CN1110855A

CN1110855A - Satellite receiving tuner

Info

Publication number: CN1110855A
Application number: CN 94104387
Authority: CN
Inventors: 辜锡镛
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-04-26
Filing date: 1994-04-26
Publication date: 1995-10-25

Abstract

The tuner for satellite receiving is a dual-input wide-band tuner for live broadcast is composed of three-classes of RF amplifiers, two sets of attenuator circuits, microwave single-crystal IC for amplifying and frequency-changing, high-frequency selection switch, MF amplifiers with comb filters in different frequency width (27/16/8 MHz), and finally, demodulator circuit for signal output.

Description

Satellite receiving tuner

The present invention relates to a kind of satellite receiver turning, be meant a kind of tuner especially with broadband direct broadcasting satellite (Direct Broadcasting Satellite is called for short DBS) of double input end demodulation function.

In direct broadcasting satellite (DBS) transmission course, the ground transmitting station with image and audio signal after multiplex circuit (Multiplexer) is made reasonable time and is distributed, be tuned as intermediate-freuqncy signal (Intermediate Fequency), after power amplification, change radiofrequency signal (950MHZ-2050MHZ) into and launch again through the antenna heavenwards; And the ground receiving platform needs low noise, wide band radio frequency receiving ability, after the weak radio-frequency signal that is received amplified, change the intermediate-freuqncy signal of lower frequency into, and then with this intermediate-freuqncy signal through demodulator circuit, take out fundamental frequency signal (promptly comprising image video signal and audio signal) wherein.But the antenna of ground receiving platform also can receive from other undesirable interference or noise signal in the atmosphere when receiving useful electromagnetic wave signal, and in addition, the circuit of receiver own also can produce noise, influences the reliability of communication system.Now, the intermediate frequency amplifying device in the general satellite receiver turning is all endeavouring to improve above-mentioned defective, but its intermediate frequency amplifying device still rests on the situation that can only handle the wide or intermediate-freuqncy signal that double frequency is wide of single-frequency.

The purpose of this invention is to provide a kind of satellite receiver turning that improves circuit structure.

The present invention mainly includes: 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 input to the radio frequency input unit earlier, be input to the amplification converter plant again, the intermediate-freuqncy signal that to amplify converter plant output again is input to the intermediate frequency amplifying device, the intermediate-freuqncy signal of this intermediate frequency amplifying device output, wherein one group of signal is imported demodulating equipment, another group signal then inputs to automatic gain control equipment, be connected with the attenuator circuit that amplifies converter plant again, it is characterized in that: this intermediate frequency amplifying device connects a PIN diode earlier, link to each other with two integrated circuits respectively and constitute first order intermediate frequency amplifier through a selector switch again, its output is connected with a comb filter, and by another selector switch with this intermediate-freuqncy signal select respectively with 27 16 or the frequency range of 8MHZ carry out filtering, again filtered signal is imported three groups of second level intermediate frequency amplifiers forming respectively by three integrated circuits respectively, again with the output signal of this second level intermediate frequency amplifier, link to each other with the third level intermediate frequency amplifier of forming by another integrated circuit, this intermediate-freuqncy signal is amplified once more.

The present invention is behind received RF signal, and through three grades of radio frequency amplifiers, two groups of attenuator circuits and microwave monocrystalline integrated circuit amplify frequency conversion, import the intermediate frequency amplifying device again intermediate-freuqncy signal is amplified.This intermediate frequency amplifying device be one with the high frequency selector switch, select the comb filter of three different frequency ranges (27/16/8MHZ), demodulate the circuit structure device of fundamental frequency signal at last by demodulator circuit, have the reception of improvement sensitiveness, reduce noise figure and have the good Practical Performance of three groups of frequency range signals outputs.

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

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

Consult Fig. 1, the present invention is made of institutes such as radio frequency input unit 1, amplification converter plant 2, intermediate frequency amplifying device 3, demodulating equipment 4 and automatic gain devices 5.

Consult Fig. 1, Fig. 2, radio-frequency input signals is earlier through radio frequency input unit 1, and by its A/B end input, selecting by A/B end input selector switch 13 is by A end input signal, or B end input signal.When A/B end input selector switch 13 is high potential, make transistor Q1, Q2 and diode D1, D4 conducting, and transistor Q3, Q4 and diode D2, D3 end.At this moment, radiofrequency signal is by the input of A end, through one group by capacitor C 1, C2, C3, C82, C4, C78, inductance L 1 and microstrip circuit (Micro-stripLine Circuit) low-pass filter circuit 11 that L4 formed, the signal that elimination frequency 2050MHZ is above, and make impedance matching.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 again, input signal is amplified back output.At this moment, R4 is a bias resistance, and C7 is a ground capacity, and capacitor C 8 is a reciprocal cross connection circuit with the parallel circuits of resistance R 3, enters diode D4 to stop high-frequency signal by resistance R 6.

In like manner, when A/B end input selector switch 13 is electronegative potential, will make transistor Q3, Q4 and diode D2, D3 keep conducting, and transistor Q1, Q2 and diode D1, D4 end.This moment, radiofrequency signal was by the input of B end, through one group of low-pass filter circuit 11 of forming by capacitor C 11, C15, C16, C83, C14, C79, inductance L 2 and microstrip circuit L5, the signal that elimination frequency 2050MHZ is above, and make impedance matching, again with the output signal of this low-pass filter circuit 11, be of coupled connections with capacitor C 18 earlier, import one group of first R.F. amplifier 12 of forming by transistor Q4 and resistance R 13 again, input signal is amplified back output.At this moment, R15 is a D.C. resistance, and C19 is a ground capacity, and capacitor C 17 is a reciprocal cross connection circuit with the parallel circuits of resistance R 12, enters diode D3 to stop high-frequency signal by resistance R 11.

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

The output signal of second level radio frequency amplifier 22, after being of coupled connections with capacitor C 26 earlier, import one group of shaping circuit of forming by capacitor C 27, C28, C29, resistance R 20, R21 and microstrip circuit L6, L7, will import amplifying signal and give exporting after the shaping, to eliminate noise.With the output signal of shaping circuit, be of coupled connections again, import the attenuator circuit 23 that another group is made up of PIN diode D6, resistance R 23, R24 and capacitor C 32, C35, C36, the noise interference when improving strong signal with capacitor C 30.At this moment, C32 is a ground capacity, R23, R24 are D.C. resistance, C35, C36 constitute match circuit, suppress the gain of low frequency signal once more, and PIN diode D6 is also controlled by automatic gain control equipment 5, the output signal of this attenuator circuit 23 is imported one group of third level radio frequency amplifier 24 of being made up of transistor Q6 and resistance R 25, R26 again, and input signal is amplified back output.At this moment, R25, R26 are bias resistance.

The output signal of third level radio frequency amplifier 24 is of coupled connections with capacitor C 37 earlier, imports one group of another shaping circuit of being made up of capacitor C 39, C40 and microstrip circuit L8, will import amplifying signal and give exporting after the shaping, so that eliminate noise once more.Again with the output signal of shaping circuit, be of coupled connections with capacitor C 41, import one group of tracking filter (Tracking Filter) 25 of being formed by diode D7, D8, D9, resistance R 30, R31, R32, capacitor C 43, C44, C46 and microstrip circuit L9, L10, L11, promptly visual (Image) filter circuit is with elimination image (Image) frequency.At this moment, capacitor C 45, C75 are a match circuit, again with the output signal of this tracking filter 25, import a micro-filtration monocrystalline integrated circuit (Micro wave Monolithic Integrated Circuit is called for short MMIC) 2b, radio frequency amplifier in this microwave monocrystalline integrated circuit and voltage controlled oscillator (Voltage Control Oscillator, be called for short VCO), produce intermediate-freuqncy signal (479.5MHZ) in the superhet mode.

Amplify the intermediate-freuqncy signal that converter plant 2 is exported, input intermediate frequency amplifying device amplifies.This input signal is PIN diode D13 of input earlier, select these input signals via integrated circuit (IC) 2 or first order intermediate frequency amplifier 31 that IC6 formed by switch SW 3 again, intermediate-freuqncy signal is amplified, import a comb filter SAW(SAW Filter again) 32, nationality help switch SW Z with intermediate-freuqncy signal select with 27 16 or the frequency range of 8MHZ give filtering.Again this signal is imported respectively by the integrated circuit (IC) 3 or second intermediate frequency amplifier 33 that IC4 or IC7 formed, imported the third level intermediate frequency amplifier of forming by integrated circuit (IC) 5 34 at last, amplify intermediate-freuqncy signal, provide enough gains to make phase detection.

Intermediate frequency amplifying device 3 amplifies the intermediate-freuqncy signal of output, wherein one group of signal is input to 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 of being formed by transistor Q102 and Q103 again, baseband signal is amplified output, import the buffer amplifier circuit of forming by transistor Q107 at last,, cooperate the circuit of outer welding system to reach the output of low output impedance and baseband signal.

Another group intermediate-freuqncy signal that intermediate frequency amplifying device 3 amplifies output inputs to AGC circuit arrangement 5, this intermediate-freuqncy signal is at first imported the intermediate-freuqncy signal wave detector of being made up of diode D104 51, to provide 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, again respectively with attenuator circuit 21,23 connect, with control attenuator circuit 21,23 attenuation degree, 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 one than high attenuation, and an automatic gain control output 54 is provided.

Claims

1, a kind of satellite receiver turning, 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 input to the radio frequency input unit earlier, be input to the amplification converter plant again, the intermediate-freuqncy signal that to amplify converter plant output again is input to the intermediate frequency amplifying device, the intermediate-freuqncy signal of this intermediate frequency amplifying device output, wherein one group of signal is imported demodulating equipment, another group signal then inputs to automatic gain control equipment, be connected with the attenuator circuit that amplifies converter plant again, it is characterized in that: this intermediate frequency amplifying device connects a PIN diode earlier, link to each other with two integrated circuits respectively and constitute first order intermediate frequency amplifier through a selector switch again, its output is connected with a comb filter, and by another selector switch with this intermediate-freuqncy signal select respectively with 27 16 or the frequency range of 8MHZ carry out filtering, again filtered signal is imported three groups of second level intermediate frequency amplifiers forming respectively by three integrated circuits respectively, again with the output signal of this second level intermediate frequency amplifier, link to each other with the third level intermediate frequency amplifier of forming by another integrated circuit, this intermediate-freuqncy signal is amplified once more.