CN1092862C - Large dynamic range low-noise factor harmonic tuner - Google Patents
Large dynamic range low-noise factor harmonic tuner Download PDFInfo
- Publication number
- CN1092862C CN1092862C CN 98103480 CN98103480A CN1092862C CN 1092862 C CN1092862 C CN 1092862C CN 98103480 CN98103480 CN 98103480 CN 98103480 A CN98103480 A CN 98103480A CN 1092862 C CN1092862 C CN 1092862C
- Authority
- CN
- China
- Prior art keywords
- amplifier
- level
- variable attenuator
- agc
- filter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- Circuits Of Receivers In General (AREA)
- Noise Elimination (AREA)
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
- Superheterodyne Receivers (AREA)
Abstract
The present invention relates to a large dynamic range low-noise factor harmonic tuner which is composed of a third-stage amplifier, a third-stage variable attenuator, a second-stage mixer, a second-stage oscillator and a second-stage filter. The purpose of the high-quality transmission of television RF can be realized through the present invention.
Description
The present invention relates to a kind of Television Reception Technology equipment, specifically a kind of large dynamic range low-noise factor harmonic tuner.
The AGC of traditional TV tuner (auto-increment control) control is the gain of modulating them by the DC bias that control has the high-frequency amplifier of AGC characteristic and an intermediate frequency amplifier.But it is less by its dynamic range of tuner that this method realizes, and the variation of amplifier gain can cause that the tuner amplitude-frequency characteristic changes, transmission to signal brings adverse influence, especially when the gain of high-frequency amplifier was low, the variation of AGC signal can make the noise factor acute exacerbation of tuner.
The objective of the invention is is providing a kind of large dynamic range low-noise system tuning device, and solves great dynamic range that conventional tuner exists and the problem of disharmony between the little noise factor with its appearance.
The object of the present invention is achieved like this: a kind of large dynamic range low-noise factor harmonic tuner is by third stage amplifier F
1, F
2, F
3Three grades of variable attenuator KS
1, KS
2, KS
3Secondary frequency mixer H
1, H
2Two-stage oscillator Z
1, Z
2Two-stage filter L
1, L
2Constituting, wherein is the circuit outgoing route of controlling (AGC) by the auto-increment that this tuner is realized, described amplifier, and variable attenuator, frequency mixer, oscillator, Filter Structures sequence are: first order amplifier F
1(HE871) → first order variable attenuator KS
1(HE412A) → first order frequency mixer H
1(MCLSRA-2CM)+first order oscillator Z
1(OSC
1) → first order filter L
1(DIP-14B) → second level amplifier F
2(HE583) → second level variable attenuator KS
2(HE412A) → second level frequency mixer H
2(MCLSRA-2CM)+second level oscillator Z
2(OSC
2) → second level filter L
2(DIP-18B) → third level amplifier F
3(HE364) → third level variable attenuator KS
3, wherein, at the variable attenuator KS of each grade
1, KS
2, KS
3The equal correspondence of output the output AGC of AGC is set
1, AGC
2, AGC
3, and, at each grade amplifier F
1, F
2, F
3, variable attenuator KS
1, KS
2, KS
3, frequency mixer H
1, H
2, filter L
1, L
2Between the identical variable capacitor of a capacitance of all connecting.What emphasize here is critical component in this programme: amplifier and variable attenuator about their multistage setting and modulation, then are that the undistorted output level of single-stage is reached+14dbm with regard to amplifier; Be that attenuation is big with regard to variable attenuator, attenuation characteristic is smooth, and control voltage is low.
Than traditional TV tuner, the contribution of the invention is that dynamic range is greater than 80 decibels (conventional tuner is 50 decibels); Noise factor: 4 decibels (conventional tuner is 8 decibels).So the present invention is improved than conventional tuner, provide necessary condition to the high-quality transmission of TV RF signals.
Again the present invention is further described below in conjunction with drawings and Examples:
Fig. 1 is the fundamental diagram of large dynamic range low-noise factor harmonic tuner.
By Fig. 1 the present invention is a kind of large dynamic range low-noise factor harmonic tuner, is by third stage amplifier F
1, F
2, F
3Three grades of variable attenuator KS
1, KS
2, KS
3Secondary frequency mixer H
1, H
2Two-stage oscillator Z
1, Z
2Two-stage filter L
1, L
2Constitute, wherein the auto-increment of realizing by this tuner is controlled the circuit outgoing route of (AGC), described amplifier, and variable attenuator, frequency mixer, oscillator, Filter Structures sequence are: first order amplifier F
1(HE871) → first order variable attenuator KS
1(HE412A) → first order frequency mixer H
1(MCLSRA-2CM)+first order oscillator Z
1(OSC
1) → first order filter L
1(DIP-14B) → second level amplifier F
2(HE583) → second level variable attenuator KS
2(HE412A) → second level frequency mixer H
2(MCLSRA-2CM)+second level oscillator Z
2(OSC
2) → second level filter L
2(DIP-18B) → third level amplifier F
3(HE364) → third level variable attenuator KS
3, wherein, at the variable attenuator KS of each grade
1, KS
2, KS
3The equal correspondence of output the output AGC of AGC is set
1, AGC
2, AGC
3, and, at each grade amplifier F
1, F
2, F
3, variable attenuator KS
1, KS
2, KS
3, frequency mixer H
1, H
2, filter L
1, L
2Between the identical variable capacitor of a capacitance of all connecting.Really, core of the present invention is to have given prominence to high-frequency amplifier and variable attenuator.This be because: for amplifier, require its gain high, dynamic range is big.Gain is high, could guarantee that the total noise of centrifuge system is little, and enough multiplication factors are arranged during small-signal; Dynamic range is big, could guarantee when big field intensity, large-signal unsaturated, thereby guarantee that near end and the user who far holds can both receive high-quality TV programme.But high-gain, big dynamically this is a pair of contradiction, and according to traditional way, the high pipe that gain often is used on small-signal amplifies, produce to prevent intermodulation, and the pipe of high output level, noise factor is past relatively poor.If but satisfying under the prerequisite of noise factor, with the undistorted output level of amplifier single-stage for+14dbm is a sufficient and necessary condition, then can guarantee the unification that matches well of large-signal and small-signal; For electrically controlled attenuator, mainly contain 3 requirements: the one, attenuation is big, and the 2nd, attenuation characteristic is smooth; The 3rd, control voltage is low.Attenuation is convenient to greatly carry out circuit arrangement, and attenuation characteristic is smooth, and the signal transmission does not distort, and control voltage is low, can alleviate the difficulty of terminal agc circuit output.
In the solution of the present invention, when amplifier that has adopted the high-gain great dynamic range respectively and electrically controlled attenuator, fixedly amplifier can arrive at a high speed its optimum gain that, in its dynamic range maximum of this point, amplitude-frequency characteristic is the most smooth.Electrically controlled attenuator is born the AGC change in gain, and when its attenuation changed, its amplitude-frequency characteristic was also constant.When both sides are mated when good, in the AGC excursion, the amplitude-frequency characteristic of whole tuner has kept good even shape, but because first order high-frequency amplifier has higher gain, so noise factor does not have much deteriorations in the AGC scope, Here it is, and this programme improves greatly one of conventional tuner.
Claims (1)
1, a kind of large dynamic range low-noise factor harmonic tuner is by third stage amplifier F
1, F
2, F
3Three grades of variable attenuator KS
1, KS
2, KS
3Secondary frequency mixer H
1, H
2Two-stage oscillator Z
1, Z
2Two-stage filter L
1, L
2Constitute, it is characterized in that circuit outgoing route by the auto-increment control (AGC) of this tuner realization, described amplifier, variable attenuator, frequency mixer, oscillator, Filter Structures sequence are: first order amplifier F
1(HE871) → first order variable attenuator KS
1(HE412A) → first order frequency mixer H
1(MCLSRA-2CM)+first order oscillator Z
1(OSC
1) → first order filter L
1(DIP-14B) → second level amplifier F
2(HE583) → second level variable attenuator KS
2(HE412A) → second level frequency mixer H
2(MCLSRA-2CM)+second level oscillator Z
2(OSC
2) → second level filter L
2(DIP-18B) → third level amplifier F
3(HE364) → third level variable attenuator KS
3, wherein, at the variable attenuator KS of each grade
1, KS
2, KS
3The equal correspondence of output the output AGC of AGC is set
1, AGC
2, AGC
3, and, at each grade amplifier F
1, F
2, F
3, variable attenuator KS
1, KS
2, KS
3, frequency mixer H
1, H
2, filter L
1, L
2Between the identical variable capacitor of a capacitance of all connecting.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98103480 CN1092862C (en) | 1998-08-05 | 1998-08-05 | Large dynamic range low-noise factor harmonic tuner |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98103480 CN1092862C (en) | 1998-08-05 | 1998-08-05 | Large dynamic range low-noise factor harmonic tuner |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1211858A CN1211858A (en) | 1999-03-24 |
| CN1092862C true CN1092862C (en) | 2002-10-16 |
Family
ID=5217939
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 98103480 Expired - Fee Related CN1092862C (en) | 1998-08-05 | 1998-08-05 | Large dynamic range low-noise factor harmonic tuner |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1092862C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106896269A (en) * | 2015-12-18 | 2017-06-27 | 苏州普源精电科技有限公司 | A kind of spectrum analyzer for improving sensitivity |
-
1998
- 1998-08-05 CN CN 98103480 patent/CN1092862C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1211858A (en) | 1999-03-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C06 | Publication | ||
| PB01 | Publication | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20021016 Termination date: 20130805 |