JP3552156B2 - In-vehicle TV diversity system - Google Patents

Description

【００４４】
図４はワンボックス車両の感度指向特性図（測定周波数１０３ＭＨｚ）、図５はワンボックス車両の感度指向特性図（測定周波数１９９ＭＨｚ）である。
図４および図５において、（ａ）図は左方向の指向特性を有する線状アンテナの感度指向特性図、（ｂ）図は右方向の指向特性を有する線状アンテナの感度指向特性図、（ｃ）図は同相位相合成の感度指向特性図、（ｄ）図は逆相位相合成の感度指向特性図、（ｅ）図は（ａ）〜（ｄ）図のダイバーシティの感度指向特性図を示す。
【００４５】
図４および図５の測定データから、左右の２本のアンテナ、同位相合成、逆位相合成のダイバーシティから得られる感度指向特性は、全方位に亘って良好な結果が得られる。
【００４６】
なお、図４および図５に示すダイバーシティの感度指向特性は、測定周波数における左右アンテナの感度と同等以上の感度が全方位に亘って得られる。
また、ダイバーシティの感度指向特性の傾向は、ＶＨＦ周波数帯（９０〜２３０ＭＨｚ）で確認することができる。
【００４７】
図６はツーリングワゴン車両の感度指向特性図（測定周波数１０２ＭＨｚ）、図７はツーリングワゴン車両の感度指向特性図（測定周波数２００ＭＨｚ）である。
図６および図７において、（ａ）図は左方向の指向特性を有する線状アンテナの感度指向特性図、（ｂ）図は右方向の指向特性を有する線状アンテナの感度指向特性図、（ｃ）図は同相位相合成の感度指向特性図、（ｄ）図は逆相位相合成の感度指向特性図、（ｅ）図は（ａ）〜（ｄ）図のダイバーシティの感度指向特性図を示す。
【００４８】
図６および図７の測定データから、左右の２本のアンテナ、同位相合成、逆位相合成のダイバーシティから得られる感度指向特性は、全方位に亘って良好な結果が得られる。
【００４９】
なお、図６および図７に示すダイバーシティの感度指向特性は、測定周波数における左右アンテナの感度と同等以上の感度が全方位に亘って得られる。
また、ダイバーシティの感度指向特性の傾向は、ＶＨＦ周波数帯（９０〜２３０ＭＨｚ）で確認することができる。
【００５０】
このように、実際の測定データもシミュレーションのデータと同様に、２本のアンテナからの２種の受信信号と、２種の受信信号を同相位相合成した信号および逆相位相合成した信号とのダイバーシティを取ることにより、４本のアンテナからの４種の受信信号のダイバーシティを取った時と同等以上の感度指向特性を得ることができる。
【００５１】
なお、本実施の形態では、同相位相合成信号および逆相位相合成信号を含めた４種の受信信号でダイバーシティを構築したが、ＴＶ電波の状態によって同相位相合成信号または逆相位相合成信号を削除してダイバーシティを構築してもよい。
【００５２】
【発明の効果】
以上説明したようにこの発明に係る車載用ＴＶダイバーシティシステムは、２個のＴＶアンテナから４種の受信信号を生成してダイバーシティを構築し、全方位に亘って良好な感度を得ることができるので、構成が単純で経済的な、感度指向特性に優れたシステムを実現することができる。
【００５３】
また、位相合成が同相または逆相の固定位相で位相合成信号を生成することができるので、車載用ＴＶダイバーシティシステムを容易に実現することができる。
【００５４】
さらに、４本のアンテナを有するダイバーシティシステムと同等以上の感度指向特性を有する車載用ＴＶダイバーシティシステムを実現することができる。
【図面の簡単な説明】
【図１】この発明に係る車載用ＴＶダイバーシティシステムの実施の形態要部ブロック構成図
【図２】Ｈ偏波に対するシミュレーション感度指向特性図
【図３】Ｖ偏波に対するシミュレーション感度指向特性図
【図４】ワンボックス車両の感度指向特性図（測定周波数１０３ＭＨｚ）
【図５】ワンボックス車両の感度指向特性図（測定周波数１９９ＭＨｚ）
【図６】ツーリングワゴン車両の感度指向特性図（測定周波数１０２ＭＨｚ）
【図７】ツーリングワゴン車両の感度指向特性図（測定周波数２００ＭＨｚ）
【図８】従来の車載用ＴＶダイバーシティシステムのブロック構成図
【符号の説明】
１…車載用ＴＶダイバーシティシステム、２Ａ，２Ｂ…ＴＶアンテナ，３，３Ａ，３Ｂ…増幅手段、４…位相合成手段、４Ａ…同位相合成手段、４Ｂ…逆位相合成手段、５…選択手段、６…受信手段、７…レベル比較手段、８…選択制御手段、９…ＴＶ受信手段。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an in-vehicle TV diversity system mounted on a vehicle and receiving TV radio waves, and more particularly to an in-vehicle TV diversity system capable of receiving TV with excellent directivity characteristics using two TV antennas.
[0002]
[Prior art]
In recent years, enjoyment of television in a car has become widespread, and an in-vehicle TV system capable of receiving a television while traveling has been commercialized.
[0003]
In many cases, a TV radio wave received at each point while a car is moving has a complex standing wave pattern composed of a sum of a large number of TV radio waves having different phases and amplitudes arriving from various directions.
When receiving such a TV radio wave, a TV diversity system is used to avoid flutter and ghosts and selectively receive only direct waves having a high reception level.
[0004]
FIG. 8 shows a block diagram of a conventional on-board TV diversity system.
In FIG. 8, two antennas orthogonal to each other (a total of four antennas (antenna 101 to antenna 104)) are arranged at the left and right ends of the rear window of the vehicle body.
Four reception signals of the TV radio wave received by the antennas 101 to 104 are sequentially selected by the reception signal changeover switch 105, and the selected reception signals are supplied to the TV tuner 107 after being amplified through the amplifier circuit 106.
The level comparison circuit 108 compares the levels of the four reception signals sequentially selected by the reception signal changeover switch 105 (for example, every 1/60 sec) and selects the reception signal having the highest reception level from the four reception signals. Then, the antenna switching signal corresponding to the received signal having the highest reception level is sent to the received signal switch 105 to specify the antenna.
[0005]
As described above, the conventional TV diversity system can sequentially switch the reception signals from the four TV antennas and select the antenna having the highest reception level, thereby enabling stable in-vehicle television reception without flutter or ghost. Has become.
[0006]
[Problems to be solved by the invention]
Since the conventional vehicle diversity system requires four TV antennas, there is a problem that a large antenna installation space is required in a relatively small space of a vehicle (for example, in a rear window or its vicinity). .
[0007]
In addition, when an antenna for AM reception, FM reception, or a mobile phone is disposed in a vehicle in addition to the TV antenna, there is a problem that interference between the antennas occurs as well as the arrangement of the antennas, and the TV antennas are not connected to each other. There is a problem that the interference of the antenna is large, and the design of the antenna itself may be difficult.
[0008]
The present invention has been made to solve such a problem, and its purpose is to generate three or four types of reception signals using two TV antennas and to optimize the reception signals from these reception signals for TV reception. Another object of the present invention is to provide an in-vehicle TV diversity system capable of selecting an appropriate reception signal.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, an in-vehicle TV diversity system according to the present invention includes: two TV antennas; two amplifying units for performing impedance matching and amplifying received signals received by the two TV antennas; Phase synthesizing means for synthesizing each of the received signals supplied from the amplifying means in one of the same phase and the opposite phase, and a phase synthesizing signal supplied from the phase synthesizing means and supplied from the two amplifying means. A selection means for selecting any one of the received signals; and a selection control means for controlling the selection means to select a received signal having the highest level . While receiving two received signals having directional characteristics in directions opposite to the vehicle, the phase combining means has a directional characteristic orthogonal to the directional characteristics of the two received signals. It is characterized in that a phase composite signal is generated .
[0010]
An in-vehicle TV diversity system according to the present invention is supplied from two TV antennas, two amplifying units for performing impedance matching and amplifying received signals received by the two TV antennas, and two amplifying units. Phase synthesizing means for synthesizing each of the received signals having the same phase or opposite phase, and a phase synthesizing signal supplied from the phase synthesizing means and a reception signal supplied from the two amplifying means. And a selection control means for controlling this selection means to select the highest level of the received signal, so that a TV equivalent to providing three TV antennas is provided. Diversity can be configured.
[0011]
Further, the in-vehicle TV diversity system according to the present invention includes two TV antennas, two amplifying units for performing impedance matching and amplifying received signals received by the two TV antennas, and two amplifying units. In-phase synthesizing means for synthesizing the supplied received signals in phase, anti-phase synthesizing means for synthesizing the received signals supplied from the two amplifying means in opposite phases, and supplying from the in-phase synthesizing means. Selecting means for selecting any one of the in-phase synthesized signal, the anti-phase synthesized signal supplied from the anti-phase synthesizing means, and the respective reception signals supplied from the two amplifying means, and the selecting means And selecting control means for controlling to select the received signal having the highest level. The two TV antennas have two directivity signals in the opposite directions of the vehicle. And the phase combining means generates a phase combined signal having a directional characteristic orthogonal to the directional characteristics of the two received signals .
[0012]
Since the phase synthesizing means according to the present invention generates two kinds of phase synthesized signals obtained by synthesizing the received signals from the two TV antennas in the same phase and in the opposite phase, the TV diversity equivalent to providing four TV antennas is provided. Can be configured.
[0013]
In addition, two TV antennas having directional characteristics in directions opposite to the vehicle and phase combining means for generating a phase combined signal having directional characteristics orthogonal to the directional characteristics of the two received signals are provided. TV radio waves can be received with high sensitivity regardless of direction.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
It should be noted that the present invention provides three types of reception signals: two types of reception signals from two TV antennas mounted on a vehicle, and one or two types of phase synthesis signals generated by performing phase synthesis of the two types of reception signals with a fixed phase. Another object of the present invention is to provide an in-vehicle TV diversity system capable of sequentially selecting four types of reception signals and performing optimal TV reception.
[0015]
FIG. 1 is a block diagram of a main part of an embodiment of an in-vehicle TV diversity system according to the present invention.
In FIG. 1, the in-vehicle TV diversity system 1 includes two TV antennas 2A and 2B, an amplifying unit 3, a phase combining unit 4, a selecting unit 5, and a receiving unit 6.
[0016]
The TV antennas 2A and 2B are attached to, for example, a rear window or a side window of a vehicle, or formed on a window as a conductor pattern as an antenna element.
The TV antenna 2A and the TV antenna 2B are arranged in the direction opposite to the vehicle, for example, in the left-right direction of the vehicle. ) Have directivity characteristics that enable reception signals with high sensitivity to TV radio waves to be obtained.
The TV antennas 2A and 2B receive the TV radio waves and supply the received signals JA and JB to the amplifier 3.
[0017]
The amplifying means 3 is composed of amplifiers 3A and 3B having an impedance matching function, suppresses the loss of the reception signals JA and JB supplied from the TV antennas 2A and 2B, amplifies them at a required amplification rate, and The received signal RA of the output impedance is supplied to the switch sw1 of the phase combining means 4 and the selecting means 5.
The amplifying unit 3 supplies the received signal RB to the phase synthesizing unit 4 and the switch sw4 of the selecting unit 5.
[0018]
The phase synthesizing means 4 comprises an in-phase synthesizing means 4A and an anti-phase synthesizing means 4B having a fixed phase shifter and a synthesizer.
The in-phase synthesizing unit 4A sets the phase of the received signal RA supplied from the amplifier 3A and the phase of the received signal RB supplied from the amplifier 3B to the same phase and synthesizes the same, and converts the in-phase synthesized signal RPA into the switch sw2 of the selecting unit 5. To supply.
[0019]
The anti-phase synthesizing unit 4B sets the phases of the reception signal RA supplied from the amplifier 3A and the reception signal RB supplied from the amplifier 3B to opposite phases and synthesizes them, and outputs the anti-phase synthesis signal RPB to the switch sw3 of the selection unit 5. To supply.
[0020]
As described above, since the phase synthesizing unit 4 includes the in-phase synthesizing unit 4A and the anti-phase synthesizing unit 4B, the received signals RA and RB received by the TV antennas 2A and 2B and the received signals RA and RB are in-phase and inverted. It is possible to generate four types of reception signals, that is, an in-phase combined signal RPA and an anti-phase combined signal RPB that are combined in phase.
[0021]
Therefore, four types of received signals can be generated using two TV antennas, which is equivalent to an arrangement in which four TV antennas are individually arranged.
[0022]
Further, the phase synthesizing means 4 performs phase synthesis so as to have a directional characteristic orthogonal to the directional characteristics of the two received signals RA and RB received by the TV antennas 2A and 2B, and generates a phase synthesized signal RPA or RPB. Such a configuration may be adopted.
[0023]
As described above, the vehicle includes two TV antennas having directional characteristics in directions opposite to the vehicle and a phase synthesizing unit for generating a phase composite signal having a directional characteristic orthogonal to the directional characteristics of the two received signals. TV radio waves can be received with high sensitivity regardless of the position and orientation of the TV.
[0024]
The selecting means 5 is constituted by electronic switches of the switches sw1 to sw4, and sets the switches sw1 to sw4 from the break state to the make state based on the selection control signal CS supplied from the receiving means 6, and sets the received signals RA and in-phase. One of the combined signal RPA, the reverse-phase combined signal RPB and the received signal RB is selected and supplied to the receiving means 6 as a received signal SR.
[0025]
The selection control signal CS is formed of, for example, a 4-bit binary code. For example, “0101” indicates sw1 in a make state, “0111” indicates sw2 in a make state, “1010” indicates sw3 in a make state, and “1110” indicates sw4 in a make state. Is set in a make-up state.
The selection control signal CS is formed with 4 bits in order to prevent malfunction when the bit pattern may become all "0" or all "1" due to an environment where the electric field of the TV radio wave is strong or disturbance noise. It is.
[0026]
Further, the selection control signal CS repeats four patterns at a constant cycle, sequentially sets the switches sw1 to sw4 to a make state, and when a later-described reception signal SR detects the highest level, the reception signal corresponding to the reception signal SR One of the switches sw1 to sw4 that has selected the RA, the in-phase synthesized signal RPA, the anti-phase synthesized signal RPB, or the received signal RB is specified and held in a make state.
In addition, the period in which one of the switches sw1 to sw4 is specified and held in the make state is set to a time sufficiently longer than a fixed period in which the selection control signal CS repeats four patterns.
[0027]
The receiving means 6 includes a level comparing means 7, a selection control means 8, and a TV receiving means 9.
The level comparing means 7 is composed of a rewritable memory such as a RAM, a level comparator, and the like, and receives the received signal RA, the in-phase combined signal RPA, the reverse-phase combined signal RPB or the received signal RB selected by the selecting means 5. SR is stored in the memory, and the level comparison of the received signal RA, the in-phase synthesized signal RPA, the anti-phase synthesized signal RPB, or the received signal RB stored in the memory is executed, and the highest received signal RA, the same phase is output. The comparison signal HO corresponding to the composite signal RPA, the reverse-phase composite signal RPB, or the received signal RB is supplied to the selection control means 8.
[0028]
The selection control means 8 selects a 4-bit binary code (“0101”, “0111”, “1010”, “1110”) based on the comparison signal HO supplied from the level comparison means 7. Is provided to the selection means 5, and control is performed to specify one of the switches sw1 to sw4 that has selected the highest level among the reception signal RA, the in-phase synthesis signal RPA, the anti-phase synthesis signal RPB, and the reception signal RB. .
Note that the selection control means 8 sweeps the binary code (“0101”, “0111”, “1010”, “1110”) at a constant period during a period in which the comparison signal HO is not supplied, and switches the switches sw1 to sw4. Without specifying one, the make operation of the switches sw1 to sw4 is controlled so that the received signal RA, the in-phase synthesized signal RPA, the anti-phase synthesized signal RPB or the received signal RB is sequentially taken into the memory of the level comparing means 7.
[0029]
The TV receiving means 9 is constituted by a so-called television set including a TV tuner, a video / audio circuit, a display and the like, and has the highest level selected by one of the switches sw1 to sw4 specified by the selecting means 5. After tuning the reception signal SR (one of the reception signal RA, the in-phase synthesis signal RPA, the anti-phase synthesis signal RPB, and the reception signal RB), amplifying the video signal or the audio signal, and the like, the video is displayed on the display. Display and output sound from an electro-acoustic converter such as a speaker.
[0030]
As described above, the in-vehicle TV diversity system 1 according to the present invention includes the two TV antennas 2A and 2B and the phase synthesizing means 4, and includes four types of reception signals SR (a reception signal RA and an in-phase synthesis signal RPA). , An inverted-phase combined signal RPB or a received signal RB), and the selecting means 5 is configured to select the highest level of the received signal SR among the four types of received signals SR so as to be able to receive TV signals. A system equivalent to the diversity system having the above can be realized.
[0031]
Next, a simulation analysis of the sensitivity directivity characteristics using the in-vehicle TV diversity system 1 shown in FIG. 1 will be described.
The vehicle type used in this simulation analysis was a one-box type vehicle body shape model, and the TV antenna supplied a linear antenna with an element length of 850 mm to the center in the height direction of the side window at the rear side of the window frame. The model was adopted.
The main specifications of the simulation analysis model are shown below.
[0032]
Commander: 4380mm
Vehicle width: 1660mm
Height: 1910mm
Antenna installation window (SW) size: 1400 mm (L) x 500 mm (H)
Analysis frequency: 110MHz
Antenna spacing: 1530mm (0.56λ at 110MHz)
(Left and right side window spacing)
[0033]
The conditions of the simulation analysis are as follows: two linear antennas have left and right directional characteristics, phase synthesis is in-phase and anti-phase, TV broadcast wave (TV radio wave) is H polarization or V polarization, and evaluation is H The sensitivity directivity of the two linear antennas with respect to polarization or V polarization, the sensitivity directivity of phase combination of in-phase and opposite phases, and the sensitivity directivity due to diversity.
[0034]
FIG. 2 is a simulation sensitivity directivity diagram for H polarization.
In FIG. 2, (a) is a sensitivity directivity diagram of a linear antenna having leftward directivity, (b) is a sensitivity directivity diagram of a linear antenna having rightward directivity, and (c) is a diagram. Is a sensitivity directivity diagram for in-phase phase synthesis, FIG. 10D is a sensitivity directivity diagram for antiphase synthesis, and FIG. 10E is a diversity sensitivity directivity diagram for FIGS.
[0035]
In FIG. 2, the sensitivity is higher in the left-right direction due to the linear antennas having the directional characteristics on the left and right, respectively, as shown in FIGS.
In-phase combining has relatively low sensitivity in the front-rear direction as shown in FIG. 3 (c), whereas anti-phase combining has high sensitivity in the front-rear direction as shown in FIG.
Diversity has high sensitivity in the front, rear, left, and right directions, and can obtain a sufficient sensitivity directivity for H polarization of TV broadcast.
[0036]
FIG. 3 is a diagram illustrating a simulation sensitivity directivity characteristic for V polarization.
3A is a sensitivity directional characteristic diagram of a linear antenna having a left directional characteristic, FIG. 3B is a sensitivity directional characteristic diagram of a linear antenna having a right directional characteristic, and FIG. Is a sensitivity directivity diagram for in-phase phase synthesis, FIG. 10D is a sensitivity directivity diagram for antiphase synthesis, and FIG. 10E is a diversity sensitivity directivity diagram for FIGS.
[0037]
In FIG. 3, the tendency of the sensitivity directivity characteristic differs from that in FIG. 2 is that the sensitivity in the front-rear direction of the in-phase phase combination in FIG. That is the point.
(E) In the diversity shown in the figure, the sensitivity is high in the front, rear, left, and right directions, and a sufficient sensitivity directivity characteristic can be obtained for the V polarization of TV broadcast.
[0038]
From the simulation analysis described above, all of the horizontal sensitivity of the two linear antennas having the directional characteristics on the left and right and the sensitivity in the front and rear directions of the anti-phase combining for the H-polarized TV broadcast wave are all different. Sensitivity in the direction is obtained.
[0039]
In addition, simulation analysis shows that, for a V-polarized TV broadcast wave, the sensitivity in the left-right direction of two linear antennas having left-right directional characteristics and the sensitivity in the front-rear direction of in-phase synthesis are all directions. Which has sufficient sensitivity directivity characteristics.
[0040]
From the simulation analysis, it is clear that diversity does not require in-phase combining for H-polarization reception and diversity does not require anti-phase combining for V-polarization reception.
[0041]
However, in general, domestic TV broadcast waves are transmitted with H polarization, but due to various scatterings and the like of TV broadcast waves, how the polarization of TV broadcast waves actually received while a vehicle is traveling is changed. It is difficult to specify whether the antennas are in the same direction, and in order to obtain good sensitivity to the H and V polarizations in all directions of the vehicle, two antennas, in-phase combining and inverse It is desirable to build diversity at the output of the phase-phase synthesis.
[0042]
Subsequently, measurement data of sensitivity directivity characteristics when the TV diversity system 1 for vehicle mounting according to the present invention is mounted on a one-box vehicle and a touring wagon vehicle and a TV broadcast wave (H polarization) is received will be shown.
The conditions of the sensitivity measurement are as follows.
[0043]

[0044]
FIG. 4 is a sensitivity directional characteristic diagram of a one-box vehicle (measurement frequency 103 MHz), and FIG. 5 is a sensitivity directional characteristic diagram of a one-box vehicle (measurement frequency 199 MHz).
4A and 4B, FIG. 4A is a sensitivity directional characteristic diagram of a linear antenna having a left directional characteristic, FIG. 4B is a sensitivity directional characteristic diagram of a linear antenna having a right directional characteristic, FIG. 3C is a sensitivity directivity diagram of the in-phase phase synthesis, FIG. 4D is a sensitivity directivity diagram of the antiphase synthesis, and FIG. 4E is a diversity sensitivity directivity diagram of FIGS. .
[0045]
From the measurement data of FIG. 4 and FIG. 5, the sensitivity directivity characteristics obtained from the two antennas on the left and right, in-phase synthesis, and anti-phase synthesis diversity can obtain good results in all directions.
[0046]
In the sensitivity directivity characteristics of the diversity shown in FIGS. 4 and 5, sensitivity equal to or higher than the sensitivity of the left and right antennas at the measurement frequency is obtained in all directions.
Further, the tendency of the diversity sensitivity directivity characteristics can be confirmed in the VHF frequency band (90 to 230 MHz).
[0047]
FIG. 6 is a sensitivity directional characteristic diagram (measurement frequency of 102 MHz) of the touring wagon vehicle, and FIG. 7 is a sensitivity directional characteristic diagram (measurement frequency of 200 MHz) of the touring wagon vehicle.
6A and 6B, FIG. 6A is a sensitivity directional characteristic diagram of a linear antenna having left directional characteristics, FIG. 6B is a sensitivity directional characteristic diagram of a linear antenna having right directional characteristics, FIG. 3C is a sensitivity directivity diagram of the in-phase phase synthesis, FIG. 4D is a sensitivity directivity diagram of the antiphase synthesis, and FIG. 4E is a diversity sensitivity directivity diagram of FIGS. .
[0048]
From the measurement data of FIG. 6 and FIG. 7, the sensitivity directivity obtained from the two antennas on the left and right, in-phase synthesis, and anti-phase synthesis diversity can obtain good results in all directions.
[0049]
In the sensitivity directivity characteristics of the diversity shown in FIGS. 6 and 7, sensitivity equal to or higher than the sensitivity of the left and right antennas at the measurement frequency can be obtained in all directions.
Further, the tendency of the diversity sensitivity directivity characteristics can be confirmed in the VHF frequency band (90 to 230 MHz).
[0050]
As described above, the actual measurement data is also the diversity of the two types of received signals from the two antennas, the signal obtained by synthesizing the two types of received signals in-phase and the phase-separated phase, similarly to the simulation data. By taking the above, it is possible to obtain sensitivity directivity characteristics equal to or higher than when diversity of four types of received signals from four antennas is obtained.
[0051]
In the present embodiment, diversity is constructed by four types of received signals including the in-phase combined signal and the out-of-phase combined signal, but the in-phase combined signal or the inverted-phase combined signal is deleted depending on the state of the TV radio wave. To build diversity.
[0052]
【The invention's effect】
As described above, the in-vehicle TV diversity system according to the present invention can generate four types of reception signals from two TV antennas to construct diversity and obtain good sensitivity in all directions. Thus, it is possible to realize a system which is simple and economical and has excellent sensitivity directivity characteristics.
[0053]
Further, since a phase synthesis signal can be generated with a fixed phase of the same phase or the opposite phase, a vehicle-mounted TV diversity system can be easily realized.
[0054]
Further, it is possible to realize an in-vehicle TV diversity system having sensitivity directivity characteristics equal to or higher than that of a diversity system having four antennas.
[Brief description of the drawings]
FIG. 1 is a block diagram of an essential part of an in-vehicle TV diversity system according to an embodiment of the present invention; FIG. 2 is a diagram illustrating a simulation sensitivity directivity characteristic for H polarization; FIG. 4) Sensitivity pattern of one-box vehicle (measuring frequency 103MHz)
FIG. 5 is a sensitivity directivity diagram of a one-box vehicle (measuring frequency: 199 MHz)
FIG. 6 is a diagram showing sensitivity directivity characteristics of a touring wagon vehicle (measurement frequency: 102 MHz).
FIG. 7 is a diagram showing sensitivity directivity characteristics of a touring wagon vehicle (measuring frequency: 200 MHz).
FIG. 8 is a block diagram of a conventional in-vehicle TV diversity system.
DESCRIPTION OF SYMBOLS 1 ... In-vehicle TV diversity system, 2A, 2B ... TV antenna, 3, 3A, 3B ... Amplifying means, 4 ... Phase combining means, 4A ... In-phase combining means, 4B ... Reverse phase combining means, 5 ... Selection means, 6 ... receiving means, 7 ... level comparing means, 8 ... selection control means, 9 ... TV receiving means.

Claims (2)

Two TV antennas, two amplifying units for performing impedance matching and amplifying received signals received by the two TV antennas, and in-phase and out-of-phase received signals supplied from the two amplifying units, respectively. And a selecting means for selecting any one of the phase synthesized signal supplied from the phase synthesizing means and the respective reception signals supplied from the two amplifying means. And selection control means for controlling the selection means to select the largest level of the received signal,
The two TV antennas receive two received signals having directional characteristics in directions opposite to the vehicle, and the phase combining means includes a phase combined signal having a directional characteristic orthogonal to the directional characteristics of the two received signals. A vehicle-mounted TV diversity system characterized by generating Two TV antennas, two amplifying units for performing impedance matching and amplifying received signals received by the two TV antennas, and combining the received signals supplied from the two amplifying units in the same phase. In-phase synthesizing means, anti-phase synthesizing means for synthesizing the respective reception signals supplied from the two amplifying means in opposite phases, in-phase synthesizing signal supplied from the in-phase synthesizing means, and the anti-phase synthesizing Selecting means for selecting any one of the antiphase combined signal supplied from the means and the respective received signals supplied from the two amplifying means, and the selecting means selecting the received signal of the highest level Selection control means for controlling the
The two TV antennas receive two received signals having directional characteristics in directions opposite to the vehicle, and the phase combining means includes a phase combined signal having a directional characteristic orthogonal to the directional characteristics of the two received signals. A vehicle-mounted TV diversity system characterized by generating

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