CN2336524Y

CN2336524Y - Frequency converter for two-wire gate-controlled walkie-talkie

Info

Publication number: CN2336524Y
Application number: CN97224529U
Authority: CN
Inventors: 金民洙
Original assignee: KTFreetel Co Ltd
Current assignee: KTFreetel Co Ltd
Priority date: 1996-12-26
Filing date: 1997-08-18
Publication date: 1999-09-01
Anticipated expiration: 2007-08-18
Also published as: KR19980044243U; KR200157638Y1

Abstract

The utility model relates to a frequency converter for a two-wire gate-controlled intercom, composed of a tuned circuit, a buffer circuit, an amplifying circuit, a frequency selection circuit and a controller. When one monitor calls another monitor, the controller controls the frequency selection circuit to lead the frequency of a transmitting part of the calling monitor to convert to the normal receiving frequency from the normal transmitting frequency and lead the frequency of a receiving part of the calling monitor to convert to the normal transmitting frequency from the normal receiving frequency. Since the frequency of other monitors does not change, the technology of the frequency division multiplex is realized. Two monitors can be used for talking.

Description

The frequency converter of double-circuit gate intercom

This invention relates to double-circuit gate intercom, specially refers to frequency converter, and this transducer can change tranmitting frequency and the receive frequency from a monitor, thereby makes it carry out communication with second monitor.

The gate intercom is a kind of Modern Family security device, and it can be by indoor televimonitor Visual Confirmation visitor's identity.A gamma camera that is installed in the porch is transferred to indoor monitor with video and audio signal.Traditional gate talkback system only is that a monitor is equipped with a gamma camera.

But,, run into the shared public inlet of two or more families sometimes according to different housing constructions.At this moment, if only be that a monitor is equipped with a gamma camera, have only one family can use security system to confirm visitor's identity so.Two or more gamma camera can certainly be installed in public porch, but this will cause waste.Therefore, for addressing this problem, just wish to be the monitor of each gamma camera outfit more than one.

A kind of embodiment of available multichannel monitor system is the double-circuit system, and its connects gamma camera and all monitors with single to lead (a.k.a lead).In order to reduce cost, wish to use simple double-circuit parallel-connection structure, with single lead is together in parallel gamma camera and monitor apparatus.

Traditional double-circuit gate intercom is by the list between gamma camera and monitor is transmitted the Voice ﹠ Video signal to lead, and these signals often transmit with the form of modulated FM signal (FM).FDD (frequency separation multiplexing) technology transmits and received signal through being usually used in separating.In the FDD system, monitor transmits with frequency A, and gamma camera is with frequency A received signal.In the time of oppositely, gamma camera transmits with frequency B, and monitor is with frequency B received signal, and it can make two frequencies that occur on the single line change each other, and can not produce any interference between two signals.Because monitor is furnished with equipment such as the loud speaker that is connected on the same circuit and microphone, so logically, except carrying out also can carrying out both-way communication between them the communication with monitor.But, if the user of the polynary monitor of a cover wants to converse with other users of this monitor, can't form a voice frequency between the two at them so, because they transmit with same frequency (frequency A), again with same frequency (frequency B) received signal.Like this, just need a monitor wherein can change its tranmitting frequency and receive frequency.For solving this problem in traditional gate intercom, adopted polynary oscillator, wherein some can be arranged to that normal frequency is used for and the gamma camera conversation, and other the other frequency of being arranged to is exclusively used in conversation between the monitor.But the oscillator that traditional Technology Need is additional had so both taken the intercom more space, had increased the expense of intercom again.And, when in a limited space, several oscillator being installed, may causing equipment malfunction or produce noise owing to interference, heating or other reason.Therefore need a kind ofly can provide multifrequency simpler method.

The present invention makes monitor can imitate gamma camera and realizes the frequency separation multiplex, thereby solves these problems and other problem.That is to say that in the present invention, monitor can transmit and with frequency A received signal with frequency B, so just can this monitor and another still transmit with frequency A and with the monitor of frequency B received signal between carry out communication.The present invention need not install other oscillator on monitor, so just reduced cost and to the interference of monitor.The present invention is the frequency that changes tuning circuit by the capacitance of the selectable increase electric capacity in parallel with intermediate frequency transformer.

One of purpose of the present invention just provides a cover double-circuit talkback system can converse it between two monitors of polynary monitor.

Another object of the present invention provides double-circuit talkback system cheaply, and it can be conversed between two monitors of polynary monitor.

Another object of the present invention provides the double-circuit talkback system that a cover has minimum oscillator, to reduce the volume of system.

Another object of the present invention provides the double-circuit talkback system that a cover has minimum oscillator, with the interference in the minimizing system.

Fig. 1 is the simplified block diagram of radiating circuit of the present invention.

Fig. 2 is the preferred embodiment schematic diagram of frequency converter of the present invention.

Fig. 3 is the preferred embodiment schematic diagram of frequency selection circuit of the present invention.

Fig. 4 is the simplified block diagram of receiving circuit of the present invention.

Fig. 1 is the simplified block diagram that adopts the frequency converter of monitor of the present invention.As shown in Figure 1, the radiating portion of monitor of the present invention comprises frequency selection circuit 1, tuning circuit 2, controller 3, buffer circuit 4 (being used to cushion the oscillator signal of self-tuning circuit) and amplifying circuit 5 (being used to amplify the signal from buffer circuit).Usually, controller 3 is controlled at first frequency with the frequency of oscillation of transmitter, and the frequency of oscillation of receiver is controlled at second frequency.When the user of another monitor of customer call of a monitor, the controller 3 of caller's monitor will be controlled frequency selection circuit 1, so that the frequency of oscillation of transmitter becomes second frequency, and the frequency of oscillation of receiver becomes first frequency.The tranmitting frequency of first monitor will be the receive frequency of second monitor like this, and the receive frequency of first monitor will be the tranmitting frequency of second monitor.Like this, first monitor can be regarded the gamma camera of another monitor as, and two monitors can carry out mutual communication.

The preferred embodiments of the present invention will be described in conjunction with Fig. 2 and Fig. 3.Fig. 2 is the simplified block diagram of the preferred embodiment of frequency converter of the present invention.Fig. 3 is a detailed maps embodiment illustrated in fig. 2.Among Fig. 2, tuning circuit 2 is by IFT (intermediate frequency transformer) 6, capacitor C3 and C4, and oscillator 7 is formed.For example, the output frequency of the tuning circuit 2 of radiating portion is 5.5MHz, and the output frequency of the tuning circuit 102 of receiving unit (shown in Figure 4) is 4.5MHz.Oscillator signal in tuning circuit 2 is cushioned by buffer circuit 4 (buffer circuit 4 often is one group of gain amplifier), and is exaggerated circuit 5 (amplifying circuit 5 can be another amplifier) amplification.The output signal of amplifying circuit 5 is modulated then.If other monitor of monitor pages, the frequency of the oscillator 7 of transmitter will become receive frequency, be 4.5MHz in the present embodiment, and receiving circuit also will be with vary in opposite ways certainly.These all are to be realized according to the signal that comes self-controller 3 by frequency selection circuit 1.

Be a preferred embodiment of the present invention as shown in Figure 3, frequency selection circuit 1 is by transistor Q1, capacitor C1, variable capacitor VC1, and resistance R 1 and R2 composition.When normal condition, controller 3 is received FREQUENCY CONTROL port FCP with low grade (0 volt).Thus, transistor Q1 disconnects, and breaks capacitor C1 and VC1 from tuning circuit 2.So, the frequency of tuning circuit 2 just depends on IFT6, capacitor C2 and C3, and the combination of oscillator 7, and its frequency is 4.4MHz in the present embodiment.On the other hand, when other any one monitor of a monitor pages, controller 3 is received FREQUENCY CONTROL port FCP with logic high voltage.Transistor Q1 connects, and the frequency of tuning circuit 2 will be by IFT at this moment, capacitor C1, VC1, C2 and C3, and the combination of oscillator 7 decides.Regulate variable capacitor VC1 and can when for example making the gate intercom, just can use this method in order to the variation of the capacitance of compensation condenser C1 in factory.And when selecting precision capacitor as capacitor C1 for use, variable capacitor VC1 has not just needed.

Therefore, characteristics of the present invention are with better simply circuit theory and the lower conversation that realizes originally between monitor that becomes.And, the invention provides more cheap and stable frequency converter.

Although disclose here and described and can implement physical circuit of the present invention, apparent the present invention is not limited to the line map shown in the figure.Obviously, under the condition of principle that does not depart from following patent requirement and scope, can make some change to those mature technique.Therefore, many equivalent electric circuits also may exist.

Claims

1. the frequency converter of double-circuit gate intercommunication, wherein, the radiating portion of each monitor uses first frequency to pass the signal to gamma camera, and the receiving unit of each monitor uses second frequency to receive signal from this gamma camera.This frequency converter is by forming with the lower part:

Tuning circuit;

Buffer circuit is to cushion the oscillator signal of self-tuning circuit;

Amplifying circuit is to amplify the signal from buffer circuit;

Frequency selection circuit; And

Controller is with the control frequency selection circuit;

Wherein, controller control frequency selection circuit is so that when second monitor of first monitor pages, the frequency of the radiating portion of first monitor is changed and is second frequency, and the frequency of the receiving unit of first monitor changes first frequency into.

2. according to the described frequency converter of claim 1, it is characterized in that this transducer is by forming with the lower part:

Transistor;

Capacitor, the control of wherein above-mentioned controller be by the transistorized switch of this controller control, being switched on or switched off the capacitor that is connected in parallel in the above-mentioned tuning circuit, thereby changed the frequency of tuning circuit.