CN2153180Y

CN2153180Y - Fm costant frequency receiver

Info

Publication number: CN2153180Y
Application number: CN 93236277
Authority: CN
Inventors: 王强
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-02-16
Filing date: 1993-02-16
Publication date: 1994-01-12
Anticipated expiration: 2003-02-16

Abstract

The utility model discloses an FM constant frequency receiver, comprising a tuning loop, an intermediate amplifying circuit, a frequency discrimination device, a low amplification circuit, and a loudspeaker. The tuning loop is formed by that a capacitor with fixed amount of capacitance and an inductor with fixed amount of inductance are connected in parallel. The finished goods of the utility model can be used in FM broadcasting areas which have the same receiving frequency as the receiving frequency of the finished goods of the utility model, and thereby, external tuning turn knobs are saved, cost is lowered, and adjustable elements are reduced. Under the condition that current development of wired broadcasting programs uses means of wireless transmission, the utility model is favorable to the popularization of the covering areas of wired broadcasting networks, the saving of investments in lines, and the improvement of sound quality. The utility model is convenient for management departments to manage broadcast users.

Description

FM costant frequency receiver

The utility model relates to a kind of broadcast receiver.

At present, existing FM receiver changes receive frequency by the variable capacitance of adjusting resonant tank, in some areas of using the dedicated broadcast modulation frequency and transmitting broadcast singal with wireless transmission, general citizens' radio band can't the special-purpose tranmitting frequency of topped broadcasting, even satisfy toppedly by the method that changes component parameters, but adjust when listening to very inconvenient.

The purpose of this utility model provide a kind of resonant tank fixedly the resonance frequency modulation of broadcasting on the special-purpose tranmitting frequency in the locality decide frequency receiver.

The utility model can be realized by following technical proposal:

That the utility model comprises is tuning, in put, frequency discrimination, lowly put, loud speaker, described tuningly be formed in parallel by the electric capacity of fixed capacity amount and the inductance of fixed inductance amount.When the utility model uses, receive the fm broadcast signal of the special-purpose tranmitting frequency emission of local broadcasting by antenna, antenna is input to resonant tank with the signal that receives, resonant tank fixedly resonance in this frequency, go out intermediate-freuqncy signal through local oscillation and its mixing, intermediate level frequency discrimination promotes the loud speaker playback through low putting then.

The utility model compared with prior art has following advantage:

The utility model belongs to a kind of frequency modulation of special use and decides frequency receiver, just can use in the FM broadcasting zone identical with its receive frequency in case produce finished product, has omitted outside tuning knob, can reduce cost, and reduces adjustable element.Use at current development wired broadcasting program under the situation of wireless transmission means, help promoting the cable radio network coverage rate, save track investment, improve sound quality, be convenient to the management of administrative department broadcasting user.

Below in conjunction with drawings and Examples the utility model is further described:

Accompanying drawing 1 is a circuit block diagram of the present utility model;

Accompanying drawing 2 is the circuit theory diagrams of a kind of embodiment of the present utility model;

Accompanying drawing 3 is the circuit theory diagrams of another kind of embodiment of the present utility model.

Embodiment one: referring to accompanying drawing 1 circuit block diagram and accompanying drawing 2 circuit theory diagrams.By integrated circuit CXA1019P is the main circuit of the present utility model of forming.The high-frequency signal that antenna receives is imported by 12 pin, the C1 that is connected into outward by 9 pin, the frequency of 41 resonance of L1 high-frequency tuning network decision receive frequency, carry out the intermediate-freuqncy signal that mixing obtains 10.7MHZ with external C2, the L2 local-oscillator circuit of 7 pin again and export, after the filtering of 10.7MHZ intermediate-frequency filter, send into 17 pin intermediate level circuits 42 and put in carrying out by 14 pin.External 1 10.7MHZ frequency discrimination ceramic filter of 2 pin and resistance serial connection are the phase-shift network of quadrature frequency discriminator 43.23 pin are that the low frequency signal behind the frequency discrimination is sent into 45 pronunciations of low discharging circuit 44,27 pin output promotion loud speaker from 24 pin.4 pin are that electronic sound volume adjustment, all the other electric capacity are high frequency bypass and low frequency filtering is used in the circuit.C1, C2 adopt fixed capacity or the outer nonadjustable variable capacitance of machine, fine setting L1, L2 decision receive frequency.

Embodiment two: press accompanying drawing 1 circuit block diagram and accompanying drawing 3 circuit theory diagrams.By integrated circuit TDA7010 is the main circuit of the present utility model of forming.The high-frequency signal that antenna receives is input to the wide-band tuning loop from 61 pin.54, the tuning 41 decision frequencies of oscillation formed of external L3, the C3 of 55 pin, after inner and input signal mixing, produce this machine intermediate frequency, in amplitude limit, put 42, frequency discrimination 43, secondary are low puts 44 and amplify the back by 52 pin output audio signals, this audio signal can promote loud speaker 45 pronunciations (omission in the accompanying drawing 2) behind power amplifier.Inside is provided with frequency locked loop and relevant squelch circuit.C3 gets fixed capacity or the outer nonadjustable variable capacitance of machine in L3, the C3 oscillation circuit, fine setting L3 decision complete machine receive frequency.All the other electric capacity are high-frequency bypass capacitor in the circuit.

Among the foregoing description one, the embodiment two, cross-over connection has automatic frequency tuning circuit 46 between the input of IC interior tuning 41 and the output of frequency discrimination 43, and this circuit can make receive frequency be stabilized on the frequency of predetermined set.42 make intermediate frequency amplifies.44 is low-frequency amplifier circuit.Promote loud speaker 45 pronunciations at last.

Claims

1, a kind of frequency modulation is decided frequency receiver, comprise tuning 41, in put 42, frequency discrimination 43 and lowly put 44, loud speaker 45, it is characterized in that: described tuning 41 are formed in parallel by the electric capacity of fixed capacity amount and the inductance of fixed inductance amount.

2, frequency modulation according to claim 1 is decided frequency receiver, it is characterized in that: cross-over connection has automatic frequency tuning circuit 46 between the output of described tuning 41 input and frequency discrimination 43.