CN1131862A - Satellite receiving tuner device with automatic threshold control demodulation circuit - Google Patents
Satellite receiving tuner device with automatic threshold control demodulation circuit Download PDFInfo
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- CN1131862A CN1131862A CN95102628A CN95102628A CN1131862A CN 1131862 A CN1131862 A CN 1131862A CN 95102628 A CN95102628 A CN 95102628A CN 95102628 A CN95102628 A CN 95102628A CN 1131862 A CN1131862 A CN 1131862A
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Abstract
A tuner device with automatically threshold-controlled demodulator for satellite receiving features that the RF signals received from satellite go through low-pass filter, RF amplifier, tracking filter, attenuator and microwave monocrystal IC for amplifying and frequency variation and then through two-stage MF amplifier, comb filter and said demodulator to change the threshold of received signal with weather variation and antenna size.
Description
The present invention relates to a kind of automatic threshold control (Auto Threshold Control that has, abbreviation ATC) satellite receiver turning of demodulator circuit, be meant a kind of tuner especially with broadband direct broadcasting satellite (Direct Broa dcastingSatellite is called for short DBS) of dual input (or single input) automatic threshold and demodulation function.
Direct broadcasting satellite (DBS) is in transmission course, after the ground transmitting station is made sound accompaniment and picture intelligence (fundamental frequency signal) appropriate time and is distributed through duplex circuit (Multiplexer), be tuned as intermediate-freuqncy signal (Inter mediate Freguency, be called for short IF), and with this signal via radio frequency modulation and power amplification, change radiofrequency signal (Radio Freguency is called for short RF) into, again this radiofrequency signal is passed through the radiation of antenna heavenwards; The ground receiving platform then need have low noise, wide band RF receiving ability, the RF signal that is received is amplified, and amplified signal is converted to lower IF signal, again the IF signal be taken out wherein fundamental frequency signal (being sound accompaniment and picture intelligence) via demodulator circuit.Because the antenna of earth station when receiving from atmospheric electromagnetic wave signal, very easily is subjected to the interference of other noise signals and infiltration and involves communication system, influences its reliability.The conventional broadband direct broadcasting satellite receiver turning with demodulation function often needs to cooperate frequency range scope that sets and the reception antenna dimensions that is suitable for, and can obtain good sensitivity in the more weak area of signal.Yet, in case the orientation of satellite-signal changes, make that the fit dimension of antenna is not right, or because of weather bad ... Deng variation, can not receive enough strong signal, will make it not in the threshold range of the signal that this tuner received, make this class tuner very easily be subjected to other noises interference or infiltrations, reduce the sensitivity of antenna receiving signal, influence the television-viewing effect.
The purpose of this invention is to provide a kind of satellite receiver turning device with automatic threshold control demodulation circuit.
The present invention is achieved in that and includes: receive the radiofrequency signal of satellite antenna, and the radio frequency input unit that this signal is carried out filtering and amplification; Output signal after the received RF input unit amplifies, and with this signal amplify, frequency conversion to be to produce the amplification converter plant of intermediate-freuqncy signal; Receive and amplify the intermediate-freuqncy signal that converter plant produces, and it is amplified, again this intermediate-freuqncy signal is carried out the intermediate frequency amplifying device of filtering amplification with the frequency range of 16MHZ or 27MHZ; It is characterized in that: also include the automatic threshold control demodulation circuit that demodulator circuit and automatic threshold control circuit are formed; Wherein, the input of demodulator circuit links to each other with the output of intermediate frequency amplifying device, is provided with in this demodulator circuit to make it export the automatic gain control circuit of good fundamental frequency signal; The input of automatic threshold control circuit links to each other with the output of demodulator circuit, and with input signal through filtering, resonance and amplification, and the conversion of signals after will amplifying becomes direct current signal, come size of current and the equiva lent impedance thereof of control flows, so that demodulator circuit remains on 8-27MHZ frequency range scope through internal circuit.Above-mentioned automatic threshold control circuit includes following parts: a buffer, the fundamental frequency signal of receiving demodulation circuit output, make it smoothly by and stop that the signal that has passed through is return and disturb; A high pass filter, the fundamental frequency signal that receives by buffer also leaches this signal HFS; A resonant circuit receives the high pass filter output signal, and with this signal amplify, resonance to be to obtain optimum gain; A direct current wave detector receives the resonant circuit output signal, and the AC portion of this signal is converted to direct current signal; A variable ratio frequency changer stretch circuit receives direct current wave detector output signal, and by this direct current signal control, make demodulator circuit can remain on 8-27MHZ frequency range scope, to adapt to different climate changes and antenna size, adjust the threshold level of tuner automatically, guarantee that TV image is clear vivid.Above-mentioned radio frequency input unit includes: first low pass filter receives the radiofrequency signal (950-2050MHZ) of satellite antenna, and the part of this signal intermediate frequency rate more than 2050MHZ is given filtering; First radio frequency amplifier amplifies first low-pass filter output signal; Second low pass filter receives the radiofrequency signal (950-2050MHZ) of satellite antenna and the part of this signal intermediate frequency rate more than 2050MHZ is given filtering; Second radio frequency amplifier amplifies second low-pass filter output signal; Switching circuit, be used to select first or second low pass filter to receive the radiofrequency signal of satellite antenna, above-mentioned amplification converter plant includes: the output signal of a received RF input unit, and this output signal carried out filtering, with the tracking filter of filtering picture frequency; Output signal that receives tracking filter, and with this signal attenuation, the attenuator circuit that disturbs with the noise that improves when the strong signal; The output signal of a receiving attenuation circuit, and this signal is produced the microwave monocrystalline integrated circuit of intermediate-freuqncy signal in the superhet mode.Above-mentioned intermediate frequency amplifying device includes: one receives intermediate-freuqncy signal of amplifying converter plant output and the first order intermediate frequency amplifier that amplifies; One with first order intermediate frequency amplifier amplified IF signal, the comb filter that amplifies with the intermediate-freuqncy signal of frequency range 15MHZ or 27MHZ; One group can receive frequency range respectively is 16MHZ intermediate-freuqncy signal or 27MHZ intermediate-freuqncy signal, and carries out the second level intermediate frequency amplifier of processing and amplifying respectively.The attenuator circuit of above-mentioned amplification converter plant can be connected with an automatic gain control circuit, with the gain or the impairment of control tracking filter output signal.First intermediate frequency amplifier circuit of above-mentioned intermediate frequency amplifying device can be connected with automatic gain control circuit, with the gain or the impairment of control intermediate-freuqncy signal.
Characteristics of the present invention are to be provided with an automatic threshold control circuit in demodulator circuit, this circuit can be from fundamental frequency (Baseband) signal of demodulator circuit output, detect high-frequency signal, and this high-frequency signal is converted to direct voltage via direct current wave detector (DC Detecter), to change diode current size in the variable ratio frequency changer stretch circuit, make the thresholding that tuner apparatus can be adjusted its received signal automatically according to climate change and antenna size, to obtain good reception sensitivity, low noise figure, improve electrical characteristics such as output gain and optimum thresholding, simultaneously can reduce the antenna size specification, to reduce the shared space of satellite antenna.
Fig. 1 is a circuit block diagram of the present invention.
Fig. 2 is the circuit theory diagrams of radio frequency input unit of the present invention
Fig. 3 is the electrical schematic diagram of amplification converter plant of the present invention and intermediate frequency amplifying device.
Fig. 4 is the electrical schematic diagram of automatic threshold control demodulating equipment of the present invention.
Consult Fig. 1, the present invention mainly includes radio frequency output device 1, amplification converter plant 2, intermediate frequency amplifying device 3 and automatic threshold control demodulating equipment 4.
Consult Fig. 1-Fig. 4 again, wherein radio frequency input unit 1 by low pass filter 11,11 ', radio frequency amplifier 12,12 ' and switching circuit 13 formed, wherein radio frequency amplifier 12,12 ' input are connected with low pass filter 11,11 ' output respectively, radio frequency amplifier 12,12 ' output then link to each other with switching circuit 13 inputs respectively, and switching circuit 13 outputs then link to each other with amplification converter plant 2.
Above-mentioned low pass filter 11,11 ' is used for receiving respectively the radiofrequency signal (950MHZ-2050MHZ) of satellite antenna, and switching circuit 13 controls formed by elements such as selector switch SW1, transistor Q1, Q2, diode D3, D4 and the resistance R 44 of A/B input, R45, R53, capacitor C 70, C71 of nationality, make the radiofrequency signal (950MHZ-2050MHZ) after the reception can deliver to the input A of this low pass filter 11 or the input B of another low pass filter 11 '; Promptly when the A/B of switching circuit 13 input selector switch SW1 is high potential, will make transistor Q2 and diode D4 keep conducting state, transistor Q3 and diode D3 then remain on nonconducting state.At this moment, to receive the radiofrequency signal (950-2050MHZ) of satellite antenna by capacitor C 60, C61, C62, C63, C64, C65, inductance L 1 and microstrip circuit (Microstripline Circuit) low pass filter 11 that SL3, SL5 formed, and with the in addition filtering of the signal of this signal intermediate frequency rate more than 2050MHZ, and make it obstruct coupling; Then, again these low pass filter 11 output signals being delivered to the radio frequency amplifier of being made up of elements such as commissure capacitor C 66, transistor Q1, diode D1, bias resistance R49, R50, R51, ground capacity C67, reciprocal cross connection circuit R52, C69 and microstrip circuit SL7 12 via its output is amplified.
This radio frequency amplifier 12 is that low pass filter 11 filtered output signals are amplified, and the signal after will amplifying delivers to via elements such as capacitor C 70 and diode D4 and amplifies converter plant 2, and wherein the reciprocal cross connection circuit of radio frequency amplifier 12 (R52, C69) can stop high-frequency signal to enter diode D4 by resistance R 53.
In like manner, when the A/B of switching circuit 13 input selector switch SW1 is electronegative potential, will make transistor Q3 and diode D3 keep conducting state, and transistor Q2 and diode D4 remain on nonconducting state.At this moment, the low pass filter of being made up of capacitor C 43, C45, C46, C47, C48, C49, inductance L 2 and microstrip circuit SL4, SL6 11 ' then receives the radiofrequency signal (950-2050MHZ) of satellite antenna, and the signal that this signal intermediate frequency rate 2050MHZ is above gives filtering, and makes its impedance matching.Then, this low pass filter 11 ' output signal being delivered to the radio frequency amplifier of being made up of commissure capacitor C 52, transistor Q4, diode D2, bias resistance R39, R41, R43, ground capacity C53, reciprocal cross connection circuit (R42, C54) and microstrip circuit SL8 12 ' is amplified again.
This radio frequency amplifier 12 ' amplifies low pass filter 11 ' the filtered output signal, signal after will amplifying again is delivered to via capacitor C 71 and diode D3 and amplifies converter plant 2, and reciprocal cross connection circuit wherein (R42, C54) can stop high-frequency signal to enter diode D3 by resistance R 44.
Amplifying converter plant 2 is made up of tracking filter 21, attenuator circuit 22 and microwave monocrystalline integrated circuit 23, wherein the input of tracking filter 21 is connected with the output of radio frequency input unit 1, its output links to each other with the input of attenuator circuit 22, the output of this attenuator circuit 22 links to each other with microwave monocrystalline integrated circuit 23 inputs, and these microwave monocrystalline integrated circuit 23 outputs then are connected with intermediate frequency amplifying device 3.Attenuator circuit 22 internal circuits then are connected with automatic gain control circuit (Automatic Gain Controe is called for short AGC).
This tracking filter (Tracking Filter) the 21st is by inductance L 3, resistance R 24, R70, capacitor C 12, C13, C14, C15, C73, C75, C76, variable capacitance diode D8, D9 and microstrip circuit SL9, SL10, SL11, elements such as SL12 are formed, the output signal of its received RF input unit 1, this output signal is given filtering, with the filtering picture frequency, again with the signal after the filtering through its output, be delivered to by commissure capacitor C 17, diode D10, resistance R 27, R28, capacitor C 19, C22, C32, match circuit (C20, C21, SL13) attenuator circuit of being formed 22, wherein match circuit (C20, C21, SL13) be to be used to suppress the low frequency signal gain.
Attenuator circuit 22 is accepted the output signal of tracking filter 21 respectively, and with this signal attenuation, disturbs with the noise that improves when the strong signal; (AGC) controls this signal gain or impairment by the automatic gain control circuit, then, signal after will decaying again is delivered to the microwave monocrystalline integrated circuit of being made up of integrated circuit (IC) 1, resistance R 58, R59 and elements such as variable capacitance diode D6, D7 (Microwave Monolithic Intergarated Circuit is called for short MMIC) 23 through its output, is amplified frequency conversion.
The output signal of microwave monocrystalline integrated circuit 23 receiving attenuation circuit 22, and with radio frequency amplifier and the voltage-controlled oscillator of this signal by its internal circuit, produce intermediate-freuqncy signal in the superhet mode, then, again with this intermediate-freuqncy signal through its output, be delivered to intermediate frequency amplifying device 3 and amplify.
This intermediate frequency amplifying device 3 is made up of first order intermediate frequency amplifier 31, comb filter 32,33,34 of second level intermediate frequency amplifiers, wherein putting 31 input in the first order links to each other with the output that amplifies converter plant 2, link to each other with comb filter 32 and put 31 output in the first order, the output of comb filter 32 is put 33,34 input and is linked to each other respectively with in the second level, puts 33,34 output in the second level and then links to each other with automatic threshold control demodulating equipment 4 inputs.Again, putting 31 internal circuit in the first order links to each other with the automatic gain control circuit.
Putting 31 in the first order is by double-gate field effect transistor (MOSFET), bias resistance R32, R33, R34, R35, R36, R69, ground capacity C25, C38, match circuit elements such as (including inductance L 4, resistance R 37, capacitor C 24, C35, C36, C41) are formed, be used to receive the intermediate-freuqncy signal of amplifying converter plant 2 outputs, and with this signal amplification, and the gain or the impairment that come control signal by the automatic gain control circuit, then, again this signal is delivered to comb filter 32 through its output.
When 16/27MHZ selector switch SW2 was high potential, transistor Q7 kept conducting, and transistor Q8, diode D12 are non-conduction; At this moment, the intermediate-freuqncy signal that intermediate frequency amplifier 33 receives frequency range 16MHZ is amplified, and the signal after will amplifying is delivered to automatic threshold control demodulating equipment 4.
When should 16/27MHZ selector switch SW2 being electronegative potential, transistor Q8, diode D12 keep conducting, and transistor Q7 is non-conduction; At this moment, the intermediate-freuqncy signal that intermediate frequency amplifier 33 receives frequency range 27MHZ is amplified, and the signal after will amplifying is delivered to from thresholding control demodulating equipment 4.
Automatic threshold control demodulating equipment 4 is made up of demodulator circuit 41 and automatic threshold control circuit 42, and wherein the input of demodulator circuit 41 links to each other with the output of intermediate frequency amplifying device 3, and the output of demodulator circuit 41 then links to each other with the input of automatic threshold control circuit 42; The output of automatic threshold control circuit 42 then links to each other with the internal wiring of demodulator circuit 41, and simultaneously, the internal wiring of this demodulator circuit 41 also links to each other with automatic gain control circuit AGC.
Consult Fig. 1 and Fig. 4, automatic threshold control circuit 42 is by buffer 421, high pass filter 422, resonant circuit 423, direct current wave detector 424 and variable ratio frequency changer stretch circuit 425 are formed, wherein the input of buffer 421 links to each other with the output of demodulator circuit 41, the output of buffer 421 links to each other with high pass filter 422 inputs, the output of high pass filter 422 links to each other with resonant circuit 423 inputs, the output of resonant circuit 423 links to each other with 424 inputs of direct current wave detector, the output of direct current inspection skin device 424 then links to each other with variable ratio frequency changer stretch circuit 425 inputs, and the output of variable ratio frequency changer stretch circuit 425 then links to each other with the internal circuit of demodulator circuit 41.
Wherein buffer 421 is made up of transistor Q9, resistance R 150, R151 and capacitor C 150, the fundamental frequency signal of receiving demodulation circuit 41 outputs, this signal is passed through, and intercept the signal passed through and return or disturb, the signal conveys that will pass through is to the high pass filter of being made up of transistor Q10, resistance R 152, R153 and capacitor C 152 422 again.
The fundamental frequency signal of high pass filter 422 reception buffers 421 outputs, just the HFS with this signal leaches, and the signal after will leaching is again delivered to the resonant circuit of being made up of inductance L 1 and capacitor C 151 423.
The direct current wave detector receives that above-mentioned signal detects, to convert thereof into direct current signal, again this direct current signal is delivered to the variable ratio frequency changer stretch circuit of forming by transistor Q12, resistance R 82, R83, R158, R159, capacitor C 130, C156 and elements such as diode D12, D13 425, make demodulator circuit 41 can remain on 8-27MHZ frequency range scope, to adapt to different climate changes, antenna size and adjust the threshold level of tuner apparatus automatically, guarantee the quality of television image.
I.e. when the 16/27MHZ selector switch remains on electronegative potential (frequency range that comb filter allows to pass through is 27MHZ), but the direct current signal of variable ratio frequency changer stretch circuit 425 nationality direct current wave detectors 424 conversion back outputs, change the collector voltage of transistor Q12, reduce the electric current of the diode D13 that flows through, and change its equivalent resistance, make demodulator circuit 41 can remain on the frequency range scope of 16-27MHZ, adapt to different weathers, antenna size, and adjust the received signal thresholding of tuner automatically, guarantee the quality of television image.
Perhaps, when the 16/27MHZ selector switch remains on high potential (frequency range that comb filter allows to pass through is 16MHZ), but the direct current signal of variable ratio frequency changer stretch circuit 425 nationality direct current wave detectors 424 conversion back outputs, change the collector voltage of transistor Q12, increase the diode D13 that flows through electric current, and change its equivalent resistance, make demodulator circuit 41 can remain on the frequency range scope of 16-27MHZ, adapt to different weathers, antenna size, and adjust the received signal thresholding of tuner automatically, guarantee the quality of television image.
Claims (7)
1, a kind of satellite receiver turning device that automatic threshold control demodulation circuit is arranged includes: receive the radiofrequency signal of satellite antenna, and the radio frequency input unit that this signal is carried out filtering and amplification; Output signal after the received RF input unit amplifies, and with this signal amplify, frequency conversion to be to produce the amplification converter plant of intermediate-freuqncy signal; Receive and amplify the intermediate-freuqncy signal that converter plant produces, and it is amplified, again this intermediate-freuqncy signal is carried out the intermediate frequency amplifying device of filtering amplification with the frequency range of 16MHZ or 27MHZ; It is characterized in that: also include the automatic threshold control demodulation circuit that demodulator circuit and automatic threshold control circuit are formed; Wherein, the input of demodulator circuit links to each other with the output of intermediate frequency amplifying device, is provided with in this demodulator circuit to make it export the automatic gain control circuit of good fundamental frequency signal; The input of automatic threshold control circuit links to each other with the output of demodulator circuit, and with input signal through filtering, resonance and amplification, and the conversion of signals after will amplifying becomes direct current signal, come size of current and the equiva lent impedance thereof of control flows, so that demodulator circuit remains on 8-27MHZ frequency range scope through internal circuit.
2, the satellite receiver turning device that automatic threshold control demodulation circuit is arranged as claimed in claim 1, it is characterized in that: above-mentioned automatic threshold control circuit includes following parts: a buffer, the fundamental frequency signal of receiving demodulation circuit output, make it smoothly by and stop that the signal that has passed through is return and disturb; A high pass filter, the fundamental frequency signal that receives by buffer also leaches this signal HFS; A resonant circuit receives the high pass filter output signal, and with this signal amplify, resonance to be to obtain optimum gain; A direct current wave detector receives the resonant circuit output signal, and the AC portion of this signal is converted to direct current signal; A variable ratio frequency changer stretch circuit receives direct current wave detector output signal, and by this direct current signal control, makes demodulator circuit can remain on 8-27MHZ frequency range scope,
3, the satellite receiver turning device that automatic threshold control demodulation circuit is arranged as claimed in claim 1, it is characterized in that: above-mentioned radio frequency input unit includes: first low pass filter, receive the radiofrequency signal (950-2050MHZ) of satellite antenna, and the part of this signal intermediate frequency rate more than 2050MHZ given filtering; First radio frequency amplifier amplifies first low-pass filter output signal; Second low pass filter receives the radiofrequency signal (950-2050MHZ) of satellite antenna and the part of this signal intermediate frequency rate more than 2050MHZ is given filtering; Second radio frequency amplifier amplifies second low-pass filter output signal; Switching circuit is used to select first or second low pass filter to receive the radiofrequency signal of satellite antenna,
4, the satellite receiver turning device that automatic threshold control demodulation circuit is arranged as claimed in claim 1, it is characterized in that: above-mentioned amplification converter plant includes: the output signal of a received RF input unit, and this output signal carried out filtering, with the tracking filter of filtering picture frequency; Output signal that receives tracking filter, and with this signal attenuation, the attenuator circuit that disturbs with the noise that improves when the strong signal; The output signal of a receiving attenuation circuit, and this signal is produced the microwave monocrystalline integrated circuit of intermediate-freuqncy signal in the superhet mode.
5, the satellite receiver turning device that automatic threshold control demodulation circuit is arranged as claimed in claim 1 is characterized in that: above-mentioned intermediate frequency amplifying device includes: one receives intermediate-freuqncy signal of amplifying converter plant output and the first order intermediate frequency amplifier that amplifies; One with first order intermediate frequency amplifier amplified IF signal, the comb filter that amplifies with the intermediate-freuqncy signal of frequency range 16MHZ or 27MHZ; One group can receive frequency range respectively is 15MHZ intermediate-freuqncy signal or 27MHZ intermediate-freuqncy signal, and carries out the second level intermediate frequency amplifier of processing and amplifying respectively.
6, the satellite receiver turning device that automatic threshold control demodulation circuit is arranged as claimed in claim 1, it is characterized in that: the attenuator circuit of above-mentioned amplification converter plant can be connected with an automatic gain control circuit, with the gain or the impairment of control tracking filter output signal.
7, the satellite receiver turning device that automatic threshold control demodulation circuit is arranged as claimed in claim 1, it is characterized in that: first intermediate frequency amplifier circuit of above-mentioned intermediate frequency amplifying device can be connected with automatic gain control circuit, with the gain or the impairment of control intermediate-freuqncy signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN95102628A CN1131862A (en) | 1995-03-20 | 1995-03-20 | Satellite receiving tuner device with automatic threshold control demodulation circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN95102628A CN1131862A (en) | 1995-03-20 | 1995-03-20 | Satellite receiving tuner device with automatic threshold control demodulation circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1131862A true CN1131862A (en) | 1996-09-25 |
Family
ID=5074412
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN95102628A Pending CN1131862A (en) | 1995-03-20 | 1995-03-20 | Satellite receiving tuner device with automatic threshold control demodulation circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1131862A (en) |
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1995
- 1995-03-20 CN CN95102628A patent/CN1131862A/en active Pending
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