CN201533362U - Multimedia broadcast receiving voice-frequency circuit - Google Patents
Multimedia broadcast receiving voice-frequency circuit Download PDFInfo
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- CN201533362U CN201533362U CN2009201995435U CN200920199543U CN201533362U CN 201533362 U CN201533362 U CN 201533362U CN 2009201995435 U CN2009201995435 U CN 2009201995435U CN 200920199543 U CN200920199543 U CN 200920199543U CN 201533362 U CN201533362 U CN 201533362U
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Abstract
The utility model discloses a multimedia broadcast receiving voice-frequency circuit which mainly comprises a decoding chip, a preamplification circuit and a power amplifying circuit, wherein a circuit device is internally provided with integrated circuit chips CXA1691BM, LM358 and UTC3020A and a corresponding peripheral component, a band-pass filter is arranged in an input circuit on a signal input end P1, a high-side filtering unit is composed of a capacitor C1, an inductor L1 and a capacitor C2, a low-side filtering unit is composed of a capacitor C3, a capacitor C5 and an inductor L2, a band-pass filtering unit is composed of a capacitor C6, a capacitor C4 and an inductor L3, three units are connected in series front to rear and then connected with a high-frequency input pin 1FMRFIN of the chip CXA1691BM, a local oscillation amplifying circuit is arranged, a dual frequency division front mounted amplifying circuit is arranged, a front mounted amplifying circuit is composed of capacitors C9, C24 and C10, resistors R17, R24, R36, R14 and R5 and the chip LM358, and the other front mounted amplifying circuit is composed of capacitors C13, C25 and C14, resistors R9, R15, R18, R23 and R37 and the chip LM358. The multimedia broadcast receiving voice-frequency circuit has excellent anti-interference property, resolves the floating problem of frequencies outputted by sound box signals and is suitable for being used in countryside frequency modulation broadcast equipment.
Description
Technical field
The utility model relates to apparatus for receiving broadcasting.Specifically a kind of CMMB reception of Mobile Digital TV frequency modulation audio circuit, automobile broadcast reception and cable TV are total to the use of cable transmission system user terminal.
Background technology
On the one hand, as the audio amplifier of broadcast reception stereo set, from common audio amplifier, active audio amplifier, the application to the high frequency audio amplifier makes laser propagation effect, playing quality that very big progress and raising all arranged.
On the other hand, because FM broadcasting can be shared with the cable TV network of present employing, the popularization of the common cable transmission system of frequency modulation is imperative, and comes into effect in some place of China, but, have now and be installed in outdoor frequency modulation audio amplifier, because application conditions is poor, variations in temperature is big, still can the frequency of occurrences drift about and the mirror image interference phenomenon, so that the high-end distortion of volume appears, in addition noiseless, thereby be unfavorable for existing frequency modulation popularizing and development of cable transmission system altogether.
Common FM receiver has direct reference, can be used for repacking into the directly FM broadcasting broadcast equipment of input of signal.Fig. 1,2 is the application circuit of the disclosed amplitude-modulation frequency modulation receiver data of Sony company just.It is made of dedicated IC chip CXA1691BM and peripheral component: comprise the input circuit that antenna receives, signal input circuit, frequency modulation head integrated circuit (tuning circuit, High Amplifier Circuit, local oscillation circuit, mixting circuit), intermediate level circuit, frequency-discriminating circuit and automatic gain control/automatic frequency tuning circuit, detection/frequency-discriminating circuit, audio frequency pre-amplification circuit, power amplification circuit and power circuit.Generally speaking, select FM signal to insert by band switch and just can take, yet nonetheless, the drift of above-mentioned existence, interference problem still do not solve.
The utility model content
The utility model is will be on the basis of above-mentioned receiver, utilize its dedicated IC chip, and to input circuit, the frequency modulation tuning circuit is transformed, overcome the frequency drift and the mirror image interference problem that exist in the above-mentioned existing FM reception audio amplifier, stablize, export noise-free effect to reach the frequency reception.
For solving the problems of the technologies described above, the utility model has adopted following technical scheme:
The voicefrequency circuit that a kind of multimedia broadcasting of the present utility model receives, mainly form by decoding chip, preposition amplification and power amplification circuit, be provided with integrated circuit (IC) chip CXA1691BM, LM358, UTC3020A and corresponding peripheral component in the circuit arrangement, comprising signal input circuit, tuning circuit, High Amplifier Circuit, local oscillation circuit, mixting circuit, intermediate level circuit, frequency-discriminating circuit and automatic gain control/automatic frequency tuning circuit, detection/frequency-discriminating circuit, the audio frequency pre-amplification circuit, power amplification circuit and power circuit is characterized in that:
1) in the input circuit of signal input part P1, is provided with a band pass filter, form high-end filter unit by capacitor C 1, inductance L 1, capacitor C 2, form the low side filter unit by capacitor C 3, C5, inductance L 2, form the bandpass filtering unit by capacitor C 6, C4, inductance L 3, connect before and after three unit, then insert the high frequency input pin 1FMRFIN of chip CXA1691BM;
2) be provided with a local oscillation amplifying circuit: form local-oscillator circuit by both-end ceramic filter Y1, resistance R 4, R10, capacitor C 27, C30 and triode Q1; Insert pin FMOSC by resistance R 3, the local oscillation circuit that inserts chip, with the high-frequency tuning loop insert pin FMRF place by capacitor C 8, C22, C26, resistance R 1, inductance L 4, the circuit element that R2 forms the vibration coupling constitutes input and joins.
3) be provided with a two divided-frequency pre-amplification circuit: a routing capacitance C9, C24, C10, resistance R 17, R24, R36, R14, R5 and chip LM358 form pre-amplification circuit; Another routing capacitance C13, C25, C14, resistance R 9, R15, R18, R23, R37 and chip LM358 form pre-amplification circuit.
Described band pass filter, the capacitor C 1 of its high-end filter unit, C5 series connection, edge joint is the inductance L 1 and capacitor C 2 ground connection in parallel of centre; The capacitor C 5 of its low side filter unit, C6 series connection, inductance L 2 in the middle of being connected and capacitor C 3 parallel connections, ground connection; The capacitor C 6 of its bandpass filtering unit, C7 series connection, inductance L 3 in the middle of being connected and capacitor C 4 parallel connections, ground connection.
Described local oscillation amplifying circuit, its local-oscillator circuit is the local oscillation amplifying circuit of a band fixed intermediate frequency: the Colpitts oscillation circuit of being made up of both-end ceramic filter Y1, resistance R 4, R10, capacitor C 30, C27, triode Q1, both-end ceramic filter Y1 ground connection, signal takes out from resistance R 4 and inserts base stage, and the output of emitter resistance R9 connects the band pass filter that is made of resistance R 3, capacitor C 28.
Described two divided-frequency pre-amplification circuit, its two divided-frequency pre-amplification circuit is an amplifying circuit that two-way is independently exported: get in the middle of a routing resistance R5, the R14 and be divided to amplifier, resistance R 17, R36, R24, capacitor C 24 ground connection are formed negative feedback amplifier circuit, signal inserts amplifier from C9 and outputs to volume potentiometer R38 through capacitor C 10; Get in the middle of another routing resistance R9, the R15 and be divided to amplifier, resistance R 18, R37, R23, capacitor C 25 ground connection are formed negative feedback amplifier circuit, signal inserts amplifier from C13 and outputs to volume potentiometer R39 through capacitor C 14.
The utlity model has following good effect:
1) the appearance value changes the tunable capacitor in the primary circuit with variation of temperature, and Frequency point is changed, and produces and frequently floats.After the improvement,, fundamentally solved the frequency drift problem of audio amplifier signal output owing to adopted both-end ceramic filter (crystal oscillator) operation element of the very high quartz crystal of stability as local oscillation circuit.Test shows, this frequency modulation audio amplifier can be in-30 ℃ of-60 ℃ of temperature ranges operate as normal and can not occur frequently floating or the failure of oscillation phenomenon.
2) owing to adopted band pass filter and corresponding bypass setting, interference free performance is good.
3) do not crosstalk with not producing in the frequency frequency modulation transmission system yet, be suitable for using in the rural FM broadcasting equipment.
Description of drawings
Fig. 1 is the functional block diagram of the IC chip of prior art.
Fig. 2 is the circuit theory diagrams of prior art.
Fig. 3 is the circuit structure diagram of the utility model embodiment.
Fig. 4 is the circuit construction of electric power schematic diagram.
Wherein the corresponding pin of IC chip is:
1 bypass filtering pin MUTE; 2 both-end ceramic filter pin FM DISCR;
3 feedback pin NF; 4 volume control pin VOL CONT;
5 local oscillation circuits insert pin AM OSC; 6 automatic frequency tracking AFC;
7 local oscillation circuits insert pin FM OSC; 8 frequency stabilization output pin REG OUT;
Pin FM RFIN is inserted in 9 high-frequency tuning loops; 10 high frequency input pin AM RF IN;
11 empty pin NC; 12 high frequency input pin FM RF IN; 13 earth terminal GND (FE GND);
14 intermediate frequencies output (connecing filter) pin FM/AM FE OUT;
15 range switch BAND SELECT; 16 intermediate frequency input pin AM IF IN;
The empty pin NC of 17 intermediate frequency input pin FM IF IN:18; 19 tuning indication pin METER;
20 intermediate frequency grounding leg IF GND; 21 AFTs/automatic gain control AFC/AGC;
22 AFTs/automatic gain control AFC/AGC;
23 detection output pin DETOUT; 24 audio frequency input pin AFIN;
25 pressurizers meet end RIPPLEFILTER; 26 supply pin VCC;
27 audio frequency power amplifier output pin AFOUT; 28 earth terminal GND.
Embodiment
Be further described below in conjunction with embodiment and accompanying drawing thereof.
Be the integrated circuit (IC) chip and the application circuit of the disclosed a kind of amplitude-modulation frequency modulation receiver of Sony company as shown in Figure 1, 2.
The IC chip of Fig. 1 is CXA1691BM series, and is powerful, often is used in the dual-purpose receiver of amplitude modulationfrequency modulation.
Fig. 2 has provided the connection principle of the dual-purpose receiver of amplitude modulationfrequency modulation.Its integrated circuit (IC) chip CXA1691BM and peripheral component are formed circuitry together.Comprising: the input circuit that antenna receives, range switch, tuning circuit, High Amplifier Circuit, local oscillation circuit, mixting circuit, intermediate level circuit, frequency-discriminating circuit and automatic gain control circuit, audio power amplifier circuit, output circuit and power circuit.Some are external, and some are built-in.
The BM series of IC chip CXA1691 has 28 pins.Antenna inserts pin 12 through band pass filter BPF, empty pin 11 and grounding leg 13 ground connection, and the input resonant tank inserts high frequency input pin 10 or 9; Local-oscillator circuit is come by inductance coil L4 coupling respectively, taps into local oscillator and inserts pin 5 (AMOSC) or directly receive pin 7 (FMOSC); Mixting circuit is built-in, constitutes AFT or automatic gain control circuit respectively by pin 7-21,22, and capacitor C 13, C14 are electrochemical capacitor.Intermediate-freuqncy signal, then inserts from intermediate frequency input pin 16 (AM) or pin 17 (FM) through all CF2 (10.7MHz) frequency-selecting in all T1, CF1 (455B) the external amplitude modulation or the frequency modulation from 14 outputs of intermediate frequency output pin; The former through in put, the control of detection, automatic gain, from pin 23 (DETOUT) output, be coupled into audio frequency input pin 24 (AFIN) by capacitor C 15 and carry out power amplification, again by audio frequency output pin 27 (AFOUT) output audio signal; The latter's frequency modulation intermediate-freuqncy signal enters pin 17 (FMIFIN) through amplifying (FMIF), again through frequency discriminator (FMDISCRIMINATAOR) frequency discrimination, the audio signal of taking out is by the external CF3 frequency-selecting of pin 2, enter audio-frequency power amplifier (AMPOWERAMP) through the volume pin again, also export 27 output audio signals from audio frequency, transfer by external playback jack (EPJ), promote the loud speaker in the audio amplifier, realize broadcast, capacitor C 8 is coupled, feeds back to the audible feedback signal of pin 3, add in the circuit, play the effect of improving tonequality.Expression is by battery pack (BATT) power supply among the figure, and equipment band switch S1 control inserts the type of receipt of modulation signal in addition.The operating state of mains switch S2 may command receiver.
Fig. 3 is a circuit structure diagram of the present utility model, and its improvement circuit has only kept the groundwork circuit and the setting of frequency modulation work in the phenomenon technology, and the structure of belt energy filter has been proposed improved concrete scheme, and local oscillation circuit is transformed.
As shown in the figure, it utilizes the family chip of integrated circuit CXA1691.This figure is an example with IC chip CXA1691BM, and selecting for use with external setting in its 28 pin is as follows successively:
1MUTE: bypass filtering pin is connected to shunt capacitance C35.
2FMDISCRI: both-end ceramic filter Y3, the series loop of resistance R 11.
The only external electrochemical capacitor C29 of 3NF feedback pin.
4VOLCONT: volume control pin and tuning indication pin 19 are connected to resistance R 7, and are connected with filter capacitor C17 to pin 19, and R6 is a divider resistance.
It is vacant that the 5AMOSC:AM local oscillation circuit inserts pin.
6AFC: automatic frequency tracking (variable capacitance) inserts pin and AFT/automatic gain control pin has resistance R 22, and is connected with capacitor C 23 to pin 7.
The 7FMOSC:FM local oscillation circuit inserts the oscillator-amplification circuit of this machine of the outer tape splicing fixed intermediate frequency of pin, by both-end ceramic filter Y2, resistance R 4, R10, R3, the capacitance three-point type local-oscillator circuit that capacitor C 30, C27, triode Q1 form, signal takes out from resistance R 4 and inserts base stage, and inserts chip pin 7 with electric capacity C28 coupling output.R1, R2 are biasing resistor, and C8, C22 are shunt capacitance; The vibration coupling circuit element of forming with the capacitor C 26 that inserts pin 9 places, C22, C8, resistance R 1, inductance L 4 constitutes the input connection.
8REGOUT: the frequency stabilization output pin is external to link to each other with the end that connects of L4, R1, and only plays connecting path.Because pin 8 is connected built-in variable capacitance diode with 6 on pin, and pin 6 is vacant.
9FMRF: the L4 that high-frequency tuning loop pin connects resonance input connection, realize input.
10AMRFIN:AM high frequency input pin is vacant.
11NC: empty pin ground connection.
12FMRFIN: the high frequency input pin connects the radio network interface of signal input part P1, and set therebetween belt energy filter is a composite construction.The capacitor C 1 of its high-end filter unit, C5 series connection are connected two electric capacity middle inductance L 1 and capacitor C 2 ground connection in parallel; The capacitor C 5 of its low side filter unit, C6 series connection, inductance L 2 and capacitor C 3 ground connection in parallel in the middle of being connected; The capacitor C 6 of its bandpass filtering unit, C7 series connection, inductance L 3 and capacitor C 4 ground connection in parallel in the middle of being connected, series connection before and after three unit, remove useless clutter, make useful modulation signal be linked into the chip input, sending and receiving emitter-base bandgap gradings in the pin 12 connect the collector electrode of same triode in the pin 9.
13GND (FEGND), earth terminal ground connection.
14FM/AMFEOUT: 17 of intermediate frequency output pin intermediate frequency input pins insert three end ceramic filter Y1.
15BANDSELECT: ground connection behind the range switch pin connection shunt capacitance C50.
16AMIFIN:AM intermediate frequency input pin ground connection or vacant.
17FMIFIN: the intermediate frequency input pin meets three end ceramic filter Y1 (described with pin 14)
18NC: empty pin ground connection.
19METER: ground connection behind the external filter capacitor C17 of tuning indication pin.
20IFGND: intermediate frequency grounding leg ground connection;
21AFC/AGC: AFT/automatic gain control pin connects electrochemical capacitor C57 ground connection;
22AFC/AGC: AFT/automatic gain control pin connects electrochemical capacitor C18 ground connection;
23DETOUT: the detection output pin connects high-frequency bypass capacitor C16 ground connection, meets coupling capacitance C58 to pin 24.
24AFIN: the audio frequency input pin meets C58;
25RIPPLEFILTER: pressurizer connects termination filter capacitor C21 ground connection.
26VCC: supply pin connects the power supply direct-flow input end.
27AFOUT: the audio frequency power amplifier output pin connects high-frequency bypass capacitor C20 ground connection, and meets coupling capacitance C12 to the output interface.
28GND: earth terminal ground connection.
Figure 4 shows that the power circuit of audio amplifier, adopt simple bridge rectifier and filtering can satisfy the needs of audio amplifier dc supply.
Below sketch the course of work of audio amplifier:
At first, the signal access port of audio amplifier and the FM signal line interface of cable tv broadcast network are connected.
Then, connect the dc supply of audio amplifier, perhaps power turn-on switch, the frequency modulation audio amplifier gets final product work.
During work, the CF signal of FM broadcasting is earlier through band pass filter, the clutter that the filtering passband is outer, to reduce noise jamming, be linked into the pin 12 of chip IC again, the resonant circuit signal combination external with pin 9 produces difference frequency, and and the local oscillation amplifying signal that enters of pin 7 carry out mixing, high frequency carrier mixed frequency signal from pin 14 outputs, select intermediate-freuqncy signal through three end ceramic filter filtering, enter pin 17 again and carry out the intermediate frequency amplification, obtain audio signal through the frequency discriminator frequency discrimination, this audio signal is introduced from volume control pin 4 and is carried out power amplification, at last from 27 outputs of audio frequency output pin, its external socket is connected with the loudspeaker unit of audio amplifier, goes out sound by loudspeaker plays.
This audio amplifier adopts metallic resistance, stable performance, and constant volume is regulated, designs simplification, sound is loud and clear, and is undistorted.
The technical program compares with improving preceding prior art performance parameter, and test value is as follows:
This improvement of test parameter prior art technical scheme
Operating frequency 87-108MHz 87-108MHz
Frequency stability 1.0 * 10
-41.1 * 10
-5
Frequency accuracy (30 ℃-+70 ℃)＜5.4KHz＜5KHz
The basic mechanical design feature index of two kinds of embodiment audio amplifiers: (87-108MHz)
| Index | 1 (outdoor) | 2 (indoor) |
| The frequency long-term stability | 1.1×10 -5 | 1.1×10 -5 |
| Frequency accuracy (30-+70 ℃) | ＜5KHz | ＜5KHz |
| Specified incoming level (FM) | 50±5dBu | 50±5dBu |
| Squelch opening level | 38±2dBu | 38±2dBu |
| Rated output power | 40W | 10W |
| Supply power mode | 220V±20％ | 220V±20％ |
| Standby current | ＜10mA | ＜8mA |
(50dBu ± 5dBu) overall performance of audio amplifier is respond well for the input of CATV coaxial cable high-frequency signal source.
Claims (4)
1. the voicefrequency circuit that receives of a multimedia broadcasting, mainly form by decoding chip, preposition amplification and power amplification circuit, be provided with integrated circuit (IC) chip CXA1691BM, LM358, UTC3020A and corresponding peripheral component in the circuit arrangement, comprising signal input circuit, tuning circuit, High Amplifier Circuit, local oscillation circuit, mixting circuit, intermediate level circuit, frequency-discriminating circuit and automatic gain control/automatic frequency tuning circuit, detection/frequency-discriminating circuit, the audio frequency pre-amplification circuit, power amplification circuit and power circuit is characterized in that:
1) in the input circuit of signal input part P1, is provided with a band pass filter, form high-end filter unit by capacitor C 1, inductance L 1, capacitor C 2, form the low side filter unit by capacitor C 3, C5, inductance L 2, form the bandpass filtering unit by capacitor C 6, C4, inductance L 3, connect before and after three unit, then insert the high frequency input pin 1FMRFIN of chip CXA1691BM;
2) be provided with a local oscillation amplifying circuit: form local-oscillator circuit by both-end ceramic filter Y1, resistance R 4, R10, capacitor C 27, C30 and triode Q1; Insert pin FMOSC by resistance R 3, the local oscillation circuit that inserts chip, with the high-frequency tuning loop insert pin FMRF place by capacitor C 8, C22, C26, resistance R 1, inductance L 4, the circuit element that R2 forms the vibration coupling constitutes input and joins.
3) be provided with a two divided-frequency pre-amplification circuit: a routing capacitance C9, C24, C10, resistance R 17, R24, R36, R14, R5 and chip LM358 form pre-amplification circuit; Another routing capacitance C13, C25, C14, resistance R 9, R15, R18, R23, R37 and chip LM358 form pre-amplification circuit.
2. the voicefrequency circuit that a kind of multimedia broadcasting according to claim 1 receives is characterized in that described band pass filter, the capacitor C 1 of its high-end filter unit, C5 series connection, and edge joint is the inductance L 1 and capacitor C 2 ground connection in parallel of centre; The capacitor C 5 of its low side filter unit, C6 series connection, inductance L 2 in the middle of being connected and capacitor C 3 parallel connections, ground connection; The capacitor C 6 of its bandpass filtering unit, C7 series connection, inductance L 3 in the middle of being connected and capacitor C 4 parallel connections, ground connection.
3. the voicefrequency circuit that a kind of multimedia broadcasting according to claim 1 receives, it is characterized in that described local oscillation amplifying circuit, its local-oscillator circuit is the local oscillation amplifying circuit of a band fixed intermediate frequency: the Colpitts oscillation circuit of being made up of both-end ceramic filter Y1, resistance R 4, R10, capacitor C 30, C27, triode Q1, both-end ceramic filter Y1 ground connection, signal takes out from resistance R 4 and inserts base stage, and the output of emitter resistance R9 connects the band pass filter that is made of resistance R 3, capacitor C 28.
4. the voicefrequency circuit that a kind of multimedia broadcasting according to claim 1 receives, it is characterized in that described two divided-frequency pre-amplification circuit, its two divided-frequency pre-amplification circuit is an amplifying circuit that two-way is independently exported: get in the middle of a routing resistance R5, the R14 and be divided to amplifier, resistance R 17, R36, R24, capacitor C 24 ground connection are formed negative feedback amplifier circuit, signal inserts amplifier from C9 and outputs to volume potentiometer R38 through capacitor C 10; Get in the middle of another routing resistance R9, the R15 and be divided to amplifier, resistance R 18, R37, R23, capacitor C 25 ground connection are formed negative feedback amplifier circuit, signal inserts amplifier from C13 and outputs to volume potentiometer R39 through capacitor C 14.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009201995435U CN201533362U (en) | 2009-11-05 | 2009-11-05 | Multimedia broadcast receiving voice-frequency circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009201995435U CN201533362U (en) | 2009-11-05 | 2009-11-05 | Multimedia broadcast receiving voice-frequency circuit |
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| Publication Number | Publication Date |
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| CN201533362U true CN201533362U (en) | 2010-07-21 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN2009201995435U Expired - Fee Related CN201533362U (en) | 2009-11-05 | 2009-11-05 | Multimedia broadcast receiving voice-frequency circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107579742A (en) * | 2017-08-10 | 2018-01-12 | 江西吉斯电子科技有限公司 | A kind of new frequency modulation transmitter |
-
2009
- 2009-11-05 CN CN2009201995435U patent/CN201533362U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107579742A (en) * | 2017-08-10 | 2018-01-12 | 江西吉斯电子科技有限公司 | A kind of new frequency modulation transmitter |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20100721 Termination date: 20161105 |