CN1104003A - Satellite receiver turning device - Google Patents

Abstract

The invention relates to a tuner with wide freq. band of two input end decode. After receiving radio freq. signals, it outputs fundamental freq. signals through three level radio freq. amplifiers, two sets of attenuation circuits, ampli-freq.-changer with microwave single chip inte grated circuit, three level middle freq. amplifiers, saw tooth filter, and decoding circuit.

Description

Satellite receiver turning device

The present invention relates to a kind of satellite receiver turning device, belong to the satellite communication equipment technical field.

At direct broadcasting satellite (Direct Broadcasting Satellitect, abbreviation DBS) in the transmission course, the ground transmitting station is with signals such as image and sound, after multiplexer (Multiplexer) is done the reasonable time distribution, be tuned as intermediate-freuqncy signal (Intermediate Fequency), after power amplification, change radiofrequency signal (Radio Fequency) into and launch again through the antenna heavenwards; The ground receiving platform then needs low noise, wide band radio frequency receiving ability, after the weak radio-frequency signal that is received amplified, be converted to the intermediate-freuqncy signal of lower frequency, and then with this intermediate-freuqncy signal through demodulator circuit, take out fundamental wave signal wherein, promptly what is called includes vision signal and voice signal.But, the reception antenna of ground receiving platform is when receiving useful electromagnetic wave signal, also can receive from other and unwanted noise and interference signal in the atmosphere, and the circuit of receiver itself also can produce noise and influence the functional reliability of communication system.

The purpose of this invention is to provide a kind of satellite receiver turning device, this device has the practical feature of improving receiving sensitivity, reducing excellent electrical properties such as noise figure and increase gain.

The present invention is actually a kind of receiver turning with broadband direct broadcasting satellite of double input end demodulation function, mainly include the radio frequency input unit, amplify converter plant, the intermediate frequency amplifying device, demodulating equipment and automatic gain control equipment constitute, its radiofrequency signal is an input radio frequency input unit at first, converter plant is amplified in input again, to amplify the intermediate-freuqncy signal that converter plant is exported then, input intermediate frequency amplifying device, the intermediate-freuqncy signal of this intermediate frequency output that amplifying device amplifies, wherein one group of signal is imported demodulating equipment, another group signal is then imported automatic gain control equipment, be connected with the attenuator circuit that amplifies converter plant again, it is characterized in that:

This radio frequency input unit has double input end, can select suitable input end signal input by input selector switch, after these two inputs connect a low-pass filter circuit respectively, connects a first R.F. amplifier again;

This amplifies converter plant, be to connect an attenuator circuit earlier, again with the output signal of this attenuator circuit, be input to a second level radio frequency amplifier, output signal with this second level radio frequency amplifier, import another group attenuator circuit, again with the output signal of this attenuator circuit, be input to a third level radio frequency amplifier, and with the output signal of third level radio frequency amplifier, import a tracking filter, with the output signal of this tracking filter, import in a microwave monolithic integrated circuit chip and amplify frequency conversion again.

Below in conjunction with drawings and Examples, specifically introduce purpose of the present invention, circuit structure and effect thereof.

Fig. 1 is a circuit block diagram of the present invention.

Fig. 2 is circuit theory diagrams of the present invention.

Consult accompanying drawing, the present invention is made of parts such as radio frequency input unit 1, amplification converter plant 2, intermediate frequency amplifying device 3, demodulating equipment 4 and automatic gain control equipments 5.

Please consult Fig. 1, Fig. 2 simultaneously, radio-frequency input signals is earlier through radio frequency input unit 1, and this radiofrequency signal is promptly selected from A end input signal by A/B end input selector switch 13 via the input of A/B end, still from B end input signal.When A/B end input selector switch 13 is high potential, to make transistor Q1, Q2 and diode D1, D4 keeps conducting state, and transistor Q3, Q4 and diode D2, D3 keeps nonconducting state, at this moment, radiofrequency signal is by the input of A end, through one group by capacitor C 1, C2, C82, C4, C78, inductance L 1 and microstrip circuit (the Microstrip line Circuit) low-pass filter circuit 11 that L4 formed, with the signal more than the elimination frequency 2050MHz, and make impedance matching, again with the output signal of this low-pass filter circuit 11, after being of coupled connections with capacitor C 12 earlier, import one group of first R.F. amplifier 12 of being formed by transistor Q1 and resistance R 2, input signal is amplified back output, at this moment, R4 is a bias resistance, and C7 is a ground capacity, capacitor C 8 is the reciprocal cross connection circuit with the parallel circuits of resistance R 3, enters diode D4 to stop high-frequency signal from resistance R 6.

In like manner, when A/B end input selector switch 13 is low-voltage, will make transistor Q3, Q4 and diode D2, D3 keep conducting state, and transistor Q1, Q2 and diode D1, D4 are in nonconducting state.At this moment, radiofrequency signal is by the input of B end, through one group by capacitor C 11, C15, C16, C83, C14, C79, the low-pass filter circuit 11 that inductance L 2 and microstrip circuit L5 are formed, the signal that is higher than 2050MHz with the elimination frequency, and make impedance matching, again with the output signal of this low-pass filter circuit 11, after being of coupled connections with capacitor C 18 earlier, import one group of first R.F. amplifier 12 of being formed by transistor Q4 and resistance R 13, the signal of importing is amplified back output, at this moment, R15 is a Dc bias resistance, C19 is a ground capacity, and capacitor C 17 is the reciprocal cross connection circuit with the parallel circuits of resistance R 12, enters diode D3 to stop high-frequency signal from resistance R 11.

The output signal of the first R.F. amplifier 12 of radio frequency input unit 1 enters via diode D3 or D4 amplifies converter plant 2, after this signal is of coupled connections with capacitor C 20 earlier, import one group by diode D5, resistance R 19, R22 and capacitor C 21, C22, the attenuator circuit 21 that C23 formed, noise when improving strong signal disturbs, at this moment, C21 is a ground capacity, R19, C22 is a D.C. resistance, capacitor C 22, the connecting circuit of C23 is a match circuit, to suppress the gain of low frequency signal, and diode D5 is by 5 controls of automatic gain control (Automatic Gain Control is called for short AGC) device, again the output signal of this attenuator circuit 21 is imported one group by transistor Q5 and resistance R 17, the second level radio frequency amplifier 22 that R22 formed, the signal of input is amplified back output, at this moment, R17, R22 is a bias resistance.

After the output signal of second level radio frequency amplifier 22 is of coupled connections with capacitor C 26 earlier, import one group by capacitor C 27, C28, C29, resistance R 20, R21 and microstrip circuit L6, L7 shaping (grade) circuit, to import amplifying signal carries out exporting after the smooth shaping, to eliminate noise, again with the output signal of shaping circuit, after being of coupled connections with capacitor C 30, import another group by diode D6, resistance R 23, R24 and capacitor C 32, C35, the attenuator circuit 23 that C36 forms, noise when improving strong signal disturbs, this moment, C32 was a ground capacity, R23, R24 is a D.C. resistance, capacitor C 35, the connecting circuit of C36 is a match circuit, suppress the gain of low frequency signal once more, and diode D6 is controlled by automatic gain control equipment 5, the output signal of this attenuator circuit 23 is imported one group by transistor Q6 and resistance R 25 again, the third level radio frequency amplifier 24 that R26 formed is amplified back output with the signal of importing, this moment R25, R26 is a bias resistance.

The output signal of third level radio frequency amplifier 24 after being of coupled connections with capacitor C 37 earlier, is imported one group of another shaping (grade) circuit of being made up of capacitor C 39, C40 and microstrip circuit L8, will import amplifying signal and give exporting after the smooth shaping, to eliminate noise.After again the output signal of shaping circuit and capacitor C 41 being of coupled connections, import one group by diode D7, D8, D9, resistance R 30, R31, R32, capacitor C 43, C44, C46 and microstrip circuit L9, L10, the tracking filter that L11 formed (Tracking Filter) 25, promptly visual (Image) filter circuit, the elimination picture frequency, at this moment, capacitor C 45, the connecting circuit of C75 is a match circuit, again with the output signal of this tracking filter 25, import a microwave monolithic integrated circuit (Microwave Monolithic Integrated Circuit is called for short MMIC) 26, radio frequency amplifier and voltage controlled oscillator (Voltage Control Oscillator is called for short VCO) through this microwave monolithic integrated circuit inside produce intermediate-freuqncy signal (479.5MHz) to play the heterodyne mode.

Amplify the intermediate-freuqncy signal that converter plant 2 is exported, input intermediate frequency amplifying device 3 amplifies.This input signal is at first imported a first order intermediate frequency amplifier 31 of being made up of integrated circuit (IC) 2, intermediate-freuqncy signal is amplified, import a sawtooth waveforms device (SAW Filte) 32 again, intermediate-freuqncy signal is carried out filtering with the frequency range of 27MHz, last second, third grade intermediate frequency amplifier 33,34 formed by integrated circuit (IC) 3, IC5 of importing in regular turn, intermediate-freuqncy signal is amplified, make phase detection so that enough gains to be provided.

Intermediate frequency amplifying device 3 amplifies the intermediate-freuqncy signal of output, wherein one group of signal is imported the demodulating equipment of being made up of integrated circuit (IC) 102 4, intermediate-freuqncy signal is demodulated baseband signal (0MHz～10MHz), import one group of differential amplifier circuit of forming by transistor Q102 and Q103 again, baseband signal is amplified output, import the buffer amplifier circuit of forming by transistor Q107 at last,, cooperate external circuit system to realize the output of low output impedance and baseband signal.

Intermediate frequency amplifying device 3 amplifies another group intermediate-freuqncy signal of output, then imports automatic gain control equipment 5.This intermediate-freuqncy signal is at first imported the intermediate-freuqncy signal wave detector of being made up of diode D104 51, to detect desired signal, import the amplifying circuit of forming by integrated circuit (IC) 101 52 again, compare with the direct current signal of direct current reference circuit 53, be connected with attenuator circuit 21,23 respectively again, attenuation degree with control attenuator circuit 21,23, promptly when a tetanic stream signal is imported, this integrated circuit (IC) 101 will be exported less electric current, make attenuator circuit 21,23 produce bigger decay and provide a kind of automatic gain to control to export 54.

Claims (2)

1, a kind of satellite receiver turning device, mainly include the radio frequency input unit, amplify converter plant, the intermediate frequency amplifying device, demodulating equipment and automatic gain control equipment constitute, its radiofrequency signal is an input radio frequency input unit at first, converter plant is amplified in input again, to amplify the intermediate-freuqncy signal that converter plant is exported then, input intermediate frequency amplifying device, the intermediate-freuqncy signal of this intermediate frequency output that amplifying device amplifies, wherein one group of signal is imported demodulating equipment, another group signal is then imported automatic gain control equipment, be connected with the attenuator circuit that amplifies converter plant again, it is characterized in that:

This radio frequency input unit has double input end, can select suitable input end signal input by input selector switch, after these two inputs connect a low-pass filter circuit respectively, connects a first R.F. amplifier again;

This amplifies converter plant, be to connect an attenuator circuit earlier, again with the output signal of this attenuator circuit, be input to a second level radio frequency amplifier, output signal with this second level radio frequency amplifier, import another group attenuator circuit, again with the output signal of this attenuator circuit, be input to a third level radio frequency amplifier, and with the output signal of third level radio frequency amplifier, import a tracking filter, with the output signal of this tracking filter, import in a microwave monolithic integrated circuit chip and amplify frequency conversion again.

2, satellite receiver turning device as claimed in claim 1 is characterized in that: radio frequency input unit wherein also can be an one-input terminal, and this input also connects a low-pass filter circuit, connects a first R.F. amplifier again.

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