JPH11122154A - Radio signal reception device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize space diversity reception with simple constitution by selecting any reception antenna of not less than a necessary reception level, based on automatic gain control voltage. SOLUTION: A high frequency signal received by a first antenna 1 is converted into an intermediate frequency (IF) by a frequency converter 4. An IF amplification part 5 amplifies an intermediate frequency signal while it is gain-controlled by AGC voltage Eg. In an AGC voltage generation part 6, the inputted intermediate frequency signal is made to pass through an integral circuit and DC voltage is obtained and it is set to be AGC voltage Eg. A comparator 7 outputs a corresponding signal (the plus voltage of a prescribed value) when inputted AGC voltage Eg exceeds reference voltage Es. A switch control part 8 maintains the setting position of the switch circuit 3 to a present position. When the corresponding signal is not outputted from the comparator 7, the switch control part 8 changes over the switch circuit 3 and sets a second antenna 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a radio signal receiving apparatus, and more particularly, to spatial diversity reception in an apparatus for receiving a radio signal such as a spread spectrum signal.

[0002]

2. Description of the Related Art Diversity reception technology is known as one of the methods for coping with deterioration of the communication environment such as fading phenomenon. On the other hand, in the communication field of the spread spectrum system, RAKE is used in the direct spread spectrum spread system.
Reception schemes are known and used. The RAKE reception method is different from the general diversity of switching antennas, and functions by internal operation. The RAKE reception method identifies a signal that has passed through each of multiple paths due to a fading phenomenon, and weights reliability. And an adaptive equalization technique. That is, this is a method of removing interference distortion of a received signal and achieving diversity.

[0003]

The diversity receiving technique is an effective measure as a means for ensuring transmission quality in a propagation environment called fading. However, its structure is reduced from the viewpoint of miniaturization of the apparatus or economy. It is desired to be simple. An object of the present invention is to provide a radio signal receiving apparatus which enables space diversity reception with a simple configuration from such a viewpoint.

[0004]

SUMMARY OF THE INVENTION The present invention provides a frequency converter for down-converting a carrier signal of a predetermined frequency from an antenna to an intermediate frequency signal of a predetermined frequency, and controlling the output level to be constant by an automatic gain control voltage. An intermediate frequency amplifying unit that amplifies the intermediate frequency signal while being amplified, and an automatic gain control voltage generating unit that amplifies an output signal of the intermediate frequency amplifying unit and converts the amplified signal into a direct current to generate the automatic gain control voltage. In a wireless signal receiving device comprising: at least two receiving antennas, a switching circuit for switching the receiving antenna, and based on the automatic gain control voltage, to select any receiving antenna above the required receiving level An antenna setting means for setting the switching circuit is provided.

The antenna setting means compares the automatic gain control voltage based on a signal received by the currently set antenna with a set reference voltage, and when the automatic gain control voltage exceeds the reference voltage, a corresponding value is set. A comparator for outputting a signal, and when the corresponding signal is input from the comparator, the antenna is maintained at the current setting position, and when the corresponding signal is not input, the antenna is switched to the antenna to which the corresponding signal is input. And a switching control unit for controlling the switching circuit.

Alternatively, the antenna setting means may include a level detecting section for detecting a level of the automatic gain control voltage for each receiving antenna, and a memory section for storing the level detected by the level detecting section in association with the receiving antenna. A discriminating unit for discriminating a maximum level among the detection levels stored in the memory unit, and controlling the switching circuit, the level detecting unit, the memory unit, and the discriminating unit, and sequentially switching the switching circuit to detect the level. And a switching control unit that controls the switching circuit so as to set the reception antenna at the maximum level determined by the determination unit.

A timer unit for measuring time is provided below the switching control unit, and every time a predetermined time period elapses by the timer unit, a level is detected by the level detection unit, and a storage in the memory unit based on the level detection is performed. Updating of data, determination of a maximum level by the determination unit based on storage data related to the update, and control of the switching circuit by the switching control unit based on the determination may be performed.

[0008]

Embodiments of the present invention will be described below with reference to the drawings based on embodiments. FIG. 1 is a main block diagram showing an embodiment of a wireless signal receiving apparatus according to the present invention,
FIG. 2 is a main block diagram showing another embodiment of the radio signal receiving apparatus according to the present invention. FIGS. 1 and 2 both show an example in which two sets of receiving antennas are provided, and as a function thereof, a device for receiving a spread spectrum signal. FIG.
, 1 is a first receiving antenna, 2 is a second receiving antenna, 3 is a switching circuit for switching between the first receiving antenna and the second receiving antenna, and 4 is a radio frequency (RF) signal from the antenna at a predetermined frequency. A frequency converter for down-converting to an intermediate frequency (IF) signal,
Reference numeral 5 denotes an intermediate frequency (IF) amplifier for amplifying the intermediate frequency signal by automatic gain control (AGC), and reference numeral 6 denotes an AGC voltage for generating an automatic gain control (AGC) voltage based on the signal from the IF amplifier 5. A generating unit 7 compares the AGC voltage with the reference voltage Es and outputs a corresponding signal. A switching control unit 8 switches and controls the switching circuit 3 based on the comparison result of the comparator 7.

Reference numeral 9 denotes a quadrature demodulation unit for quadrature demodulation based on the signal from the IF amplifying unit 5 and outputting signals of an in-phase component I and a quadrature component Q. Reference numeral 10 designates both the I signal and the Q signal. And a spread demodulation unit for performing spread spectrum demodulation. Also,
In FIG. 2, the same components as those in FIG.
Is a level detection unit that detects the level of the AGC voltage for each reception antenna, 22 is a memory unit that stores the AGC voltage level detected by the level detection unit 21 in association with the reception antenna,
Reference numeral 23 denotes a discrimination unit for discriminating the maximum level in the data stored in the memory unit 22, and reference numeral 24 denotes a switching control unit for switching to the reception antenna having the maximum level of the AGC voltage based on the discrimination result of the discrimination unit 23.

Next, the operation of the present invention will be described separately for each figure. (1) Embodiment of FIG. 1 As an initial state, the switching circuit 3 is set to a predetermined receiving antenna side under the control of the switching control unit 8. In this embodiment, this setting is set to the first antenna 1 side. 1st
The high frequency (RF) signal received by the antenna 1 is converted into an intermediate frequency (IF) by the frequency converter 4 and sent to the IF amplifier 5. The IF amplifier 5 amplifies the intermediate frequency signal while gain control is performed by the AGC voltage Eg. The amplified intermediate frequency signal is supplied to a quadrature demodulator 9 and an AGC voltage generator 6.
Branch input to In the AGC voltage generator 6, the input intermediate frequency signal is further amplified by an amplifier, and then passed through an integration circuit formed by an operational amplifier (operational amplifier) or the like to obtain a DC voltage. Since this DC voltage increases and decreases according to the antenna reception level, this DC voltage is used as the AGC voltage. This AG
The manner in which the C voltage is increased or decreased depends on the circuit configuration of the IF amplifier 5.
The mode is divided into a mode that increases when the reception level increases and a mode that decreases when the reception level increases. In the present embodiment, the former mode is used.

The AGC voltage Eg is fed back to the IF amplifier 5 and used for the above-mentioned automatic gain control.
It is also input to the comparator 7. The comparator 7 compares the input AGC voltage with a preset reference voltage Es,
When the AGC voltage Eg exceeds the reference voltage Es, a corresponding signal (for example, a plus voltage of a predetermined value) is output. This corresponding signal is sent to the switching control 8. The switching control unit 8 maintains the set position of the switching circuit 3 at the current position when the corresponding signal is input. The output of the corresponding signal from the comparator 7 is because the antenna at the current setting position (the first antenna 1 based on the above premise) indicates the required reception level.

On the other hand, when the corresponding signal is not output from the comparator 7, the switching control section 8 switches the switching circuit 3 to set the second antenna 2. In most cases, the switching level increases the reception level, and the AGC voltage Eg exceeds the reference voltage Es. This is due to the fact that, in the case of spatial diversity reception, arrangement is usually made so that one of the antennas can receive at a normal level. However, it is not 100% reliable, and this is the limit of the present embodiment. The other intermediate frequency signal branched from the IF amplifier 5 is supplied to the quadrature demodulator 9 and the spread demodulator.
At 10, predetermined demodulation processing is performed. The above is the description of the operation of the embodiment shown in FIG. Also, if the receiving antenna is 3
In the case where the number is equal to or more than the set and the corresponding signal is not output from the comparator 7, the switching control unit 8 sequentially switches the switching circuit 3 in the same manner as described above, and sets the receiving antenna to which the corresponding signal has been input from the comparator 7. I do.

(2) Embodiment of FIG. 2 The embodiment shown in FIG. 2 is different from that of FIG. It is set to the antenna on the side. Therefore, as an initial operation, the switching control unit 24 switches the switching circuit 3 according to a predetermined order. In this embodiment, this switching order is first
, And then switch to the second antenna 2. Also, the reception level of each antenna is detected based on the AGC voltage Eg from the AGC voltage generator 6 as in FIG. This detection is performed by the level detection unit 21, and the level detection unit 21 converts the detected level into digital data and outputs the digital data. The reception level data of each antenna detected by the level detection unit 21 is stored in the memory unit 22 in association with each antenna under the control of the switching control unit 24. Memory section
After the above data is stored in the storage unit 22, the determination unit 23 determines the antenna on the higher-level side based on the stored data under the control of the switching control unit 24. The switching control unit 24 sets the antenna on the side with the higher AGC voltage based on the above determination by the determination unit 23. Thereby, the optimum antenna is selected.
The above is the description of the operation of the embodiment shown in FIG.

Further, the embodiment of FIG.
A timer unit (not shown) for measuring time may be provided under 24, and the antenna may be reset every predetermined time. That is, the reception level of each antenna is detected by the level detection unit 21 every time a predetermined time elapses, the data stored in the memory unit 22 is updated by the detection, the re-determination is performed by the determination unit 23, and the receiving antenna is reset according to the re-determination. . With this method, it is possible to select the optimum antenna even when the fading environment changes. The functional blocks having the same reference numerals as those in FIG. 1 are the same as those in FIG. When there are three or more receiving antennas, the reception level of each antenna is checked before final antenna setting, and switching control is performed so that the antenna having the highest reception level is set (switching control unit). twenty four).

[0015]

As described above, according to the present invention, it is possible to perform space diversity reception with a simple configuration using an automatic gain control (AGC) voltage in an existing circuit. Therefore, for example, by using the present invention for reception in mobile communication by the spread spectrum method, a received image or the like can be stabilized. Thus, it can be said that the present invention can contribute to improving the performance of a device that receives a radio signal.

[Brief description of the drawings]

FIG. 1 is a main block diagram showing an embodiment of a wireless signal receiving apparatus according to the present invention.

FIG. 2 is a main part block diagram showing another embodiment of the wireless signal receiving apparatus according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 first receiving antenna 2 second receiving antenna 3 switching circuit 4 frequency converter 5 intermediate frequency (IF) amplifier 6 AGC voltage generator 7 comparator 8 switching controller 9 quadrature demodulator 10 spreading demodulator 21 level detector 22 Memory unit 23 Judgment unit 24 Switching control unit

Claims (4)

[Claims] 1. A frequency converter for down-converting a carrier signal of a predetermined frequency from an antenna to an intermediate frequency signal of a predetermined frequency, and amplifying the intermediate frequency signal while controlling the output level to be constant by an automatic gain control voltage. A wireless signal receiving apparatus comprising: an intermediate frequency amplifying unit that amplifies an output signal of the intermediate frequency amplifying unit; and an automatic gain control voltage generating unit that generates the automatic gain control voltage by converting the amplified signal into a direct current. , At least two receiving antennas, a switching circuit for switching between the receiving antennas, and an antenna setting for setting the switching circuit to select any of the receiving antennas having a required reception level or higher based on the automatic gain control voltage And a wireless signal receiving device. 2. The automatic gain control voltage based on a signal received by a currently set antenna, wherein the antenna setting means includes:
A comparator that compares a set reference voltage and outputs a corresponding signal when the automatic gain control voltage exceeds the reference voltage, and maintains the antenna at the current set position when the corresponding signal is input from the comparator. 2. The wireless communication system according to claim 1, further comprising: a switching control unit that controls the switching circuit so as to switch to an antenna to which the corresponding signal is input when the corresponding signal is not input. Signal receiver. 3. A level detecting section for detecting a level of the automatic gain control voltage for each receiving antenna, and a memory section for storing a level detected by the level detecting section in association with the receiving antenna. A discriminating unit for discriminating a maximum level among the detection levels stored in the memory unit, and controlling the switching circuit, the level detecting unit, the memory unit, and the discriminating unit, and sequentially switching the switching circuit to detect the level. 2. The wireless signal according to claim 1, further comprising: a switching control unit that controls the switching circuit so as to set the reception antenna at the maximum level determined by the determination unit after the determination. Receiver. 4. A timer section for measuring time is provided below the switching control section, and each time a predetermined time elapses by the timer section, a level is detected by the level detection section, and a storage in the memory section based on the level detection is performed. 4. The radio signal according to claim 3, further comprising: updating the data, determining a maximum level by the determination unit based on the stored data related to the update, and controlling the switching circuit by the switching control unit based on the determination. Receiver.