CN205453684U - Intercom modulation demodulation circuit - Google Patents

Abstract

The utility model discloses an intercom modulation demodulation circuit, including resistance R1, electric capacity C1, triode VT, electric capacity C1 diode VD1 and inductance L, resistance R1 one end is connecting resistance R3, resistance R5 and power VCC respectively, and electric capacity C1, resistance R2 and triode VT base are connected respectively to the resistance R1 other end, and triode VT collecting electrode is the connecting resistance R3 other end and electric capacity C2 respectively. The utility model discloses a triode is constituteed with some resistor -Capacitor units, the drift that effectively prevents voltage controlled oscillator will cause drift and the throw off of comparator operating point, when modulating signal vi adds to frequency modulation modulated circuit, the "Frequency" of circuit can change, when the positive half cycle of modulating signal vi comes, "Frequency" rises, when modulating signal vi burden half cycle comes, "Frequency" descends, thereby the frequency modulated(FM) signal that messenger's frequency modulation modulated circuit output frequence changes along with modulating signal vi voltage variation, the modem demand that satisfies the intercom that can be fine, simple structure of the circuit, low cost, and small in size.

Description

A kind of transmitter receiver modulation-demodulation circuit

Technical field

This utility model relates to a kind of signal processing circuit, specifically a kind of transmitter receiver modulation-demodulation circuit.

Background technology

Development along with wireless communication technology, the application with transmission that gathers of wireless data is constantly expanding, in terms of observing and controlling industrial, military, some measuring control point ratio is relatively decentralized, the laying and the maintenance that make Wireline are both needed to higher cost, especially for the data transmission on moving link and the collection of data so that Data Over Cable becomes impossible.Therefore wireless RF data tranmission techniques is used to carry out the development trend that data communication is modern test and control Data transfer system.

Existing transmitter receiver modulation-demodulation circuit uses comparator to constitute mostly, tracking frequency can offset in the widest frequency range, but, for the signal that frequency deviation is less, owing to demodulated output signal is little, the drift of voltage controlled oscillator will cause the drift of comparator operating point to produce error, and this utility model provides a kind of modulation and demodulation method not using comparator.

Utility model content

The purpose of this utility model is to provide a kind of transmitter receiver modulation-demodulation circuit, with the problem solving to propose in above-mentioned background technology.

For achieving the above object, the following technical scheme of this utility model offer:

nullA kind of transmitter receiver modulation-demodulation circuit，Including resistance R1、Electric capacity C1、Audion VT、Electric capacity C1 diode VD1 and inductance L，Described resistance R1 one end connects resistance R3 respectively、Resistance R5 and power supply VCC，The resistance R1 other end connects electric capacity C1 respectively、Resistance R2 and audion VT base stage，Audion VT colelctor electrode connects the resistance R3 other end and electric capacity C2 respectively，The electric capacity C2 other end connects electric capacity C3 respectively、Electric capacity C5、Inductance L and output end vo，The electric capacity C3 other end connects electric capacity C4 respectively、Diode VD2 negative pole、Resistance R4 and audion VT emitter stage，The described electric capacity C5 other end connects diode VD1 negative pole respectively、The resistance R5 other end、Resistance R6 and resistance R7，The resistance R7 other end connects modulated signal Vi，The described inductance L other end connects the resistance R6 other end respectively、Diode VD1 positive pole、The electric capacity C4 other end、Diode VD2 positive pole、The resistance R4 other end、The resistance R2 other end and the electric capacity C1 other end ground connection.

As this utility model further scheme: described diode VD2 is Zener diode.

Compared with prior art, the beneficial effects of the utility model are: this utility model transmitter receiver modulation-demodulation circuit uses audion and some Resistor-Capacitor Units to form, the drift effectively preventing voltage controlled oscillator will cause the drift of comparator operating point to produce error, when modulated signal Vi is added to fm modulation circuit, the frequency of oscillation of circuit can change, when the positive half cycle of modulated signal Vi comes, frequency of oscillation rises, when modulated signal Vi negative half period comes, frequency of oscillation declines, so that the FM signal that fm modulation circuit output frequency changes with modulated signal Vi change in voltage, it is well positioned to meet the modulation /demodulation demand of transmitter receiver, circuit structure is simple, low cost, volume is little.

Accompanying drawing explanation

Fig. 1 is the circuit diagram of transmitter receiver modulation-demodulation circuit.

Detailed description of the invention

Below in conjunction with the accompanying drawing in this utility model embodiment, the technical scheme in this utility model embodiment is clearly and completely described, it is clear that described embodiment is only a part of embodiment of this utility model rather than whole embodiments.Based on the embodiment in this utility model, the every other embodiment that those of ordinary skill in the art are obtained under not making creative work premise, broadly fall into the scope of this utility model protection.

nullRefer to Fig. 1，In this utility model embodiment，A kind of transmitter receiver modulation-demodulation circuit，Including resistance R1、Electric capacity C1、Audion VT、Electric capacity C1 diode VD1 and inductance L，Described resistance R1 one end connects resistance R3 respectively、Resistance R5 and power supply VCC，The resistance R1 other end connects electric capacity C1 respectively、Resistance R2 and audion VT base stage，Audion VT colelctor electrode connects the resistance R3 other end and electric capacity C2 respectively，The electric capacity C2 other end connects electric capacity C3 respectively、Electric capacity C5、Inductance L and output end vo，The electric capacity C3 other end connects electric capacity C4 respectively、Diode VD2 negative pole、Resistance R4 and audion VT emitter stage，The described electric capacity C5 other end connects diode VD1 negative pole respectively、The resistance R5 other end、Resistance R6 and resistance R7，The resistance R7 other end connects modulated signal Vi，The described inductance L other end connects the resistance R6 other end respectively、Diode VD1 positive pole、The electric capacity C4 other end、Diode VD2 positive pole、The resistance R4 other end、The resistance R2 other end and the electric capacity C1 other end ground connection；Described diode VD2 is Zener diode.

Operation principle of the present utility model is: referring to Fig. 1, VT, R1 ~ R4 and form amplifying circuit, C1 is shunt capacitance, and C2 is coupling capacitor, and the capacity of the two electric capacity is the biggest, and oscillator signal is equivalent to short circuit；C3, C4, C5, VD1 and L constitute frequency selection circuit, VD1 is varactor, power supply provides backward voltage through R5, R6 dividing potential drop for it, make it can be equivalent to electric capacity, its capacity is in addition to being affected by the backward voltage provided by R5, also with to send modulated signal Vi here relevant, the volume change of VD1 can make the frequency of frequency selection circuit change.

Circuit oscillation process: after switching on power, VT turns on, its colelctor electrode output various frequency signal of 0 ~ ∞, these signals are added to by C3, C4, C5, VD1, L constitutes on frequency selection circuit, frequency selection circuit therefrom selects the signal that frequency is f0, the signal voltage of the f0 taking C4 two ends feeds back to VT base stage and amplifies (because C1 capacity is the biggest, right, the signal of IO is equivalent to short circuit, therefore C4 lower end is equivalent to be directly connected to the base stage of VT), the signal of the f0 that VT amplifies output is added to again frequency selection circuit, so it is repeated, the signal amplitude of the f0 of VT output is increasing, VT amplification is more and more less simultaneously, when amplification is equal with attenuation multiple, the signal amplitude of VT output will not increase again and keep stable.

Frequency modulation modulated process: when being added to fm modulation circuit without modulated signal Vi, circuit can output frequency be the signal of f0.When the positive half cycle of modulated signal Vi is added to varactor VD1 negative pole by R7, the DC voltage that positive half-cycle signal voltage is added to VD1 negative pole with power supply by R5 superposes, the backward voltage of VD1 increases, its capacity reduces, the frequency of frequency selection circuit rises (higher than f0), the signal frequency of circuit oscillation output raises, when modulated signal Vi negative half period is added to varactor negative pole, negative half-cycle signal voltage and V, the DC voltage superposition of 1 negative pole, the backward voltage of VD1 reduces, its capacity increases, the frequency of frequency selection circuit declines (less than f0), the signal frequency of circuit oscillation output declines.

It is to say, when modulated signal Vi is added to fm modulation circuit, the frequency of oscillation of circuit can change.When the positive half cycle of modulated signal Vi comes, frequency of oscillation rises, and when modulated signal Vi negative half period comes, frequency of oscillation declines, so that the FM signal that fm modulation circuit output frequency changes with modulated signal Vi change in voltage.

It is obvious to a person skilled in the art that this utility model is not limited to the details of above-mentioned one exemplary embodiment, and in the case of without departing substantially from spirit or essential attributes of the present utility model, it is possible to realize this utility model in other specific forms.Therefore, no matter from the point of view of which point, embodiment all should be regarded as exemplary, and be nonrestrictive, scope of the present utility model is limited by claims rather than described above, it is intended that all changes fallen in the implication of equivalency and scope of claim included in this utility model.Should not be considered as limiting involved claim by any reference in claim.

In addition, it is to be understood that, although this specification is been described by according to embodiment, but the most each embodiment only comprises an independent technical scheme, this narrating mode of description is only for clarity sake, description should can also be formed, through appropriately combined, other embodiments that it will be appreciated by those skilled in the art that as an entirety, the technical scheme in each embodiment by those skilled in the art.

Claims (2)

1. null1. a transmitter receiver modulation-demodulation circuit，Including resistance R1、Electric capacity C1、Audion VT、Electric capacity C1 diode VD1 and inductance L，It is characterized in that，Described resistance R1 one end connects resistance R3 respectively、Resistance R5 and power supply VCC，The resistance R1 other end connects electric capacity C1 respectively、Resistance R2 and audion VT base stage，Audion VT colelctor electrode connects the resistance R3 other end and electric capacity C2 respectively，The electric capacity C2 other end connects electric capacity C3 respectively、Electric capacity C5、Inductance L and output end vo，The electric capacity C3 other end connects electric capacity C4 respectively、Diode VD2 negative pole、Resistance R4 and audion VT emitter stage，The described electric capacity C5 other end connects diode VD1 negative pole respectively、The resistance R5 other end、Resistance R6 and resistance R7，The resistance R7 other end connects modulated signal Vi，The described inductance L other end connects the resistance R6 other end respectively、Diode VD1 positive pole、The electric capacity C4 other end、Diode VD2 positive pole、The resistance R4 other end、The resistance R2 other end and the electric capacity C1 other end ground connection.
2. Transmitter receiver modulation-demodulation circuit the most according to claim 1, it is characterised in that described diode VD2 is Zener diode.