JPH098529A - Glass antenna for receiving automobile television broadcast - Google Patents

Abstract

PURPOSE: To obtain an excellent S/N at a weak electric field and to realize a video image with less distortion even in the weak electric field by controlling a voltage control ratio of a booster amplifier in response to a signal level corresponding to reception sensitivity. CONSTITUTION: A booster amplifier is inserted and connected to a transmission cable between a glass antenna 5 and a television receiver and a voltage control rate of the booster amplifier is controlled in response to a signal level corresponding to the reception sensitivity. In this case, since a gain of the booster amplifier is increased at a weak electric field, a high reception sensitivity is obtained and distortion is prevented by applying AGC to the booster amplifier to reduce the gain of the booster amplifier. That is, an output 6 of a fixed gain amplifier 1 is connected to a television receiver input, and when reception sensitivity is increased and a booster AGC signal voltage given to a booster AGC signal input 3 is decreased, a bias current of a PIN junction diode 2 is reduced, a high frequency resistance is increased to reduce a radio wave signal given to the input of the fixed gain amplifier 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass antenna for automobile television reception according to the NTSC system, the PAL system and the like.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, in a glass antenna for receiving a television broadcast wave, in order to compensate for a lack of receiving sensitivity of the antenna, a feeding terminal of an antenna conductor functioning as a glass antenna 5 and a television receiving terminal are provided. Voltage amplification factor (gain) at a suitable part of the transmission cable between
However, the pre-amplifier 110, which is constant, is inserted and connected. However, since the preamplifier 110 is inserted, there is a problem that waveform distortion, intermodulation, etc. occur in a strong electric field and the noise is amplified as it is.

In FIG. 7, 8 is an intermediate frequency (I
F) AGC (auto gain control) signal, 9 is a video IF amplifier circuit, 10 is a high frequency (RF) amplifier circuit, 12
Is the RF AGC signal, 14 is the AGC detection circuit, 17 is the video detection output, and the arrow indicates the signal traveling direction.

Further, in the conventional glass antenna for automobile television reception, sufficient reception sensitivity is often not obtained due to physical restrictions such as the area and height of the window glass plate. Furthermore, the direction of arrival of television broadcast waves constantly changes, so an antenna with omnidirectional characteristics is required, but complete omnidirectional characteristics cannot be realized, and there is a point with relatively low reception sensitivity called a null point. Occurs. Further, due to insufficient reception sensitivity, there is a problem that the S / N ratio is deteriorated and the image is disturbed.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned drawbacks of the prior art, does not require the preamplifier 110, is low in noise, has no adverse effect such as image distortion, and is non-mixed modulation. Provided is a glass antenna for receiving an automobile television which is omnidirectional and has high reception sensitivity.

[0006]

According to the present invention, a booster amplifier is inserted and connected to a suitable portion of a transmission cable between a glass antenna and a television receiver, and the voltage of the booster amplifier is changed according to the signal level of the receiving sensitivity. Provided is a glass antenna for receiving an automobile TV, which is characterized by controlling an amplification factor.

Further, according to the present invention, a received signal from the glass antenna is amplified by a booster amplifier inserted and connected between the glass antenna and the television receiver, and the amplified received signal is subjected to high frequency amplification and video intermediate frequency amplification. In a glass antenna for automobile television reception that processes in the order of video detection, the output signal of the AGC detection circuit or the amplified signal of the output signal of the AGC detection circuit is fed back to the booster amplifier, and the booster amplifier outputs the amplified signal in accordance with the signal level of the reception sensitivity. Provided is a glass antenna for receiving an automobile TV, which is characterized by controlling a voltage amplification factor.

Further, according to the present invention, the received signal from the glass antenna is amplified by a booster amplifier inserted and connected between the glass antenna and the television receiver, and the amplified received signal is subjected to high frequency amplification and video intermediate frequency amplification. , In a glass antenna for automobile television reception that processes video detection in order, the output signal of the AGC detection circuit or the amplified signal of the output signal of the AGC detection circuit is distributed and fed back to both the tuner and the booster amplifier to obtain the signal level of the reception sensitivity. There is provided a glass antenna for receiving a car television, which controls a voltage amplification factor of a booster amplifier according to the above.

Further, according to the present invention, when the gain of the booster amplifier is saturated when the output signal of the AGC detection circuit or the amplified signal of the output signal of the AGC detection circuit is distributed and fed back to both the high frequency amplification circuit and the booster amplifier. First, there is provided the above glass antenna for automobile television reception, wherein feedback is performed so as to increase the gain of the RF AGC signal feedback of the high frequency amplifier circuit.

Further, according to the present invention, the output signal of the AGC detection circuit or the amplified signal of the output signal of the AGC detection circuit is binarized with a specific threshold as a boundary, and this binarized signal is fed back to the booster amplifier, The booster amplifier is controlled so that one of the binarized signals has a high voltage amplification factor and the other of the binarized signals has a low voltage amplification factor. A receiving glass antenna is provided.

In the glass antenna of the present invention, an antenna conductor produced by, for example, printing a conductive metal-containing paste such as a conductive silver paste on the inside surface of a glass plate of a window and baking it is usually used. Use as an antenna. The window glass plate provided with the antenna conductor is a rear window glass plate, a side window glass plate, a front window glass plate, a roof window glass plate, or the like.

In the present invention, a booster amplifier having a high voltage amplification factor (high gain) is inserted and connected between the glass antenna and the television receiver, and the lack of receiving sensitivity of the glass antenna alone is compensated by this booster amplifier.

In the present invention, it is desirable to provide the booster amplifier near the glass antenna. The reason is that it is possible to reduce the influence of external noise (vehicle noise, CPU noise, etc.) mixed on the line between the glass antenna and the tuner, rather than being provided on the tuner side, and the output of the booster amplifier and the transmission cable. This is because it is easy to obtain impedance matching and the transmission loss is reduced.

[0014]

In the present invention, high reception sensitivity is obtained by increasing the gain of the booster amplifier in a weak electric field. But,
If the gain of the booster amplifier is kept high, distortion will occur in the strong electric field, which will cause a failure.

Further, since the video signal is amplitude-modulated and transmitted, in a normal television receiver, the AGC compensates for the fluctuation of the reception state which is affected by the reception sensitivity. In the present invention, the AGC is utilized to feed back the AGC signal to the booster amplifier, and the AGC is applied to the booster amplifier to reduce the gain of the booster amplifier.
Prevents distortion in a strong electric field.

[0016]

【Example】

(Embodiment 1) FIG. 1 shows a circuit diagram of a booster amplifier of Embodiment 1. In FIG. 1, 1 is a fixed gain amplifier, 2 is P
IN junction type diode, 3 is booster AGC signal input,
4 is a voltage-current conversion circuit, 5 is a glass antenna, 6 is an output of the fixed gain amplifier 1, 7 is a PIN junction type diode 2
Is the bias resistance.

In FIG. 1, the output 6 of the fixed gain amplifier 1 is connected to the television receiver input. In the first embodiment, when the receiving sensitivity increases and the booster AGC signal voltage input to the booster AGC signal input 3 decreases, the bias current of the PIN junction diode 2 decreases and the high frequency resistance of the PIN junction diode 2 increases. Then, the signal by the radio wave given to the input of the fixed gain amplifier 1 becomes small.

In the first embodiment, the PIN junction type diode 2
The maximum value of the bias current is 15mA, and P
The high frequency resistance of the IN junction type diode 2 was 4Ω, and at this time, the gain of the entire booster amplifier was 13 dB at 200 MHz.

The minimum value of the bias current of the PIN junction diode 2 was 100 μA. As a result, the input current of the fixed gain amplifier 1 was reduced, and the gain of the entire booster amplifier was 200 MHz and attenuated to -1 dB.

In the first embodiment, the PIN junction type diode is used, but instead of the PIN junction type diode 2, the P type junction diode is used.
N-junction type diodes can also be used. This is because it is sufficient if the high frequency resistance depends on the bias current. However, when the PN junction type diode is used, it is desirable to use the PIN junction type diode because the variable width of the high frequency resistance is small and becomes non-linear.

FIG. 2 is a circuit diagram of the next stage of the booster amplifier shown in FIG. In FIG. 2, 8 is an IFAGC signal, and 9
Is a video intermediate frequency amplifier circuit, 10 is a high frequency amplifier circuit, 11
Is a booster amplifier, 12 is an RF AGC signal, 13 is a distribution circuit, 14 is an AGC detection circuit, 15 is an AGC detection output,
Reference numeral 17 is a video detection output, 101 (inside a dotted line) is a television receiver, 150 is a video detection circuit, and an arrow indicates a traveling direction of a signal. In addition, in FIG. 2, the names of the parts having the same numbers and the same symbols as in FIG. 1 are the same as those in FIG.

The AGC detection circuit 14 takes out the output of the video detection circuit 150 during the video synchronization signal period and produces the IF AGC signal 8 and the AGC detection output 15.

As shown in FIG. 2, the AGC feedback loop includes a booster amplifier 11 and a high frequency amplifier circuit 1.
0, the video intermediate frequency amplifier circuit 9 is composed of three amplifiers. Further, the high frequency amplifier circuit 10 includes a tuner.

FIG. 3 is a circuit diagram of an example of the distribution circuit 13 shown in FIG. In FIG. 3, 16 is a variable resistor for booster AGC start voltage, and 117 is a variable resistor for RF AGC start voltage. Also, in FIG. 3, the same numbers as in FIGS.
The names of the parts having the same reference numerals are the same as those in FIGS. 1 and 2.

The maximum voltages of boosters AGC and RFAGC were 9 V and 5 V, respectively, and the minimum voltages were both 0.5 V. The AGC start voltage for delaying the AGC is set to operate in the signal order of the RFAGC signal and the booster AGC signal, and the booster AGC start voltage variable resistor 1
6. Adjusted by the variable resistor 117 for RF AGC start voltage.
The reason why the adjustment is performed in this way is that the RFA of the high frequency amplifier circuit 10 starts only when the gain of the booster amplifier 11 is saturated.
This is because the S / N ratio is improved by increasing the gain of the GC signal feedback and increasing the gain of the booster amplifier 11 as much as possible.

When the IFAGC signal 8 and the AGC detection output 15 are fed back, they may be amplified and fed back.

(Embodiment 2) FIG. 4 is a circuit diagram of a booster amplifier of a type different from that of FIG. 1, and is a booster amplifier of Embodiment 2. In FIG. 4, 18 is a power supply. Further, in FIG. 4, the names of the same numbers and the same symbols as in FIG.
And the same name.

In the second embodiment, the booster amplifier is constructed by using the dual gate FET. Booster AGC at this time
The signal voltage was applied directly to the second gate of the FET, eliminating the need for a voltage-current conversion circuit.

(Embodiment 3) FIG. 5 is a circuit diagram of a booster amplifier of a type different from that of FIG. 1, which is a booster amplifier of Embodiment 3. In FIG. 5, 19 is a comparator.
Further, in FIG. 5, the names of the parts having the same numbers and the same numerals as those in FIGS. 1 and 2 are the same as those in FIGS.

In the third embodiment, without applying AGC to the booster amplifier, the bias current is reduced and the gain is reduced by 13 dB when the input voltage exceeds a certain level. This bias current control signal is obtained by binarizing the RFAGC signal 12 by the comparator 19 with hysteresis.

In other words, in the third embodiment, the output signal of the video detection circuit or the amplified signal of the output signal of the video detection circuit is binarized with a specific threshold as a boundary, and this binarized signal is fed back to the booster amplifier, The booster amplifier was controlled so that one of the binarized signals has a high voltage amplification factor, and the other of the binarized signals has a low voltage amplification factor.

FIG. 6 shows a booster amplifier 200 of the third embodiment.
It is an input / output characteristic of MHz, and each resistance value was determined in FIG. 5 so as to have this input / output characteristic.

As described above, the first to third embodiments have less noise than the conventional example in which the preamplifier is inserted and connected between the glass antenna and the receiver, have no adverse effects such as image distortion, and are free of any mixture. It is omnidirectional due to modulation, and has a high receiving sensitivity of several dB in a running test within a fixed time. Moreover, the S / N ratio equivalent to that of the V-shaped pole antenna was obtained even with the glass antenna, and distortion in a strong electric field was hardly confirmed.

[0034]

According to the present invention, since the booster amplifier gain is increased in a weak electric field, high receiving sensitivity can be obtained.
Further, when the gain remains high, distortion occurs in a strong electric field, which causes a failure.
By using C, the AGC signal is fed back to the booster amplifier, and the booster amplifier is subjected to AGC to reduce the gain of the booster amplifier, thereby preventing distortion in a strong electric field.

For the above reasons, the present invention can obtain a good S / N ratio in a weak electric field and at the same time obtain an image with little distortion even in a strong electric field.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a booster amplifier according to a first embodiment.

FIG. 2 is a circuit configuration diagram of a next stage of the booster amplifier shown in FIG.

3 is a circuit diagram of an example of a distribution circuit 13 shown in FIG.

FIG. 4 is a circuit diagram of a booster amplifier of a type different from that of FIG.

FIG. 5 is a circuit diagram of a booster amplifier of a type different from that of FIG.

FIG. 6 is an input / output characteristic diagram of the booster amplifier according to the third embodiment.

FIG. 7 is a circuit diagram of a conventional glass antenna for receiving a car television.

[Explanation of symbols]

 1: Fixed gain amplifier 2: PIN junction type diode 3: Booster AGC signal input 4: Voltage-current conversion circuit 5: Glass antenna 6: Output of fixed gain amplifier 1 7: Bias resistance of PIN junction type diode 2 8: IFAGC signal 9 : Video intermediate frequency amplification circuit 10: High frequency amplification circuit 11: Booster amplifier 12: RF AGC signal 13: Distribution circuit 14: AGC detection circuit 15: AGC detection output 17: Video detection output 101: Television receiver 150: Video detection circuit

Claims (5)

[Claims] 1. A booster amplifier is inserted and connected to a suitable portion of a transmission cable between a glass antenna and a television receiver, and a voltage amplification factor of the booster amplifier is controlled according to a signal level of reception sensitivity. Glass antenna for car TV reception. 2. A received signal from a glass antenna is amplified by a booster amplifier inserted and connected between the glass antenna and a television receiver, and the amplified received signal is subjected to high frequency amplification, video intermediate frequency amplification, and video detection. In a glass antenna for automobile television reception, which is processed in order, an output signal of an AGC (auto gain control) detection circuit or an AGC
A glass antenna for automobile television reception, characterized in that the amplified signal of the output signal of the detection circuit is fed back to the booster amplifier to control the voltage amplification factor of the booster amplifier according to the signal level of the reception sensitivity. 3. A received signal from a glass antenna is amplified by a booster amplifier inserted and connected between the glass antenna and a television receiver, and the amplified received signal is subjected to high frequency amplification, video intermediate frequency amplification, and video detection. In a glass antenna for car television reception, which is processed in sequence, the output signal of the AGC detection circuit or the amplified signal of the output signal of the AGC detection circuit is distributed and fed back to both the tuner and the booster amplifier, and the booster is boosted according to the signal level of the reception sensitivity. A glass antenna for automobile TV reception, characterized by controlling the voltage amplification factor of the amplifier. 4. A high frequency amplifier circuit for distributing an output signal of the AGC detection circuit or an amplified signal of the output signal of the AGC detection circuit,
4. The glass antenna for car television reception according to claim 3, wherein when the gain of the booster amplifier is saturated, the feedback is performed so as to increase the gain by the RF AGC signal feedback of the high frequency amplifier circuit when the gain of the booster amplifier is saturated. . 5. The output signal of the AGC detection circuit or the amplified signal of the output signal of the AGC detection circuit is binarized with a specific threshold value as a boundary, and the binarized signal is fed back to a booster amplifier to output the binarized signal. The booster amplifier is controlled so that a high voltage amplification factor is obtained in one case and a low voltage amplification factor is obtained in the other case of the binarized signal. Glass antenna for car TV reception.