JP2003264417A - Radio receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio receiver capable of detecting at least the direction of a transmitter of a radio signal, selecting and receiving only the radio signal from a specific direction. <P>SOLUTION: The radio receiver is provided with a plurality of sub-antennas B1, B2 in addition to the main antenna A, and constituted so that only the radio signal from the specific direction is selected and received by the main antenna A by detecting the direction of the transmitter of the radio signal based on RSSI (received signal strength indicator) signals from sub-RF (radio frequency) reception circuits D1, D2 corresponding to the respective sub-antennas B1, B2 by a processing part E and performing on/off control of a main RF reception circuit C corresponding to the main antenna A based on the detection result. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio receiving apparatus which performs a receiving operation while controlling a receiving state by using a plurality of antennas.

[0002]

2. Description of the Related Art As a radio receiving apparatus for performing radio reception using a plurality of antennas, there is a diversity receiving apparatus described in Japanese Patent Laid-Open No. 7-123037. This diversity receiver is provided with an external antenna and an internal antenna, and whether the antenna used for reception is the external antenna or the internal antenna depending on whether the received signal strength of the external antenna exceeds a predetermined threshold value. To decide.

[0003]

By the way, when receiving a radio signal, there is a technical demand to select and receive only the radio signal from a specific direction.

However, in the diversity receiving apparatus described above, the receiving operation is controlled only based on the received signal strength of a single antenna (external antenna), and therefore the direction of the transmission source of the radio signal received by each antenna, etc. Cannot be detected, and it is not possible to select and receive only radio signals from a specific direction.

In view of the above problems, the present invention can detect at least the direction of the transmission source of a radio signal,
An object of the present invention is to provide a wireless reception device capable of selecting and receiving only a wireless signal from a specific direction.

[0006]

[Means for Solving the Problems] A technical means for achieving the above-mentioned object is a main antenna, a plurality of sub-antennas,
A receiving circuit that performs wireless reception via the main antenna, and at least detects the direction of the transmission source of the radio signal received by each sub-antenna based on the received signal strength of each sub-antenna, and And a control unit that controls the reception state of the reception circuit based on the control circuit.

[0007] Preferably, the control unit detects at least the direction of the transmission source based on the received signal strength of each sub-antenna and the received signal strength of the main antenna.

Further, preferably, the control section relates to the correlation between the received signal strength when a radio signal to be received is received by the antenna and the distance between the transmission source of the radio signal to be received and the reception antenna. Correlation information is registered in advance, and based on the received signal strength of each sub-antenna and the correlation information, at least the direction of the transmission source of the radio signal received by each sub-antenna is detected, and its detection Based on the result, it is preferable to determine whether or not the receiving operation for the wireless signal is necessary.

[0009]

1 is a block diagram of a radio receiving apparatus according to an embodiment of the present invention. This wireless receiving device is, for example, a vehicle-mounted type, and includes a main antenna A, a plurality (for example, two) of sub-antennas B1 and B2, a main RF receiving circuit (reception circuit) C, and sub-antennas B1 and B2. The same number of sub-RF receiving circuits D1 and D2 and the processing unit E are provided. Among these, the sub-antennas B1 and B2 and the sub-RF receiving circuits D1 and D2 share what is provided in another radio receiving device with the radio receiving device. For example, when the wireless receiving device according to the present embodiment is a Bluetooth (R) receiving device, the antenna and the RF receiving circuit provided in another wireless receiving device such as a GPS receiving device and a VICS receiving device are sub-antennas B1 and B2. And RF receiver circuits D1 and D2. The sub antennas B1 and B2 and the sub RF
The receiving circuits D1 and D2 may be provided exclusively for the wireless receiving device according to the present embodiment, instead of being shared with other devices.

The structure of each RF receiving circuit C, D1, D2 is as follows.
Similar to the above, as shown in FIG. 1, a band pass filter 1, a high frequency amplifier 3, a frequency converter 5, an intermediate frequency band pass filter 7, an amplification / limiter circuit 9,
The detection circuit 11 is provided. Each antenna A, B1, B
The received signal received at 2 is given to the high frequency amplifier 3 via the band pass filter 1 and amplified, and then frequency converted to an intermediate frequency by the frequency converter 5. The received signal whose frequency has been converted is the intermediate frequency band pass filter 7
The signal is sent to the amplification / limiter circuit 9 for amplification and amplitude limitation, and then sent to the detection circuit 11 for detection. The extracted signal extracted from the received signal by the detection circuit 11 is sent to the corresponding processing unit (for example, the processing unit E in the case of the main RF receiving circuit C) and used for various processes.

Further, from the amplification / limiter circuit 9 of each sub-RF receiving circuit D1, D2, the corresponding sub-antenna B1,
A received signal strength indication signal (RSSI signal) of the received signal received by B2 is output. These RSSI signals are sent to the processing unit E.

The processing section E includes the sub RF receiving circuits D1 and D2.
Control of the main RF receiving circuit C based on the RSSI signals of the sub-antennas B1 and B2 given from the main antenna A
The received signal received by the main RF receiving circuit C is processed via.

The processing unit E includes each sub-RF receiving circuit D1,
Based on the RSSI signal given from D2, the direction of the transmission source of the radio signal received by the sub-antennas B1 and B2 based on a predetermined reference position (for example, the position of the main antenna A) is detected, and the detection is performed. Based on the result, the necessity of receiving the radio signal transmitted by the main antenna A is determined,
The main RF receiving circuit C is turned on and off (selection of transmitted wireless signals). In the present embodiment, the main RF receiver circuit C is turned off in the normal state, and the sub antenna B is
Only when the transmission sources of the radio signals received by 1 and B2 are located in the direction registered in advance with respect to the reference position (for example, the direction toward the vehicle front side with respect to the reference position). The circuit C is turned on so that the main antenna A receives the radio signal. Deputy R
As a general rule, the F receiving circuits D1 and D2 are always kept in the ON state.

The direction of the transmission source of the radio signal being transmitted is detected as follows. That is, in the processing unit E, the correlation information about the correlation between the received signal strength when the wireless signal to be received by the antenna is received and the distance between the transmission source of the wireless signal to be received and the receiving antenna is registered in advance. The detection of the direction of the transmission source is performed by using this correlation information.

There are cases where the correlation is derived by theoretically considering the spatial propagation loss of the radio signal and cases where it is based on actual measurement. When theoretically deriving the correlation, the wireless signal is received by each of the sub-antennas B1 and B2 based on the transmission intensity of the wireless signal to be received from the transmission source and the distance from the transmission source. The received signal strength at that time is theoretically derived, and a numerical table (or a relational expression or the like) indicating the relationship between the received signal strength and the distance is registered in the processing unit E as correlation information. In this case, a numerical table (or a relational expression or the like) may be prepared for each of the sub-antennas B1 and B2, or a common numerical value table (or a relational expression or the like).
May be shared for analysis of the reception signal strength of each sub-antenna B1, B2 in consideration of the reception characteristics of each sub-antenna B1, B2.

When the correlation is obtained by actual measurement,
For example, the transmission source of the radio signal to be received and each sub-antenna B
Each sub-antenna B while changing the distance between 1 and B2.
The received signal strengths of B1 and B2 are measured, and based on the measurement result, a numerical table or the like showing the correlation between the distance and the received signal strength for each sub-antenna B1 and B2 is created, and the numerical table is used as correlation information. Is registered in the processing section E.

Then, the processing section E uses each of the above-mentioned correlation information to make each sub-antenna B based on the RSSI signal given from each sub-RF receiving circuit D1, D2.
1, B2 and the distance to the wireless signal transmission source are detected, and the direction of the wireless signal transmission source with respect to the reference position is detected by a triangulation method based on the derived result.

Here, each sub-antenna B is provided in the processing section E.
Information on the positional relationship of the sub-antennas B1, B2, etc. necessary for detecting the direction of the transmission source with respect to the predetermined position based on the distance from the wireless signal transmission source to the transmission source of B1, B2 is also registered in advance. As the information on the positional relationship, for example, information indicating the positional relationship of the sub-antennas B1 and B2 with respect to the predetermined position is used.

Further, the processing section E includes each sub-RF receiving circuit D.
When detecting the direction of the transmission source using the RSSI signals from 1 and D2, the time average is obtained by adding the values of the reception strengths indicated by the RSSI signals for each sub-antenna B1 and B2 for a predetermined time and then dividing. The direction is detected by using the calculated value. By this averaging process, it is possible to suppress errors due to fluctuations in the RSSI signal due to changes in the reception state of radio signals. Here, regarding how much time the value of the RSSI signal is added and averaged, when the position of the transmission source moves, the averaging time does not adversely affect the direction detection of the transmission source. Set short.

FIG. 2 shows the main RF receiving circuit C by the processing unit E.
3 is a flowchart showing the control operation of FIG. Step S1
Then, RS given from each sub-RF receiving circuit D1, D2
The signal value of the SI signal is time averaged for a predetermined time.

In step S2, the direction of the radio signal received by each of the sub-antennas B1 and B2 with respect to the reference position of the transmission source with respect to the reference position of the sub-antennas B1 and B2 based on the signal value of each RSSI signal averaged over time Is detected.

In step S3, it is judged whether or not the wireless signal should be received with respect to the direction of the transmission source detected in step S2. For example, the transmission source has a predetermined direction registered in advance with respect to the reference position. If the transmission source is not located in a predetermined direction registered in advance with respect to the reference position, it is determined that it should not be received. Then, the process proceeds to step S5.

At step S4, the main RF receiving circuit C is switched from off to on and the radio signal is received through the main antenna A, while at step S5,
The main RF reception circuit C is maintained in the off state (or switched off when in the on state), and the main antenna A does not receive the radio signal.

The processing unit E has the steps S1 to S as described above.
The main RF receiver circuit C is controlled by repeating the process of 5.

As described above, according to this embodiment, the direction of the transmission source of the radio signal can be detected based on the RSSI signal from the plurality of sub antennas B1 and B2, and the main RF signal can be detected based on the detection result. By controlling the receiving circuit C to be turned on and off, it is possible to select and receive only a radio signal from a specific direction.

In the present embodiment, the sub RF receiver circuit D
Although the direction of the transmission source of the radio signal is detected based on the RSSI signals of 1 and D2, the main RF receiving circuit C also has the R direction.
The SSI signal is output and the RSS of the main RF receiving circuit C is output.
Even if the direction of the transmission source of the radio signal is detected based on the I signal and the RSSI signals of the sub RF reception circuits D1 and D2, the necessity of the radio signal reception operation is determined based on the detection result. Good. Thus, the RS of the main RF receiver circuit C
By using the SI signal as well, the direction of the transmission source and the like can be detected more accurately.

Further, in the present embodiment, the direction of the transmission source of the radio signal with respect to the reference position is detected based on the RSSI signals from the sub RF reception circuits D1 and D2.
It is also possible to detect not only the direction but also the distance from the reference position to the transmission source, and thereby detect the position of the transmission source with respect to the reference position. Then, the main RF receiving circuit C may be controlled based on the detected position of the transmission source.

[0028]

According to the invention described in claims 1 to 3, at least the direction of the transmission source of the radio signal can be detected based on the received signal strengths of the plurality of sub-antennas, and based on the detection result. By controlling the reception state of the reception circuit, it is possible to select and receive only the radio signal from a specific direction.

According to the second aspect of the invention, at least the direction of the transmission source of the radio signal is detected based on the reception signal strength of each sub-antenna and the reception signal strength of the main antenna. The direction of the signal transmission source and the like can be detected more accurately.

[Brief description of drawings]

FIG. 1 is a block diagram of a wireless reception device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a control operation of a main receiving circuit by a processing unit.

[Explanation of symbols]

A main antenna B1, B2 secondary antenna C Main RF receiver circuit D1, D2 Sub RF receiver circuit E processing unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiaki Hayashi             1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi             Auto Network Technical Laboratory Co., Ltd. F term (reference) 5J021 AA05 DB04 EA04 FA13 FA17                       FA24 FA26                 5K067 AA21 EE10 FF02 HH23 KK03                       KK15

Claims (3)

[Claims] 1. A main antenna, a plurality of sub-antennas, a receiving circuit that performs radio reception via the main antenna, and a radio received by each sub-antenna based on a received signal strength of each sub-antenna. A radio receiving apparatus comprising: a control unit that detects at least a direction of a signal transmission source and controls a reception state of the reception circuit based on the detection result. 2. The wireless reception device according to claim 1, wherein the control unit detects at least the direction of the transmission source based on the reception signal strength of each sub-antenna and the reception signal strength of the main antenna. A wireless receiving device. 3. The radio receiving apparatus according to claim 1, wherein the control unit receives the radio signal strength to be received by an antenna, the transmission source and the reception antenna of the radio signal to be received. Correlation information regarding the correlation with the distance with is registered in advance, based on the received signal strength and the correlation information of each sub-antenna, of the transmission source of the radio signal received by each sub-antenna A wireless receiving apparatus, which detects at least a direction, and determines whether or not a receiving operation for the wireless signal is necessary based on the detection result.