JP2005244738A - Onboard antenna assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To assure a certain amount of receiving signal level, and be able to improve a receiving ratio even if the vehicle is moving in a place where the receiving signal level is not sufficiently obtained. <P>SOLUTION: Making a receiving signal of an antenna element 10a as a standard, the standard signal and the receiving signals of all antenna elements 10a to 10d are composed by multiplexers 24a to 24d, and phase difference of the received signals in respective antenna elements, are obtained as DC voltage. A control circuit 30 discriminates phase difference of respective other antenna elements 10b to 10d making antenna element 10a as a standard based on phase difference signals of respective antennas, if antenna phase difference is in 0°±90°, the antenna received signal is outputted to the compositor 15 as it is, and if antenna phase difference is in 180°±90°, phase of the antenna received signals are reversed by phase inversion circuits 16b to 16d, outputs to the compositor 15, and in-phase composition is performed and sent to a tuner 18. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an in-vehicle antenna device mounted on an automobile.

When a TV broadcast wave is received by a TV (television) receiver mounted on an automobile, a change in received signal strength (fading) due to movement of the reception point becomes a problem. For this reason, conventionally, a method is generally used in which a plurality of antennas are installed at a certain distance from a vehicle, and a signal having a strong received signal strength is selected from signals received by each antenna, that is, a diversity method is used (for example, patents). Reference 1).
Japanese Patent Laid-Open No. 3-196704

  In a conventional TV receiving vehicle-mounted antenna using a diversity system, stable video can be received when sufficient received power is obtained from one or more of a plurality of antennas. There is a problem that satisfactory video cannot be obtained when the reception level of the antenna is not sufficient. Especially in automobiles, the space for installing antennas is limited, and it is difficult to get enough space between antennas, so the effect of diversity is often not obtained. The signal level itself is low, and there are many places and areas that cannot be handled by the diversity method, leading to a decrease in the reception rate.

  Also, with conventional analog broadcast waves, even if the antenna reception level decreases, the ratio of image and audio noise only increases. However, with terrestrial digital broadcast waves, both video and audio are blocked, so this is necessary. There is also a high possibility that no information will be obtained.

  The present invention has been made to solve the above-described problems, and can secure a certain reception signal level even in a place where the reception signal level cannot be sufficiently obtained, thereby improving the reception rate even while the vehicle is moving. An object is to provide an in-vehicle antenna device.

  In a first aspect of the present invention, in a vehicle-mounted antenna device capable of receiving broadcast waves by combining received signals from a plurality of antenna elements, a part of the signals from the antenna elements are extracted, A monitoring control unit that monitors the phase difference of the reception signal of the antenna element; and a signal synthesis unit that controls the phase of the reception signal of each antenna element based on the control signal from the monitoring control unit and performs in-phase synthesis. It is characterized by that.

  In a second aspect based on the first aspect, the monitoring controller determines whether or not the phase difference of the received signal of the other antenna element with respect to the reference antenna element is within a range of 0 ° ± 90 °. The control signal is output to the signal synthesizer, and the signal synthesizer includes a phase inversion circuit. The in-phase synthesis is performed by directly inverting the phase of the received signal of each antenna element by the control signal from the monitoring controller. It is characterized by doing.

  The present invention does not select the antenna element having the maximum reception level from among a plurality of antenna elements as in the diversity system, but is configured to increase the level of the reception signal by combining all the reception signals of each antenna element. It is a thing. In this case, each received signal is synthesized when the phase difference of the received signal obtained from each antenna element is 0 ° ± 90 °, but the phase difference is outside the range of 0 ° ± 90 °, that is, 180 ° ± 90. Conversely, in the range of °, the received signal is weakened. Therefore, if one antenna element is used as a reference and the phase difference of a received signal obtained from another antenna element is within a range of 0 ° ± 90 ° with respect to the phase of a signal received by the reference antenna element, for example. If it is synthesized as it is and is in the range of 180 ° ± 90 °, the phase of the received signal is inverted and synthesized. Thereby, the reception signals of all the antenna elements can be synthesized in phase, and the reception signal level can be increased and sent to the tuner unit.

  According to the present invention, it is possible to synthesize the received signals of all installed antenna elements in the same phase, and even if the received signal strengths of all the antenna elements cannot be sufficiently obtained, they are synthesized in the same phase. By doing so, the reception level can be secured, and the reception rate can be improved even while the vehicle is moving.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a vehicle-mounted antenna device according to an embodiment of the present invention. In FIG. 1, a plurality of antenna elements 10a to 10d, for example, four antenna elements are attached to the vehicle 1 as shown in FIGS. 2 and 3, for example. The antenna elements 10a to 10d can receive radio waves in the UHF band of 470 to 770 MHz, for example.

FIG. 2 shows an example in which a film-like antenna is used as the antenna elements 10a to 10d and is attached to the front window glass 2 and the rear glass 3 of the vehicle 1.
FIG. 3 shows an example in which a planar antenna such as a spiral antenna is used as the antenna elements 10 a to 10 d and is mounted on the vehicle body upper roof (roof top) 4 of the vehicle 1. In this case, the antenna elements 10a to 10d are arranged at a certain distance from the vehicle body upper roof 4 so that the influence from the vehicle body metal part is reduced. For example, the antenna elements 10b to 10d are mounted on the upper roof 4 of the vehicle body with an insulator having a certain thickness interposed therebetween.

  The signals received by the antenna elements 10a to 10d are divided into two by the two distributors 11a to 11d, one signal is input to the monitoring control unit 12, and the other signal is a switch provided in the signal synthesis unit 13. A circuit, for example, is input to the switching terminal c of the diode switches 14a to 14d. The diode switches 14a to 14d include fixed terminals a and b and a switching terminal c so that the switching terminal c is switched to the fixed terminal a or b side by a control signal sent from a control circuit 30 described later in detail. It has become.

  The signal extracted from the fixed terminal a of the diode switches 14a to 14d is directly input to the synthesizer 15, and the signal extracted from the fixed terminal b is input to the synthesizer 15 via the phase inverting circuits 16a to 16d. As the phase inversion circuits 16a to 16d, for example, SCPJ-2-750-75 manufactured by Mini-Circuits is used, so that phase inversion can be performed over the entire UHF-TV band of 470 to 770 MHz.

  The synthesizer 15 synthesizes the antenna reception signals sent via the diode switches 14 a to 14 d and outputs them to the tuner 18 for receiving digital broadcast via the transmission line, for example, the coaxial cable 17. When the channel is switched, the tuner 18 outputs a signal corresponding to the selected channel, that is, a channel selection signal. The channel selection signal output from the tuner 18 is sent to the control circuit 30.

  On the other hand, the monitoring control unit 12 is provided with band-pass filters (BPF) 21a to 21d, and one signal distributed by the two distributors 11a to 11d is input to the band-pass filters 21a to 21d. The band-pass filters 21a to 21d are those whose filter bands are switched by a control command from the control circuit 30. For example, in the UHF band of 470 to 770 MHz, the filter band is set every 6 MHz corresponding to the selected channel of the tuner 18. Can be switched.

  The output signal of the band-pass filter 21b is amplified by the operational amplifier 22a and then input to the two distributor 23 and divided into two, and one of the signals is input to one terminal of the multiplier 24a.

  The output signals of the bandpass filters 21b to 21d are input to one input terminal of the multipliers 24b to 24d via the operational amplifiers 22b to 22d. The other signal divided into two by the two distributor 23 is amplified by the operational amplifier 25, then divided into four by the four distributor 26, and input to the other input terminals of the multipliers 24a to 24d. . That is, the signal received by the antenna element 10a is used as a reference, and the reference signal and the reception signals of the antenna elements 10a to 10d are multiplied by the multipliers 24a to 24d. By this multiplication processing, the phase difference from the signals received by the other antenna elements 10b to 10d is obtained as a DC voltage with reference to the signal received by the antenna element 10a.

  The antenna phase difference signals output from the multipliers 24a to 24d are sent to the A / D converter 29 via low-pass filters (LPF) 27a to 27d and operational amplifiers 28a to 28d. The low-pass filters 27a to 27d are for selecting a DC component, and the pass band is set to several tens Hz or less, for example, 50 Hz or less. The A / D converter 29 converts the antenna phase difference signal output from the operational amplifiers 28a to 28d into a digital signal, and outputs the digital signal to the control circuit 30 including, for example, a microcomputer.

  The control circuit 30 switches the bandpass filters 21a to 21d to the corresponding channels according to the channel selection signal sent from the tuner 18, and based on the antenna phase difference signal output from the A / D converter 29, Determining whether the phase difference between the other antenna elements 10b to 10d with respect to the antenna element 10a is in the range of 0 ° ± 90 ° or other range, that is, in the range of 180 ° ± 90 °, The diode switches 14a to 14d are switched and controlled according to the determination result.

  That is, the control circuit 30 keeps the switching terminal c of the diode switch 14a with respect to the reference antenna element 10a switched to the fixed terminal a side, and the antenna phase difference is different from the other antenna elements 10b to 10d. If it is in the range of 0 ° ± 90 °, the switching terminal c of the diode switches 14b to 14d is switched to the fixed terminal a side and the antenna reception signal is output to the synthesizer 15 as it is, and the antenna phase difference is in the range of 180 ° ± 90 °. , The switching terminals c of the diode switches 14b to 14d are switched to the fixed terminal b side, and the phase of the antenna reception signal is inverted by the phase inversion circuits 16b to 16d and output to the combiner 15. As a result, in the combiner 15, the reception signals of the antenna elements 10 a to 10 d are combined in phase within the phase difference range of 0 ° ± 90 ° and sent to the tuner 18 via the coaxial cable 17.

Next, the overall operation of the above embodiment will be described.
When a desired TV channel is selected by the tuner 18, a channel selection signal is output from the tuner 18 and sent to the control circuit 30. The control circuit 30 switches and controls the frequency bands of the bandpass filters 21a to 21d based on the channel selection signal sent from the tuner 18. As a result, of the broadcast waves received by the antenna elements 10a to 10d, the broadcast wave of the channel selected by the tuner 18 passes through the bandpass filters 21a to 21d and is input to the operational amplifiers 22a to 22d and amplified. .

  Then, the output signal of the operational amplifier 22a is divided into two by the two distributor 23 as a reference signal, and the one signal and the output signals of the operational amplifiers 22b to 22d are respectively input to one input terminals of the multipliers 24a to 24d. The The other signal distributed by the two distributors 23 is divided into four by the four distributors 26 and input to the other input terminals of the multipliers 24a to 24d. The multipliers 24a to 24d multiply the signals input to both the input terminals, and output the multiplication results to the A / D converter 29 via the low-pass filters 27a to 27d and the operational amplifiers 28a to 28d.

  As described above, the reception signal of the antenna element 10a is used as a reference, and the reference signal and the reception signals of all the antenna elements 10a to 10d are combined by the multipliers 24a to 24d, so that the reception signal of the antenna element 10a is used as a reference. The phase difference from the reception signals of the other antenna elements 10b to 10d is obtained as a DC voltage.

  The A / D converter 29 converts the phase difference of the received signals of the antenna elements 10 a to 10 d into a digital signal and outputs it to the control circuit 30. Based on the phase difference signal of each antenna output from the A / D converter 29, the control circuit 30 has a phase difference of 0 ° ± 90 ° between the other antenna elements 10b to 10d with the antenna element 10a as a reference. It is discriminated whether it is in the range or 180 ° ± 90 °, and the diode switches 14b to 14d are controlled to switch according to the discrimination result.

  That is, the control circuit 30 keeps the switching terminal c of the diode switch 14a with respect to the reference antenna element 10a switched to the fixed terminal a side, and the antenna phase difference is different from the other antenna elements 10b to 10d. If it is in the range of 0 ° ± 90 °, the switching terminal c of the corresponding diode switch 14b-14d is switched to the fixed terminal a side, and the antenna reception signal is output to the combiner 15 as it is, and the antenna phase difference is 180 ° ± 90. If within the range, the switching terminals c of the corresponding diode switches 14b to 14d are switched to the fixed terminal b side, and the phase of the antenna reception signal is inverted by the phase inverting circuits 16b to 16d and output to the combiner 15. As a result, the received signals of the antenna elements 10a to 10d are all in the phase difference range of 0 ° ± 90 ° and are synthesized in phase by the synthesizer 15. The antenna reception signal combined in phase by the combiner 15 is sent to the tuner 18 through the coaxial cable 17.

  As described above, the reception signals of all the antenna elements 10a to 10d can be combined in the same phase. For this reason, even if the reception signal strengths of all the antenna elements 10a to 10d cannot be sufficiently obtained. By combining them in-phase, the reception level can be secured, and the reception rate can be improved even while the vehicle is moving.

  In the above description, when the operation of the signal synthesizer 13 is controlled by the control circuit 30 based on the antenna phase difference, the switching terminal c of the diode switch 14a with respect to the reference antenna element 10a is fixed. If the antenna phase difference is within the range of 0 ° ± 90 ° for the other antenna elements 10b to 10d, the antenna reception signal is output to the synthesizer 15 as it is. If the antenna phase difference is in the range of 180 ° ± 90 °, the phase of the antenna reception signal is inverted by the phase inversion circuits 16b to 16d and output to the combiner 15. However, for example, the reference antenna element 10a is used. The switching terminal c of the diode switch 14a is switched to the fixed terminal b side, that is, the phase inversion circuit 16a is inserted. If the antenna phase difference is in the range of 0 ° ± 90 ° with respect to the other antenna elements 10b to 10d, the phase of the antenna reception signal is inverted by the phase inversion circuits 16b to 16d. If it is output to the combiner 15 and the antenna phase difference is in the range of 180 ° ± 90 °, the in-phase combination can be performed even if the antenna reception signal is output to the combiner 15 as it is.

Then, the control circuit 30 changes the other antenna element 10b when the switching terminal c of the diode switch 14a with respect to the reference antenna element 10a is switched to the fixed terminal a side and when the switching terminal c is switched to the fixed terminal a side. In consideration of switching of the diode switches 14b to 14d with respect to 10 to 10d, the diode switches 14a to 14d are switched so that the number of phase inversion circuits 16a to 16d interposed between the antenna elements 10a to 10d and the combiner 15 is reduced. Control.
As described above, the switching loss of the phase switch circuits 16a to 16d is controlled by the control circuit 30 so that the number of the phase switch circuits 16a to 16d inserted in the transmission line is reduced. Can be reduced.

  Moreover, although the case where the four antenna elements 10a-10d were used was shown in the said embodiment, the number of antenna elements can be set arbitrarily.

Furthermore, in the above embodiment, the bands of the bandpass filters 21a to 21d are switched in accordance with the channel switching of the tuner 18, but the bands of the bandpass filters 21a to 21d are fixed according to a specific channel. Also good.
Further, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.

The block diagram which shows the structure of the vehicle-mounted antenna apparatus which concerns on one Embodiment of this invention. The figure which shows the example which mounted | wore with the window glass of the vehicle in the same embodiment. The figure which shows the example which attached the antenna element to the vehicle body upper roof in the same embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Front window glass, 3 ... Rear glass, 4 ... Car body upper part roof, 10a-10d ... Antenna element, 11a-11d ... 2 distributor, 12 ... Monitoring control part, 13 ... Signal composition part, 14a-14d DESCRIPTION OF SYMBOLS ... Diode switch, 15 ... Synthesizer, 16a-16d ... Phase inversion circuit, 17 ... Coaxial cable, 18 ... Tuner, 21a-21d ... Band pass filter (BPF), 22a-22d ... Operational amplifier, 23 ... Two dividers, 24a-24d ... multiplier, 25 ... operational amplifier, 26 ... 4 distributor, 27a-27d ... low pass filter (LPF), 28a-28d ... operational amplifier, 29 ... A / D converter, 30 ... control circuit.

Claims (2)

In the in-vehicle antenna device that can receive broadcast waves by synthesizing the reception signals of multiple antenna elements,
A part of the signal from each antenna element is taken out, and a monitoring control unit that monitors a phase difference of a received signal of another antenna element with respect to a reference antenna element, and each antenna based on a control signal from the monitoring control unit An in-vehicle antenna device comprising: a signal synthesis unit that performs in-phase synthesis by controlling a phase of a reception signal of an element.   The supervisory control unit determines whether or not the phase difference of the received signal of the other antenna element with respect to the reference antenna element is within a range of 0 ° ± 90 °, and outputs a control signal to the signal synthesis unit. The in-vehicle unit according to claim 1, wherein the unit includes a phase inversion circuit, and a received signal of each antenna element is directly or in phase inverted by the phase inversion circuit by a control signal from the monitoring control unit. Antenna device.

Images