JP5733040B2 - Antenna system - Google Patents

Description

  The present invention relates to an antenna system that uses a plurality of antennas to cancel noise.

  As a prior art, a portable terminal having a configuration for canceling noise using an antenna that receives an external radio signal and a noise sensor unit that detects noise generated from a noise source in the terminal itself is known. (For example, refer to Patent Document 1). The mobile terminal selects a noise profile from the memory unit that stores a noise profile that is predicted to be generated in response to the usage state of the terminal, and the memory unit based on the usage state of the terminal. And a control unit that controls the operation of the noise sensor unit according to the noise profile.

JP 2008-244987 A

  By the way, the level and phase of noise mixed in the main antenna and the noise cancellation antenna are greatly influenced by the correlation between the noise generation source and each antenna. For example, such correlation includes the distance from the noise generation source to each antenna, the presence / absence of a dielectric located between and near the noise generation source and each antenna, and the like.

  However, in the above-described conventional technology, since it is necessary to mount a noise sensor unit functioning as a noise canceling antenna in the immediate vicinity of the noise source, the level and phase of noise mixed in the antenna are affected in the order of μm, and the mobile terminal It is not easy to apply to mass-produced products such as larger automobiles.

  In addition, since the above-described conventional technology is feedforward control that cancels noise using pre-profiled data, the state of the number, type, position, etc. of noise sources changes due to changes in the user's usage environment, etc. There is a possibility that the accuracy of noise cancellation is lowered.

  Therefore, an object of the present invention is to provide an antenna system that can easily realize a configuration that increases the accuracy of noise cancellation.

In order to achieve the above object, an antenna system according to the present invention includes:
The main antenna,
Noise cancellation antenna,
A control unit for tuning a signal received by the noise cancellation antenna;
A combining unit that combines a signal received by the main antenna and a signal obtained by tuning by the control unit;
A receiver for receiving the signal synthesized by the synthesizer;
A detector for monitoring the level of the signal received by the main antenna ;
A detection unit for detecting whether or not the noise source is operating ,
Wherein, when said noise source is the monitored level by detection unit is lower than a predetermined threshold when it is detected by the detecting unit deactivated, from the noise source is actuated, the reception unit In accordance with the reception result, the tuning is performed so that noise is removed from the signal synthesized by the synthesis unit.

  According to the present invention, it is possible to easily realize a configuration that increases the accuracy of noise cancellation.

It is a lineblock diagram of antenna system 1 which is one embodiment of the present invention. It is the flowchart which showed the process of the noise cancellation tuning which the antenna system 1 performs.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Since a vehicle is equipped with a plurality of devices such as electronic devices and radio wave receivers, there is often a problem of radio wave interference due to noise. As a countermeasure, realization of a noise removing device at the receiving antenna unit is required. In order for the noise removal device to function effectively, it is necessary to generate a signal having the same amplitude and a phase difference of 180 ° on the noise cancellation antenna side as the noise mixed in the main antenna.

The noise removal apparatus performs noise cancellation by adjusting the amplitude (also referred to as gain of the noise cancellation antenna) and / or phase of the signal received by the noise cancellation antenna and synthesizing it with the signal received by the main antenna. . The noise removal performance of the noise removal device can be derived based on the following theoretical formulas (1) to (4). However, in order to effectively obtain the noise cancellation effect, the noise amplitude and / or accuracy with accuracy within about 1 dB is obtained. Or the phase needs to be controlled.

Here, A represents the amplitude of noise mixed in the main antenna, B represents the amplitude of noise mixed in the noise cancellation antenna, and C represents the amplitude of the signal after noise cancellation. Φ ₁ represents the phase of noise mixed into the main antenna, and φ ₂ represents the phase of noise mixed into the noise cancellation antenna.

  For example, according to the theoretical formulas (1) to (4), in order to ensure a noise removal performance of 10 dB, the phase of the noise received by the noise cancellation antenna is controlled within 18 ° and the amplitude within 1.6 dB. In order to ensure a noise removal performance of 20 dB, it is necessary to control the phase within 5.5 ° and the amplitude within 0.45 dB.

  In the embodiment of the present invention described below, in order to control the amplitude and / or phase with such accuracy, an apparatus for determining whether tuning is possible and an apparatus for performing feedback tuning by actual measurement are configured. In addition, when an amplifier is used for a control unit that tunes a signal received by a noise cancellation antenna, the control unit is easily affected by noise other than the noise to be removed, and it is difficult to ensure appropriate reception performance. Therefore, a control unit that tunes a signal received by a noise cancellation antenna includes an attenuator and a phase adjuster as a tuning device without an amplifier.

  FIG. 1 is a configuration diagram of an antenna system 1 according to an embodiment of the present invention. The antenna system 1 is a system mounted on a vehicle and includes a noise removing device. The antenna system 1 includes a main antenna 11, a noise cancellation antenna 12, a state detection unit 13, a tuning switch 14, a tuning availability monitor device 15, a signal synthesizer 16, a receiver 17, a control unit 18, And a memory 19.

In FIG. 1, a symbol N ₁ represents a noise wave from the noise source 22 received by the main antenna 11, and a symbol N ₂ represents a noise wave from the noise source 22 received by the noise cancellation antenna 12. Symbol S ₁ represents a desired broadcast wave from the transmission station 21 received by the main antenna 11, and symbol S ₂ represents a desired broadcast wave from the transmission station 21 received by the noise cancellation antenna 12.

  The main antenna 11 is a first antenna whose main purpose is to receive a desired broadcast wave that has arrived from a transmission station 21 outside the vehicle. There may be one main antenna 11 or a plurality of main antennas 11. By providing a plurality of main antennas 11, a diversity antenna can be configured.

  The noise cancellation antenna 12 is a second antenna whose main purpose is to receive noise in order to remove noise generated by a noise source 22 inside or outside the vehicle. There may be one or more noise cancellation antennas 12.

The mounting position and performance of the noise cancellation antenna 12 are such that the level of the noise wave N ₁ is smaller than the level of the noise wave N _{2 and} the level of the desired broadcast wave S ₁ is greater than the level of the desired broadcast wave S _2. To do. In addition, the mounting position and performance of the noise cancellation antenna 12 may be determined so that changes in the amplitude and phase of noise mixed in the noise cancellation antenna 12 are reduced depending on the usage conditions of the user.

  The noise cancellation antenna 12 may be, for example, a structure that is disposed closer to the noise source 22 than the main antenna 11 and can ensure a noise gain, and may be a metal object having a sufficient length for reception. Further, the noise cancellation antenna 12 may be arranged at a position where the change in the degree of noise coupling is small after the noise cancellation tuning is performed at the time of vehicle shipment. Moreover, it is good to arrange | position in the position which is hard to receive the influence of another noise source.

  When the main antenna 11 is an AM radio antenna provided on a rear glass or the like and the noise source 22 is a high voltage unit (for example, an inverter, a DC-DC converter, etc.) mounted in a trunk, Examples include a defogger pattern, a seat frame, a trunk, a high-voltage unit housing, and a wire harness around the high-voltage unit.

  The state detection unit 13 is vehicle state detection means that can detect whether or not the noise source 22 that generates noise to be removed is operating. The state detection unit 13 can transmit the operating state of the noise source 22 to the entire antenna system 1.

  The tuning switch 14 switches whether or not to perform noise cancellation tuning by switching the signal path between the signal synthesizer 16 and the control unit 18 in accordance with a command from the state detection unit 13. Means.

  The tuning availability monitoring device 15 is mounted in the vicinity of the main antenna 11 and is a means for determining whether or not noise cancellation tuning can be performed according to the reception level of the signal received by the main antenna 11. The tuning availability monitoring device 15 may be mounted on the receiver 17.

  The signal synthesizer 16 cancels the noise of the noise source 22 by synthesizing the signal received by the main antenna 11 and the signal obtained by tuning the signal received by the noise cancellation antenna 12 by the control unit 18. A combining means for transmitting a signal to the receiver 17.

  The receiver 17 is a receiving unit that receives the signal synthesized by the signal synthesizer 16 and acquires the desired broadcast wave received by the main antenna 11. At the time of noise cancellation tuning, the receiver 17 controls the control unit 18 to control the amplitude and / or phase of the signal received by the noise cancellation antenna 12 so that the measured value of the signal level synthesized by the signal synthesizer 16 is minimized. Control is performed by varying the parameter, and the control parameter of the control unit 18 that minimizes the measured value is detected for each frequency of the broadcast wave received by the main antenna 11. The control parameter of the control unit 18 that minimizes the signal level measurement value synthesized by the signal synthesizer 16 is stored in the memory 19 of the control unit 18 for each frequency of the broadcast wave received by the main antenna 11. The memory 19 is a storage device that can overwrite and save the newly tuned result.

  The control unit 18 performs feedback control to vary the amplitude and / or phase of the signal received by the noise cancellation antenna 12 by using an attenuator and / or a phase adjuster that operates according to a control parameter from the receiver 17. The attenuator adjusts the amount of attenuation of the signal level received by the noise cancellation antenna 12, and the phase adjuster adjusts the phase of the signal received by the noise cancellation antenna 12.

Control so that the amplitude value of the noise wave N ₂ is attenuated by the attenuator to the amplitude value of the noise wave N ₁ , and the phase of the noise wave N ₂ is inverted by the phase adjuster with respect to the phase of the noise wave N _1. By adjusting according to the control parameter of the unit 18, the signal level measurement value synthesized by the signal synthesizer 16 is tuned to be minimized.

  The antenna system 1 having such a configuration detects whether the noise cancellation tuning is affected by an external broadcast wave and noise, determines whether or not the tuning is possible, and performs feedback control of the noise cancellation tuning according to the control parameters necessary for noise cancellation. Implement a noise cancellation signal using only the attenuator and phase adjuster.

  FIG. 2 is a flowchart showing a noise cancellation tuning process performed by the antenna system 1. The noise cancellation tuning may be performed at the time of shipment from the factory or when it is desired to re-tune.

  When a tuning start signal is input to the state detection unit 13 (step S10), the state detection unit 13 turns off the tuning switch 14 (step S20). The state detection unit 13 detects whether or not the noise source 22 is turned off (step S30). When the noise source 22 is not turned off (that is, when the noise source 22 is operating), the state detection unit 13 is not in a situation where noise cancellation tuning can be performed, so that the noise source 22 is turned off. (Step S40). If the noise source 22 is off, the noise source 22 is not operating, and the process proceeds to step S50.

The tuning availability monitoring device 15 compares whether the level of the desired broadcast wave S ₁ detected at each frequency is sufficiently smaller than the predetermined value N ₁ ′ or background noise, and stores the comparison result (step S50).

Tuning availability monitoring device 15, the receiver 17 is at all frequencies used to determine whether the level of the desired broadcast wave S ₁ is smaller than the predetermined value N _{1 '(step} S60). In all the frequencies which the receiver 17 is used, when the level of the desired broadcast wave S ₁ is not smaller than the predetermined value N1 '(step S70), where the signal wave does not arrive to the user to the noise canceling tune Information is provided (step S80). On the other hand, in some of the frequency of the total frequency receiver 17 is used, when the level of the desired broadcast wave S ₁ is not smaller than the predetermined value N1 '(step S70), the noise cancellation in a part of the frequency As tuning is not possible, the non-tunable frequency is recorded in the memory 19 of the control unit 18 and provided to the user (step S90).

In all frequencies or a part of the frequency receiver 17 is used, when the level of the desired broadcast wave S ₁ is smaller than the predetermined value N1 'is equipped with (step S60, S90), the noise cancellation tuning exemplary environment The noise source 22 is activated and the tuning switch 14 is turned on to the tuning permission side (step S100).

  The receiver 17 performs noise cancellation tuning by operating the control unit 18 so that the synthesized signal measurement value from the signal synthesizer 16 is minimized for each tunable frequency, and stores the smallest control parameter in the memory. 19 is overwritten and saved (step S120). By operating in this way, noise cancellation tuning is completed.

  When noise cancellation control is performed to remove noise from the signal received by the main antenna 11 after the noise cancellation tuning is completed (step S130), the receiver 17 performs control adapted to the frequency of the desired broadcast wave that the user wants to use. The parameter is read from the memory 19. The receiver 17 adjusts the amplitude and / or phase of the signal received by the noise cancellation antenna 12 by the control unit 18 that operates according to the read control parameter. As a result, a signal from which noise has been removed from the signal received by the main antenna 11 is input from the signal synthesizer 16 to the receiver 17.

As described above, the antenna system 1 includes the main antenna 11, the noise cancellation antenna 12, the control unit 18 that tunes the signal received by the noise cancellation antenna 12, and the signal received by the main antenna 11 and the tuning by the control unit 18. A signal synthesizer 16 for synthesizing the signals obtained in this manner, a receiver 17 for receiving the signal synthesized by the signal synthesizer 16, and a tuning availability monitor device 15 for monitoring the level of the signal received by the main antenna 11. The control unit 18 includes a signal synthesizer according to the reception result of the receiver 17 when the level monitored by the tuning availability monitoring device 15 when the noise source 22 is inactive is lower than the predetermined value N ₁ ′. 16 so that noise is removed from the signal synthesized at 16. And performs tuning. Therefore, according to the antenna system 1, the structure which raises the precision of noise cancellation is easily realizable.

  The antenna system 1 is also arranged so that the noise cancellation antenna 12 receives a broadcast wave with a signal level lower than that of the main antenna 11 and receives a noise wave with a signal level higher than that of the main antenna 11. The unit 18 tunes the signal received by the noise cancellation antenna 12 without amplifying it. Thereby, it is possible to reduce the influence on the tuning accuracy due to noise generated from a noise source different from the noise source 22 that emits noise to be canceled.

DESCRIPTION OF SYMBOLS 1 Antenna system 11 Main antenna 12 Noise cancellation antenna 13 State detection part 14 Tuning switch 15 Tunable propriety monitor apparatus 16 Signal synthesizer 17 Receiver 18 Control part 19 Memory 21 Transmitting station 22 Noise source S ₁ Desired broadcast received with the main antenna 11 Wave S ₂ Desired broadcast wave received by noise cancellation antenna 12 N ₁ Noise wave received by main antenna 11 Noise wave received by N ₂ noise cancellation antenna 12

Claims (4)

The main antenna,
Noise cancellation antenna,
A control unit for tuning a signal received by the noise cancellation antenna;
A combining unit that combines a signal received by the main antenna and a signal obtained by tuning by the control unit;
A receiver for receiving the signal synthesized by the synthesizer;
A detector for monitoring the level of the signal received by the main antenna ;
A detection unit for detecting whether or not the noise source is operating ,
Wherein, when said noise source is the monitored level by detection unit is lower than a predetermined threshold when it is detected by the detecting unit deactivated, from the noise source is actuated, the reception unit An antenna system that performs the tuning so that noise is removed from the signal synthesized by the synthesis unit in accordance with the reception result. The antenna system according to claim 1, wherein the detection unit instructs the noise source to be deactivated when the noise source is activated. The antenna system according to claim 1 or 2, wherein information is provided to a user if the level is not less than the threshold. The noise cancellation antenna is arranged to receive a broadcast wave having a signal level lower than that of the main antenna, and to receive a noise wave having a signal level higher than that of the main antenna,
The antenna system according to any one of claims 1 to 3, wherein the control unit tunes a signal received by the noise cancellation antenna without amplifying the signal.

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