CN2093474U - Dynamic balancing switching amplitude modulation floating carrier broadcast tv transmitter - Google Patents

Abstract

The utility model relates to a dynamic balancing switching amplitude modulation floating carrier broadcast transmitter. The circuit is mainly composed of a dynamic balance on off modulation signal amplifying circuit and a carrier frequencies amplitude-modulated pulse amplifying circuit. The dynamic balance on off modulation signal amplifying circuit makes the real-time level of output level and input signals strictly maintain a dynamic balance relation, realizing the high-fidelity power amplification of modulation signals; the modulation signals are sent into the carrier frequencies pulse amplifying circuit as a floating supply, modulating the range of carrier frequency pulse square wave, and then the large power amplitude-modulated pulse signals of broadcast or television can be obtained and directly transmitted by antennas; the still carrier level of transmitters can be adjusted freely. The utility model has the advantages that electric power consumptions are directly proportional to carrier frequencies output power; the decreasing of volume decreases the power consumption; efficiency can reach above 98%; circuits are simple and electroacoustic index is superior; the transmitter is provided with digital acoustic effect.

Description

Dynamic balancing switching amplitude modulation floating carrier broadcast TV transmitter

The utility model relates to the radio transmission technology, is about a kind of dynamic balance switch, amplitude modulation, floating carrier broadcast transmitter.

Now over half in the world high-power in, the shortwave transmitting station also using electron tube Class C amplifying emission machine because the overall efficiency of this transmitter is lower than 50%, thereby power consumption is extremely huge, has belonged to superseded row; In order to raise the efficiency, released the pulse width modulation transmitter seventies, overall efficiency is also only about 70%; The end of the eighties, U.S. Harris Corporation has developed digital am transmitter, the potential pulse square wave that width is not waited in the mode of encoding is superimposed as the signal staircase waveform and realizes the modulation amplification, but this transmitter circuitry complexity, cost is high, particularly those power switch pipe hear rates of undertaking the broad pulse amplification are very big, also have bigger harmonic loss simultaneously, thereby overall efficiency can only be about 90%.

On the other hand, current broadcast transmitter all is to adopt the mode of fixed carrier to work, signal magnitude no matter, and the operating voltage of transmitter never changes.The average am depth of broadcast program generally has only about 30%, and this has wasted with regard to making the more than half energy of transmitter.Therefore, the overall efficiency that the front is listed is actually an inapt numeral much larger than actual efficiency.For overcoming this drawback, West Germany has adopted the floating carrier radiation pattern of recently realizing limitation in series feed pulse-width modulated transmitter by the initial duty that changes modulating pulse, truly have energy-saving effect, this mode is real unfortunately the difficulties that one is reluctant to bring to the notice of others of trimming the feet to fit the shoes, thereby far from ideal.

In view of the problem that above-mentioned prior art exists, the purpose of this utility model is to provide a kind of high efficiency, amplitude modulation, floating carrier broadcasting cheaply and television transmitter.

The purpose of this utility model is to realize like this, promptly adopt dynamic balancing HF switch scanning technique that the audio or video modulation signal is directly carried out the high-fidelity power amplification, go the amplitude of modulated carriers pulse square wave then, thereby obtain broadcasting or TV highpowerpulse amplitude-modulated signal, the direct sending transmitting antenna.Whole transmitter circuitry mainly is made up of dynamic balance switch type modulation signal amplification circuit and carrier frequency pulse power amplification circuit two parts.The dynamic balance switch type modulation signal amplification circuit keeps link to form by sampling link, voltage comparator, promotion level, power switch pipe and dynamic balancing.Voltage comparator is constantly followed the tracks of the sampled level of each instantaneous level of modulating input signal and the corresponding output of power switch pipe of comparison, make a kind of dynamic balancing relation of the strict maintenance of real-time level of the output level and the input signal of amplifier, thereby realize the high-fidelity power amplification of modulation signal.The high potential modulation voltage that draws thus is sent to the carrier frequency pulse amplifying circuit again and makes floating power supply; The CF signal source that the carrier frequency pulse circuit is made of radio-frequency pulse generator and frequency-halving circuit, promotion level and power switch pipe are formed for three grades.The operating frequency of transmitter is promptly determined by radio-frequency pulse generator.The radio-frequency pulse of radio-frequency pulse generator output promptly draws duty ratio behind two divided-frequency be 0.5 stable carrier frequency square wave, drives the power amplification that the final stage power switch pipe is finished the carrier frequency square wave through promoting level then; Because promoting the operating voltage of level and final stage power switch pipe promptly is the high power modulation signal voltage that modulation signal amplification circuit is sent here, thereby the final stage power switch pipe is directly exported carrier frequency pulse amplitude modulation square wave.It must filtering, directly is sent to the antenna emission, can reduce the power consumption of transmitter so effectively.Simultaneously, adjust the reference voltage of comparator in-phase input end in the modulation signal amplification circuit, can change the initial level of floating carrier easily, be convenient to the user and freely adjust as required.

Specific embodiment of the present utility model is provided by accompanying drawing.By detailed description, can further understand feature of the present utility model to accompanying drawing.

The circuit diagram of accompanying drawing 1 transmitter.

Accompanying drawing 2 is the surface structure schematic diagram of transmitter.

Referring to Fig. 1: circuit by audio signal amplify, the dynamic balance switch type modulation signal amplifies and carrier frequency pulse power amplification three parts are formed.Input audio signal is through 1:1 isolating transformer B ₁Send into high-quality integrated transporting discharging NE5534 and carry out the high-quality voltage amplification, good to guarantee the electroacoustic index.The CF signal source circuit is made up of NOR gate CD4002 and d type flip flop CD4013.Wherein, CD4002 and crystal Y ₁With C ₅R ₁₁C ₆Constitute stable radio-frequency pulse generator, produce the radio-frequency pulse that doubles than transmitter operating frequency, with sending CD4013 to carry out two divided-frequency, thereby obtain the carrier frequency pulse square wave that needs, and guaranteed that its duty ratio is 0.5 by its.In the dynamic balance switch type modulation signal amplification circuit, R ₅And R ₆Be connected between power switch pipe output stage and the ground wire, their contact is sampling point A; The audio signal of being amplified by NE5534 is through capacitor C ₂Be coupled to the in-phase input end B of comparator LM339; The inverting input of comparator accesses the sampling point A of sample link, and its output termination promotes level Tr ₁Base stage; Tr ₁Grounded emitter, collector electrode meets power switch pipe Tr ₂Base stage, and pass through resistance R ₈Connect+200 volts of power supplys; Tr ₂Emitter be connected on+200 volts of power supplys on, current collection is power output pole very, passes through inductance L ₁Be connected with the carrier frequency pulse power amplification circuit.C ₃Be connected on Tr ₂And between the ground wire, constitute dynamic balancing and keep link.Carrier frequency pulse square wave from the CF signal source inserts a promotion level Tr ₃Base stage, Tr ₃Grounded emitter, collector electrode passes through resistance R ₁₂With power switch pipe Tr ₄Emitter meets L together ₁Output, and pass through R ₁₀C ₄Earth connection.Tr ₄Base stage meet Tr ₃Collector electrode, its collector electrode is the output stage of carrier frequency pulse amplitude-modulated wave.Potentiometer W ₁Be connected on+15 volts of power supplys and ground wire between, its slip termination comparator in-phase input end B is used for adjusting the reference voltage of comparator, uses the adjustment that realizes transmitter static load ripple level.

The course of work of foregoing circuit is such: at the beginning of the switch power supply, when not having audio signal, 2 current potentials of A, B are zero, and comparator LM339 exports negative voltage, force to promote pipe Tr ₁End, thereby power switch pipe Tr ₂Also end amplifier no-output voltage.Along with the foundation of supply voltage, B point current potential raises rapidly; When B point current potential is raised to when being higher than A point current potential number millivolt, comparator is exported positive voltage immediately, forces Tr ₁Saturation conduction, thus drive Tr ₂Saturation conduction, output capacitor C ₃On voltage rise rapidly, A point current potential also and then rises; In case A point current potential is raised to when being higher than B point current potential number millivolt, the output of comparator is turned into negative voltage immediately, causes to make Tr ₁End, thereby Tr ₂End capacitor C ₃On voltage discharge immediately and fall; One when A point current potential drops to than low several millivolts of this moment B point current potential, and the output of comparator is turned into positive voltage immediately again, makes Tr again ₁And Tr ₂Saturation conduction repeats said process once again.So move in circles, guarantee that output voltage stabilization is on a fixed value.Down in a flash, when B point current potential rose to another level, according to above-mentioned equilibrium process, output voltage was stabilized in again on another fixed value.After the stable foundation of supply voltage, B point current potential just finally is stabilized in one by potentiometer W ₁On the fixed value that sliding end is determined, capacitor C ₃On output voltage also and then be stabilized on the corresponding fixed value, this voltage has just determined the static load ripple level of transmitter.

After audio modulation signal adds, by isolation capacitance C ₂Coupling, B point current potential just floats along with the variation of modulation signal, according to above-mentioned dynamic balancing spotting scaming process, output C ₃On the high power modulation signal voltage that promptly obtained amplifying, footpath L ₁And R ₁₀, C ₄The filtering switching pulse, direct sending carrier frequency amplifier tube Tr ₃And Tr ₄Make floating voltage, thereby realize the high efficiency amplitude modulation of carrier frequency pulse.Because the switching frequency of spotting scaming is high, so fidelity is splendid.Tr ₄The carrier frequency pulse amplitude-modulated wave of output, footpath C ₇, L ₂, C ₈Directly feed into transmitting antenna ANT after the coupling coupling.C ₉～C ₁₃, R ₁₄, R ₁R ₅, W ₂, D ₁, D ₂And V ₁Constitute the modulation indicating circuit; C ₁₄～C ₁₈, R ₁₆～R ₁₉, D ₃～D ₈, W ₃, W ₄, L ₃And V ₂, V ₃Constitute incident, reflection power indicating circuit.

In foregoing circuit, voltage comparator select for use LM339, LM306 or UA710 all can, require input offset voltage as far as possible little, operating rate is as far as possible high.Promote pipe Tr ₁Select for use common in, low-power transistor or field effect transistor all can, for example adopt to look and put pipe BF871.Tr ₂Can select high power transistor or VMOS pipe for use, for example with IRF9150 type VMOS pipe.Not enough as the single tube output current, desirable multitube parallel meets the demands.Crystal Y ₁Should add constant temperature, to guarantee the stability of frequency.Tr ₃In can selecting for use, the small-power high frequency transistor, as 3DG918, BFR91 etc.Tr ₄Then specifically select appropriate high power valve or field effect transistor for use according to the requirement of operating frequency and power output.Not enough as the single tube output current, desirable multitube parallel.Because circuit is switch work entirely, so can not do requirement to the linearity of high and low frequency pipe.

Referring to Fig. 2, on the plate face of transmitter casing, be furnished with audio level indication VU, modulation indication V ₁, power output indication V ₂, reflection power indication V ₃And ± 15V and+200V power supply indication gauge outfit, the input volume is regulated RW ₂Adjust W with the static load ripple ₁

For the high-power transmitter more than 3 kilowatts, can make a plurality of about 1.5～3 kilowatts unit and be integral by the line transformer stack combinations.Like this, even a certain unit is out of order in broadcast, also unlikely causing broken, and can recover normal behind the replacement trouble unit.

+ 200V power supply can be obtained by the direct rectification of AC network, without power transformer; Or adopt application number to provide for 91205389.5 dynamic balance switch type D.C. regulated power supply, to guarantee that overall efficiency is the highest.± 15V power supply then should adopt the active servo voltage stabilizing circuit, to guarantee the tonequality ideal.

Compare with prior art, the utility model has the advantages that very outstandingly, show as follows:

1) because audio or video and carrier-frequency circuit are HF switch work, excessive hear rate and the harmonic loss of the long-time conducting of power switch pipe when having avoided large-signal in pulsewidth modulation or the digital am transmitter (broad pulse), the multilevel voltage that has saved again in the general emitter amplifies, the power consumption of voltage comparator and promotion level is minimum, thereby this engine efficiency can reach more than 98%.

2) utilize only about 30% characteristics of broadcast program average am depth, adopt adjustable float carrier wave working method, can make transmitting station economize on electricity in every month more than half.

3) adopt the mode of direct transmitted pulse amplitude-modulated wave, utilize the listening of people, persistence of vision characteristics, listen to or watch under the prerequisite of effect not influencing, the power consumption of transmitter is reduced by half at least.

4) because carrier-frequency circuit has adopted pulse to amplify mode, can save huge mechanical tuning device, make that to switch frequency very convenient, dispatch from the factory and just can make the full frequency band transmitter, also significantly reduce maintenance load.

5) adopt dynamic balance switch to scan the power amplification that realizes audio or video, the switch scanning very high frequency, fidelity is fabulous, has guaranteed good electroacoustic index, makes transmitter have the digital sound effect.

6) power consumption is directly proportional with the carrier frequency power output, reduces volume and has also just reduced power consumption, thereby overcome the big chronic disease of existing all kinds of transmitter small-signal power consumption.

7) circuitry is simple in structure, and is cheap.

Be not difficult to find out that from above advantage promotion and application of the present utility model have earth shaking meaning.

Claims (1)

1, a kind of dynamic balance switch, amplitude modulation, floating carrier broadcast transmitter, its circuit mainly comprises dynamic balance switch type audio modulation signal amplifying circuit and carrier frequency pulse power amplification circuit, wherein the carrier frequency pulse amplifying circuit promotes level Tr by the carrier frequency pulse signal source ₃And power switch pipe Tr ₄Constitute; Of the present utility model being characterised in that:

1) the dynamic balance switch type modulation signal amplification circuit is by R ₅, R ₆Sampling link, voltage comparator, promotion level Tr that series connection constitutes ₁, power switch pipe Tr ₂Keep link to form with dynamic balancing, the sampling link is connected on Tr ₂Between output stage and the ground wire, R ₅With R ₆Contact be sampling point, connect the inverting input of comparator, the in-phase input end of comparator is the input of audio or video signal, it and be connected on+static load ripple between 15 volts of power supplys and the ground wire adjusts potentiometer W ₁Sliding end connect; The output termination of comparator promotes level Tr ₁Base stage, and pass through R ₈With Tr ₂Emitter connects+200 volts of power supplys together; Be connected on Tr ₂C between output stage and the ground wire ₃Constitute dynamic balancing and keep link;

2) the carrier frequency pulse square wave input Tr of the output of the CF signal source in the carrier frequency pulse circuit ₃Base stage, Tr ₃Collector electrode passes through R ₁₂With Tr ₄Emitter is connected with the audio or video amplifying signal output of dynamic balance switch type modulation signal amplification circuit together, with this modulation signal voltage as Tr ₃And Tr ₄Floating power supply, finish amplitude modulation(PAM) to the carrier frequency pulse square wave; Adjust W ₁Can change static load ripple level; The direct antennas ANT emission of the high-power amplitude-modulated pulse signal of gained.

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