CN204408615U

CN204408615U - Cable television system stereophonic signal emitter

Info

Publication number: CN204408615U
Application number: CN201520169193.3U
Authority: CN
Inventors: 吴圣铎
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-03-24
Filing date: 2015-03-24
Publication date: 2015-06-17
Anticipated expiration: 2025-03-24

Abstract

The utility model provides a kind of cable television system stereophonic signal emitter, its feature it draw together: 5V DC power supply, band pass filter, pre-amplification circuit, power amplification and emission of radio frequency signals circuit, the model that high-gain High frequency amplification integrated circuit (IC) 1 is selected is the model that μ PC1651, NPN transistor VT1 select is BFR91A.The equal transmitted frequency of wired city TV's system is the number cover FM stereophonic program of 88 ~ 108MHz, wireless receiving is carried out because major part can only carry antenna by FM receiver, even if manage with radio frequency line, user side box FM output to be linked with FM receiver input, because moving, it is also very inconvenient to use.Therefore, most family does not all effectively utilize the FM signal resource in cable TV, causes the waste of signal resource.Cable television system stereophonic signal emitter described in the utility model well solves the problem.

Description

Cable television system stereophonic signal emitter

Technical field

The utility model belongs to radio frequency technical field, particularly a kind of cable television system stereophonic signal emitter.

Background technology

At transmission multi-channel tv programs simultaneously, all in cable television system, transmitted frequency is the number cover FM stereophonic program of 88 ~ 108MHz to wired city TV's system, and on user side box, have TV and FM two output interfaces, wherein FM is FM multiplex output interface.Because most of FM receiver does not arrange FM signal input interface, therefore antenna can only be carried by FM receiver and carry out wireless receiving, even if manage user side box FM output to be linked with FM receiver input with radio frequency line, because moving, it is also very inconvenient to use.Therefore, most family does not all effectively utilize the FM signal resource in cable TV, causes the waste of signal resource.

Below describe in detail cable television system stereophonic signal emitter described in the utility model necessity involved in implementation process, guardian technique content.

Utility model content

Goal of the invention and beneficial effect: wired city TV's system at transmission multi-channel tv programs simultaneously, all in cable television system, transmitted frequency is the number cover FM stereophonic program of 88 ~ 108MHz, on user side box, have TV and FM two output interfaces, wherein FM is FM multiplex output interface.Because most of FM receiver does not arrange FM signal input interface, therefore antenna can only be carried by FM receiver and carry out wireless receiving, even if manage user side box FM output to be linked with FM receiver input with radio frequency line, because moving, it is also very inconvenient to use.Therefore, most family does not all effectively utilize the FM signal resource in cable TV, causes the waste of signal resource.Cable television system stereophonic signal emitter described in the utility model solves the problem well.

Circuit working principle: cable TV signal is after distributing, one tunnel exports as TV signal, another road exports FM signal through band pass filter, FM signal is exported through band pass filter, the FM signal exported outputs signal little 10db than TV signal, usually this is because the sensitivity of FM receiver is far above the sensitivity of television set.Do not arrange 88 ~ 108MHz band pass filter in some user side box, the effect of emitter is that the FM signal that FM interface exports is carried out filtering again, and is launched by antenna open circuit after carrying out power amplification, receives for FM receiver.Consider that the output of some user side box FM signal does not arrange band pass filter or filter effect is bad, therefore the input of emitter arranges especially and forms 88 ~ 108MHz band pass filter by inductance coil L1, electric capacity C1 ~ C2, for improving the performance of amplifying circuit, reduce the generation of combination frequency.In circuit, inductance coil L2, oscillator coil L3 are series resonant circuit, and also play certain band pass filter effect, the gain of complete machine is about 30db.

Technical scheme: cable television system stereophonic signal emitter, it comprises 5V DC power supply, band pass filter, pre-amplification circuit, power amplification and emission of radio frequency signals circuit, it is characterized in that:

Band pass filter: it is made up of radiofrequency signal socket RF, electric capacity C1, inductance L 1, electric capacity C2, radiofrequency signal socket RF connects one end of electric capacity C1, one end of another termination inductance coil L1 of electric capacity C1 and one end of electric capacity C2, the right side termination pre-amplification circuit of the shell end of radiofrequency signal socket RF and the other end connection circuit ground GND, the electric capacity C2 of inductance coil L1;

Pre-amplification circuit: it is made up of high-gain High frequency amplification integrated circuit (IC) 1, the model that high-gain High frequency amplification integrated circuit (IC) 1 is selected is μ PC1651, high-gain High frequency amplification integrated circuit (IC) 1 inputs the right-hand end of termination capacitor C2, the positive source connection circuit positive pole VCC of high-gain High frequency amplification integrated circuit (IC) 1, the power cathode connection circuit ground GND of high-gain High frequency amplification integrated circuit (IC) 1, connects power amplification and emission of radio frequency signals circuit after the output tandem electric inductance coil L2 of high-gain High frequency amplification integrated circuit (IC) 1 and electric capacity C3;

Power amplification and emission of radio frequency signals circuit: it is by resistance R1, resistance R2, NPN transistor VT1, oscillator coil L3, resistance R3, electric capacity C5, electric capacity C4 and transmitting antenna ANT forms, the model that NPN transistor VT1 selects is BFR91A, the base stage of NPN transistor VT1 connects one end of the right-hand end of electric capacity C3 and one end of resistance R1 and resistance R2, the collector electrode of NPN transistor VT1 connects one end of oscillator coil L3 and one end of coupling capacitance C4, the other end connection circuit positive pole VCC of oscillator coil L3, the other end of coupling capacitance C4 meets transmitting antenna ANT, one end of emitter connecting resistance R3 of NPN transistor VT1 and one end of electric capacity C5, the other end of resistance R3 and the other end connection circuit ground GND of electric capacity C5,

The positive pole of 5V DC power supply is connected with circuit anode VCC, and the negative pole of 5V DC power supply is connected with circuit ground GND.

Accompanying drawing explanation

Accompanying drawing 1 is the embodiment circuit working schematic diagram that the utility model provides a cable television system stereophonic signal emitter.

Embodiment

According to the cable television system stereophonic signal emitter circuit working schematic diagram shown in accompanying drawing 1 and accompanying drawing explanation, and according to annexation between components and parts in each several part circuit described in utility model content, and components and parts technical parameter described in execution mode requires and circuit production main points are carried out enforcement and can be realized the utility model, is further described correlation technique of the present utility model below in conjunction with embodiment.

The technical parameter of components and parts and selection requirement

VT1 is NPN transistor, selects low noise ultra high frequency transistor, and the model selected is BFR91A, requires multiplication factor β >=110;

IC1 is high-gain High frequency amplification integrated circuit, and the model selected is μ PC1651;

Inductance coil L1 ~ L3 all uses the enamelled wire of 0.51mm, and on ￠ 4mm metal cylinder, single flat is made around tread flaking, and inductance coil L1 is flat to be put down put down around 20 circles around 16 circles, oscillator coil L3 around 5 circles, inductance coil L2;

Resistance all selects 1/8W metalfilmresistor, and the resistance of resistance R1 is 5K Ω, and the resistance of resistance R2 is 510 Ω, and the resistance of resistance R3 is 56 Ω;

Electric capacity C1 ~ C5 all selects high frequency Leaded Ceramic Disc Capacitor, and the capacity of electric capacity C1 ~ C3 is 47PF, and the capacity of electric capacity C4 ~ C5 is 1000PF;

ANT is transmitting antenna, uses the telescopic antenna that length is 60cm;

The voltage of DC power supply DC is 5V, requires 5V DC power supply maximum output current >=100mA.

Circuit production main points and circuit debugging

Because utility model works is at hyper band, when design and fabrication printed circuit board, the configuration of components and parts and wire length will meet high-frequency design requirement, be welded to connect line as far as possible short, be advisable to be close to copper foil plate, high-gain High frequency amplification integrated circuit (IC) 1 and NPN transistor VT1 can directly be welded on copper-clad surface;

In order to avoid working point enters non-linear region, to the operating current of NPN transistor VT1 (BFR91A) be adjusted slightly larger, require the operating current >=30mA of NPN transistor VT1, if operating current does not meet, can the resistance of appropriate change resistance R1 realize;

Cable TV RF cable is connected to emitter radiofrequency signal input interface, FM receiver is received a FM signal near the centre frequency 98MHz of 88 ~ 108MHz, suitable shortening transmitting antenna ANT also pulls open certain distance, make the sound slightly noise received, then the spacing of coil L1 ~ L3 is stirred respectively, pass through adjusting inductance, make the tonequality in FM receiver best, noise is minimum, can ensure in 88 ~ 108MHz frequency range, have good operating characteristic with logical filter like this, sweep generator debugging is used as having ready conditions, then effect can be better,

Finally the transmitting antenna ANT of emitter is all pulled out, satisfied audibility can be obtained within the scope of 20m.

Circuit components layout of the present utility model, circuit structure design, its shape and size etc. of outward appearance are not all key technologies of the present utility model; neither the claimed technology contents of the utility model; because not affecting the utility model specific implementation process, therefore do not illustrate one by one in the description.

Claims

1. a cable television system stereophonic signal emitter, it comprises 5V DC power supply, band pass filter, pre-amplification circuit, power amplification and emission of radio frequency signals circuit, it is characterized in that:

Described band pass filter is made up of radiofrequency signal socket RF, electric capacity C1, inductance L 1, electric capacity C2, radiofrequency signal socket RF connects one end of electric capacity C1, another termination inductance coil L1 one end of electric capacity C1 and one end of electric capacity C2, the right side termination pre-amplification circuit of the shell end of radiofrequency signal socket RF and the other end connection circuit ground GND, the electric capacity C2 of inductance coil L1;

Described pre-amplification circuit is made up of high-gain High frequency amplification integrated circuit (IC) 1, the model that high-gain High frequency amplification integrated circuit (IC) 1 is selected is μ PC1651, high-gain High frequency amplification integrated circuit (IC) 1 inputs the right-hand end of termination capacitor C2, the positive source connection circuit positive pole VCC of high-gain High frequency amplification integrated circuit (IC) 1, the power cathode connection circuit ground GND of high-gain High frequency amplification integrated circuit (IC) 1, connects power amplification and emission of radio frequency signals circuit after the output tandem electric inductance coil L2 of high-gain High frequency amplification integrated circuit (IC) 1 and electric capacity C3;

Described power amplification and emission of radio frequency signals electricity routing resistance R1, resistance R2, NPN transistor VT1, oscillator coil L3, resistance R3, electric capacity C4, electric capacity C5 and transmitting antenna ANT forms, the model that NPN transistor VT1 selects is BFR91A, the base stage of NPN transistor VT1 connects one end of the right-hand end of electric capacity C3 and one end of resistance R1 and resistance R2, the collector electrode of NPN transistor VT1 connects one end of oscillator coil L3 and one end of coupling capacitance C4, the other end connection circuit positive pole VCC of oscillator coil L3, the other end of coupling capacitance C4 meets transmitting antenna ANT, one end of emitter connecting resistance R3 of NPN transistor VT1 and one end of electric capacity C5, the other end of resistance R3 and the other end connection circuit ground GND of electric capacity C5,

The positive pole of described 5V DC power supply is connected with circuit anode VCC, and the negative pole of 5V DC power supply is connected with circuit ground GND.