CN1739252A

CN1739252A - Signal distribution system cascadable AGC device and method

Info

Publication number: CN1739252A
Application number: CNA2003801087178A
Authority: CN
Inventors: K·P·巴尔格罗夫; D·汉考克
Original assignee: R F MAGIC Inc
Current assignee: Entropic Communications LLC
Priority date: 2002-12-11
Filing date: 2003-12-11
Publication date: 2006-02-22
Also published as: CN1739245A; CN100555885C

Abstract

A cascadable AGC amplifier in a signal distribution system includes a low noise cascadable amplifier having a through path and a cascadable output. The cascadable amplifier is also configured to provide AGC over a predetermined input power range. The cascadable AGC amplifier can be configured to provide gain or attenuation. When the cascadable AGC amplifier is implemented in a signal distribution system, typically as part of a signal distribution device, an input signal can be gain controlled and supplied to multiple signal paths without distortion due to degradation of signal to noise ratio or distortion due to higher order amplifier products. The distributed signal is not significantly degraded by distortion regardless of the number of cascadable AGC amplifiers connected in series or the position of the cascadable AGC amplifier in the signal distribution system.

Description

Signal distribution system cascadable AGC device and method

Technical field

The present invention relates to electronic communication field.More specifically, the present invention relates to radio frequency (RF) signal allocation field.

Background technology

Signal distribution system, for example the RF signal distribution system typically is arranged in the branch configuration.In branch configuration, described signal is typically risen in center or branch road, and distributes this signal from the source points of described branch to a plurality of end points.Each distribution branch from branch road can be divided into one or more smaller branching.In addition, described smaller branching oneself can be before arriving the destination, and one or many is divided into littler branch.

Before arriving destination equipment, typically amplify several times RF signal of communication along various signal allocation path along system assignment.Yet before the equipment of arriving at the destination, various factors has reduced the quality of described primary signal.

Quality of signals often is measured as the ratio of signal power and noise power, i.e. signal to noise ratio (snr).Signal power can be defined as the power of the signal section that comprises desired information.Noise power can be defined as the merging with incoherent random fluctuation of described information power and the distortion product do not expected.The described distortion product of not expecting can be defined as those not signal components of replicating original information.Although employed noise power is meant the merging of unrelated signal and distortion product, yet can use other definition of noise to come the metric signal quality here.For example, can only represent described noise power, or represent described noise by unrelated signal and some distortion product by uncorrelated signal.

Signal to noise ratio (snr) is the ratio of measuring-signal and noise and the suffered distortion of signal typically.Thermal noise often is bigger part for receiving radio wave for the noise power in the system of signal source.The frequent representative of thermal noise level can not be by using noise floor active or that inactive component further reduces.Passive signal is cut apart or but the passive loss that caused of decaying has reduced signal power typically do not reduce thermal noise level.Similarly, signal attenuation can cause the reduction of SNR.

Can use signal amplifier to remedy some influence of the decay in the signal distribution system.Yet for example the active equipment of amplifier does not provide signal gain and does not influence noise and the distortion that reduces signal quality.For example, amplifier typically is incorporated into uncorrelated noise in the signal, and this has further reduced SNR.Some amplifier noise composition is quantified as noise figure of amplifier, and it also can be expressed as noise factor.When described system as the system that typically use to receive the RF signal near the low power condition operation of noise floor the time, noise figure of amplifier may directly cause signal fadeout and SNR reduction.

In addition, amplifier may be introduced the distortion product that reduces SNR.A general amplifier distortion product often introducing in-band noise in broadband or multichannel distribution system is the third order intermodulation distortion product.Based on the characteristic of the amplifier that is called three rank point of cut-offs (IP3), typically predict the level of the third order intermodulation distortion of introducing by specific amplifier.Described three rank point of cut-offs have been represented the operating point of fabricating, and at this operating point of fabricating, amplifier third order distortion product equals the signal component expected on amplitude.Wish higher amplifier IP3.Yet amplifier IP3 is often relevant with the amplifier power consumption.Like this, compare the amplifier with low IP3, the amplifier with higher IP3 typically consumes more power.Because about the restriction of the ability of the restriction of power loss and the heat that is associated with high-power equipment about loosing, so the amplifier power consumption is very important.In addition, the amplifier with low-noise factor often correspondingly has lower IP3.

No matter be inactive component or active equipment, can typically be used for operating in the signal specific parameter sets of the ad-hoc location in signal distribution system.Yet, based on the quantity that is positioned at the branch before or after the equipment, and the quantity that is positioned at the passive and active equipment before or after the equipment, the signal parameter in the ad-hoc location in the signal distribution system often changes at all.Like this, be that best equipment may be the main noise source in another signal parameter set at an operating parameter set.

Wish that signal allocation equipment and method are for being constant for the change in signal power and the distribution system configuration.In addition, wish that typically described equipment minimizes the reduction of its SNR under many operating conditions.By comprising or delete the signal branch that has minimum influence for other branch of described signal distribution system that equipment also will allow the establishment of the many branches in the signal allocation path.

Summary of the invention

The AGC amplifier is disclosed and the method for distributing signal in signal distribution system.The feedback that described AGC amplifier uses power detector and imports to the control of variable gain amplifier is to safeguard the power output of variable gain amplifier in predetermined AGC set-point (setpoint).Described detector can be connected to the output of described variable gain amplifier, so that the AGC function with reference to output to be provided.Can select described AGC set-point is the interior signal power of optimum operation scope of described signal distribution system.

The output of described AGC amplifier can be connected to series connection (in-line) signal path, and also can be connected to cascade output.Described cascade output allows single AGC amplifier to provide described AGC function at two signal paths.Described noise is introduced and is minimized at the equipment that is connected with the cascade of described AGC amplifier.Another AGC amplifier with tandem paths and cascade output can be connected in series with the cascade output of an AGC amplifier, to produce the additional signals path.

The AGC amplifier can be implemented in the integrated circuit, and described integrated circuit can comprise add ons.Described integrated circuit can comprise the cross point switch of connecting with the signal path output of connecting of described AGC amplifier.Described integrated circuit also can comprise the frequency band conversion equipment of connecting with the signal path output of connecting of described AGC amplifier.

Described AGC amplifier and system for delivering can be implemented in the satellite TV distribution system, and wherein signal is received and is assigned to a plurality of positions in the building of settlement for example as the satellite downlink signal.Alternatively, described AGC amplifier and system for delivering can be implemented in cable TV, cable radio, terrestrial television, terrestrial radio, phone or the data distribution system.

Description of drawings

In conjunction with the accompanying drawings, according to following detailed, feature of the present invention, purpose and advantage will become apparent, and similar reference symbol is represented corresponding part among the figure, and wherein:

Fig. 1 is configured to reception from the signal of satellite and with the functional block diagram of this signal allocation to the signal distribution system of a plurality of subscriber equipmenies;

Fig. 2 A-2D is the functional block diagram of AGC amplifier;

Fig. 3 A-3B is the functional block diagram of cascade amplifier configuration;

Fig. 4 is the functional block diagram that is connected with optional feature with the integrated band conversion switch that two signal outputs are provided;

Fig. 5 is the functional block diagram of cascade integrated band conversion switch;

But Fig. 6 utilizes cascade AGC amplifier to come the flow chart of the method for distributing signal.

Embodiment

Signal distribution system typically is used for linking together on the distal portions geography with communication system.Often exist signal to rise or the centrostigma of branch.Described signal distribution system can be used to provide the one or more equipment of the signal of concern to one or more geographical position.

Fig. 1 is the functional block diagram of signal distribution system 100, and this signal distribution system 100 is can be in the settlement or the typical case of the satellite TV system that is implemented of other building.Described signal distribution system 100 comprises antenna 120, and described antenna has the antenna feed (antenna feed) 122,124 of two inputs of being coupled to low noise block 126.The output of described low noise block 126 is coupled to two inputs that distribute switch (distribution switch) 130.Utilize first and second transmission lines 142,144, the output that distributes switch is connected to first, second and the 3rd set-top box (set top box) 152,154,156.The output of described first set-top box 152 is connected to first output equipment 162.Demultiplexer 170 will be divided into two signals by the signal that described second transmission line 144 is coupled to described distribution switch 130.The output of first demultiplexer 170 is coupled to second set-top box 154, and the output of secondary signal separator 170 is coupled to the 3rd set-top box 156.The output of described second set-top box 154 is connected to second output equipment 164, and the output of described the 3rd set-top box 156 is connected to the 3rd output equipment 166.

Described antenna 120 comprises two antenna feed 122,124.Yet, can use a plurality of antennas.In addition, each antenna 120 can have one or more antenna feed 122,124, and each antenna 120 is not limited to only have two feedbacks 122,124.Alternatively, described antenna 120 can be a kind of configuration of not using antenna feed, for example whip antenna (whip) or box horn (horn).

One or more signals that described antenna 120 receives from satellite 110.In addition, described satellite 110 can provide the specific polarization and the signal of modulation type.Once more, may exist more than one satellite 110 of signal to described antenna 120 is provided.From the signal of particular satellite 110 with can be from the signal of another satellite (not shown) at identical frequency band, or can be at different frequency bands.Signal from a plurality of satellites may each all have identical polarity and modulation type, or may be different mutually.

In the signal distribution system 100 of Fig. 1, each of antenna feed 122,124 is connected to the independent input of low noise block 126, and described low noise block outputs signal to described distribution switch 130.Certainly, described distribution switch 130 is not limited to 2 * 2 exchange, but may have any amount of input port and output port.For example, described distribution switch 130 can be that for example 2 * 4 switches, 4 * 4 switches and some other switch are arranged.

Described distribution switch 130 is configured to the satellite-signal that processing receives.Described distribution switch 130 can for example amplify the satellite-signal that is received, filtering and down-conversion.It is right that described distribution switch 130 can be configured to low noise block transducer (LNB), and each piece will be an intermediate frequency from the conversion of signals of one of described distribution switch 130 inputs.Described distribution switch 130 can also be configured to each input signal that allows to offer described input and be connected to any one that a plurality of switches are exported.Therefore, the signal that is provided from first antenna feed 122 can be the piece that is converted described distribution switch 130 and be routed to any switch output.Similarly, the signal that provides from second antenna feed 124 can be the piece that is converted described distribution switch 130 and be routed to any switch output.Typically, described distribution switch 130 is configured so that be routed to specific switch output from the signal of a signal source only.Alternatively, be converted the one or more outputs that can be routed to identical distribution switch 130 of signal.

When with described antenna 120 with when distributing switch 130 to be mounted geographically position away from the signal destination of expectation, utilize cable the output of described distribution switch 130 can be connected to remote location.The output of described distribution switch 130 is typically by can being that the transmission line of coaxial cable is routed to the far-end destination.Described distribution switch 130 can be positioned at this locality of described low noise block 126 and

antenna feed

122 and 124, maybe can be positioned at the position away from described low noise block 126 and

antenna feed

122 and 124.

In one embodiment, described distribution switch 130 and antenna 120, low noise block 126 and

antenna feed

122 and 124 are by colocated.In another embodiment, described distribution switch 130 can be positioned at the position away from described antenna 120.For example, cable or transmission line can be coupled to the signal from described low noise block 126 to be located at one or more set-top box 152 and near the 154 interior distribution switches 130 of structure.Similarly, in other embodiments, described distribution switch 130 can be in the centre position between described antenna 120 and set-top box 152 and 154.In certain embodiments, ignored described low noise block 126 and can utilize cable to be coupled to described distribution switch 130 from the signal of described antenna feed 122 and 124.Similarly, use cable or some other distribution system, can be coupled to set-top box or other destination equipment from the output signal of described distribution switch 130.

In first embodiment, described distribution switch is positioned at this locality of described low noise block 126 and antenna 120.First transmission line 142 will be assigned to the remote location in the described signal distribution system 100 from the signal of first output port of described distribution switch 130.The end of described first transmission line 142 is connected to first set-top box 152 that is positioned at away from described distribution switch 130.

Second transmission line 144 will be assigned to demultiplexer 170 from the signal of second output port of described distribution switch 130.First output of described demultiplexer 170 is coupled to described second set-top box 154.This second set-top box 154 can be positioned at the position away from described distribution switch 130 and demultiplexer 170, also can be positioned at the position away from described first set-top box 152.Second output of described demultiplexer 170 is coupled to the 3rd set-top box 156.The output of described the 3rd set-top box 156 is coupled to the 3rd output equipment 166.

Described first and

second transmission lines

142 and 144 can be parallel line, twisted-pair feeder, coaxial line, waveguide etc., or any other is used for the device of distributing signal.In addition, although transmission line typically is used to minimum signal loss and signal reflex, not the device of transmission line yet described system can use that other is used for distributing signal.For example, wired, wire harness etc. can be used to give described set-top box 152,154 with the signal allocation from described distribution switch 130.Yet, for the signal that can think radio frequency (RF) signal, utilize transmission line typically to distribute described signal.Described RF information signal can be for example in KHz arrives the scope of several GHz.Certainly, described signal distribution system 100 is not limited to distribute the RF signal, and can distribute other signal of baseband signal for example or light signal.

Described transmission line 142,144 imperfect typically inactive components.Therefore, described transmission-line attenuation signal power.Yet the decay that is caused by described transmission line 142,144 does not typically decay to noise power the degree identical with signal power.For example the passive attenuator of the length of transmission line may not reduce thermal noise significantly.In addition, described transmission line 142,144 can cause the signal fadeout about cable of other type.For example, described transmission line can influence glacing flatness, inclination, phase distortion, group delay distortion, reflection, interference, noise reception (noise pick-up) and the microphone noise of the signal that is distributed.Therefore, typically reduced the SNR of the signal of distributing to described set-top box 152,154 by described transmission line 142,144 caused losses.

Described first and

second transmission lines

142 and 144 are coupled to the corresponding output of set-top box 152,154 and 156.By described demultiplexer 170, described second transmission line 144 is coupled to the described second and the 3rd set-top box 154 and 156.In one embodiment, the frequency band of exporting from the signal of described distribution switch 130 does not correspond to by described

output equipment

162 and 164 employed frequency bands.Therefore, described set-top box 152,154 can also be converted to signal frequency the operational frequency bands with described output equipment 162,164,166 compatibilities.In addition, the output signal from described distribution switch 130 can be and the incompatible form of described output equipment 162,164,166 employed forms.Described set-top box 152,154 and 156 thereby can operate to signal processing stage.For example, can be to come the described satellite downlink signal of digital modulation with the incompatible form of described output equipment 162,164 and 166, described output equipment is television receiver typically.Described set-top box 152,154 and 156 can be configured to demodulation described by the signal of digital modulation, handle the signal of institute's demodulation, and modulate TV channel carrier wave frequency with the signal that is used to send to TV output equipment 162,164 and 166 then.

Alternatively, if output is with certain form from the signal of described distribution switch 130, and with the frequency band of described output equipment 162,164 and 166 compatibilities, then may not need described set-top box 152,154 and 156.In another possibility, can be integrated in described output equipment 162,164 and 166 by described set-top box 152,154 and 156 performed one or more functions.In another embodiment, described demultiplexer 170 can be configured to the execution signal processing, for example frequency inverted or demodulation.

In the described embodiment of Fig. 1, each in the described set-top box 152,154 and 156 is connected to single output equipment 162,164 and 166.Yet for example more than one output equipment of 162,164 can be connected to the output from for example 152 single set-top box.Alternatively, can merge output, or be connected to for example 162 single output equipment in addition, although described configuration is not typical from a more than set-top box 152,154 and 156.

For example 162 output equipment can be configured to be tuned to by the particular channel in one or more frequency bands that set-top box provided of 152 for example.Described output equipment 162 can be handled the signal from selected channel, with present some for example the media content of video or audio frequency give the user.

For example, described output equipment 162,164 and 166 can be a television receiver, and can show the TV signal corresponding to the signal of being launched by described satellite 110.Described output equipment 162,164 and 166 can be the equipment of other type in other signal distribution system.For example, described output equipment 162,164 and 166 can be phone, radio receiver, computer, the network equipment etc., or other is used for the device of output signal.

Described output equipment 162,164 and 166 can have the scope of such signal quality: think that on this scope output is acceptable.For example, described output equipment 162,164 and 166 can provide acceptable output at the input SNR on predetermined level, and described predetermined level has been represented desired minimum SNR.Yet the SNR to described output equipment 162,164 and 166 input is typically determined by performed signal processing in described set-top box 152,154 and 156.Therefore, described signal quality typically is relevant to the signal quality of the input of described set-top box 152,154 and 156.Therefore, described signal distribution system 100 typically is configured in described output provides signal to described set-top box 152,154 and 156, and described signal has the SNR greater than the minimum value of expectation.

Although Fig. 1 is the functional block diagram of satellite-signal distribution system, other signal distribution system has similar structure.For example, the geographic area of settlement provides single access point can to distribute the cable distribution system of TV, radio, data and/or TV signal for example typically to be.From the signal of an access point thereby typically separated, amplify, distribute and can merge, satellite TV signal for example with other signal.Communication system with wireless communication link also can have similar structure.For example, terrestrial television or radio system can comprise individual antenna, and use the signal distribution system 100 that can amplify, separate, distribute and/or merge received signal, will arrive a plurality of output equipments in the signal allocation that individual antenna received.

Described signal distribution system is not limited to the settlement, but the position that can expand to many settlements, shopping centre or have nothing to do with inhabitation or building.Described signal distribution system is characterised in that its characteristic, and is not limited to any application-specific.

In addition, although Fig. 1 only shows the demultiplexer 170 between described distribution switch 130 and set-

top box

154 and 156, however can be at the element of placing between described distribution switch 130 and set-top box 152,154 and 156 except described transmission line 142,144 and demultiplexer 170.Additional distributing equipment can comprise active or Passive Power distributor, active or Passive Power combiner, amplifier, attenuator, filter, switch, cross point switch, multiplexer, demultiplexer, Frequency Transfer Unit, encoder, decoder etc., or is used for any other device of distributing signal.In the described additional signal distributing equipment each may be introduced the noise that signal stood that is assigned with.

For example, the bidirectional passive power divider allows to be divided into two output signals in the same manner at the signal of an input, and each has a half-power of primary signal, and keeps impedance matching at all of the port.Desirable bidirectional passive distributor has reduced the SNR of 3dB.Yet in the reality, described decline is often higher.

The active signal distributing equipment may cause signal fadeout, for example by producing the distortion product that reduces SNR.When the input signal power to described equipment increases, typically increase by the distortion that active equipment caused.In addition, the position of the active equipment in the described signal distribution system 100 may influence the effect that equipment is had on SNR.Therefore the active equipment that is positioned at the input of described signal distribution system can stand bigger signal power, and compares the identical equipment that for example is positioned at 142 line end, has reduced more SNR, wherein deamplification power significantly.

Because the increase ratio of described distortion is typically greater than the increase ratio of signal power, therefore for input signal bigger for described capacity of equipment, SNR reduces.Bigger input signal can be defined in the signal that produces predetermined distortion level in the active equipment.For example, when measuring with respect to the required input signal of generation 1dB amplifier output compression, signal is bigger.Alternatively, when measuring with respect to the required incoming signal level of the specific three rank products of generation, described signal is bigger.That is, if double-tone intermodulation test has produced for example third order intermodulation distortion product of the predetermined level that is lower than output signal of 40dB, then can be defined as be bigger to signal.Definition than large-signal is relevant with the described signal distribution system of the equipment of use, and formerly definition is not exhaustive.

On the contrary, when described signal hour, the uncorrelated noise level may be controlled determining of SNR.Because attenuator typically reduces signal power, and may not reduce uncorrelated noise power with identical amount, so the SNR after the attenuator may reduce.The placement of inactive component also may influence by the caused SNR reduction of described equipment amount.The attenuator that is positioned at than the large-signal place may not influence SNR, and the same attenuator that is positioned at than the small-signal place may reduce SNR significantly.

Therefore, exist in the optimum signal scope of maximization SNR in the described system.Described the best depends on signal distribution system accurately and the characteristic of the information signal that distributed.Below automatic gain control (AGC) amplifier of describing in detail can help system be kept the optimum operation scope, and therefore help in system, to keep best SNR.Described AGC amplifier can reduce the influence of subsequent allocations equipment to the SNR at described set-top box 152,154 and 156 places.In addition, described AGC amplifier can minimize adverse effect to the dispense path of adding or remove in the described signal distribution system 100.Described AGC amplifier can for example be integrated in described distribution switch 130 or the demultiplexer 170.

Fig. 2 A is the functional block diagram of AGC amplifier to 2D, and described amplifier can for example be integrated in the distribution switch 130 of Fig. 1 and/or in the demultiplexer 170.Described AGC amplifier also can be implemented in the M signal treatment facility, and for example demultiplexer 170 or some are called other signal allocation equipment of distributing equipment or signal handling equipment alternatively.Typically, described AGC amplifier is not added as stand-alone device, but it is realized in conjunction with other distributing equipment.

In certain embodiments, the M signal distributing equipment may not comprise the AGC amplifier.There is not the described M signal treatment facility of AGC amplifier can be configured to be used in the interior ad-hoc location of described signal distribution system.In other embodiments, described M signal distributing equipment can for example comprise the AGC amplifier as the initialize signal treatment element.

Realize that with signal allocation equipment the AGC amplifier allows the performance of described signal distribution system 100 not to be subjected to the influence of this signal allocation devices'physical locations basically.That is, the performance of described signal distribution system 100 basically with at cable operation front end or at the location independent of the signal allocation equipment of cable operation rear end.

Realize that in the described distributing equipment 130 of described low noise block 126 and then described AGC amplifier can compensate the change in gain of this low noise block 126.Therefore, embodiment local or realize described distributing equipment 130 and low noise block 126 in single house the production that can advantageously eliminate low noise block 126 gains is regulated.Therefore, produce regulating step by eliminating, the AGC function that realizes in described allocation block 130 can provide lower production cost.

Fig. 2 A each in the embodiment of the described AGC amplifier shown in the 2D can be used as integrated circuit, discrete device, or the combination of integrated circuit and discrete device, and is implemented with signal allocation equipment.Integrated circuit can for example comprise a plurality of independently AGC amplifiers concurrently, and wherein each AGC amplifier control is received from the power of the signal of satellite downlink.Can make integrated circuit with multiple basic material, for example silicon, germanium, GaAs, indium phosphide, sapphire, diamond etc., or any other suitable basic material.In addition, can utilize the various manufacturing technologies that comprise bipolarity, FET, BiCMOS, CMOS, SiGe etc., make AGC amplifier embodiment.

Fig. 2 A is the functional block diagram of an AGC amplifier embodiment.Described AGC amplifier comprises variable gain amplifier (VGA) 210 and is connected to the detector 220 of the output of this VGA 210.The output of described detector 220 is connected to the gain controlling input of described VGA 210 to control described Amplifier Gain.

Described AGC amplifier has been realized to attempt that the power output of power amplifier is maintained predetermined optimizing level, being also referred to as the AGC set-point with reference to the AGC function of output.Described AGC function is the process of attempting signal power is maintained the AGC set-point.When described output signal was lower than described AGC set-point, described AGC function had increased the gain of described amplifier 210.Described AGC function can continue to increase the gain of described VGA 210 when needed, up to maxgain value.As long as described output signal power keeps below described AGC set-point, described VGA 210 just continues to provide maxgain value.

On the contrary, when described output signal power was higher than the AGC set-point, described AGC function reduced the gain of described VGA 210.Described AGC function can continue to reduce the gain of VGA 210 when needed, up to minimum value.As long as described output signal power keeps greater than the AGC set-point, described AGC function just continues to provide minimum gain value.

In the system of the signal distribution system 100 of for example Fig. 1, typically there is the restriction of input reference signal.That is, arrive the input of described signal distribution system 100 typically within preset range.In described system, can dispose described AGC scope so that never reach one or more AGC restrictions.For example, described input signal from satellite 110 can change on preset range.If in described distribution switch 130 or the AGC amplifier in the demultiplexer 170 have AGC scope greater than described input reference signal, then described AGC function can never reach its restriction.

At first, the input signal that will have an input signal power Pin offers the input 215 of described VGA 210.The control signal that can initial setting up offers described VGA 210 is controlled described VGA210 so that maximum available gain Gmax to be provided.Described the VGA 210 thereby output signal with the power output Pout that is substantially equal to Pin+Gmax is provided for example, measures with the decibel (dBm) with respect to milliwatt.

Be connected to the input of power detector 220 from the output of described VGA 210.Described power detector 220 is measured output signal power, and produces the control signal of possibility related output signal power.For example, described power detection 220 can be configured to the output voltage that provides relevant with given power level.Alternatively, described power detector 220 can be configured to the output current that provides relevant with given power level.

Described power detector 220 can be configured to the power of measuring the combining amplifier output signal, comprises signal, noise and the distortion of expectation.Described power detector 220 can be broadband detector and can be on broadband the detection power level.Alternatively, described power detector 220 can be measured the only power of a part from the power output of described VGA 210.For example, described power detector 220 can be measured the power in the bandwidth, and wherein said bandwidth representative is from the only part of the bandwidth of the signal output of described VGA210.Described bandwidth can be for example whole within desired signal bandwidth from the output of described VGA 210.Alternatively, described bandwidth can partly overlap, or outside the desired signal bandwidth of described VGA 210 outputs.

The output of described power detector 220 is connected to the control input of described VGA 210.The AGC function that provides with reference to output can be provided described AGC amplifier.For example, described power detector 220 can detect the power output of described VGA 210.Described power detector 220 also can comprise the comparator with the AGC set-point of being coupled to a comparator input.The power output that is detected can be provided for second input of described comparator, and itself and AGC set-point are compared.Can for example use integrator that filtering is carried out in the output of described comparator.The output of described integrator can be the detector output control signal of control amplifier gain.

For example, to the input of described power detector 220, produced control voltage greater than the high power signals of described AGC set-point.Described control magnitude of voltage is corresponding to the amplifier gain value less than the original gain value.The gain of the described VGA 210 of described high power detector 220 outputs having reduced makes that the power that output detected at described VGA 210 is substantially equal to described AGC set-point.

Although show VGA 210 as amplifier, described AGC function can or only decay and is implemented with the combination that only gains, gain and decay.In addition, described VGA 210 can be with multiple stage and multiple equipment and is implemented.For example, described VGA 210 can be configured to multiple cascade variable gain amplifier, with the amplifier of variable attenuator cascade, or parallel multiple variable gain amplifier etc.

In addition, described power detector 220 can be diode detector, crystal detector etc.Described power detector 220 can be configured to sample mean power, peak power, RMS voltage, average voltage, crest voltage, average current, RMS electric current, peak current or some other value about signal level.Described power detector can be individual equipment or can be constructed by multiple equipment.As discussed above, described power detector 220 may comprise for example detector, comparator, integrator or some other Signal Regulation piece.

Although show described power detector 220 so that the AGC function with reference to output to be provided, yet this power detector 220 can be configured to the signal power that detects other position, for example in the input of described VGA 210.Described power detector 220 can be configured to the signal power of detection away from some other position of described VGA210, for example in the input to the set-top box of Fig. 1.

Can utilize various technology to realize actual AGC function, comprise feedback and feedforward.No matter whether with of the output of AGC functional configuration for the use feedback, or the output of use feed-forward technique, described AGC function also can be provided in the stable basically output level on the predetermined AGC scope.

Fig. 2 B is the functional block diagram of the embodiment of AGC amplifier.Described AGC amplifier is included in the fixed gain amplifier 232 of the input of described AGC amplifier.The output of described fixed gain amplifier 232 is connected to the input of VGA 234.The output of described VGA 234 is connected to power detector 240.Be connected to the control input of described VGA 234 from the output signal of described power detector 240, to control the gain of described VGA 234.

Except realization fixed gain amplifier 232 before the VGA 234, the AGC amplifier embodiment among Fig. 2 B is similar to the embodiment of Fig. 2 A.The same operation effectively of the AGC amplifier of Fig. 2 B with the AGC amplifier of Fig. 2 A.The gain of described fixed gain amplifier 232 can be set to the low restriction in the described AGC amplifier gain.Yet, provide decay if dispose described VGA, can eliminate the gain of described fixed gain amplifier 232 by the decay among the described VGA 234.For example, for the front-end amplifier that has than in the AGC amplifier of low-noise factor is provided, described fixed gain amplifier 232 can be contained in the AGC amplifier.

Fig. 2 C is the functional block diagram of the embodiment of another AGC amplifier.Described AGC amplifier is included in the VGA 252 of described AGC amplifier input.The output of this VGA 252 is connected to fixed gain amplifier 254.The output of this fixed gain amplifier 254 is the output of described AGC amplifier.The output of described VGA 252 also is connected to the input of described power detector 260.The output that is detected is offered the control input of described VGA 252.Therefore, in the embodiment of Fig. 2 C, described power detector 260 detects the power in interstages, rather than the inputing or outputing of described AGC amplifier.Certainly, by with the described AGC amplifier of fixed gain amplifier cascade, can revise the embodiment of the embodiment of Fig. 2 A with corresponding diagram 2C.Although fixed gain amplifier 254 is implemented after VGA252, yet described synthetic AGC amplifier can be understood that the output of being correlated with.

Fig. 2 D is another embodiment of AGC amplifier.Described AGC amplifier is the embodiment that is coupled to the VGA of signal allocation equipment.Described AGC amplifier comprises VGA 270 in the input of described AGC amplifier.The output of described VGA 270 is connected to the input of frequency mixer 280.LO284 drives the LO port of described frequency mixer 280.The output of described frequency mixer 280 is the output of described AGC amplifier.The output of described frequency mixer 280 also is connected to the input of described power detector 290.The output that is detected is provided for the control input of described VGA 270.

In described AGC amplifier configuration, described AGC function and frequency band conversion combination.The set-point with tracking AGC is exported in described AGC booster output control, and also signal can be converted to the output frequency bandwidth from the incoming frequency bandwidth frequency.As before noticing, for example 270 VGA can make up with multiple signal allocation equipment.The described demultiplexer 170 of Fig. 1 can be represented another embodiment with the VGA of signal allocation device coupled.

Described VGA 270 operates in the above described manner with respect to other AGC amplifier embodiment.The output of described VGA 270 is connected to the input port of frequency mixer 280.Described frequency mixer 280 is transformed into second frequency band with signal from first frequency band.It can be the LO port of the described frequency mixer 280 of LO 284 drivings of fixed frequency LO or variable frequency LO.Described frequency mixer 280 provides such output signal: it comprises the frequency content as frequency input signal and LO frequency sum, and as the frequency content of the difference of frequency input signal and LO frequency.

Described power detector 290 can be configured to the signal that detects in the predetermined frequency band.Therefore, described power detector 290 can detect the signal in the desired frequency band, and ignores the signal outside the frequency band of concern.Therefore described AGC amplifier can be configured to provides the signal amplitude of being controlled that merges with frequency inverted.

The advantage that comprises the AGC stage in the distribution switch 130 of the system of for example Fig. 1 or the signal distribution system in the demultiplexer 170 can realize realizing describing with the AGC signal allocation by fixed gain signal allocation relatively.Fig. 3 A and 3B show the embodiment of cascade amplifier configuration.Configuration among Fig. 3 A comprises fixed gain amplifier, and the configuration of Fig. 3 B comprises described AGC amplifier.Described cascade amplifier configuration may be included in the signal allocation switch of Fig. 1, for example so that three separate copies of the single input signal of going to three diverse geographic locations in the described signal distribution system to be provided.

Fig. 3 A is the embodiment of fixed gain signal allocation part 300, for example the distribution portion that can be implemented in the distribution switch of Fig. 1.For example, can distribute equipment in the described distribution portion 300 at the front end of signal distribution system, centre position or near end.Described fixed gain distribution portion 300 comprises three gain equipments 310,320 and 330 connected in series.For example each gain equipment of 310 can be configured to the active power distributor, and it has the fixed gain of 0dB, the noise factor of 3dB (NF), and+the input third order intermodulation point (IIP3) of 30dBm.Alternatively, each gain equipment can comprise the amplifier in conjunction with the signal allocation equipment of some other type.

The first fixed gain equipment 310 comprises fixed gain amplifier 312, is thereafter the Passive Power distributor 314 with the first output 318a and second output 318b.Can be configured to 0dB by described fixed gain amplifier 312 and Passive Power distributor 314 to the synthetic gain of one of output of for example 318b.The second output 318b of the described first fixed gain equipment 310 is connected to the input of the second fixed gain equipment 320.The described second fixed gain equipment 320 also comprises fixed gain amplifier 322 and has the first output 328a and the Passive Power distributor 324 of the second output 328b.The second output 328b of the described second fixed gain equipment 320 is connected to the input of the 3rd fixed gain equipment 330.Also disposing described the 3rd fixed gain equipment 330 similarly with fixed gain amplifier 332, is the Passive Power distributor 334 with two outputs 338a, 338b after this fixed gain amplifier 332.

The optional signal allocation part 350 that comprises the AGC amplifier has been shown among Fig. 3 B.The embodiment that comprises the signal allocation part 350 of described AGC amplifier can be implemented in the distribution switch of Fig. 1.

Three gain equipments 360,370 and 380 are cascaded in described signal allocation part.In the described gain equipment 360,370 and 380 each all comprises the AGC amplifier of back with the Passive Power distributor.In the described gain equipment 360,370 and 380 each also can comprise the AGC amplifier in conjunction with one or more other signal allocation equipment.

For example each in 360 the gain equipment may have the AGC function with reference to output, have 0dBm the AGC set-point ,+NF of the 3dB of the IIP3 of 30dBm and 0dB gain.For example 360 gain equipment may have-20dB is to the gain ranging of+20dB.In the described AGC amplifier each may for example be one of AGC amplifier configuration shown in Fig. 2 A-2C.

The input of input signal to described first gain equipment 360 is provided.The input of described input signal to AGC amplifier 362 is coupled.Connect the input that outputs to power detector 364 of described AGC amplifier 362.Connect the control input of the described AGC amplifier of outputing to of described power detector 364.The output of described AGC amplifier 362 also is connected to the input of the power divider 366 with first and second outputs that are respectively 368a and 368b.

The second output 368b of described first gain equipment 360 is connected to the input of second gain equipment 370.Be coupled to the input of AGC amplifier 372 from the output of described first gain equipment 360.The output of described AGC amplifier 372 is connected to the input of power detector 374.The output of described power detector 374 is connected to the control input of described AGC amplifier.The output of described AGC amplifier 372 also is connected to the input of the power divider 376 with first and second outputs that are respectively 378a and 378b.

The second output 378b of described second gain equipment 370 is connected to the input of the 3rd gain equipment 380.Be coupled to the input of the AGC amplifier 382 in the 3rd gain equipment 380 from the output of described second gain equipment 370.The output of described AGC amplifier 382 is connected to the input of power detector 384.The output of described power detector 384 is connected to the control input of AGC amplifier.The output of described AGC amplifier 382 is connected to the input of the power divider 386 with first and second outputs that are respectively 388a and 388b.

The performance of described fixed gain distribution portion 300 can compare at the performance of two kinds of operating conditions and described variable gain distribution portion 350.Under first operating condition, the less relatively and uncorrelated noise of described input signal is the key factor of restriction SNR.Under second operating condition, the relatively large and distortion product of described input signal is the key factor of restriction SNR.

Under described first operating condition, described input signal is less relatively.The configuration of described fixed gain distribution portion 300 does not change.Yet described variable gain distribution portion 350 disposes himself automatically, and the gain up to the maximum gain level is provided.

For example the active equipment of amplifier typically has a plurality of noise sources related with it.If described headend equipment has very big gain, then can reduce the noise effect of cascade amplifier.The noise effect of follow-up phase becomes and can ignore, and therefore, can minimize the reduction of SNR.In addition, other noise of after first gain stage or headend equipment, being introduced, comparing does not have front-end gain equipment less to reduce SNR.Therefore, comprise that the front-end gain stage has reduced the reduction of whole system SNR.By checking noise factor, the performance of described fixed gain distribution portion 300 can compare with described variable gain distribution portion 350.Following formula has provided the noise factor in the cascade system:

{nf}_{cascade} = {nf}_{1} + Σ_{i = 2}^{N} \frac{{nf}_{i} - 1}{Π_{j = 1}^{l - 1} A_{j}},

N=stage number wherein, A _jThe gain in=the j stage

Noise factor value in the given formula is a ratio, and given with dB at the specified noise factor of equipment.Therefore, before application of formula, for example the NF of 310 or 370 gain equipment need be converted to ratio from decibel.Table 1 provides the summary at the cascade noise coefficient of two gain allocation parts 300,350.Psig be illustrated in gain equipment what input or output is the signal power of unit with dBm.With dB is the gain that unit provides described element, and providing with dB at each gain equipment is the noise factor of unit, and to provide with dB in the output of each gain equipment be the corresponding cascade noise coefficient of unit.

Table 1

The fixed gain distribution portion
The fixed gain distribution portion								Psig(dBm)	-20		-20		-20		-20
Gain(dB)		0		0		0		Psig(dBm)	-20		-20		-20		-20
Gain(dB)		0		0		0		NF(dB)		3		3		3
Nftot(dB)		3		4.8		6		NF(dB)		3		3		3
Nftot(dB)		3		4.8		6		The variable gain distribution portion
Psig(dBm)	-20		0		0		0	The variable gain distribution portion
Psig(dBm)	-20		0		0		0	Gain(dB)		20		0		0
NF(dB)		3		3		3		Gain(dB)		20		0		0
NF(dB)		3		3		3		NFtot(dB)		3		3.02		3.04

Therefore, as can be seen, when comparing with fixed gain part 300, described variable gain distribution portion 350 comprises the ability of the gain in the initial amplifier section, has caused significantly reducing by the follow-up phase introducing signal fadeout that noise caused.The noise of being introduced after the initial gain part has not less reduced SNR for having described gain part.Therefore, can be by comprising the initial gain part, the SNR that reduces whole system reduces.

Under described second operating condition, described input signal is relatively large.The configuration of described fixed gain distribution portion 300 does not change.Yet described variable gain distribution portion 350 disposes himself automatically, and the decay up to the maximum attenuation level is provided.When input signal was relatively large, for example the distortion components of third order intermodulation distortion product may be the principal element that reduces SNR.Can calculate and the cascade IIP3 of more described signal allocation part 300,350, distribute the advantage of distributing with respect to fixed gain with the explanation variable gain.The cascade IIP3 of gain part is provided by following formula:

\frac{1}{{IP}_{tot}} = \frac{1}{{IP 3}_{i}} + Σ_{i = 2}^{N} \frac{Π_{j = 1}^{l - 1} A_{j}}{{IP 3}_{i}}

The IP3 value is a linear term in the formula, rather than the dBm value.Similarly, providing yield value is ratio rather than dB.Table 2 provides the summary of cascade IIP3 at two gain allocation parts 300,350.Psig is the signal power that input or output of unit representation at described gain equipment with dBm.With dB is the gain that unit provides described element.The IIP3 that with dBm is unit is provided for each gain equipment, and to provide with dB in the output of each gain equipment be the corresponding cascade IIP3 of unit.

Table 2

The fixed gain distribution portion
The fixed gain distribution portion								Psig(dBm)	+20		+20		+20		+20
Gain(dB)		0		0		0		Psig(dBm)	+20		+20		+20		+20
Gain(dB)		0		0		0		NF(dBm)		+30		+30		+30
Nftot(dB)		+30		+27		+25.2		NF(dBm)		+30		+30		+30
Nftot(dB)		+30		+27		+25.2		The variable gain distribution portion
Psig(dBm)	+20		0		0		0	The variable gain distribution portion
Psig(dBm)	+20		0		0		0	Gain(dB)		-20		0		0
NF(dB)		+30		+30		+30		Gain(dB)		-20		0		0
NF(dB)		+30		+30		+30		Nftot(dB)		+30		+29.96		+29/91

Therefore, as can be seen, when with fixed gain part 300 relatively the time, described variable gain distribution portion 350 comprises the ability of the decay in the initial amplifier section, has caused significantly reducing of the signal fadeout that noise caused introduced by follow-up phase.The distortion that is caused after the initial decay stage has not less reduced SNR with respect to having for the decling phase.Can be by comprising the SNR reduction that initial decay partly reduces whole system.

Compare fixed gain configuration, comprise that the AGC function is in the signal allocation part thereby can improve signal quality.Under the extreme condition of low input-signal power and high input signal power, the variable gain part has illustrated that with respect to the advantage of fixed gain part described variable gain distribution portion has flexibility with regard to it with regard to the position in the signal distribution system.Described variable gain distribution portion does not need to be placed in front end or the terminal stage in the described signal distribution system.

Fig. 4 is the functional block diagram of the specific embodiment of signal distribution system 400, and described signal distribution system comprises the have frequency band conversion integrated crosspoint switch 410 and the external component of (frequency band conversion switch).Described frequency band conversion switch 410 comprises four inputs of LNB, exports and be configured to two outputs of junctor top box corresponding to the cascade of each input.Dispose described frequency band conversion switch 410 has dual band crossover frequencies planning (dual band-stacked frequencyplan) with connection LNB signal.Described dual band crossover frequencies planning comprises frequency band piece and following frequency band piece.The planning of dual band crossover frequencies has been safeguarded in the output of described frequency band conversion switch, but allow from any LNB signal go up or down the frequency band piece be configured to export the frequency band piece.Similarly, the last or following frequency band piece from any LNB signal can be configured to export down the frequency band piece.The more detailed description of described frequency band conversion switch 410 is provided below.

Described frequency band conversion switch 410 comprises and is configured to four inputs of connection up to four LNB.Each LNB provides the signal that meets the dual band crossover frequencies planning with last frequency band piece and following frequency band piece.For example, described LNB signal can be the satellite downlink signal from selected transponder group.Described frequency band piece down can be 950-1450MHz, and described upward frequency band piece can be 1650-2150MHz.

Each signal input is connected to the input of amplifier 420a-420d.Described amplifier 420a-420d is configured to can buffer memory and the low noise amplifier (LNA) that amplifies from the input signal of LNB.Be connected to corresponding input on the cross point switch 430 from each the output among the amplifier 420a-420d.In addition, be connected to the corresponding cascade output of described frequency band conversion switch 410 from each the output among the amplifier 420a-420d.

Described cross point switch 430 is configured to 4 * 4 switches.The LNB input signal of any four amplifications can independently side by side optionally be routed to any four outputs of described cross point switch 430.For example, described cross point switch 430 can comprise dibit (two-bit) control at each output.The dibit controlling value of can programming is with the signal from one of described four inputs of route optionally.Described frequency band conversion switch 410 for example can receive the dibit control word from set-top box.Alternatively, described set-top box can send one or more control messages to the microprocessor in the local realization of described cross point switch, and described microprocessor can produce one or more dibit control words.In the embodiment shown in fig. 4, be connected to frequency band conversion equipment 440a-440d from four outputs of described cross point switch 430 each.One or more outputs from described cross point switch 430 can be coupled to identical frequency band conversion equipment, for example 440a.

Described frequency band conversion equipment 440a-440d is configured to optionally frequency conversion signal or does not carry out frequency inverted and transmit signal.Among the described frequency band conversion equipment 440a-440d each can irrespectively be selected frequency inverted with miscellaneous equipment or pass through.Because the planning of dual band crossover frequencies is used among the described embodiment, therefore when selecting frequency inverted, described frequency band conversion equipment 440a-440d is configured to the position of the described upper and lower frequency band piece of exchange.

Among the described frequency band conversion equipment 440a-440d each comprises frequency mixer.Described frequency band conversion switch 410 also comprises one or more local oscillators (LO).In an embodiment with dual band crossover frequencies planning, single LO can be routed to all frequency band conversion equipment 440a-440d.In another embodiment, when realizing the planning of dual band crossover frequencies, the frequency of described local oscillator can be fixed.Can use the LO frequency of 3.1GHz or 2x (band center mean value) to carry out frequency inverted.

In another embodiment, described frequency band conversion equipment 440a-440d can use a plurality of variable frequency LO.For example, each among the described frequency band conversion equipment 440a-440d can have the LO output frequency of independent separate control.Therefore, each among the described frequency band conversion equipment 440a-440d can with by the performed frequency inverted of any other frequency band conversion equipment its input signal of frequency inverted irrespectively.

LO buffer memory amplifier (not shown) will be given among the described frequency band conversion equipment 440a-440d each from the signal allocation of LO output.The output of described frequency band conversion equipment 440a-440d is connected to the output of described frequency band conversion switch 410.

Each output of described frequency band conversion switch 410 is the dual band overlap signal.Each output of described frequency band conversion switch 410 is connected to filter 450a-450d.Described filter 450a-450d is configured in one of predetermined frequency band of dual band crossover frequencies planning and transmits signal.Described filter 450a-450d refuses the outer signal of passband, is included in the signal of the frequency band of not expecting.Described filter 450a-450d can be configured maybe can be configured to have fixed passband with the scalable passband.

In the present embodiment, the described filter 450a-450d band pass filter that is configured to have fixed passband.The described first filter 450a is configured to the band pass filter by the last frequency band piece of described frequency planning.The second filter 450b is configured to by the described band pass filter of frequency band piece down.Similarly, the 3rd filter 450c is configured to by last frequency band piece, and the 4th filter 450d is configured to by following frequency band piece.The output of the described first and second filter 450a-450b is connected to other first and second input of branch of the first signal combiner 460a.Similarly, the output of the described third and fourth filter 450c-450d is connected to other first and second input of branch of secondary signal combiner 460b.Described filter 450a-450d is not limited to band pass filter, and can for example be band pass filter (BPF), low pass filter (LPF) or high pass filter (HPF).In other embodiments, can use other frequency to select equipment, to limit the frequency response of described output.Described filter 450a-450d can have the passband narrower than the band bandwidth of described input signal.For example the input to filter of 450a for example can comprise multiple carrier wave.Yet described filter 450a can be configured to the subclass of transmitting all carrier waves.

Described signal combiner 460a-460b is configured to and is accumulated in the signal that its input is provided, and provides the signal that is added up in output.Output from described signal combiner 460a-460b is the frequency band conversion output of signal distribution system 400.Each output is connected to set-top box with further processing and distribute to end user device.

As mentioned above, one or more frequencies select equipment can be used as filter 450a-450d.For example, can use homodromy to come signal is carried out filtering and frequency band overlapping.Described homodromy can be used as filter, for example 450a and 450b, and signal combiner 460a.

Certainly, described frequency band conversion switch 410 is not limited to operate with frequency band overlapping input signal.For example, each in the described LNB signal can provide the signal in the same frequency band.Described frequency band conversion switch 410 can be configured to frequency inverted and merge the part of single frequency band input signal.Described cross point switch 430 can be for example be routed to the first frequency band conversion equipment 440a with the output of the described first amplifier 420a.LO in the described first frequency band conversion equipment 440 can be configured to frequency conversion signal, the feasible output frequency that is converted into expectation from one or more channels of described input signal.The described first filter 450a can be configured to the channel that only transmits described expectation, and refuses all not desired frequency and channels.

Similarly, the output that can be configured to the described second amplifier 420b of described cross point switch 430 is routed to the second frequency band conversion equipment 440b.The described second frequency band conversion equipment 440b can be configured to the output frequency of a part of frequency inverted for expecting with input signal.The described second filter 450b can be configured to the channel that only transmits described expectation, and refuses all not desired frequency and channels.

In conjunction with the first and second frequency band conversion equipment 440a-440b of the described first and second filter 450a-450b, can be configured in the artificial frequency band of getting rid of and produce selected channel.The described combiner 460a thereby the filtered output that can add up, to produce from the synthesized output signal of single frequency band input signal independently, wherein each filter comprises one or more channels.In an embodiment of described single frequency band input signal configuration, for example every pair of frequency band conversion equipment of 440a and 450a and filter are configured to frequency inverted from each the one or more channels in one or more input signal frequency bands.Described frequency conversion signal can be integrated in single band signal or the band multiplex signal.

Similarly, some embodiment can have band multiplex conversion equipment and multiple filter.In the described band multiplex conversion equipment each can frequency inverted from one or more channels of one or more input frequency bands.Can add up the output of described multiple filter so that the single composite signal of the channel queue (line up) with expectation to be provided.

Can service band in signal distribution system an embodiment of conversion switch 410, this signal distribution system is used for providing in the settlement distribution of satellite TV signal.Described AGC amplifier 420a-420d provides variable gain and decay based on the power of input signal.The measurement point of described AGC function is in the output of described AGC amplifier 420a-420d, and the gain of described cross point switch 430 and frequency band conversion equipment 440a-440b is fixed.

The back is with each AGC amplifier 420a-420d of cross point switch 430, frequency band conversion equipment 440a-440d, filter 450a-450d and signal combiner 460a-460b, and can be configured to provides minimum-7dB whole gains to maximum+7dB scope.Corresponding path NF can for example change to low 10dB from high 24dB, and described frequency band conversion switch 410 is passed in the output of described path from the AGC amplifier of for example 420a to the frequency band conversion equipment of for example 440a.Described signal path is when providing decay the time to experience higher NF, and is unit value (unity) when gaining or has lower NF when bigger.Similarly, the scope of the IIP3 that is associated with described signal path can be from minimum-7dBm to maximum+7dBm.For example, the IIP3 of described signal path can be-15 ,-10 ,-7 ,-6 ,-5 ,-4 ,-3 ,-2 ,-1,0 ,+1 ,+2 ,+3 ,+4 ,+5 ,+6 ,+7 ,+10 ,+15 ,+20 ,+25 or+30dBm.

When the configuration amplifier provided decay, the IIP3 of described AGC amplifier 420a was higher typically, and this will cause the synthetic IIP3 of described signal path.The IIP3 of described AGC amplifier 420a can change pro rata with Amplifier Gain.

Because described AGC amplifier 420a also provides signal to export to cascade, therefore the characteristic with AGC amplifier 420a is identical basically in the characteristic of the AGC function of cascade output.Also, therefore in main signal path and signal path, experienced the advantage of AGC function by described cascade output owing to before cascade output, provide described AGC function.

Can in signal distribution system, use 410 configurations of described frequency band conversion switch, can expect that in this signal distribution system the input of described frequency band conversion switch 410 changes on the scope of-10dBm at-50dBm.Described AGC amplifier 420a-420d can be configured to have with reference to output-the AGC set-point of 17dBm, wherein said output is meant the output signal of described switch 400.Described frequency band conversion switch 410 does not need the power of the output of the described switch 400 of actual measurement.Because equipment described frequency band conversion switch 410 after has fixed gain, so AGC output can be understood as about any point and export, and is described any after the gain or the AGC amplifier of fixing of decaying.

Utilize described AGC set-point, when input signal is-24dBm or when lower, for example the AGC amplifier of 420a provides the gain of 7dB.In addition, when described input signal is-10dBm or when bigger, described AGC amplifier 420a provides-gain of 7dB, or the decay of 7dB.Therefore, in the input power range of-10dBm, described AGC amplifier 420a provides-the fixedly power output of 17dBm at-24dBm.

The band multiplex that Fig. 5 is in signal distribution system and is connected is changed the functional block diagram of switch 510,520,530,540 and 550.Described frequency band conversion switch 510,520,530,540 and 550 can be configured to LNB the distribution of Fig. 1 switch is provided.Yet as previously noted, one or more frequency band conversion switches 510,520,530,540 and 550 can be positioned at other position of signal distribution system.For example, one or more frequency band conversion equipment can be positioned at the input of described signal near, in the centre position of described signal distribution system, or near the terminal of described signal distribution system or the destination equipment.

The first frequency band conversion switch 510 comprises the LNA input, and described input can be connected to the LNB of piece conversion satellite downlink transmission.The output of the described first frequency band conversion switch 510 is connected to the input of the second frequency band conversion switch 520, and this second frequency band conversion switch also has the output that is connected to the 3rd frequency band conversion switch 530.The cascade output of the described first frequency band conversion switch 510 is connected to the input of the 4th frequency band conversion switch 540.The output of described the 4th frequency band conversion switch 540 is connected to the input of the 5th frequency band conversion switch 550.

In the described frequency band conversion switch 510,520,530,540 and 550 each can be the frequency band conversion switch of Fig. 4, and can comprise one of AGC amplifier of Fig. 2 A-2C.Can be similar to the described first frequency band conversion switch 510 and dispose in described frequency band conversion switch 510,520,530,540 and 550 each.In the first frequency band conversion switch 510, the input of VGA 512 receives the input signal from LNB.Described VGA 512 typically has low-noise factor, makes to be lower than 3dB, 4dB, 5dB, 6dB, 8dB, 10dB, 12dB, 14dB, 15dB, 20dB, 25dB, 30dB, 35dB or 40dB from the noise factor of the frequency band conversion switch 510 that is input to frequency band conversion output.Typically near the noise factor value of VGA 512, and may for example be lower than 3dB, 4dB, 5dB, 6dB, 8dB, 9dB, 10dB, 12dB, 14dB, 15dB, 20dB, 24dB, 25dB, 30dB, 35dB or 40dB from the noise factor of the frequency band conversion switch 510 that is input to cascade output.

In addition, described VGA 512 introduces the IIP3 of frequency band conversion switch 510.Described frequency band conversion switch 510 typically have from frequency band conversion equipment be input to the measured IIP3 of output, its greater than-40 ,-30 ,-20 ,-10 ,-8 ,-7 ,-6 ,-5 ,-4 ,-3 ,-2 ,-1,0 ,+1 ,+2 ,+3 ,+4 ,+5 ,+6 ,+7 or+8 ,+15 ,+20 ,+22 ,+25 ,+26 ,+27 ,+28 ,+29 or+30dBm.Similarly, described frequency band conversion switch 510 typically has from being input to the measured IIP3 of cascade output, its greater than-10 ,-5 ,+1 ,+2 ,+3 ,+4 ,+5 ,+6 ,+7 ,+8 ,+9 ,+10 ,+15 ,+20 ,+25 or+30dBm.

The output of described VGA 512 is connected to detector 514 and N * M cross point switch 516.Described detector 514 detects the power of being exported by VGA 512, and the output that is detected of the control input that is connected to VGA 512 is provided.In addition, the output of VGA 512 drives the cascade output of the described first frequency band conversion switch 510.The output of described N * M cross point switch 516 is connected to frequency band conversion equipment 518.

Although only show a VGA 512 and detector 514 in the first frequency band conversion switch 510, yet more than one VGA 512 and cascade output can be included in the frequency band conversion switch, as shown in Figure 4.Therefore, in signal band conversion switch 510, give two signal paths for example rising in 512 single VGA, the advantage with the AGC function that meets the signal allocation path is provided.

In the frequency band conversion switch 520,530,540 and 550 of back each also can be connected to signal path in its cascade output, and equally can be by using input AGC stage control signal level and minimizing the noise of introducing later.Be connected to the 4th frequency band conversion switch 540 of the cascade output of the described first frequency band conversion switch 510, do not introduce noise to the originating terminal signal path and control the noise that follow-up phase is introduced.

Fig. 6 is the flow chart that is used in the system for delivering 600 in the signal communications system, and described system for example is a satellite communication system shown in Figure 1.Described method 600 starts from receiving the piece 602 of distributing signal.Can receive described signal from satellite, as shown in Figure 1, maybe can receive this signal from being configured to the antenna, cable or the optical link that receive ground signal.In addition, can be from the described signal of the combined reception in source.

After having received the signal that to be assigned with, typically amplify this signal, shown in piece 610 by low noise amplifier.Because gain can change to negative value from the postiive gain value, therefore under all operations condition, amplifier can not be a low noise amplifier, and can be attenuator under some operating condition.In the present context, negative yield value refers to decay.

After amplifying, in piece 612, measure power output.Owing to measure power output after gain stage, therefore the follow-up AGC function based on measured power output can be called with reference to the AGC that exports.In piece 614, measured power output thereby be used as the factor that is used to change gain.As discussed above, described gain can typically change in the scope from postiive gain to decay.

In piece 620, cascade output also is provided, and described cascade output can be provided after described AGC function.Described gain control signal may be provided in cascade output, as shown in Figures 4 and 5.

In addition, in piece 630, for example signal is routed to the path, destination by N shown in Figure 4 * M cross point switch.The signal that is routed to the destination by N * M cross point switch is typically irrelevant with the signal that offers described cascade output.Therefore, shown in the frequency band conversion switch of Fig. 4, the output of described AGC part is provided as cascade output, and the input that is provided for described N * M cross point switch is to be routed to one of M possible dispense path.

In piece 640, thereby can frequency band conversion be routed to the signal of dispense path.The frequency band conversion piece can comprise frequency mixer, optionally signal is transformed into the second frequency piece from the first frequency piece.In addition, the frequency band conversion piece can be configured to and have the path of passing through of signal not being carried out frequency inverted.

After frequency band conversion, can carry out filtering to signal, to remove the unwanted frequency composition outside noise and the concern frequency band from the output of frequency band conversion piece.In piece 660, two or more filtering signals can be merged to produce composite signal.Described two or more filtering signal can be risen in one or more independently signal allocation path.In the described filtering signal each can be in different frequency bands.Alternatively, in the frequency band that one or more filtering signals can overlap mutually at another frequency band with filtering signal.

Although by showing method 600 from a piece to Next mode, yet the order of method piece is not limited to order shown in Figure 6.

The method in conjunction with the signal allocation of the AGC of the AGC amplifier of signal allocation equipment and use binding signal distributing equipment has been described in the discussion that provides above.But the AGC amplifier of binding signal distributing equipment allows to insert the cascade device of series connection, and reduces the SNR of system indistinctively.Described AGC amplifier also can comprise cascade output, and with the establishment of permission additional signal dispense path, and this additional path does not reduce the performance of its signal path that branches out and/or its signal path of presenting significantly.Described cascade output can be used to provide described AGC function, and does not have follow-up signal allocation function.For example, when described signal allocation function was the frequency band conversion function, this may be favourable especially.

The AGC amplifier of binding signal distributing equipment can be used as series devices and is inserted into, the reduction of this series devices and its location independent ground minimization system SNR in described signal distribution system.Use with reference to the AGC function of output to come on the input operation scope, to keep the power output relative fixed, thereby kept the optimum signal opereating specification in the described distribution system.

Described electronics connection, coupling and be connected about various device or element.Described connection and coupling can be direct or indirect.Connection between first and second equipment can be that direct connection maybe can be indirect connection.Connection can comprise insertion element indirectly, and described element can be from first equipment to the described signal of second device processes.

One of ordinary skill in the art appreciates that and to utilize various any different technologies and technical ability to come expression information and signal.For example, run through data, instruction, order, information, signal, bit, symbol and the chip of top description institute reference, can illustrate by voltage, electric current, electromagnetic wave, electromagnetic field or particle, light field or particle or its any combination.

One of ordinary skill in the art appreciates that in conjunction with the described various illustrative components, blocks of embodiment disclosed herein, module, circuit and algorithm steps, may be implemented as electronic hardware, computer software or both combinations.For the interchangeability of hardware and software clearly is described, with regard to its functional aspect various illustrative components, piece, module, circuit and step have been described usually above.Describedly functionally be implemented as hardware or software depends on employed application-specific of whole system and design limit.The technical staff can be described functional at each application-specific accomplished in various ways, but described realization never should depart from the scope of the present invention.

Various illustrative components, blocks, module and the circuit described in conjunction with embodiment disclosed herein can be implemented or carry out by following elements: general processor, digital signal processor (DSP), application-specific integrated circuit (ASIC) (ASIC), field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components or be used to carried out any combination of the said elements of function described herein.General processor can be a microprocessor, but alternatively, processor can be any processor, controller, microcontroller or state machine.Processor also may be implemented as the combination of computer equipment, for example following combination: DSP and microprocessor, a plurality of microprocessor, in conjunction with one or more microprocessors or any other described configuration of DSP nuclear.

Can directly be included in hardware, the processor performed software module or both combinations in conjunction with the step of described method of embodiment disclosed herein or algorithm.Software module can be arranged in the storage medium of RAM memory, flash memory, ROM memory, eprom memory, eeprom memory, register, hard disk, detachable disk, CD-ROM or any other form.Exemplary storage medium can be coupled to processor, so that described processor can read information and information is write this storage medium from described storage medium.In optional scheme, described storage medium can be integrated into processor.Described processor and storage medium can be arranged in ASIC.

Any technical staff of this area provides the top description of disclosed embodiment, so that can make or use the present invention.The various modifications of described embodiment are clearly to those skilled in the art, and the General Principle of definition here can be applied to other embodiment and not break away from the spirit and scope of the present invention.Therefore, the embodiment shown in the invention is not restricted to here, but meet and principle disclosed herein and the consistent scope the most widely of novelty.

Claims

1. the method for a distributing signal in having the satellite-based signal distribution system of a plurality of transponder groups, described method comprises the following steps:

Reception is from the signal of satellite transponder group;

The piece switching signal is an intermediate frequency;

The power of the signal in the variable gain amplifier of adjusting integrated circuit;

Utilize detector in the described integrated circuit to detect the power output of variable gain amplifier; And

Be based in part on the result who detects described power output, regulate the gain of variable gain amplifier.

2. according to the method for claim 1, also comprise the following steps:

The output of described variable gain amplifier is connected to the series connection signal path; And

The output of described variable gain amplifier is connected to the cascade signal path.

3. according to the process of claim 1 wherein, the power of regulating described signal comprises the signal that amplifies in the described variable gain amplifier.

4. according to the process of claim 1 wherein, the power of regulating described signal comprises the signal in the described variable gain amplifier of decaying.

5. according to the process of claim 1 wherein, the gain of regulating described variable gain amplifier comprises regulates described variable gain amplifier, optionally to amplify or to decay described signal.

6. according to the method for claim 5, wherein, the gain of regulating described variable gain amplifier also comprises regulates this variable gain amplifier, thereby when the power output of the described variable gain amplifier described signal of decaying during greater than the set-point be scheduled to.

7. according to the method for claim 5, wherein, the gain of regulating described variable gain amplifier also comprises regulates this variable gain amplifier, thereby amplifies described signal during less than predetermined set point when the power output of described variable gain amplifier.

8. according to the method for claim 1, also comprise one of a plurality of outputs that the output signal from described variable gain amplifier are routed to the crosspoint router.

9. according to the method for claim 1, also comprise the output signal frequency band conversion from described variable gain amplifier is arrived one of a plurality of frequency bands.

10. signal allocation equipment, it is configured to be used in has concentrated signal input and in the signal distribution system of the multipurpose ground of remote location equipment, described equipment comprises:

Variable gain amplifier on integrated circuit substrate, described variable gain amplifier has input, output and control input, and be configured to the control signal of importing based on the control of described variable gain amplifier at least in part, the signal that optionally amplifies or decay and received in described concentrated signal input;

Power detector on described integrated circuit substrate, described power detector has the input of the output that is connected to described variable gain amplifier, output with the control input that is connected to described variable gain amplifier, and be configured to the power output that is based in part on described variable gain amplifier, provide detected output as described control signal; And

Signal handling equipment on described integrated circuit substrate, the input of described signal handling equipment is coupled to the output of described variable gain amplifier, and the output of described signal handling equipment is coupled to first output of described signal allocation equipment.

11. according to the signal allocation equipment of claim 10, wherein, described variable gain amplifier also comprises such cascade output: it is connected to the output of described variable gain amplifier, and is connected to the output of described signal allocation equipment.

12. according to the signal allocation equipment of claim 10, wherein, described signal handling equipment comprises demultiplexer.

13. according to the signal allocation equipment of claim 10, wherein, described signal handling equipment comprises frequency band conversion equipment.

14. according to the signal allocation equipment of claim 10, wherein, described signal handling equipment comprises cross point switch.

15. according to the signal allocation equipment of claim 10, wherein, the satellite downlink signal that described variable gain amplifier optionally amplifies or decays and received in described concentrated signal input.

16. according to the signal allocation equipment of claim 10, wherein, the satellite television down link signal that described variable gain amplifier optionally amplifies or decays and received in described concentrated signal input.

17. according to the signal allocation equipment of claim 10, wherein, the cable TV signal that described variable gain amplifier optionally amplifies or decays and received in described concentrated signal input.

18. according to the signal allocation equipment of claim 10, wherein, the terrestrial television signal that described variable gain amplifier optionally amplifies or decays and received in described concentrated signal input.

19. according to the signal allocation equipment of claim 10, wherein, the telephone signal that described variable gain amplifier optionally amplifies or decays and received in described concentrated signal input.

20. according to the signal allocation equipment of claim 10, wherein, the data-signal that described variable gain amplifier optionally amplifies or decays and received in described concentrated signal input.

21. the method for a distributing signal in the signal distribution system with a plurality of band overlapping sets of signals, described method comprises the following steps:

Reception is from the sets of signals of a plurality of described band overlapping sets of signals;

The power of the sets of signals in the variable gain amplifier of adjusting integrated circuit;

Utilize detector in the described integrated circuit to detect the power output of described variable gain amplifier;

To be assigned to destination equipment from the output signal of described variable gain amplifier.

22. according to the method for claim 21, wherein, the power output that detects described variable gain amplifier comprises, detects described power output in the frequency band than the bandwidth of described sets of signals.

23. according to the method for claim 21, wherein, the power output that detects described variable gain amplifier comprises, detects described power output in than the narrow frequency band of the frequency band of described sets of signals.

24. according to the method for claim 21, wherein, described a plurality of band overlapping sets of signals comprise:

First sets of signals in the 950-1450MHz frequency band; And

Secondary signal group in the 1650-2150MHz frequency band.

25., wherein, regulate described gain and comprise the postiive gain of regulating described variable gain amplifier according to the method for claim 21.

26., wherein, regulate described gain and comprise the decay of regulating described variable gain amplifier according to the method for claim 21.

27. the signal allocation equipment in the signal distribution system of the multipurpose ground equipment with concentrated signal input and remote location, described equipment comprises:

First variable gain amplifier on first integrated circuit substrate, described first variable gain amplifier has input, series connection output, cascade output and control input, and is configured at least in part based on the control signal of the control input of described first variable gain amplifier and has gain;

First power detector on described first integrated circuit substrate, described first power detector has the input of the output that is connected to described first variable gain amplifier, and the output that is connected to the control input of described first variable gain amplifier, and be configured to power output, detected output is offered described first variable gain amplifier as control signal based on described first variable gain amplifier;

Second variable gain amplifier on second integrated circuit substrate, described second variable gain amplifier has input, series connection output, cascade output and the control input of the cascade output that is connected to described first variable gain amplifier, and is configured at least in part based on the control signal of the control input of described second variable gain amplifier and has gain; With

Second power detector on described second integrated circuit substrate, described second power detector has the input of the output that is connected to described second variable gain amplifier, and the output that is connected to the control input of described second variable gain amplifier, and be configured to power output, detected output is offered described second variable gain amplifier as control signal based on described second variable gain amplifier.

28. according to the signal allocation equipment of claim 27, wherein, the series connection of described first variable gain amplifier output is connected to first of described multipurpose ground equipment.

29. according to the signal allocation equipment of claim 28, wherein, the series connection of described second variable gain amplifier output is connected to second of described multipurpose ground equipment.

30. according to the signal allocation equipment of claim 27, wherein, the gain of described first variable gain amplifier comprises postiive gain.

31. according to the signal allocation equipment of claim 27, wherein, the gain of described first variable gain amplifier comprises negative gain.

32. according to the signal allocation equipment of claim 27, wherein, described first variable gain amplifier be the gain of unit with dB, change pro rata with the control signal of the control of this first variable gain amplifier input.

33. the method for a distributing signal in having the satellite-based signal distribution system of a plurality of transponder groups, described method comprises the following steps:

Reception is from the signal of the first satellite transponder group;

The automatic gain of regulating integrated circuit is controlled the power of the signal in (AGC) amplifier; And

Regulate described AGC Amplifier Gain.

34. according to the method for claim 33, wherein, the signal power of regulating in the described AGC amplifier comprises the power of regulating with reference to the signal in the AGC amplifier of output.

35. the method according to claim 33 also comprises the following steps:

The output of described AGC amplifier is connected to the series connection signal path; And

The output of described AGC amplifier is connected to the cascade signal path.

36., also comprise the power of the signal in the cascade signal path of regulating additional AGC amplifier according to the method for claim 35.

37. the signal allocation equipment in the signal distribution system of the one or more destinations equipment with at least one signal input and remote location, described equipment comprises:

With reference to automatic gain control (AGC) amplifier of output, described AGC amplifier has input, output and control input, and is configured to the control signal of importing based on the control of this AGC amplifier at least in part signal gain is provided; And

Signal handling equipment, it has the input of this signal handling equipment of the output of being coupled to described AGC amplifier, and the output of being coupled to first this signal handling equipment of exporting of described signal allocation equipment.

38. according to the signal allocation equipment of claim 37, wherein, described signal gain is at least in part based on the postiive gain of described control signal.

39. according to the signal allocation equipment of claim 37, wherein, described signal gain is at least in part based on the decay of described control signal.

40. according to the signal allocation equipment of claim 37, wherein, described AGC amplifier comprises:

Variable gain amplifier, it has the gain controlling input of the control input of being coupled to described AGC amplifier;

Detector, it is configured to sampled signal after the output of described variable gain amplifier, and the output of described detector is coupled to the gain controlling input of described variable gain amplifier.

41. according to the signal allocation equipment of claim 40, wherein, described detector is configured to the output sampled signal at described variable gain amplifier.

42. according to the signal allocation equipment of claim 40, wherein, described detector is configured to described output sampled signal at signal handling equipment.

43. according to the signal allocation equipment of claim 40, wherein, when the output of described detector during greater than the AGC set-point, described variable gain amplifier is configured to provides signal gain.

44. according to the signal allocation equipment of claim 40, wherein, when the output of described detector during less than the AGC set-point, described variable gain amplifier is configured to provides signal gain.

45. according to the signal allocation equipment of claim 40, wherein, when the output of described detector during greater than the AGC set-point, described variable gain amplifier is configured to provides signal attenuation.

46. according to the signal allocation equipment of claim 37, wherein, described AGC amplifier comprises:

Detector, it is configured to the input sample signal at described variable gain amplifier, and the output of described detector is coupled to the gain controlling input of described variable gain amplifier.

47. the signal allocation equipment according to claim 37 also comprises:

Semiconductor chip is made described AGC amplifier and signal handling equipment on this semiconductor chip;

Cascade output, it is coupled to the output of described AGC amplifier.

48. signal allocation equipment according to claim 37, wherein, described signal handling equipment comprises one or more equipment, and these one or more equipment are to be selected from the group that comprises demultiplexer, signal combiner, amplifier, attenuator, filter, frequency band conversion equipment and multiplexer.

49. according to the signal allocation equipment of claim 37, comprise also being configured to the antenna of reception that the output of described antenna is coupled to the input of described AGC amplifier from the signal of one or more satellites.

50. according to the signal allocation equipment of claim 49, wherein, described signal handling equipment comprises frequency band conversion equipment.

51. signal allocation equipment according to claim 37, also comprise low noise block transducer (LNB), it is configured to reception from the signal of at least one signal input, the signal of this reception of frequency inverted, and exports described input of being given described AGC amplifier by the signal of frequency inverted.