A kind of C-band tuner being convenient to adjustment noise factorTechnical field
The present invention relates to a kind of C-band tuner being convenient to regulate noise factor, belong to satellite signal receiving device fabrication manufacturing technology field.
Background technology
General satellite television receiving system mainly comprises: antenna, feed, low noise block downconverter, cable, clamped nipple, satellite receiver, television receiver, wherein low noise block downconverter is also referred to as tuner, is by low noise amplifier and the integrated assembly of low-converter.The satellite downlink microwave signal received due to the ground-plane antenna in satellite television receiving system has been very faint through the long-distance transmissions of about about 40000 km, and usual antenna feed outgoing carrier power is about-90 dBmW; If feeder loss is 0.5 dB, then low noise amplifier input carrier power is-90.5 dBmW; The loss of the first frequency converter and band pass filter is about 10 dB, and the gain of putting in first is about 30 dB; Like this, if low noise amplifier provides gain 40 dB ~ 50 dB, then low-converter output can export the signal of-30 dBmW ~-20 dBmW.It can thus be appreciated that the effect of satellite television low-converter is under the condition ensureing original signal mass parameter, and the signal of the satellite downlink frequency received is carried out low noise amplification and frequency conversion.
Because the optimum condition of maximum power gain design and minimal noise designing requirement is different, can not meet simultaneously, so usually take the compromise proposal of noise factor and power gain, namely in actual production, we need to sacrifice power gain and standing-wave ratio exchanges low-noise characteristic for, therefore carry out to the signal that the noise factor of tuner regulates to realize satellite downlink frequency the critical process that low noise amplification is the tuner manufacturing.
Summary of the invention
The present invention, just for the deficiency that prior art exists, provides a kind of C-band tuner being convenient to regulate noise factor, is convenient to regulate the noise factor of C-band tuner, meets actual operation requirements.
For solving the problem, the technical solution used in the present invention is as follows:
Be convenient to the C-band tuner regulating noise factor, comprise:
For the probe of receiving polarization signal;
For receiving the polarized signal of described probe transmission, and the first stage amplifier of low noise amplification is carried out to polarized signal, and be provided with the microstrip line for signal transmission between described probe and described first stage amplifier;
For receiving the one-level amplifying signal of described first stage amplifier transmission, and to the two-stage amplifier that one-level amplifying signal amplifies again;
Secondary amplifying signal for exporting described two-stage amplifier carries out the band pass filter of He Ne laser;
For generation of the local oscillation circuit of local frequency;
For receiving the signal of the target frequency bands that described band pass filter exports, and the local frequency that the signal of target frequency bands and described local oscillation circuit export is carried out the mixting circuit of mixing.
As the improvement of technique scheme, described probe comprises the horizontal probe for receiving horizontal polarization signals and the Vertrical probe for receiving perpendicular polarization signal, and described first stage amplifier comprises the first triode amplified for perpendicular polarization signal one-level and the second triode amplified for horizontal polarization signals one-level; Be provided with horizontal microstrip line between described horizontal probe and described second triode, between described Vertrical probe and described first triode, be provided with vertical microstrip line.
As the improvement of technique scheme, comprise integrated circuit (IC) chip, described mixting circuit is integrated in described integrated circuit (IC) chip, and described local oscillation circuit comprises phase-locked loop resonator, described phase-locked loop is also integrated in described integrated circuit (IC) chip, and is also provided with the power amplification circuit for amplifying mixer output signal in described integrated circuit (IC) chip.
As the improvement of technique scheme, described integrated circuit (IC) chip is RDA3570 chip.
Compared with prior art, implementation result of the present invention is as follows in the present invention:
A kind of C-band tuner being convenient to adjustment noise factor of the present invention, have employed microstrip line and replace welding wire jumper, microstrip line is directly etched on printed circuit board, calculated the best design of microstrip line by ads simulation software during design, and the optimization length of microstrip line can be determined in conjunction with actual tests inching, to realize the input impedance expected, thus considerably improve the production efficiency of C-band tuner, and reduce production cost, be beneficial to batch production, and make the quality of the C-band tuner produced in batches more stable.
In addition, present invention employs dual polarization probe and share the structure of two-stage amplifier, not only making that the C-band tuner scope of application increases, function strengthens, and relative to the C-band tuner of conventional bipolar probe, there is the advantage that structure simplifies; And select integrated circuit (IC) chip by integrated for the functional module in C-band tuner, thus be conducive to improving further C-band tuner production efficiency, reduce manufacturing cost and improve the quality of products.
Accompanying drawing explanation
Fig. 1 is a kind of C-band tuner structure schematic diagram being convenient to regulate noise factor of the present invention.
Embodiment
Below in conjunction with specific embodiments content of the present invention is described.
As shown in Figure 1, be a kind of C-band tuner structure schematic diagram being convenient to adjustment noise factor of the present invention.A kind of C-band tuner being convenient to adjustment noise factor of the present invention, comprising: for the probe of receiving polarization signal; For receiving the polarized signal of described probe transmission, and the first stage amplifier of low noise amplification is carried out to polarized signal, and be provided with the microstrip line for signal transmission between described probe and described first stage amplifier; For receiving the one-level amplifying signal of described first stage amplifier transmission, and to the two-stage amplifier Q3 that one-level amplifying signal amplifies again; Secondary amplifying signal for exporting described two-stage amplifier Q3 carries out the band pass filter L of He Ne laser; For generation of the local oscillation circuit of local frequency; For receiving the signal of the target frequency bands that described band pass filter L exports, and the local frequency that the signal of target frequency bands and described local oscillation circuit export is carried out the mixting circuit of mixing.Further with improvement, described probe comprises the horizontal probe T1 for receiving horizontal polarization signals and the Vertrical probe T2 for receiving perpendicular polarization signal, and described first stage amplifier comprises the first triode Q1 amplified for perpendicular polarization signal one-level and the second triode Q2 amplified for horizontal polarization signals one-level; Be provided with horizontal microstrip line W1 between described horizontal probe T1 and described second triode Q2, between described Vertrical probe T2 and described first triode Q1, be provided with vertical microstrip line W2.Further optimally, also comprise integrated circuit die I C, described mixting circuit is integrated in described integrated circuit die I C, and described local oscillation circuit comprises phase-locked loop resonator Y, described phase-locked loop is also integrated in described integrated circuit die I C, and is also provided with the power amplification circuit for amplifying mixer output signal in described integrated circuit die I C.Particularly, described integrated circuit die I C can be RDA3570 chip.
The size of input impedance determines the noise factor of the total system of C-band tuner, and gain and noise are two the topmost parameters weighing tuner capability and performance; And the overall noise coefficient of C-band tuner is determined by the noise of amplifier and input impedance.
The overall noise coefficient formulas of n level cascade amplifier is:
Wherein, Fifor the noise factor of i level amplifier, Gaifor the gain of i level amplifier;
The noise factor of linear two-port network and the relevance formula of genertor impedance are:
Wherein, Ysfor signal source admittance, Yoptfor two-port network obtains Minimum noises coefficients Fmintime optimum signal source admittance, Rnbe a constant with resistance dimension, usually claim it to be the equivalent noise resistance at linear Two-port netwerk networking, it shows that the noise factor F of network is to the sensitivity of signal source admittance change; Above-mentioned formula S expressed as parameters method represents, be then:
Wherein, Fmin, Rnand Γoptfor datum.
According to above-mentioned formula, can by adjustment Γschange noise factor; The condition obtaining maximum transmission power gain according to biconjugate matched design genealogy of law system is: Γs=Γin*, Γl=Γout*;
Can obtain thus:
Wherein:
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Wherein:
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In order to take into account noise factor and power gain, make the combining properties optimization of noise factor and power gain, can by manual welding wire jumper between probe and first order amplifier, and the overall impedance by regulating the welding length of wire jumper and thickness to regulate probe and welding wire jumper, thus sacrifice certain power gain and standing-wave ratio to exchange low-noise characteristic for.But manual welding wire jumper not only operating efficiency is lower, and be unfavorable for batch production and quality control, the quality of lot of product is uneven, and present invention employs microstrip line replacement welding wire jumper, microstrip line is directly etched on printed circuit board, calculated the best design of microstrip line by ads simulation software during design, and the optimization length of microstrip line can be determined in conjunction with actual tests inching, to realize the input impedance expected, thus considerably improve the production efficiency of C-band tuner, and reduce production cost, be beneficial to batch production, and make the quality of the C-band tuner produced in batches more stable.
The horizontal polarization signals received is delivered to the one-level amplification that the second triode Q2 carries out signal by horizontal probe T1, the secondary amplification of signal is carried out again by two-stage amplifier Q3, then integrated circuit die I C is inputed to by the signal of band pass filter L select target frequency range, for phase-locked, mixing the specific product model of the integrated circuit die I C of amplifying power can be RDA3570, integrated circuit die I C is connected with crystal resonator Y simultaneously, then intermediate-freuqncy signal is exported to receiver or other Signal reception treatment facility by intermediate-freuqncy signal output M, thus complete the collection of horizontal polarization signals, the perpendicular polarization signal received is delivered to the one-level amplification that the first triode Q1 carries out signal by Vertrical probe T2, the secondary amplification of signal is carried out again by two-stage amplifier Q3, then integrated circuit die I C is inputed to by the signal of band pass filter L select target frequency range, then export intermediate-freuqncy signal to receiver or other Signal reception treatment facility by intermediate-freuqncy signal output M, thus complete the collection of perpendicular polarization signal.One is provided with for regulating the microstrip line W3 of impedance, to reduce the noise factor of the finned tuner total system of a kind of C-band described in the present embodiment between one stage signal amplifier second triode Q2 and the first triode Q1.Particularly, supply power voltage is by inputing to Circuits System from feeder ear V after voltage-stabiliser tube regulation voltage.Remaining resistance R1 ~ R11, electric capacity C1 ~ C12 all for regulating circuit performance according to actual needs, provide judgement voltage.
Above content is detailed description made for the present invention in conjunction with specific embodiments, can not assert that the present invention specifically implements to be only limitted to these explanations.For those skilled in the art, without departing from the inventive concept of the premise, some simple deduction or replace can also be made, all should be considered as belonging to the scope of protection of the invention.