CN1145271C

CN1145271C - Active antenna for communication system

Info

Publication number: CN1145271C
Application number: CNB99104553XA
Authority: CN
Inventors: 朱元荣; 党文栓; 余万里
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 1999-03-30
Filing date: 1999-03-30
Publication date: 2004-04-07
Anticipated expiration: 2019-03-30
Also published as: CN1268788A

Abstract

The present invention relates to an active antenna used in DECT which adopts a time division duplex communication system. The present invention comprises an active circuit which is composed of an emission magnifying device, a receiving amplifying device and a receiving and sending conversion control device. Under the control of the active circuit receiving and sending control signals, the magnifying emission of indoor communication signals and the magnifying receiving of outdoor communication signals are completed. The active antenna can overcome signal fading and compensate cable consumption, and function of a system can be largely improved. The communication distance of a wireless local loop system based on DECT can achieve 15Km.

Description

Active antenna for communication system

The invention belongs to communication technical field, particularly the antenna that in the communication system of the employing time division duplex (TDD) such, uses such as DECT.

Wireless access system based on Digital European Cordless Telephone system (hereinafter to be referred as DECT) standard more and more causes people's interest, except other factors of dect standard itself, the inherence propagation characteristic of the frequency that it is worked also is the main cause that this system communication distance is restricted.Specifically, because DECT is operated in the 1900MHZ frequency, it is more serious that various buildings and trees are blocked the signal fadeout that causes, make a user who is in the bottom of certain building nearer all compare difficulty with extraneous communication apart from the base station, and for being in apart from the user of base station than distant positions, it is just poorer to overcome the ability of blocking the difficult communication that causes.In order to address the above problem, can consider antenna is installed on the outdoor high bar, by radio frequency cable antenna and other parts are coupled together then.Yet because sizable loss of cable, so simple improvement can not make systematic function obtain how many benefits.

Purpose of the present invention designs a kind of active antenna exactly, utilize this active antenna, the performance of system will obtain very big improvement, can effectively overcome signal fadeout, reduce the loss of cable, make communication distance reach 15km based on the wireless local loop system of DECT.

For achieving the above object, a kind of active antenna for communication system of the present invention includes source circuit, and described active circuit is connected and composed by emission amplifying device, reception amplifying device, transmitting-receiving conversion control device; Described active circuit finishes to the amplifying emission of indoor communications signal with to the amplification of outdoor signal of communication receiving under the control of transmitting-receiving control signal.

Described emission amplifying device, receiving system are respectively emission amplifier, reception amplifier; Described transmitting-receiving conversion control device is connected and composed by transmit-receive switch, control circuit and other accessory circuits.

Described other accessory circuits are connected and composed by high pass filter, low pass filter, demodulator, finish filtering and demodulation to indoor signal.

Described indoor signal comprises modulated carrier signal of communication, transmitting-receiving control signal and circuit working dc power signal.

Described transmitting-receiving control signal is controlled transmit-receive switch by control circuit, make active circuit receive mode of operation and launch between the mode of operation and change, neither work in emission mode and also do not work and receive the operating state that the transmitting-receiving of mode of operation stops simultaneously by between two kinds of mode of operations of transmitting-receiving, increasing by one, prevent that active circuit from producing self-oscillation.

Described transmitting-receiving control signal produces in indoor equipment and is modulated on the carrier wave that is lower than the communication work frequency, and its modulation system can adopt amplitude modulation(PAM), frequency modulation(FM), phase modulated.

The present invention is further illustrated below in conjunction with accompanying drawing.

Fig. 1 has provided the active antenna formation block diagram that the present invention proposes.

Fig. 2 is the another kind of presentation graphs of transmit-receive switch

Fig. 3 is the transitional period figure of transmit-receive switch work

Fig. 4 is the transitional period figure that transmit-receive switch is worked when preventing self-oscillation

Fig. 5 is the control principle figure of control circuit

According to Fig. 1, this active antenna is that 101 antenna and label are that 301 the active circuit two parts that tower puts that are commonly called are formed by label.In order to guarantee the two-way communication between the user, active circuit 301 can amplify the signal of communication that other equipment (hereinafter to be referred as indoor equipment) of whole communication system are delivered to port one 14 goes out through aerial radiation then, delivers to 114 after also requiring active circuit 301 to amplify the signal that receives from antenna (101) simultaneously.According to dect standard, these two kinds of working methods are separated in time, are referred to as time division duplex usually.For satisfying this requirement, as shown in Figure 1, active circuit 301 mainly comprises: emission amplifier 104, reception amplifier 105, transmit-receive switch 201 and 202, control circuit 111 and other accessory circuits.Simultaneously, in the communication system of using this active antenna, typically, require indoor equipment to deliver to and comprise following three kinds of signals in 114 the signal: the modulated carrier signal of communication is limited with the control signal (being called for short the transmitting-receiving control signal) and the necessary dc power signal of circuit working of source circuit operating state.Transmitting-receiving control signal wherein is to produce in indoor equipment and be modulated on a certain carrier wave that is lower than the communication work frequency, mixes with dc power signal and signal of communication then after radio frequency cable is sent to 114 ports of active antenna together.Wherein, when system only need be from the active antenna received signal, indoor equipment is sent to along radio frequency cable in the signal of active antenna had only DC power supply and transmitting-receiving control signal.The modulation of transmitting-receiving control signal can be adopted variety of ways such as amplitude modulation(PAM), frequency modulation(FM), phase modulated, and is corresponding, and the selection of demodulator 110 is also just different.

During system works, from signal 10, leach lower control signal of frequency and dc power signal, then dc power signal is obtained the complete machine working dc power through low pass filter 113 further filtering by low pass filter 109.Control signal is wherein then delivered to demodulator 110 after through high pass filter 112 filtering, the transmitting-receiving control signal that demodulates is sent to and does further processing in the control circuit 111, controlled J1, J2, J3, J4, the needed control signal of J5, J6.

When system requirements signal 10 in the modulated carrier signal of communication when aerial radiation is gone out (hereinafter to be referred as the emission mode of operation), the control signal that is added to J1, J2, J3 makes that switch 102,106 is connected, emission amplifier 104 operate as normal; The control signal that is added to J4, J5, J6 is not worked switch 103,107 disconnections, reception amplifier 105.Like this, signal 10 arrives antennas 101 through path 6, switch 106, amplifier 104 amplifications and switch 102 backs successively again and is radiate by antenna 101 behind high pass filter 108 filtering control signals and dc power signal.

When system requirements was sent to port one 14 (hereinafter to be referred as receiving mode of operation) to the signal that receives from antenna 101, the control signal that is added to J1, J2, J3 was not worked switch 102,106 disconnections, emission amplifier 104; The control signal that is added to J4, J5, J6 makes switch 103,107 connections, reception amplifier 105 operate as normal.Like this, the signal 1 that receives from antenna 101 arrives port ones 14 through switch 103, amplifier 105 amplifications, switch 107 and high pass filter 108 backs successively.

Two transmit-receive switches 201 among Fig. 1 and 202 certainly be expressed as shown in Fig. 2 A and Fig. 2 B like that, but can more help the description of following design philosophy according to mode shown in Figure 1.Be understood that easily at a time, tower puts 301 or work in emission mode, or works in receiving mode, can not be operated in two states simultaneously.Therefore a kind of straightforward procedure of controlling the transmitting-receiving conversion of expecting easily is exactly to make the polarity of control signal J1, J2, J3 and control signal J4, J5, J6 opposite, as shown in Figure 3.In fact, the speed or the response time of switch that are control signal all are limited, then the so-called transitional period shown in Figure 3 just can appear, in this intrinsic transitional period, originally the switch that was in on-state begins progressively to tend to disconnect, and what follow is to insert loss progressively to increase; Originally the switch that was in off-state begins progressively to tend to connect, and what follow is to insert loss progressively to reduce; Originally out-of-work amplifier begins progressively to tend to normal operating conditions, and what follow is progressively to increase in the prescribed direction transmission gain; Originally the amplifier of operate as normal begins progressively to tend to quit work, and what follow is progressively to reduce in the prescribed direction transmission gain.In this transitional following period of time, switch 102,103,106 and 107 is in simultaneously and inserts the bigger accurate on-state of loss, and amplifier 104 and 105 is in the lower accurate normal operating conditions of prescribed direction transmission gain simultaneously.So, constituted the signal path of a closure to switch 106 again along switch 106, emission amplifier 104, switch 102, switch 103, reception amplifier 105, switch 107 successively, make whole active circuit part very easily produce self-oscillation, thereby influence the operate as normal of circuit.

According to this patent, make active circuit avoid producing self-oscillatory solution to be, between two kinds of working mode change of active circuit transmitting-receiving, increase by one and neither work in transmitting-receiving that emission mode the do not work in receiving mode yet state that quits work simultaneously.Specifically show on the control signal variation as shown in Figure 4.Total mentality of designing is to launch mode of operation when receiving working mode change, stopping emission work earlier, and then starts the reception mode of operation; When receiving mode of operation, stop reception work earlier, and then start the emission mode of operation to the emission working mode change.Illustrative ground supposition switch 102,103,106,107 all is to connect during for high level in control signal, disconnect during low level among Fig. 4; Emission amplifier 104 and reception amplifier all are to quit work when time work is with normal magnifying state, low level for high level in control signal.

As an illustrative example, we still adhere to the supposition among Fig. 4, and the modulation of further supposing control signal in the indoor equipment adopts is simple amplitude modulation mode, then provided to circuit schematic shown in Figure 5 a kind of method for designing that realizes the control circuit 111 of control relation shown in Figure 4.The control signal that demodulates by demodulator 110 shown in signal among Fig. 58, by low pass filter make that the rising edge of control signal and trailing edge become slowly, be input to the in-phase end of voltage comparator 402 and 403 end of oppisite phase then respectively.In voltage comparator 402, end of oppisite phase is with reference to comparative level V _TrefSetting shown in signal 410; In voltage comparator 403, in-phase end is with reference to comparative level V _RrefSetting shown in signal 411.According to above supposition, the control signal of the output of voltage comparator 402 as J1, J2 and J3, signal waveform as shown in Figure 5; The control signal of the output of voltage comparator 403 as J4, J5 and J6, signal waveform as shown in the figure.The relativeness of these two groups of control signals shows that this design can be satisfied the described requirement of Fig. 4.

Method of the present invention mainly is at based on the wireless access communication system of Digital European Cordless Telephone standard.But clearly, to those skilled in the art, the method that the present invention discloses can easily be used other aspects very much, such as being used to design various transmitting-receiving subassemblies etc.

Claims

1, a kind of active antenna for communication system, the active circuit that comprise antenna, is connected with antenna is formed, described active antenna can be gone out the signal that other equipment of whole communication system are sent here by aerial radiation, also can give communication system other equipment the signal that antenna receives, it is characterized in that: described active circuit comprises:

The emission amplifying device amplifies the signal from other equipment of whole communication system;

Receive amplifying device, the signal from antenna is amplified;

Two transmit-receive switches (201,202), an end of each transmit-receive switch is connected with the emission amplifying device, and the other end is connected with the reception amplifying device, makes the emission amplifying device form relation in parallel with the reception amplifying device;

Control circuit (111) links to each other with described two transmit-receive switches, so that described transmit-receive switch (201,202) is controlled.

2, active antenna as claimed in claim 1 is characterized in that: described active circuit also further comprises the demodulator (110) of contacting mutually with control circuit (111).

3, active antenna as claimed in claim 2 is characterized in that: described active circuit also further comprises the high pass filter (112) of connecting with demodulator (110).

4, active antenna as claimed in claim 3 is characterized in that, described active circuit also further comprises the low pass filter (109,113) of connecting with high pass filter (112).

5, active antenna as claimed in claim 4 is characterized in that, described active circuit comprises further that also an end links to each other with low pass filter (109), the high pass filter (108) that the other end links to each other with transmit-receive switch (202).