CN2646959Y - Transmitting and receiving apparatus of small area full solid-state FM/SCA broadcast - Google Patents

Abstract

A transmitting and receiving apparatus of small area full solid-state FM/SCA broadcast comprises a vice-carrier wave modulation circuit comprising a frequency input and amplification circuit, a 67kHz oscillation circuit (OCS) and smooth circuit, an FM modulation circuit, a radio frequency power amplification circuit and an LC match network. The FM modulation circuit is connected with the radio frequency power amplification circuit. The power amplification circuit is connected with the LC match network and output to an emitting antenna. The frequency input 1 is first modulated on a 67kHz frequency carried circuit and sent to the FM modulation circuit, and amplified by the radio frequency power amplification level and connected with the LC match network. A reception apparatus comprises a high frequency amplification circuit which is provided with two parallel outputs on output end, wherein, one path reaches a special chip FM mixed frequency circuit through a capacitance and demodulates a frequency 2 signal through a first middle amplifier, a second middle amplifier and an FM demodulation circuit, while the other patch is connected with a frequency selection network to select out the SCA signal. The broadcast function has more types if opening the FM/SCA.

Description

The sending and receiving device of all solid state FM/SCA broadcasting in zonule

One, technical field

The invention belongs to a new technology of frequency modulation (FM) broadcasting category, the signal sending and receiving device that especially utilizes FM subcarrier sc A to broadcast.

Two, background technology

It is generally acknowledged that FM receiver can only be used for receiving FM broadcasting, few people know by FM can also realize the SCA function.SCA broadcasting is piloting first that the U.S. carried out in 40 years the earliest, pilots specifically and achieves success, and belong to government and support energetically that fiscal the profit financial support that become up to this class radio station just stops.The broadcasting purpose of SCA has a lot, it can make the pure background music that does not intercut any advertisement, aim at dining room, cafe, market and supermarket background music is provided, also can be used as medical news, dialect program or athletic competition report, the program that the press service aspect is provided is also arranged.

International SCA subcarrier adopts 67kHz and 92kHz mostly, the report that is used for traffic at European SCA the earliest, the frequency of subcarrier is 57kHz, the broadcasting of SCA subcarrier is usually used in the broadcast program of non-public formula, transmitting background music uses for coffee-house or dining room, also there is the demand of this respect in megastore and supermarket, also are used for doing the quotations on the stock market report, do the transmission of data information abroad in addition.The SCA modulation system belongs to frequency modulation (FM) mode, and maximum frequency deviation is ± 7.5kHz that it transmits from high-fidelity also has a segment distance.In the ideal case, the SCA of FM stereophonic broadcast can only represent 10% of the total transmission of power of FM at most, therefore the user has a hunch that signal is more weak when receiving SCA broadcasting, sometimes noise is also big relatively, this mainly is that the SCA modulation system determines, whether the processing according to the design conditions of FM receiver and SCA signal transmission end is appropriate, and the actual SCA signal of receiving should be able to bear the clashing of main carrier in FM broadcasting station.It more than is the certain situation of early stage high power valve FM/SCA.

Three, summary of the invention

The present invention's purpose is exactly the demand that this respect is arranged at the domestic market, all be single frequency modulated transmitter for example as the radio station, campus, some colleges and universities are in order to satisfy the teaching needs, usually need purchase several frequency modulated transmitters, colleges and universities have several transmitters, uneconomical just one side, main waste limited frequency resource, make the electromagnetic environment of surrounding area become badly, have a cover " all solid state FM/SCA broadcast system in zonule ", machine can support two with, for example FM sends English, SCA broadcasts Japanese, and English and Japanese send simultaneously, selects to listen to for the student.Also can send two other English Broadcasting of level simultaneously, the present invention also provides the service of goods chance for some other special user.

1, sends part

Dispensing device is partly seen block diagram 1.Audio frequency input 1,2 can be respectively from microphone, tape or CD, the audio output part branch of VCD video disc player, the gain of audio frequency amplifying stage should not be too big, the distortion factor requires to be controlled at about 1%, 67kHz oscillating circuit (OCS) and smoothing circuit are to be served as by an integrated circuit, constitute so-called subcarrier circuit, be referred to as primary modulation again, promptly audio frequency input 1 is modulated at earlier on the 67kHz carrier frequency, smoothing circuit is that the 67kHz distorted waveform is proofreaied and correct, be sent to the FM modulation circuit again through smoothing circuit output, this process claims secondary modulation, is sent to the radio-frequency power amplifying stage then and amplifies.The design's circuit can provide the radio-frequency power grade of 0.5～5W, can satisfy and cover medium scale campus.Must be the LC matching network after the power amplifier, be mainly used to the each harmonic on filtering main signal 88.5MHz both sides, the filtering harmonic wave is actual to be inhibition to harmonic wave, finally allows main signal 88.5MHz be gone out by antenna transmission with the loss of minimum.Audio signal 2 is sent to the FM modulation circuit after being amplified by audio frequency, and this is general frequency modulation modulated process, here no longer statement.

2, receiving unit

The circuit block diagram of receiving system such as Fig. 2.High Amplifier Circuit is the one-level low noise amplifier, be mainly used to amplify 88～108MHz high-frequency signal, the High Amplifier Circuit output has 2 the tunnel to be arranged in parallel, the one routing capacitance special chip mixting circuit that goes directly, the SCA desired signal is then selected by frequency-selective network in another road, make this signal present maximum at the frequency-selective network two ends, choose the back directly to be sent to the SCA mixting circuit, produce an intermediate frequency after the mixing, amplify through the two-stage intermediate frequency, demodulate audio signal 1 by the SCA demodulator circuit, same, the FM mixing of block diagram down of high-frequency signal process, in put I, in put II and FM demodulation circuit, demodulate audio signal 2.The behind of receiver is provided with a toggle switch, selects when listening to for the user.Because the tranmitting frequency 88.5MHz of transmitter system falls in 88～108MHz scope, the user both can listen to the campus program of radio station, simultaneously FM broadcasting that again can the uppick locality.

The beneficial effect of the invention

In those early years the stock market information that once intercutted at the city FM radio station has utilized the SCA technology exactly, because the checking station, city requires power big, it is power emission tube that some equipment still adopt electron tube, power consumption is big, is unfavorable for popularizing civilian, and " all solid state FM/SCA broadcast system in zonule " can fill up this blank, except supplying with the campus use, also can be used for other special dimensions, and cost is low, stable and reliable for performance.

Offer the FM/SCA broadcast capability and also have a lot, except being used for language broadcasting, can also provide background music, function leaved for development also has the transmission etc. of colour TV signal of transmission, data fax, telegram and the low scanning occasion of data information.

Four, description of drawings

Fig. 1 is a dispensing device circuit block diagram of the present invention

Fig. 2 is a receiving system circuit block diagram of the present invention

Fig. 3 is vibration of the 67KHz in the dispensing device of the present invention and smoothing circuit

Fig. 4 is the complete circuit of the SCA demodulator in the receiving system of the present invention

Five, embodiment

Fig. 3 is 67KHzOSC and smoothing circuit, audio signal is delivered to the 2nd pin of U1 the 67KHz frequency of oscillation is modulated, the frequency of oscillation of oscillator is by R1, R2 and the common decision of C3, here the 67KHz frequency of oscillation is mainly determined by an adjustable resistance R 2, regulates the height that the R2 value can change frequency of oscillation.C3 is an output capacitance, the 67KHz square-wave signal is sent to next stage by it, transistor amplifier circuit TR, R3 and coupling transformer T1 form smoothing circuit jointly, the adding of this grade is beneficial to improving distorted waveform, the main function of this grade is that square wave is converted to sine wave, except that above-mentioned functions, also the 67KHz frequency there is certain gain amplifier simultaneously.Can finish from audio frequency by Fig. 3 circuit and to be injected into this process of 67KHz frequency modulation(FM).

Fig. 4 is the complete circuit of SCA demodulator, and integrated circuit U1 was a communication equipment special chip originally, here we as the SCA demodulation, it has characteristics such as low in energy consumption, gain height and demodulation characteristics are good with it.High-frequency signal after the amplification at first carries out frequency-selecting through frequency-selective network, make this signal present maximum at the LC two ends, be sent to mixting circuit (being 1,2 pin of U1) then and carry out mixing, the intermediate frequency after the mixing can be 455KHz, also can be near the 465KHz equifrequent the 455KHz.

6,7,8 pin of U1 inside are quadrature network, quadrature coil T2 can make the intermediate-freuqncy signal of choosing produce phase shift, the output amplitude of quadrature detector is directly proportional with the frequency deviation of input FM signal, audio signal after the demodulation is sent by 9 pin after internal damping amplifies, thereby has finished the demodulating process to SCA.

Claims (3)

1, the dispensing device of all solid state FM/SCA broadcasting in zonule, comprise audio frequency input and amplifying circuit, the sub-carrier modulation circuit that 67kHz oscillating circuit (OSC) and smoothing circuit constitute, the FM modulation circuit, rf power amplifier circuit and LC matching network are formed, connect rf power amplifier circuit behind the FM modulation circuit, power amplification circuit connects the LC matching network and transports to transmitting antenna, it is characterized in that described 67kHz oscillating circuit (OSC) and smoothing circuit are to constitute the sub-carrier modulation circuit by an integrated circuit and transistor T R1, wherein the input of one road audio frequency is modulated at earlier on the 67kHz carrier-frequency circuit, connect the smoothing circuit that the 67kHz distorted waveform is proofreaied and correct again, the FM modulation circuit is sent in smoothing circuit output again, connecting the radio-frequency power amplifying stage then and amplify, is the LC matching network after the power amplifier.

2, by the dispensing device of all solid state FM/SCA broadcasting in the described zonule of claim 1, it is characterized in that forming smoothing circuit jointly by transistor T R, R3 and coupling transformer T1.

3, the receiving system of all solid state FM/SCA broadcasting in zonule, comprise that high-frequency amplifier circuit High Amplifier Circuit output has 2 tunnel outputs in parallel, the one routing capacitance special chip FM mixting circuit that goes directly, by put in the level of back I, in put II and FM demodulation circuit, demodulate audio signal (2); It is characterized in that another road connects frequency-selective network and selects the SCA desired signal, choose the back directly to be sent to the SCA mixting circuit, produce an intermediate frequency after the mixing, amplify through the two-stage intermediate frequency, demodulate audio signal (1) by the SCA demodulator circuit, the behind of receiver is provided with the toggle switch that an output in parallel is selected.

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