CN104749974A - Method and device for acquiring comparison voltage signal and extracting reverse control signal - Google Patents
Method and device for acquiring comparison voltage signal and extracting reverse control signal Download PDFInfo
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- CN104749974A CN104749974A CN201310753463.0A CN201310753463A CN104749974A CN 104749974 A CN104749974 A CN 104749974A CN 201310753463 A CN201310753463 A CN 201310753463A CN 104749974 A CN104749974 A CN 104749974A
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- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
Abstract
The invention discloses a method and a device for acquiring a comparison voltage signal and extracting a reverse control signal, aiming at solving the problem of periodic variation of time domain of the reverse control signal caused by long-distance transmission. A comparison voltage signal acquisition device comprises a maximum level acquisition module and a comparison voltage acquisition module; the maximum level acquisition module is adopted to detecting a maximum level of transmitted signals on a cable; the comparison voltage acquisition module acquires a comparison voltage according to the maximum level detected by the maximum level acquisition module, compares the comparison voltage with a reference comparison voltage and acquires a maximum value as an optimal comparison voltage; the optimal comparison voltage is adopted to extract the reverse control signal in the signals transmitted on the cable; the relationship between the comparison voltage and the maximum level conforms to a long-distance transmission function of the cable; the reference comparison voltage is higher than a multimedia data signal in the signals transmitted on the cables and smaller than an extreme comparison voltage; and the extreme comparison voltage and the maximum level output by the cable with an extreme length conform to the long-distance transmission function.
Description
Technical field
The present invention relates to field of multimedia data transmission, particularly relate to a kind of method and the device that obtain comparative voltage signal and extract reverse control signal.
Background technology
In existing Multimedia Data Transmission technology, usually in same cable, transmit two kinds of data, one is forward transmission data (i.e. multimedia data signal), and another is reverse control signal.Prior art is the mode of employing amplitude superposition in transmission, by reverse control signal with the amplitude being greater than multimedia data signal directly and multimedia data signal be superimposed upon in same cable and transmit, then in controlled end (such as analogue camera), by amplitude comparator, reverse control signal is extracted from the signal of cable transmission.Exactly because the amplitude of reverse control signal is greater than multimedia data signal, so the method for extracting signal adopted in prior art is: set the comparative voltage of a medium voltage between multimedia data signal and reverse control signal as amplitude comparator, by being made comparisons by the medium voltage of the signal that cable transmits and this setting, thus extract reverse control signal.
But along with increasing of the large-range monitoring demand such as highway, safe city, the distance between controlled end and control end (such as back-end processing device) is more and more far away, can cause signal attenuation.For reverse control signal, belong to the asynchronous control signal that serial ports is this kind of, this signal itself is very high for time domain critical, and its time domain cycle slightly changes and all likely causes data correctly to identify, thus limits the length limit of cable.
Reverse control signal is after the cable transmission of certain distance, following two kinds of changes can be there are, one is voltage amplitude variation (diminishing), and another kind is signal edge change (slowing down), and these two kinds changes all can cause the change of reverse control signal on the time domain cycle.
In conjunction with above-mentioned reverse control signal extracting method of the prior art, illustrate that two kinds change the direct impact of extracting reverse control signal below respectively.
First, voltage amplitude variation:
As shown in Figure 1, VDD1 represents the amplitude of original reverse control signal, and Vref is the comparative voltage extracting reverse control signal, and VDD2 is the signal amplitude (VDD2<VDD1) of reverse control signal after long-distance transmissions decay.As can be seen from Figure 1, if original signal is not direct through overdamping and Vref compares, the signal time domain cycle T 1 recovered, but if after have passed through long range propagation, signal can be decayed, and the amplitude of signal may diminish, and is equivalent to signal and is compressed.If same for the signal after decay and Vref compared, the time domain cycle of the reverse control signal recovered will shorten to T2, which results in the change of signal on the time domain cycle.
Secondly, signal edge changes:
As shown in Figure 2, here premised on the constant ideal conditions of amplitude, simple hypothesis reverse control signal is that edge slows down.Because signal rising edge is change in positive exponent, negative edge be in negative exponent change, so the rising edge of signal and negative edge are different at the slope of the identical some correspondence of voltage, although rising edge and negative edge all slow down, but the rising edge caused compares delay, comparing with negative edge postpones different, thus causes the change of reverse control signal on the time domain cycle that recover.
Summary of the invention
The embodiment of the present invention provides a kind of method and the device that obtain comparative voltage signal and extract reverse control signal, to solve the problem of the reverse control signal time domain mechanical periodicity that existing long range propagation causes.
The embodiment of the present invention provides a kind of device obtaining comparative voltage signal, and this device comprises:
Maximum level acquisition module, uploads the maximum level of defeated signal for detecting cable;
Comparative voltage acquisition module, maximum level for detecting according to maximum level acquisition module obtains comparative voltage, and this comparative voltage and reference comparison voltages are compared, obtain wherein maximal value as best comparative voltage, this best comparative voltage is for extracting the reverse control signal in the signal that described cable transmits, the relation character of this comparative voltage and described maximum level closes and states the long range propagation function of cable, this reference comparison voltages is greater than the multimedia data signal in the signal that described cable transmits, and be less than limit comparative voltage, the maximum level that this limit comparative voltage and cable export when limiting length meets long range propagation function.
Utilize said apparatus, the maximum level of the signal that the cable detected by maximum level acquisition module transmits, comparative voltage is obtained according to above-mentioned maximum level again by comparative voltage acquisition module, and the long range propagation function of the relation character zygonema cable of comparative voltage and described maximum level, thus ensure when long range propagation, the time domain cycle of reverse control signal is constant, avoid amplitude and the impact of edge change on reverse control signal of the voltage that length of cable causes, and then add the upper limit of length of cable.Above-mentioned reference comparison voltages is set to be greater than the multimedia data signal in described signal, ensure that the multimedia data signal that cable transmits can not be compared for reverse control signal by mistake.
Preferably, above-mentioned maximum level acquisition module is peak detection module.
Preferably, above-mentioned comparative voltage acquisition module can include but are not limited to following two kinds of implementations:
The first implementation, this comparative voltage acquisition module comprises:
Division module, for obtaining described comparative voltage;
Constant voltage source, for providing described reference comparison voltages;
Switch module, for described comparative voltage and reference comparison voltages are compared, obtain wherein maximal value as best comparative voltage.
The second implementation, this comparative voltage acquisition module comprises division module, constant voltage source, the first unidirectional conducting switch and the second unidirectional conducting switch:
Division module is for obtaining described comparative voltage;
Constant voltage source is used for providing described reference comparison voltages;
When comparative voltage is greater than reference comparison voltages, the first unidirectional conducting switch conducting, this second unidirectional conducting switch ends, and division module exports comparative voltage as described best comparative voltage;
When comparative voltage is less than described reference comparison voltages, the second unidirectional conducting switch conducting, this first unidirectional conducting switch ends, and constant voltage source exports reference comparison voltages as described best comparative voltage.
The embodiment of the present invention additionally provides a kind of method obtaining comparative voltage signal, and the method comprises:
The maximum level of the signal that cable transmits detected;
Comparative voltage is obtained according to the maximum level detected;
Comparative voltage and reference comparison voltages are compared, and obtain wherein maximal value as best comparative voltage, the relation of this comparative voltage and described maximum level meets the long range propagation function of described cable, and this reference comparison voltages is greater than the multimedia data signal in the signal that described cable transmits.
Utilize said method, by the maximum level of signal that cable that the cable that detects transmits transmits, comparative voltage is obtained again according to above-mentioned maximum level, and the long range propagation function of the relation character zygonema cable of comparative voltage and described maximum level, thus ensure when long range propagation, the time domain cycle of reverse control signal is constant, avoids amplitude and the impact of edge change on reverse control signal of the voltage that length of cable causes, and then adds the upper limit of length of cable.Above-mentioned reference comparison voltages is set to be greater than the multimedia data signal in described signal, ensure that the multimedia data signal that cable transmits can not be compared for reverse control signal by mistake.
The embodiment of the present invention additionally provides a kind of reverse control signal extraction element, and this device comprises:
Maximum level acquisition module, uploads the maximum level of defeated signal for detecting cable;
Comparative voltage acquisition module, maximum level for detecting according to maximum level acquisition module obtains comparative voltage, and this comparative voltage and reference comparison voltages are compared, obtain wherein maximal value as best comparative voltage, the relation character of this comparative voltage and described maximum level closes and states the long range propagation function of cable, this reference comparison voltages is greater than the multimedia data signal in the signal that described cable transmits, and be less than limit comparative voltage, the maximum level that described limit comparative voltage and described cable export when limiting length meets long range propagation function,
Voltage comparison module, for the signal that cable transmits and above-mentioned best comparative voltage being compared, thus extracts the reverse control signal in the signal that cable transmits.
The maximum level of the signal that the cable detected by maximum level acquisition module transmits, comparative voltage is obtained according to above-mentioned maximum level again by comparative voltage acquisition module, voltage comparison module is utilized the signal that the cable that cable transmits transmits and best comparative voltage to be compared, thus the reverse control signal in the signal that extraction cable transmits, and the long range propagation function of the relation character zygonema cable of comparative voltage and described maximum level.Utilize said apparatus, ensure when long range propagation, the time domain cycle of reverse control signal is constant, avoids amplitude and the impact of edge change on reverse control signal of the voltage that length of cable causes, and then adds the upper limit of length of cable.Above-mentioned reference comparison voltages is set to be greater than the multimedia data signal in described signal, ensure that the multimedia data signal that cable transmits can not be compared for reverse control signal by mistake.
Preferably, above-mentioned maximum level acquisition module is peak detection module.
Preferably, above-mentioned comparative voltage acquisition module can include but are not limited to following two kinds of implementations:
The first implementation, this comparative voltage acquisition module comprises:
Division module, for obtaining described comparative voltage;
Constant voltage source, for providing described reference comparison voltages;
Switch module, for described comparative voltage and reference comparison voltages are compared, obtain wherein maximal value as best comparative voltage.
The second implementation, this comparative voltage acquisition module comprises division module, constant voltage source, the first unidirectional conducting switch and the second unidirectional conducting switch:
Division module is for obtaining described comparative voltage;
Constant voltage source is used for providing described reference comparison voltages;
When comparative voltage is greater than reference comparison voltages, the first unidirectional conducting switch conducting, this second unidirectional conducting switch ends, and division module exports comparative voltage as best comparative voltage;
When comparative voltage is less than described reference comparison voltages, the second unidirectional conducting switch conducting, this first unidirectional conducting switch ends, and constant voltage source exports reference comparison voltages as best comparative voltage.
The embodiment of the present invention additionally provides a kind of reverse control signal extracting method, and the method comprises:
The maximum level of the signal that cable transmits detected;
Comparative voltage is obtained according to the maximum level detected;
Comparative voltage and reference comparison voltages are compared, and obtain wherein maximal value as best comparative voltage, the relation character of this comparative voltage and above-mentioned maximum level closes and states the long range propagation function of cable, this reference comparison voltages is greater than the multimedia data signal in the signal that cable transmits, and being less than limit comparative voltage, the maximum level that this limit comparative voltage and cable export when limiting length meets long range propagation function.
The signal that above-mentioned best comparative voltage and cable transmit is compared, thus extracts the reverse control signal in the signal that cable transmits.
By the maximum level of signal that the cable that detects transmits, comparative voltage is obtained again according to above-mentioned maximum level, the signal that cable transmits and optimal reference comparative voltage are compared, thus the reverse control signal in the signal that extraction cable transmits, and the long range propagation function of the relation character zygonema cable of comparative voltage and described maximum level.Utilize said method, ensure when long range propagation, the time domain cycle of reverse control signal is constant, avoids amplitude and the impact of edge change on reverse control signal of the voltage that length of cable causes, and then adds the upper limit of length of cable.Above-mentioned reference comparison voltages is set to be greater than the multimedia data signal in described signal, ensure that the multimedia data signal that cable transmits can not be compared for reverse control signal by mistake.
Accompanying drawing explanation
Fig. 1 is the time domain change schematic diagram that in prior art, the change of reverse control signal on level causes;
Fig. 2 is the time domain change schematic diagram that in prior art, the change of reverse control signal on edge causes;
The device schematic diagram of the acquisition comparative voltage signal that Fig. 3 provides for the embodiment of the present invention;
The method flow diagram of the acquisition comparative voltage signal that Fig. 4 provides for the embodiment of the present invention;
The device schematic diagram of the extraction reverse control signal that Fig. 5 provides for the embodiment of the present invention;
The method flow diagram of the extraction reverse control signal that Fig. 6 provides for the embodiment of the present invention;
Fig. 7 is the capacitor charging circuit schematic diagram of the embodiment of the present invention;
Fig. 8 is the capacitor discharging circuit schematic diagram of the embodiment of the present invention;
The circuit diagram of the extraction reverse control signal that Fig. 9 provides for the embodiment of the present invention;
The voltage oscillogram of each point of the circuit of the extraction reverse control signal that Figure 10 provides for the embodiment of the present invention.
Embodiment
The embodiment of the present invention provides a kind of and obtains comparative voltage signal and extract the method for reverse control signal and device, transmits to solve prior art middle and long distance the problem that the reverse control signal that causes changes in time domain.
Below in conjunction with accompanying drawing, embodiments of the present invention is further illustrated.
Embodiments provide a kind of device obtaining comparative voltage signal, as shown in Figure 3, this device comprises:
Maximum level acquisition module 301, uploads the maximum level of defeated signal for detecting cable;
Preferably, this maximum level acquisition module 301 is peak detection module.
Comparative voltage acquisition module 302, maximum level for detecting according to maximum level acquisition module 301 obtains comparative voltage, and this comparative voltage and reference comparison voltages are compared, obtain wherein maximal value as best comparative voltage, this best comparative voltage is for extracting the reverse control signal in the signal that described cable transmits, the relation character of this comparative voltage and described maximum level closes and states the long range propagation function of cable, this reference comparison voltages is greater than the multimedia data signal in the signal that described cable transmits, and be less than limit comparative voltage, the maximum level that this limit comparative voltage and cable export when limiting length meets long range propagation function.
The limiting length of so-called cable refers to this cable in actual applications, accessible maximum length.The limiting length of cable is added up by production firm usually, experiment obtains.
The long range propagation function of this cable can be capacitor charge and discharge pattern function etc.
Preferably, this comparative voltage acquisition module 302 can include but are not limited to following two kinds of implementations:
The first implementation, this comparative voltage acquisition module 302 comprises:
Division module, for obtaining described comparative voltage;
Constant voltage source, for providing described reference comparison voltages;
Switch module, for described comparative voltage and reference comparison voltages are compared, obtain wherein maximal value as best comparative voltage.
Preferably, above-mentioned switch module can be the diode of an one-way conduction, can also be a control circuit.Comparative voltage and reference comparison voltages can be realized to compare, obtain wherein maximal value and be all applicable to the embodiment of the present invention as the circuit of best comparative voltage.
The second implementation, this comparative voltage acquisition module 302 comprises division module, constant voltage source, the first unidirectional conducting switch and the second unidirectional conducting switch:
Division module is for obtaining described comparative voltage;
Constant voltage source is used for providing described reference comparison voltages;
When comparative voltage is greater than reference comparison voltages, the first unidirectional conducting switch conducting, this second unidirectional conducting switch ends, and division module exports comparative voltage as best comparative voltage;
When comparative voltage is less than described reference comparison voltages, the second unidirectional conducting switch conducting, this first unidirectional conducting switch ends, and constant voltage source exports reference comparison voltages as best comparative voltage.
Preferably above-mentioned unidirectional conducting switch can be diode, can certainly be made up of logic control circuit and single-pole switch.The circuit that may be used for controlling described division module and constant voltage source is all applicable to the embodiment of the present invention, does not do concrete restriction to this embodiment of the present invention.
Utilize said apparatus, the maximum level of the signal that the cable detected by maximum level acquisition module 301 transmits, comparative voltage is obtained according to above-mentioned maximum level again by comparative voltage acquisition module 302, and the long range propagation function of the relation character zygonema cable of comparative voltage and described maximum level, thus ensure when long range propagation, the time domain cycle of reverse control signal is constant, avoid amplitude and the impact of edge change on reverse control signal of the voltage that length of cable causes, and then add the upper limit of length of cable.Above-mentioned reference comparison voltages is set to be greater than the multimedia data signal in described signal, ensure that the multimedia data signal that cable transmits can not be compared for reverse control signal by mistake.
The embodiment of the present invention additionally provides a kind of method obtaining comparative voltage signal, and as shown in Figure 4, the method comprises:
S401: the maximum level signal that cable transmits being detected;
S402: obtain comparative voltage according to the maximum level detected;
S403: comparative voltage and reference comparison voltages are compared, and obtain wherein maximal value as best comparative voltage, the long range propagation function of the relation character zygonema cable of this comparative voltage and maximum level, this reference comparison voltages is greater than the multimedia data signal in the signal that described cable transmits, and being less than limit comparative voltage, the maximum level that this limit comparative voltage and cable export when limiting length meets long range propagation function.
Utilize said method, by the maximum level of signal that cable that the cable that detects transmits transmits, then obtain comparative voltage according to above-mentioned maximum level, and the long range propagation function of the relation character zygonema cable of comparative voltage and described maximum level.Ensure when long range propagation, the time domain cycle of reverse control signal is constant, avoids amplitude and the impact of edge change on reverse control signal of the voltage that length of cable causes, and then adds the upper limit of length of cable.Above-mentioned reference comparison voltages is set to be greater than the multimedia data signal in described signal, ensure that the multimedia data signal that cable transmits can not be compared for reverse control signal by mistake.
The embodiment of the present invention additionally provides a kind of reverse control signal extraction element, and as shown in Figure 5, this device comprises:
Maximum level acquisition module 301, uploads the maximum level of defeated signal for detecting cable;
Comparative voltage acquisition module 302, maximum level for detecting according to maximum level acquisition module 301 obtains comparative voltage, and this comparative voltage and reference comparison voltages are compared, obtain wherein maximal value as best comparative voltage, the relation character of this comparative voltage and described maximum level closes and states the long range propagation function of cable, this reference comparison voltages is greater than the multimedia data signal in the signal that described cable transmits, and be less than limit comparative voltage, the maximum level that this limit comparative voltage and cable export when limiting length meets long range propagation function,
Voltage comparison module 501, for the signal that cable transmits and above-mentioned best comparative voltage being compared, thus extracts the reverse control signal in the signal that cable transmits.
The maximum level of the signal that the cable detected by maximum level acquisition module 301 transmits, comparative voltage is obtained according to above-mentioned maximum level again by comparative voltage acquisition module 302, voltage comparison module 501 is utilized the signal that cable transmits and best comparative voltage to be compared, thus the reverse control signal in the signal that extraction cable transmits, and the long range propagation function of the relation character zygonema cable of comparative voltage and described maximum level.Utilize said apparatus, ensure when long range propagation, the time domain cycle of reverse control signal is constant, avoids amplitude and the impact of edge change on reverse control signal of the voltage that length of cable causes, and then adds the upper limit of length of cable.Above-mentioned reference comparison voltages is set to be greater than the multimedia data signal in described signal, ensure that the multimedia data signal that cable transmits can not be compared for reverse control signal by mistake.
Preferably, above-mentioned maximum level acquisition module 301 is peak detection module.
Preferably, above-mentioned comparative voltage acquisition module 302 can include but are not limited to following two kinds of implementations:
The first implementation, this comparative voltage acquisition module 302 comprises:
Division module, for obtaining described comparative voltage;
Constant voltage source, for providing described reference comparison voltages;
Switch module, for described comparative voltage and reference comparison voltages are compared, obtain wherein maximal value as best comparative voltage.
The second implementation, this comparative voltage acquisition module 302 comprises division module, constant voltage source, the first unidirectional conducting switch and the second unidirectional conducting switch:
Division module is for obtaining described comparative voltage;
Constant voltage source is used for providing described reference comparison voltages;
When comparative voltage is greater than reference comparison voltages, the first unidirectional conducting switch conducting, this second unidirectional conducting switch ends, and division module exports comparative voltage as best comparative voltage;
When comparative voltage is less than described reference comparison voltages, the second unidirectional conducting switch conducting, this first unidirectional conducting switch ends, and constant voltage source exports reference comparison voltages as best comparative voltage.
The embodiment of the present invention additionally provides a kind of reverse control signal extracting method, and as shown in Figure 6, the method comprises:
S601: the maximum level signal that cable transmits being detected;
S602: obtain comparative voltage according to the maximum level detected;
S603: comparative voltage and reference comparison voltages are compared, and obtain wherein maximal value as best comparative voltage, the relation character of this comparative voltage and above-mentioned maximum level closes and states the long range propagation function of cable, this reference comparison voltages is greater than the multimedia data signal in signal, and being less than limit comparative voltage, the maximum level that this limit comparative voltage and cable export when limiting length meets long range propagation function.
S604: the signal that above-mentioned best comparative voltage and cable transmit is compared, thus extract the reverse control signal in the signal that cable transmits.
By the maximum level of signal that the cable that detects transmits, comparative voltage is obtained again according to above-mentioned maximum level, the signal that cable transmits and best comparative voltage are compared, thus the reverse control signal in extraction signal, and the long range propagation function of the relation character zygonema cable of comparative voltage and described maximum level.Utilize said method, ensure when long range propagation, the time domain cycle of reverse control signal is constant, avoids amplitude and the impact of edge change on reverse control signal of the voltage that length of cable causes, and then adds the upper limit of length of cable.Above-mentioned reference comparison voltages is set to be greater than the multimedia data signal in described signal, ensure that the multimedia data signal that cable transmits can not be compared for reverse control signal by mistake.
Meet the charging and recharging model of electric capacity below for the long range propagation function of cable, the embodiment of the present invention is illustrated.
First introduce the charge and discharge process of electric capacity below.
Figure 7 shows that capacitor charging circuit schematic diagram, this circuit comprises resistance R, electric capacity C and constant voltage source Va, and the constant voltage that this constant voltage source provides is VC, when being charged to some time t, the voltage Vt at electric capacity C two ends as shown in Equation (1):
Vt=VC*e^（t/（R*C）） （1）；
Wherein, e is a math constant.
Figure 8 shows that capacitor discharging circuit schematic diagram, this circuit comprises resistance R and electric capacity C.Suppose before discharge, the voltage at electric capacity C two ends is VC, when discharging into some time t, the voltage Vt at electric capacity C two ends as shown in Equation (2):
Vt=VC*（1—e^（t/（R*C））） （2）
Wherein, e is a math constant.
Long range propagation function due to cable meets the charging and recharging model of electric capacity, then the rising edge of signal can be modeled as the process to capacitor charging, and the negative edge of signal can be modeled as the process to capacitor discharge.To ensure that after long range propagation the reverse control signal time domain cycle is constant, only need to ensure in same period, before and after signal attenuation, the difference of intersection point in time domain of rising edge and best comparative voltage waveform, and negative edge is equal with the difference of intersection point in time domain of best comparative voltage waveform.Namely, in the capacitor charge and discharge model of correspondence, when the duration of charging is identical with discharge time, the magnitude of voltage at electric capacity two ends is identical.According to the time of the discharge and recharge of above-mentioned introduction and the relation formula (1) of electric capacity both end voltage and formula (2), when ensure that the duration of charging is identical with discharge time, the magnitude of voltage at electric capacity two ends is identical, then only need ensure the voltage Vt=VC/2 at electric capacity two ends.Then best comparative voltage is 1/2nd of reverse control signal maximum level.
The device of the extraction reverse control signal in the embodiment of the present invention comprises: maximum level acquisition module 301, comparative voltage acquisition module 302 and voltage comparison module 501.Below for circuit theory diagrams, be described the embodiment of the present invention, but be not limited in circuit described below, each functional module can use the functional module met in the embodiment of the present invention, or hardware programmable device etc.Such as maximum level acquisition module 301 is peak detection module, and this peak detection module can adopt peak detection chip to complete this practical function.
As shown in Figure 9, suppose that maximum level acquisition module 301 comprises diode D1(when the forward voltage drop of diode is greater than certain value, its conducting, otherwise it is in off state), electric capacity C1(electric capacity is used for energy storage); Comparative voltage acquisition module 302 comprises diode D2 and D3, resistance R1 and resistance R2, and a constant voltage source Vr(is used for providing a constant voltage Vref), voltage comparison module 501 is realized by voltage comparator F.
For in whole Multimedia Transmission System, also comprise back-end processing and analogue camera and cable, the device of said extracted reverse control signal is arranged at analogue camera place.
Illustrate below and how to obtain best comparative voltage according to the above-mentioned circuit provided.
Before reverse control signal occurs, the signal that cable transmits is multimedia data signal, and when reverse control signal occurs, the signal that cable transmits is mixed signal.Mixed signal comprises multimedia data signal and reverse control signal.As shown in Figure 10, wherein VCC represents the maximum level of multimedia data signal to the waveform of a point shown in Fig. 9, and VDD represents the maximum level of reverse control signal; When after peak detection module, the voltage of the b point shown in Fig. 9 will keep the maximum level occurred in the signal, and as shown in Figure 10, before reverse control signal occurs, b point remains on the maximum level VCC of multimedia data signal to b point waveform; When reverse control signal one occurs, b point remains the maximum level VDD of reverse control signal;
Next, when when the magnitude of voltage of b point is VCC, diode D2 ends, diode D3 conducting, then the voltage of the d point shown in Fig. 9 is Vref, when the magnitude of voltage of b point is VDD, diode D2 conducting, diode D3 ends, and is the voltage at resistance R2 two ends, namely passes through the method at the voltage of d point, utilize the principle of diode, best comparative voltage and reference comparison voltages Vref are compared, which voltage is high, and which voltage the output of d point is.Ensure when reverse control signal occurs, the best comparative voltage that d point exports equals the half of reverse control signal maximum level, only need ensure R1=R2.As shown in Figure 10, before reverse control signal occurs, the voltage of d point is reference comparison voltages Vr.After reverse control signal occurs, the voltage of d point is VDD/2.
And the setting of Vr here, ensure that the constant voltage Vref that Vr provides is greater than multimedia data signal maximum level VCC.The object of such setting avoids before reverse control signal occurs, multimedia data signal is compared into reverse control signal by mistake, because if Vref is higher than the level of multimedia data signal, signal then on cable can not be compared for high level by voltage comparison module 501, voltage comparison module 501 output low level, when only occurring the reverse control signal higher than Vref, just can export high level by trigger voltage comparison module 501.
Through the method described in the embodiment of the present invention or device process, the reverse control signal time domain cycle after long range propagation, equal with the time domain cycle of original reverse control signal.Reverse control signal after the method utilizing the embodiment of the present invention to provide or device process, makes the decay at signal amplitude or edge all can not have an impact to the time domain cycle, and then adds the transmission range of reverse control signal; And in implementation procedure, can not have an impact to multimedia data signal, the simplicity of design of circuit, strong adaptability is portable high.
Those skilled in the art should understand, embodiments of the invention can be provided as method, system or computer program.Therefore, the present invention can adopt the form of complete hardware embodiment, completely software implementation or the embodiment in conjunction with software and hardware aspect.And the present invention can adopt in one or more form wherein including the upper computer program implemented of computer-usable storage medium (including but not limited to magnetic disk memory, CD-ROM, optical memory etc.) of computer usable program code.
The present invention describes with reference to according to the process flow diagram of the method for the embodiment of the present invention, equipment (system) and computer program and/or block scheme.Should understand can by the combination of the flow process in each flow process in computer program instructions realization flow figure and/or block scheme and/or square frame and process flow diagram and/or block scheme and/or square frame.These computer program instructions can being provided to the processor of multi-purpose computer, special purpose computer, Embedded Processor or other programmable data processing device to produce a machine, making the instruction performed by the processor of computing machine or other programmable data processing device produce device for realizing the function of specifying in process flow diagram flow process or multiple flow process and/or block scheme square frame or multiple square frame.
These computer program instructions also can be stored in can in the computer-readable memory that works in a specific way of vectoring computer or other programmable data processing device, the instruction making to be stored in this computer-readable memory produces the manufacture comprising command device, and this command device realizes the function of specifying in process flow diagram flow process or multiple flow process and/or block scheme square frame or multiple square frame.
These computer program instructions also can be loaded in computing machine or other programmable data processing device, make on computing machine or other programmable devices, to perform sequence of operations step to produce computer implemented process, thus the instruction performed on computing machine or other programmable devices is provided for the step realizing the function of specifying in process flow diagram flow process or multiple flow process and/or block scheme square frame or multiple square frame.
Although describe the preferred embodiments of the present invention, those skilled in the art once obtain the basic creative concept of cicada, then can make other change and amendment to these embodiments.So claims are intended to be interpreted as comprising preferred embodiment and falling into all changes and the amendment of the scope of the invention.
Obviously, those skilled in the art can carry out various change and modification to the present invention and not depart from the spirit and scope of the present invention.Like this, if these amendments of the present invention and modification belong within the scope of the claims in the present invention and equivalent technologies thereof, then the present invention is also intended to comprise these change and modification.
Claims (10)
1. obtain a device for comparative voltage signal, it is characterized in that, comprising:
Maximum level acquisition module, uploads the maximum level of defeated signal for detecting cable;
Comparative voltage acquisition module, maximum level for detecting according to described maximum level acquisition module obtains comparative voltage, and described comparative voltage and reference comparison voltages are compared, obtain wherein maximal value as best comparative voltage, described best comparative voltage is for extracting the reverse control signal in the signal that described cable transmits, the relation of described comparative voltage and described maximum level meets the long range propagation function of described cable, described reference comparison voltages is greater than the multimedia data signal in the signal that described cable transmits, and be less than limit comparative voltage, the maximum level that described limit comparative voltage and described cable export when limiting length meets long range propagation function.
2. device as claimed in claim 1, it is characterized in that, described maximum level acquisition module is peak detection module.
3. device as claimed in claim 1, it is characterized in that, described comparative voltage acquisition module comprises:
Division module, for obtaining described comparative voltage;
Constant voltage source, for providing described reference comparison voltages;
Switch module, for described comparative voltage and reference comparison voltages are compared, obtain wherein maximal value as best comparative voltage.
4. device as claimed in claim 1, it is characterized in that, described comparative voltage acquisition module comprises division module, constant voltage source, the first unidirectional conducting switch and the second unidirectional conducting switch:
Described division module is for obtaining described comparative voltage;
Described constant voltage source is used for providing described reference comparison voltages;
When described comparative voltage is greater than described reference comparison voltages, the first unidirectional conducting switch conducting, described second unidirectional conducting switch cut-off, described division module exports described comparative voltage as described best comparative voltage;
When described comparative voltage is less than described reference comparison voltages, described second unidirectional conducting switch conducting, described first unidirectional conducting switch cut-off, described constant voltage source exports described reference comparison voltages as described best comparative voltage.
5. obtain a method for comparative voltage signal, it is characterized in that, comprising:
The maximum level of the signal that cable transmits detected;
Comparative voltage is obtained according to the maximum level detected;
Described comparative voltage and reference comparison voltages are compared, and obtain wherein maximal value as best comparative voltage, the relation of described comparative voltage and described maximum level meets the long range propagation function of described cable, described reference comparison voltages is greater than the multimedia data signal in the signal that described cable transmits, and being less than limit comparative voltage, the maximum level that described limit comparative voltage and described cable export when limiting length meets long range propagation function.
6. extract a device for reverse control signal, it is characterized in that, comprising:
Maximum level acquisition module, uploads the maximum level of defeated signal for detecting cable;
Comparative voltage acquisition module, maximum level for detecting according to described maximum level acquisition module obtains comparative voltage, and described comparative voltage and reference comparison voltages are compared, obtain wherein maximal value as best comparative voltage, the relation of described comparative voltage and described maximum level meets the long range propagation function of described cable, described reference comparison voltages is greater than the multimedia data signal in the signal that described cable transmits, and be less than limit comparative voltage, the maximum level that described limit comparative voltage and described cable export when limiting length meets long range propagation function,
Voltage comparison module, for the signal that described cable transmits and described best comparative voltage being compared, thus extracts the reverse control signal in the signal that described cable transmits.
7. device as claimed in claim 6, it is characterized in that, described maximum level acquisition module is peak detection module.
8. device as claimed in claim 6, it is characterized in that, described comparative voltage acquisition module comprises:
Division module, for obtaining described comparative voltage;
Constant voltage source, for providing described reference comparison voltages;
Switch module, for described comparative voltage and reference comparison voltages are compared, obtain wherein maximal value as best comparative voltage.
9. device as claimed in claim 6, it is characterized in that, described comparative voltage acquisition module comprises division module, constant voltage source, the first unidirectional conducting switch and the second unidirectional conducting switch:
Described division module is for obtaining described comparative voltage;
Described constant voltage source is used for providing described reference comparison voltages;
When described comparative voltage is greater than described reference comparison voltages, the first unidirectional conducting switch conducting, described second unidirectional conducting switch cut-off, described division module exports described comparative voltage as described best comparative voltage;
When described comparative voltage is less than described reference comparison voltages, described second unidirectional conducting switch conducting, described first unidirectional conducting switch cut-off, described constant voltage source exports described reference comparison voltages as described best comparative voltage.
10. extract a method for reverse control signal, it is characterized in that, comprising:
The maximum level of the signal that cable transmits detected;
Comparative voltage is obtained according to the maximum level detected;
Described comparative voltage and reference comparison voltages are compared, and obtain wherein maximal value as best comparative voltage, the relation of described comparative voltage and described maximum level meets the long range propagation function of described cable, described reference comparison voltages is greater than the multimedia data signal in the signal that described cable transmits, and being less than limit comparative voltage, the maximum level that described limit comparative voltage and described cable export when limiting length meets long range propagation function;
The signal that described best comparative voltage and described cable transmit is compared, thus extracts the reverse control signal in the signal that described cable transmits.
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