig. 4.In this embodiment, the signal that receives from each feeder line is an individual signals by frequency division multiplex.This frequency division multiplex signal is sent back to this front end through optical fiber.Fig. 7 A illustrates the optical fiber that optical receiver 141 is advanced in an input.Input to optical receiver 141 can be the signal of emission on the optical fiber 92 of Fig. 4.Fig. 7 B illustrates the frequency spectrum output of optical receiver 141.

The high pass filter 59 of Fig. 4 works to receive the signal of illustrative ground in 50 to 750 mhz band.Set-top box in the system of Fig. 4 also plays a part to launch in 50 to 750 mhz band.Therefore,, before being transmitted to the cable front end, optical fiber link at first receives at this feeder terminal at them by receiver from the transmission of set-top box (this returns transmission).Principle of the present invention will stand good and be transformed into cable amplifier and coaxial cable in optical sender and optical fiber link.

Tabulation 1

Equipment at feeder terminal	Return medium
Equipment at feeder terminal	Return medium	Optical sender	Fiber optic cables
Amplifier	Coaxial cable	Optical sender	Fiber optic cables
Amplifier	Coaxial cable	Transmitting set	Air
Microwave transmitter	Air	Transmitting set	Air
Microwave transmitter	Air	The satellite transmission transmitter	Air and space
Telephone modem	Telephone wire	The satellite transmission transmitter	Air and space

Should be understood that according to principle of the present invention, is to propagate in the frequency band of giving at the receiver of feeder line end from the signal of set-top box, rather than at return path in the frequency band of cable front end.

But according to principle of the present invention, each feeder terminal also comprises and is used to receive those signals and launches the device that those signals are got back to this node or this cable front end.In Fig. 4, the device that is used for being received in 50-750 mhz band signal is an optical sender 60,64,68 and 82.This optical sender this signal of feeding advances optical fiber, and those signals are received at this node or cable front end.

Fig. 8 illustrates one group of signal level chart more relevant with frequency ratio that is used for respectively according to cable front end, set-top box, amplifier and the optical sender of the cable system of principle of the present invention.As shown in Figure 8, this front end can receive in the 50-750 mhz band, but can not launch on whole 50-750 mhz band.This 300-350 megahertz part is by trap.The emission in 300-350 megahertz part of this set-top box, and in 50-300 megahertz and 350-750 mhz band, receive.This amplifier is only in forward work, and the transmission signal leaves this front end.Owing to do not have sign-changing amplifier, exempted and need adjust this sign-changing amplifier, adjusting this sign-changing amplifier is operation time-consuming and effort.

Very clear from Fig. 8, the signal of being launched by the set-top box in the system of Fig. 4 will send corresponding feeder terminal to " forward " direction, and they are received at this, and send back to this node or cable front end.

Fig. 9 illustrates the chart of a noise 100 that enters together corresponding to Fig. 3, in company with the frequency spectrum 300-350 megahertz part according to the emission of the set-top box of principle of the present invention.Clearly for the portions of the spectrum that is used now by the set-top box in the system of Fig. 4, the noise that enters is insignificant.Therefore, in this return path, provide in fact do not have enter noise inverse signal to this cable front end.

Also comprise band resistance (trap) filter (112) during according to the beginning of auxiliary feeder in this system (Fig. 4) of the system of an embodiment of the principle of the invention (promptly 110), to guarantee from the transmission of set-top box the 50-750 mhz band only by a feeder terminal reception in the system.Above-mentioned band stop filter 112 is positioned at the beginning of auxiliary feeder 110, to guarantee that this signal that is used for each set-top box only receives (promptly at a feed end, since band stop filter 112 hinder from signal received by band pass filter 81, only receive from the signal of set-top box 55 by band pass filter 67).

Figure 10 illustrates a system that is similar to Fig. 4, here this two-way amplifier of the prior art systems of Fig. 1 is retained, can continue the system of previous effect with the set-top box that a prior art is provided in new combined system, new combined system allows new set-top box to launch in the 50-750 mhz band, and the prior art set-top box is launched in the 5-40 mhz band.

Figure 11 illustrates one group of signal level chart more relevant with frequency ratio that is used for respectively according to cable front end, set-top box, amplifier and the optical sender of the cable system of principle of the present invention.As shown in figure 11, this front end can receive in the 50-750 mhz band, and receives in the 5-40 megahertz as prior art, but can not launch on the 50-750 mhz band.This 300-350 megahertz part is by trap.The emission in 300-350 megahertz part of this new set-top box, and in 50-300 megahertz and 350-750 mhz band, receive.This two-way amplifier is worked as previously mentioned and is transmitted 5-40 megahertz signal towards the direction of this front end, and transmits 50-750 megahertz signal with forward and leave this front end.This embodiment illustrates the system of a combination, and wherein the set-top box of the prior art set-top box and novelty of the present invention is worked in combined system.The system of this combination provides a kind of method, makes cable operator go to continue as the set-top box service of existing user with existing (prior art), and to use the set-top box that meets the principle of the invention be new user's service.Therefore, keep the system that this existing systems and upgrading meet the principle of the invention.

Figure 12 illustrates an expression band stop filter except that the signal 300-350 megahertz (trap) frequency band part, by the chart of signal in the 5-750 mhz band.The existence of above-mentioned filtering prevents to be received more than a feeder terminal from the signal of set-top box (in the 300-350 mhz band).

Figure 13 and 14 illustrates expression prior art set-top box respectively and according to the schematic diagram of the set-top box of the principle of the invention.In the prior art set-top box of Figure 13, high pass filter 104 is removed the signal in the 5-40 mhz band, and by the signal in the 50-750 mhz band.This set-top box also comprises a low pass filter 101, and it removes the signal in the 50-750 mhz band, and by the signal in the 5-40 mhz band.

The set-top box of Figure 14 is very different.Specifically, the set-top box of Figure 14 comprises a band stop filter 102, and it is by the 50-750 megahertz, but the signal of reduction in the 300-350 mhz band.This set-top box also comprises a band pass filter 103, and it is by the signal in the 300-350 mhz band.Therefore, this set-top box of Figure 14 receives in identical (height) frequency band (that is, the 50-750 megahertz) and emission, but the set-top box of prior art receives and emission in the frequency band of high and low (very different) respectively.Figure 14 further illustrates an optional characteristic in this set-top box, and as being done by the prior art set-top box, it allows this set-top box also to launch an inverse signal in low-frequency band (5-40 megahertz).This optional characteristic will be worked with the system of Figure 10, allow this front end to go to receive in the 5-40 mhz band with in the 50-750 mhz band.This new set-top box will have two independently frequency band ranges now, and this front end can be from this set-top box received signal therein.

Fig. 4 also illustrates an auxiliary feeder 110 that stretches out from feeder line 66.Importantly, only received by the receiver at a feeder terminal from the transmission of the set-top box of Fig. 4 system, this transmitter top box is connected to this feeder line.For example, be connected to receiver 82 receptions of auxiliary feeder (110) in order to prevent the signal from the set-top box that is connected to feeder line 66, this auxiliary feeder comprises a band stop filter 112, removes the above-mentioned transmission of discussing before as herein.

Alternatively, this cable front end can be configured to simultaneously poll (promptly starting) set-top box and corresponding feeder terminal optical sender, only makes that the signal from receiver is received at this front end.Certainly, in this case, the software that this cable front end need add.This will allow cable operator to go to select this size of returning frequency band and position.The band stop filter of frequency agile and the band pass filter of frequency agile can also use in this system, go to utilize any part of the frequency band that the Systems Operator wants.The frequency band range of Xuan Zeing only is illustrative herein, and just as those skilled in the clear, other frequency band and/or NOTCH may suit.For example, this operator can use 700 megahertzes and above frequency band to be used for this return path.In this case, the structure of this set-top box will be transformed into shown in Figure 15.Allow this new set-top box also to send a signal to this front end in the optional characteristic shown in Figure 15 through the 5-40 mhz band.This set-top box can be communicated by letter in 5-40 mhz band and 700 megahertzes and above frequency band with this front end.

The signal that receives for the node 42 at Fig. 4 exists diverse ways that it is taken back cable front end to Fig. 4.The reception that the embodiment of Fig. 7 A illustrates the optical fiber 92 of Fig. 4 is received by optical receiver 141.Fig. 7 B illustrates the frequency spectrum that is received by optical receiver 141.The 300-350 mhz band of Fig. 7 B directly is mapped as the 300-350 mhz band of Fig. 7 A.Fig. 7 C illustrates the frequency band that is received by optical receiver 142.The module frequency transducer 146 conversions 300 megahertz (f of Fig. 7 A _c) to 350 megahertz (f _d) frequency band is 240 megahertz (f _d) to 290 megahertz (f _c) frequency band.Optical receiver 141, module frequency transducer 146,147 and 148 frequency spectrum are synthesized device 149 combinations.The output spectrum of synthesizer 149 illustrates at Fig. 7 A.Fig. 7 A is illustrated in that each feeder line output is independently in the frequency spectrum of synthesizer 149.The set-top box of this permission in each feeder line is with identical frequency emission, and another set-top box in another feeder line is like this equally simultaneously.Thereby provide the in fact higher bandwidth of effectively returning for this cable system.

Can expect that the novel set-top box of this that illustrates can have wireless capability that increase to give them herein, allowing they and other communicate by letter with the equipment wireless in the commercial undertaking in family, such as with personal computer, video telephone, phone or the like.

This optical sender, optical receiver, high pass filter, band pass filter, band stop filter, transducer receiver, transmitter and other parts herein all are commercially available or easily from available component configuration.According to principle of the present invention, can use any effective above-mentioned part as required herein.

Though should be understood that with utilizing the set-top box illustrative and described the present invention, can also use any bi-directional communication device, such as cable modem.

Claims

1. cable system, comprise a front end and a cable node, front end is used for providing forward signal at high frequency band, described node is connected to described front end through bi-directional communication channels, described system comprises a main line that has a plurality of forward direction amplifiers along the there, described system comprises a plurality of feeder lines, each is expanded between a described amplifier and feeder terminal, the primary importance of each described feeder line before any one of described a plurality of feeder terminals comprises a final amplifier, described system comprises first device and second device, first device is used to receive described forward signal, the described forward signal of the second device response is used for transmitting described signal at high frequency band, described first and second devices are arranged in the described primary importance of each feeder line, and described system comprises a backward channel that is connected between each described second device and the described node.

2. as the cable system in claim 1 requirement, wherein said backward channel comprises an optical cable, and described second device comprises an optical sender.

3. as the cable system in claim 1 requirement, wherein said main line also comprises sign-changing amplifier.

4. as at the cable system that claim 1 requires, also comprise at least one be connected one in the described main line amplifier and the auxiliary feeder between at least one feeder terminal, described auxiliary feeder comprises a band stop filter.

5. as the cable system in claim 2 requirement, wherein each described feeder line also comprises a high pass filter in described primary importance.

6. as the cable system in claim 2 requirement, wherein each described feeder line also comprises a band pass filter in described primary importance.

7. as the cable system in claim 6 requirement, wherein each described feeder line also comprises a demodulator and a modulator in described primary importance.

8. as at the cable system that claim 7 requires, the demodulator-modulator that wherein is used for each feeder line is to being to work on different frequencies.

9. as the cable system in claim 1 requirement, wherein each described feeder line comprises a module frequency transducer.

10. as the cable system in claim 1 requirement, wherein said node comprises a synthesizer, is used for being suitable for sending to described front end through single optical cable in the signal of this transmission.

11. the cable system as requiring in claim 9 also comprises the set-top box that is connected to described feeder line, each described set-top box is configured in different frequency emission.

12. the cable system as requiring in claim 1 also comprises the set-top box that is connected to described feeder line, each described set-top box is configured in identical frequency emission, and described node comprises the device that is used for from the signal frequency division multiplex of described feeder line.

13. as the cable system that requires in claim 1, also comprise the set-top box that is connected to described feeder line, a set-top box in each described feeder line is configured at high frequency band with identical frequency emission, while, in another described feeder line, described node comprised the device that is used for from the signal frequency division multiplex of each described feeder line as another set-top box.

14. as the cable system that requires in claim 12, wherein said set-top box is configured to launch in 50 to 750 mhz band.

15. the cable system as requiring in claim 1 also comprises at least one auxiliary feeder, described auxiliary feeder comprises a band stop filter, and this band stop filter is positioned at the position that described auxiliary feeder is connected in a described feeder line.

16. as the cable system that requires in claim 11, wherein said set-top box is partly launched at the 300-350 mhz spectrum, and partly receives at 50-300 megahertz and 350-750 mhz band.

17. as the cable system that requires in claim 12, wherein said set-top box is partly launched at the 300-350 mhz spectrum, and partly receives at 50-300 megahertz and 350-750 mhz spectrum.

18. as the cable system that requires in claim 11, wherein each described feeder line comprises a band stop filter, is used to stop the signal from a described set-top box to be received more than a feeder terminal.

19. as the cable system that requires in claim 12, wherein each described feeder line comprises a band stop filter, is used to stop the signal from a described set-top box to be received more than a feeder terminal.

20. a set-top box comprises a band pass filter, be operated in the 300-350 mhz band to pass through signal, the same section that described set-top box is configured in frequency spectrum not only receives but also launch, and described set-top box also is configured in echo-signal of 5-40 mhz band emission.

21. a set-top box comprises a high pass filter, it is above with by echo-signal to be operated in 700 mhz band, and described set-top box is configured in the 50-700 mhz band and goes to receive, and described set-top box also is configured to go emission in the 5-40 mhz band.

22. as the cable system that requires in claim 2, wherein said front end comprises the device that is used for set-top box of while poll and corresponding feeder terminal optical sender, makes only to be received at front end from the signal quilt of this receiver at this feeder terminal.

23. cable system, comprise a cable front end, be used at high frequency band emission forward signal, and be used for receiving echo-signal at high frequency band, described system comprises at least one node, is connected to described front end through a bi-directional communication channels, described system also comprises a main line, be connected between described node and the main line end, described main line comprises along forward direction amplifier there, and is not used in the amplifier that returns of signal in the low-frequency band.

24. cable system, comprise a cable front end, configuration is used at high frequency band emission forward signal, and be used for receiving echo-signal at high frequency band, described system comprises a node, be connected to described front end through a bi-directional communication channels, described system comprises a main line that is connected between described node and the main line end, and comprise the forward direction amplifier along the there, described system does not have sign-changing amplifier, described system comprises a plurality of feeder lines, each extend out to a plurality of line feed terminals loads from described main line, and comprise a final amplifier that before any one of described a plurality of line feed terminals loads, is positioned at primary importance, described system comprises a return path that is used at described high frequency band signal, and described return path is connected between the described feeder line and described cable front end of described primary importance.

25. cable system, comprise a cable front end, be used at high frequency band emission forward signal, and be used for receiving echo-signal at high frequency band, described system comprises a node, be connected to described front end through a bi-directional communication channels, described system comprises a main line that is connected between described node and the main line end, and comprise the forward direction amplifier along the there, described system comprises a plurality of feeder lines, each is connected between described main line and a plurality of feeder terminal, each described feeder terminal comprises first device and second device, this first device is used for being received in the forward signal of described high frequency band, the forward signal of this second device response in described high frequency band, be used for transmitting the described signal at described high frequency band, described system comprises the device that is connected between each described feeder terminal and the described front end, is used for delivering the described signal at described high frequency band.

26. a set-top box comprises a band stop filter and a receiver, described band stop filter operation removes the first of the signal band that can be applied to described receiver, described set-top box also comprises a band pass filter and a transmitter, described band pass filter only be operated by in first's frequency band of removing from the signal of described transmitter, described set-top box also comprises the low pass filter and second transmitter that also is operated in the low-frequency band that are operated in the low-frequency band.

27. as the set-top box that requires in claim 26, this low pass filter band is lower than 50MHz here.

28. a set-top box comprises a low pass filter and a relevant receiver, described low pass filter operation removes only to send to the signal than lower part of described receiver at high frequency band, described set-top box also comprises a relative high pass filter and a transmitter, described relative high pass filter is operated the signal that only sends in the high part of described transmitter at described high frequency band, described set-top box also comprises a low low pass filter, it is operated in the frequency band lower than described low pass filter, and second a relevant transmitter that is operated in lower low-frequency band.

29. as the set-top box that claim 28 requires, this lower low pass filter band is lower than 50 megahertzes here.

30. cable system, comprise a main line and a plurality of feeder line, each described feeder line is connected between the node and feeder terminal in the described main line, each described feeder line comprises a plurality of taps, and a bi-directional communication device is connected to described tap each, each described feeder line comprises the forward direction amplifier, the signal that is used for being transmitted in high frequency band is transmitted to described bi-directional communication device from described front end, and be used for being transmitted in " returning " signal of described high frequency band to described feeder terminal, described bi-directional communication device is configured to not only receive but also launch in described high frequency band, each described feeder terminal comprises that one is used for receiving the receiver that sends and one at described high frequency band and is used for transmitting the device that sends to described node that receives at described high frequency band.

31. as the cable system that requires in claim 30, wherein said receiver is an optical sender.

32. as the cable system that requires in claim 30, wherein said bi-directional communication device and described front end both send in described high frequency band.

33. as the cable system that requires in claim 30, wherein said feeder terminal also comprises an optical fiber link to this node.

34. as the cable system that requires in claim 30, wherein at least one feeder line comprises an auxiliary feeder, described auxiliary feeder comprises a band stop filter.

35. as the cable system that requires in claim 33, wherein at least one feeder line comprises an auxiliary feeder, described auxiliary feeder comprises a band stop filter.

36. as the cable system that requires in claim 30, wherein said bi-directional communication device comprises set-top box.

37. as the cable system that requires in claim 34, wherein said bi-directional communication device comprises set-top box.

38. system, comprise a main line and a plurality of feeder line that is connected between described main line and the corresponding feeder terminal, each described end comprises a receiver that is suitable for the signal in high frequency band, described system comprises a front end and bi-directional communication device, described front end is connected to described main line, and described bi-directional communication device is connected to described feeder line, described front end and described bi-directional communication device both are configured in and remove to send signal in the described high frequency band, described feeder line comprises the forward direction amplifier, it only sends to described bi-directional communication device by the signal at described high frequency band, only send to described feeder terminal by the inverse signal in described high frequency band, described feeder terminal comprises second device that is used for installing and being used for sending at described high frequency band in first of described high frequency band received signal described signal.

39. as in the system that claim 38 requires, wherein said equipment comprises set-top box.

40. as in the system that claim 38 requires, wherein said first device comprises the receiver of a signal in described high frequency band, and second device is used for producing and is suitable for the signal that sends at described high frequency band.

41. as in the system that claim 38 requires, wherein said second device comprises that a frequency converter and one are used for the transmitter that transmits at described high frequency band.

42. cable system that comprises a cable front end and a main line, described main line has tap along the there, described system has at least one and connects feeder line between a described tap and the feeder terminal, described feeder line comprises at least one set-top box, described set-top box is configured to transmit in the different part of high frequency band with described cable front end, and described set-top box and described cable front end also are configured to received signal in described high frequency band.

43. as the cable system that claim 42 requires, wherein said feeder terminal has one with received signal in described high frequency band, and the device of the signal that emission receives in described high frequency band.

44. as the cable system that claim 43 requires, wherein said system comprises the device that is used to comprise a trap, wherein can not launch at front end described in the described high frequency band, described set-top box is arranged in described trap emission.

45. as the cable system that claim 43 requires, wherein said feeder terminal also has a module frequency transducer.

46. cable system, comprise a cable front end, a return node and a plurality of feeder line, each described feeder line is connected between described return node and the feeder terminal, each described feeder line comprises a plurality of taps, a plurality of bi-directional communication devices are connected to described tap, described cable front end and described bi-directional communication device are configured to launch in high frequency band, each described feeder terminal comprises and is used for receiving second device that the transmission of this reception was installed and was used for launching again through optical fiber link at high frequency band in first of transmission at described high frequency band.

47. as the cable system that claim 46 requires, wherein said second device comprises a frequency converter.

48. as the cable system that claim 46 requires, wherein said second device comprises a demodulator and a modulator.

49. as the cable system that claim 46 requires, wherein said optical fiber link turns back to described return node.

50. as the cable system that claim 46 requires, wherein said optical fiber link turns back to described cable front end.

51. cable system as claim 46 requirement, comprise that a tap from a described feeder line reaches the auxiliary feeder of (assisting) feeder terminal, described auxiliary feeder comprises a band stop filter and described tap, and described auxiliary feeder also comprises a receiver and transmit the device that the signal that receives is got back to described node in this described high frequency band.

52. as the cable system that claim 46 requires, wherein said bi-directional communication device comprises set-top box.

53. as the cable system that claim 46 requires, wherein said front end is configured launching in the described high frequency band the trap part therein, and described bi-directional communication device is configured to launch in described trap part.

54. as the cable system that claim 52 requires, wherein said front end is configured launching in the described high frequency band the trap part therein, and described set-top box is configured to launch in described trap part.

55. cable system as claim 53 requirement, wherein said bi-directional communication device comprises a band stop filter, band stop filter has a receiver that links, and from described front end received signal, described equipment also comprises a band pass filter and a relevant transmitter.

56. cable system as claim 54 requirement, wherein said set-top box comprises a band stop filter, band stop filter has a receiver that links, and from described front end received signal, described set-top box also comprises a band pass filter and a relevant transmitter.

57. the cable system as claim 46 requires also comprises sign-changing amplifier, it transmits signal in this low-frequency band.

58. a cable system that comprises a module frequency transducer comprises first and second feeder terminals at least, described feeder terminal also comprises an optical sender.

59. the cable system as claim 58 requires comprises the forward direction amplifier that is carried at signal in the high frequency band.

60. the cable system as claim 59 requires comprises sign-changing amplifier, it carries signal in low-frequency band.

61., comprise having in described high frequency band, receiving and the set-top box of emitter as the cable system that claim 58 requires.

62. cable system, comprise a feeder line and through the auxiliary feeder of bridge amplifier from wherein stretching out, described auxiliary feeder comprises a band stop filter at described bridge amplifier, described auxiliary feeder comprises that also a receiver goes this high frequency band received signal and one at its terminal optical sender.

63. as the cable system that claim 62 requires, it also comprises the only forward direction amplifier in auxiliary feeder.

64. as the cable system that claim 62 requires, it also comprises two-way amplifier in auxiliary feeder.