KR860000163B1 - A telephone for car - Google Patents

Abstract

A receiver/transmitter for a car telephone uses two separated antennas. One of the antennas is switched automatically towards the strong intensity of the electric field, so that the fading phenomenon caused by the road state or wave interference is compensated. The two antenna method has an advantage in that one of the antennas receives reradiated wave from the other one and also compensates for wave attenuation.

Description

Transceiver Circuit of Car Phone

1 is a block diagram of an overall configuration of a circuit board for a vehicle telephone transceiver according to the present invention.

2 is an internal configuration diagram of the central control unit 8.

3 is a detailed circuit diagram of the present invention.

4 shows a first embodiment of the switching circuit breaker 9 shown in FIG.

FIG. 5 shows a second embodiment of the switching circuit breaker 9 shown in FIG.

The present invention is a vehicle telephone. Since two receiving antennas such as mobile radios are spatially isolated from the moving vehicle, two receiving antennas are automatically selected so that the receiving antennas with strong electric field strength are automatically selected and received to compensate for attenuation of the field strength before receiving due to fading. It relates to a transceiver circuit of a vehicle telephone.

In the case of receiving and receiving one receiving antenna as in the related art, a fading phenomenon occurs in which the received electric field intensity fluctuates in time due to interference between radio waves different from two or more passages or changes in the state of the electric wave path. Sensitivity deteriorated significantly because the call was weakened and the call could not be made or the call could be disconnected.

Especially in urban areas, fading may be aggravated by radio wave shielding in high-rise buildings. Even when the antenna is fully incident, only 50% of the induced radio wave current may be incident on the receiving antenna, and the remaining 50% may be radiated again. .

However, when two receiving antennas are installed, a part of the re-radiated radio wave is incident again, thereby reducing the attenuation of the electric field strength of the radio wave.

In the case of low frequency, it is possible to receive a good signal even with one receiving antenna due to the diffraction characteristics of the radio wave. However, in case of a high frequency (UHF) used in a general vehicle telephone or a high frequency radio, the radio wave has a straight line characteristic, so the length and width of Even if the vehicle is not long, it is possible to receive a good reception by installing two the Annas at any time.

In other words, based on the theory of wavelength calculation, this is explained.

end. At 880 MHz, the wavelength λ is

Therefore, it is possible to efficiently and satisfactorily receive the reception of selecting the one with the higher intensity of the incident radio wave power by installing two reception antennas in a vehicle equipped with a vehicle telephone or a radio.

This will be described below with reference to the drawings.

1 is a block diagram of an overall configuration of a circuit board for a vehicle telephone transceiver according to the present invention.

When the reception antenna R ¹ is selected at the time of reception, the reception high frequency current incident through the reception antenna R ¹ passes through the reception band pass filter 1 having good passband characteristics and large attenuation of the stop band. The filter is applied to the mixer 5 through the switching circuit 4. The mixer is mixed with the local oscillation frequency oscillated in the local oscillator (Local Oscillator ⁶ ) and delivered to the intermediate frequency amplifier (IF Amo).

In addition, even when the transmitting and receiving antenna T / R ² is selected, the signal is transmitted to the intermediate frequency amplifier through the reception band pass filter 2 and the switching circuit 4.

In this case, one of the electric field intensity fluctuations of the electric wave incident on either the receiving antenna R ¹ or the transmitting and receiving antenna T / R ² is operated by the switching circuit 4 under the control of the central controller 8. Is delivered.

That is, when the reception high-plate current incident on either of the antenna (R ¹ ) or (T / R ² ) becomes weak, the current source transmitted from the mixer 5 to the intermediate frequency amplification portion is the received field strength amplifier 7. Since the amplified signal is input to the central control unit 8 and the input signal is detected at a DC voltage level below a predetermined reference value, the central control unit 8 operates the switching circuit 4. A logic adjustment signal (low or high) may be applied to the switching circuit 4.

In the switching circuit 4, the antenna R ¹ or (T / R ² ) with a strong electric field strength of the radio wave incident by the input logic adjustment signal is selected, and the weak side is blocked so as to receive it efficiently. Good reception is possible.

2 is an internal circuit configuration diagram of the central control unit 8 according to the present invention, and is composed of a microprocessor 9a, an A / D converter 8b, an interface unit 8c, and a storage device 8d.

As illustrated in FIG. 1, the reception high frequency currents incident through the reception antenna R ¹ and the transmission / reception antenna T / R ² during reception are received in the reception band pass filter 1, 4, and the switching circuit ( 4), the mixer 5, the intermediate frequency amplifier, and the received field strength amplifier 7 are input to the A / D converter (analog / digital converter, 8b) of the central controller 8.

The A / D converter 8b converts the received analog signal into a digital signal and applies it to the microprocessor 8a through the interface unit 8c. The microplotter 8a applies a logic adjustment signal (low or high) to the switching circuit 4 via the interface 8c in comparison with the reference level previously stored in the memory device 8a.

3 is a detailed circuit diagram of the present invention.

First, the high frequency current modulated for transmitting radio waves is transmitted from the high frequency amplifier (RF AMP) to the transmit bandpass filter (3) consisting of seven poles in which the variable capacitor (3a) and the coil (3b) are connected in series. It is inputted and filtered, and is radiated through a transmission / reception antenna (T / R ² ).

On the other hand, the reception high frequency current incident through the reception antenna R ^{1 is} connected to the variable capacitor Ia and the coil Ib in series, so that the attenuation of the low band is large and the pass band characteristics are excellent. The filter is filtered through the band call filter 1 and input to the switching circuit 4.

In addition, a received high frequency current incident on the T / R ² antenna is also input to the switching circuit 4 via the reception band pass filter 2. In this case, the central control unit 8 transmits a logic adjustment signal (low or high) to the switching circuit 4 as described in FIG. 2 to provide an antenna R ¹ or T / R ² having a strong electric field intensity. Switch to the) side and cut off the signal input from the weak side.

That is, when a weak reception high frequency current is incident on the reception antenna R ¹ , the signal of the current source transmitted from the mixer 5 of FIG. 1 to the intermediate frequency amplifier is amplified by the reception field strength amplifier 7 and the central control unit ( 8), it is recognized that the signal is low compared with the reference level stored in the memory device 8d of the central control device 8, and is normally low through the logic adjustment output terminal of the interface unit 8c. Output the signal as high signal. This high signal is applied to the base of transistor Q ¹ through resistor R ³ .

In this case, the transistor Q ¹ is turned on and conducts, and since the connection point 4a is turned low by the DC power supply Vds +, the DC bias current does not flow through the coil L ¹ . ¹ ) is turned off. Therefore, the resistance of the diode D ¹ increases (from tens of ohms to several tens of KΩ), so that the high frequency current flowing through the diode D ¹ is blocked.

In addition, since the low-level signal is input to the base of the transistor Q ² , the transistor Q ² is turned off, and the connection point 4b is turned high, and the diode D ² and the capacitor C are -C. ⁴ ) is saturated and conducting, so that the received high abacus signal incident on the receiving antenna R ¹ and passing through the receiving bandpass filter 1 is grounded through the capacitor C ⁴ and the diode D ² . Is entered.

Therefore, the signal transmitted to the mixer 5 through the coil L ⁴ is attenuated by a predetermined amount or more (25 dB or more) and is blocked from being delivered to the mixer 5.

However, the signal incident to the transmitting and receiving antenna (T / R ² ) and filtered by the reception bandpass filter 2 is transmitted to the mixer 5 through the coil L ³ since the coil L ¹ is open. This received high frequency signal is transmitted with almost no attenuation (1 dB or less). On the other hand, when a weak reception high frequency current enters the T / R ² antenna, the signal of the current source is amplified by the reception field intensity amplifier 7 through the intermediate frequency amplifier in the mixer 5 of FIG. The low signal compared to the reference level input to the control device 8 and stored in the memory device 8d is recognized as a low signal, and is output as a high signal through the logic adjustment output terminal of the interface unit 8c as usual. And outputs the signal to the base of the transistor Q ¹ through the resistor R ³ .

In this case, since the transistor Q ¹ is in the off state and the transistor Q ² is in the on state, the received high frequency signal incident to the transceiving combined antenna T / R ² and transmitted to the mixer 5 is blocked. Since a switching action is performed in which a received high frequency signal having a strong electric field intensity incident to the receiving antenna R ¹ is transmitted to the mixer 5, efficient and good reception is possible.

In addition, since the noise signals input to each antenna R ¹ T / R ² are bypassed by the capacitors C ³ and C ⁶ , the noise is significantly attenuated and stable operation is performed. As an embodiment of the switching circuit 4 blocking section 9 shown in FIG. 5 is a circuit configured to perform stable operation using transistor Q ⁴ instead of diode D ¹ as another embodiment of the switching circuit 4 and the blocking unit 9 shown in FIG.

Claims (2)

As described in the text and shown in the drawings, the variable capacitors 1a, 2a, coils 1b, and 2b are connected in series to a conventional reception antenna R ₁ and a transmission / reception antenna T / R ² . Receive bandpass filters (1) and (2), which are connected to each other and are composed of multiple poles, are connected. (5) is connected to the intermediate frequency amplifier, the intermediate frequency amplifier is connected to the receiving field strength amplifier (7), the transmission and reception unit of the vehicle telephone configured to be connected to the switching circuit (4) through the central control unit (8) Circuit. According to claim 1, wherein the transistor against the base of the (Q ¹⁾ (R ^3), the capacitor in series (C ^1), a coil (L ¹⁾ a collector connecting point (4a) of the connection and the transistors (Q ^1), the resistance (R ⁴ ) is connected, and a resistor (R ⁵ ) to which a DC power supply (Vdc +) is connected is connected, and an anode of a diode (D ¹ ) is connected to a connection point between a conde wire (C ¹ ) and a coil (L ¹ ). is grounded, and the coil (L ¹⁾ and a resistance (R ⁴⁾ connection points, the capacitor (C ²⁾ a and a ground is connected, the capacitor (C ¹⁾ is a coil junction (4c) connected to (L ³⁾ and passes through the reception band between filter (2) it is connected, and, in the resistance transistor (Q ^1), the collector junction (4a) and the transistor between the base of (Q ₂₎ and the resistance (R ⁷⁾ is connected to the collector junction (4b) of the transistor (Q ²⁾ of the (R ⁶ ), condenser (C ⁵ ) and coil (L ² ) are connected, and the connection point (4f) to which coil (L ² ) is connected, anode of condenser (C ⁴ ) and diode (D ² ) is connected, condenser (C ⁴⁾ Connected to the connection point (4e), the coil is (L ⁴⁾ is connected, a coil (L ⁴⁾ has a connection point (4d) connected to a coil (L | ³⁾ switches configured such that, the capacitor (C ⁶⁾ and a mixer (5) is open connection Circuit.

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