JP2006020062A - Diversity receiving apparatus and receiving method in diversity receiving apparatus - Google Patents

Abstract

The processing time at the start of reception is shortened by cooperatively performing antenna selection and AGC processing in a diversity receiver, and reception of one antenna selected by a switch 13 from a plurality of antennas 11 and 12 is performed. A diversity receiver that amplifies a signal by a variable gain amplifier 16, converts the signal to a digital signal by an A / D converter 18, and then guides the digital signal to a demodulator 19, and receives the signal measured from an output signal of the A / D converter 18 The level determination unit 23 that determines the level, the switch control unit 24 that controls the switch 13 so that either the standby antenna or the non-standby antenna is selected as the reception antenna according to the level determination result, and the gain of the variable gain amplifier 16 The first gain is set at the time of standby, and a second smaller than the first gain is selected after the reception antenna is selected. A gain control unit 25 for controlling in response to the reception level of the receiving antenna after setting the gain.
[Selection] Figure 1

Description

  The present invention relates to a diversity receiver using a plurality of antennas and a reception method in the diversity receiver.

  In a wireless LAN or other wireless communication system, in order to maintain a good reception state, selection diversity in which reception is performed using one antenna selected from a plurality of antennas, or reception signals of a plurality of selected antennas are combined. Therefore, a diversity receiver using the combined diversity that is output in this manner is often used.

On the other hand, although not limited to a diversity receiver, a wireless communication device generally requires AGC (automatic gain control) to keep the level of a received signal at an appropriate value during reception. In a conventional diversity receiver, for example, as disclosed in Patent Document 1, AGC processing is performed independently of antenna selection. AGC processing is performed by controlling the gain of a variable gain amplifier that amplifies the received signal in accordance with the reception level.
JP-A-6-318891

  In the technique described in Patent Document 1, since AGC processing based on the reception level is performed after antenna selection, there is a problem that processing time required at the start of reception becomes long. In general, in a receiving apparatus, a received signal is amplified by a variable gain amplifier and then demodulated after being converted into a digital signal by an A / D converter. Regarding the measurement of the reception level, it is advantageous in terms of simplification of the circuit configuration to use digital signal processing instead of the analog signal stage.

  When the reception level is measured by digital signal processing, the dynamic range of the A / D converter is limited, so that the input level of the A / D converter falls within the dynamic range in order to perform AGC processing accurately. It is necessary to perform the AGC operation after setting the gain of the variable gain amplifier. Therefore, it is not preferable to perform the AGC process after completing the antenna selection when shifting from the standby time to the start of reception because the processing time is further increased.

  An object of the present invention is to shorten the processing time at the start of reception by performing antenna selection and AGC processing in cooperation in a diversity receiver.

  In order to solve the above problems, according to a first aspect of the present invention, a plurality of antennas; a switch for selecting one antenna from the plurality of antennas; and a variable for amplifying a received signal obtained by the selected antennas A gain amplifier; an A / D converter that converts a reception signal amplified by the variable gain amplifier into a digital signal; a level measurement unit that measures a reception level of the selected antenna from the digital signal; and the reception level A level determination unit that determines whether or not is higher than a first reference level; any one of a first antenna selected by the switch during standby and a second antenna other than the first antenna according to a determination result of the level determination unit A switch controller that controls the switch so that is selected as a receiving antenna; The variable gain amplifier is set according to the reception level of the receiving antenna after setting the gain to the first gain at the time of standby, and after setting the receiving antenna to the second gain smaller than the first gain. There is provided a diversity receiver including a gain controller for controlling the gain of the receiver.

  According to a third aspect of the present invention, in the diversity receiver that combines and outputs the output signals of a plurality of receiving units, each of the plurality of receiving units includes a plurality of antennas; and one antenna from the plurality of antennas. A variable gain amplifier that amplifies the received signal obtained by the selected antenna, an A / D converter that converts the received signal amplified by the variable gain amplifier into a digital signal; A level measurement unit that measures the reception level of the selected antenna; a first level determination unit that determines whether the reception level is higher than a first reference level; and according to a determination result of the first level determination unit, Either the first antenna selected by the switch during standby or the second antenna other than the first antenna is for reception. A switch control unit that controls the switch to be selected as an antenna; a second level determination unit that determines whether a reception level of the reception antenna is higher than a second reference level; and the second level determination unit When the reception level of the reception antenna is higher than the second reference level, a gain for setting the output of the variable gain amplifier to a specified level is set for the variable gain amplifier according to the determination result of A diversity receiver comprising: a gain controller configured to set, for the variable gain amplifier, a gain for setting the output of the variable gain amplifier to a level equal to or lower than the specified level when the reception level is equal to or lower than the second reference level. Is done.

  According to a third aspect of the present invention, in a reception method in a diversity receiver that demodulates a reception signal obtained by one antenna selected from a plurality of antennas after amplification by a variable gain amplifier, Setting a gain to a first gain; determining whether a reception level of a first antenna selected at the time of standby is higher than a first reference level when the reception signal is detected at the time of standby; When the reception level of the first antenna is higher than the first reference level, the first antenna is selected as a reception antenna, and when the reception level of the first antenna is equal to or lower than the first reference level, the first antenna is selected. Selecting a second antenna other than the antenna as a receiving antenna; and said first antenna or second antenna After container has been selected, the reception method in the diversity receiver and a step of setting the gain of the variable gain amplifier to said first gain is smaller than the second gain is provided.

  According to a fourth aspect of the present invention, in a reception method in a diversity receiver for demodulating a received signal from one antenna selected from a plurality of antennas after amplification by a variable gain amplifier, the variable gain amplifier at standby Setting the gain of the first antenna to a first gain; and determining whether the reception level of the first antenna selected during the standby is higher than a first reference level when the reception signal is detected during the standby When the reception level of the first antenna is higher than the first reference level, the first antenna is selected as a reception antenna, and when the reception level of the first antenna is equal to or lower than the first reference level, the first antenna is selected. Temporarily selecting a second antenna other than one antenna as a receiving antenna; and the second antenna is temporarily selected When the reception level of the second antenna is equal to or lower than the first reference level, the first antenna is selected as a reception antenna, and the reception level of the first antenna is equal to or lower than the first reference level and the second antenna. Selecting the second antenna as a receiving antenna if the receiving level is higher than the first reference level; determining whether the receiving level of the receiving antenna is higher than a second reference level; When the reception level of the reception antenna is higher than the second reference level, a gain for setting the output of the variable gain amplifier to a specified level is set for the variable gain amplifier, and the reception level of the reception antenna is the first level. If the reference level is 2 or less, the gain for reducing the output of the variable gain amplifier to a level below the specified level is increased Receiving method in the diversity receiver comprising the steps of setting with respect to the vessel is provided.

  According to the fifth aspect of the present invention, diversity for demodulating after combining received signals from a plurality of receiving units that amplify a received signal obtained by one antenna selected from a plurality of antennas by a variable gain amplifier In the reception method in the receiving apparatus, the step of setting the gain of the variable gain amplifier to a first gain at the time of standby; and when the reception signal is detected at the time of standby, the reception level of the first antenna selected at the time of standby is Determining whether the level is higher than a first reference level; if the reception level of the first antenna is higher than the first reference level, the first antenna is selected as a reception antenna, and reception by the first antenna If the level is lower than the first reference level, the second antenna other than the first antenna is used as a receiving antenna. Selecting; determining whether the reception level of the reception antenna is higher than a second reference level; and, if the reception level of the reception antenna is higher than the second reference level, the variable gain amplifier A gain for setting the output to a specified level is set for the variable gain amplifier, and when the reception level of the receiving antenna is equal to or lower than the second reference level, the output of the variable gain amplifier is set to a level equal to or lower than the specified level. There is provided a reception method in a diversity receiver comprising the step of setting a gain for the variable gain amplifier.

  According to the sixth aspect of the present invention, diversity is obtained by synthesizing received signals from a plurality of receiving units that amplify and output a received signal obtained by one antenna selected from a plurality of antennas by a variable gain amplifier and then demodulate the received signal. In the reception method in the receiving apparatus, the step of setting the gain of the variable gain amplifier to a first gain at the time of standby; and when the reception signal is detected at the time of standby, the reception level of the first antenna selected at the time of standby is Determining whether the level is higher than a first reference level; if the reception level of the first antenna is higher than the first reference level, the first antenna is selected as a reception antenna, and reception by the first antenna If the level is lower than the first reference level, the second antenna other than the first antenna is used as a receiving antenna. Selecting, when the reception level of the first antenna is higher than the first reference level, selecting the first antenna as a reception antenna, and when the reception level of the first antenna is less than or equal to the first reference level Tentatively selecting a second antenna other than the first antenna as a receiving antenna; and when the second antenna is temporarily selected, if the reception level of the second antenna is less than or equal to the first reference level, the second If one antenna is selected as a receiving antenna, and the reception level of the first antenna is equal to or lower than the first reference level and the reception level of the second antenna is higher than the first reference level, the second antenna is used for reception. Selecting as an antenna; determining whether a receiving level of the receiving antenna is higher than a second reference level; When the reception level of the reception antenna is higher than the second reference level, a gain for setting the output of the variable gain amplifier to a specified level is set for the variable gain amplifier, and the reception level of the reception antenna is the first level. And a step of setting the gain of the variable gain amplifier so that the output of the variable gain amplifier is lower than the specified level when the reference level is less than or equal to two reference levels.

  The reception level measurement of the non-standby antenna can be omitted, and the reception level can be determined simultaneously with the detection of the reception signal to set the gain of the variable gain amplifier for AGC. Processing time to start is shortened. Further, when the reception level is equal to or lower than the second reference level, C / N can be improved by making the output of the variable gain amplifier proportional to the input level.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
As shown in FIG. 1, in the diversity receiver according to the first embodiment of the present invention, received signals from a plurality of antennas 11 and 12 are input to an antenna selection switch 13. In the antenna selection switch 13, the reception signal of one antenna is selected according to the control signal from the switch control unit 24.

  The received signal selected by the antenna selection switch 13 is amplified by a low noise amplifier (LNA) 14 and then inputted to a down converter (D / C) 15, and converted into an IF (intermediate frequency) band by the down converter 15. Is done. The received signal converted into the IF band is input to a variable gain amplifier (VGA) 16, and is adjusted to an appropriate level according to the gain controlled by the gain control unit 25 by the variable gain amplifier 16. In the quadrature demodulator 17, the received signal output from the variable gain amplifier 16 is demodulated using two orthogonal local signals, and two orthogonal baseband signals (referred to as I / Q signals) are generated. The generated I / Q signal is converted into a digital signal by the A / D converter 18 and then demodulated by the demodulator 19 by digital signal processing.

  The digital reception signal output from the A / D converter 18 is also input to the reception level measurement unit 20. In the reception level measurement unit 20, first, the relative level calculation unit 21 calculates the relative level (relative power) of the reception signal. Next, the absolute level calculation unit 22 calculates the absolute level (absolute power) of the received signal, that is, the reception level, based on the relative level and the gain value set by the gain control unit 25.

  Information on the reception level thus calculated is input to the level determination unit 23 and the gain control unit 25. The level determination unit 23 determines whether the reception level is higher than the first reference level Vref1. The switch control unit 24 controls the antenna selection switch 13 based on the determination result of the level determination unit 23. The gain control unit 25 sets the gain at the time of standby and reception start of the variable gain amplifier 16 according to the determination result of the level determination unit 23 and then according to the reception level of the reception antenna measured by the reception level measurement unit 20. AGC is performed by controlling the gain of the variable gain amplifier 16.

  Next, an operation example of the diversity receiver according to the present embodiment will be described using the flowchart shown in FIG. Here, the antenna 11 will be described as a standby antenna used for standby, and the antenna 12 will be described as a non-standby antenna other than that. Note that “waiting” is a state in which a received signal is not detected and the next received signal is waited. For example, a standby state is entered every time reception of a received signal in units of wireless packets is completed. As a standby antenna, an antenna that has been selected as a receiving antenna until just before entering a standby state is generally selected.

  First, the gain control unit 25 sets a gain G1 that can determine whether or not the reception level is higher than the first reference level Vref1 as a standby gain (step S10). By doing so, it is possible to determine whether or not the reception level of the standby antenna 11 is higher than the first reference level Vref1 simultaneously with the detection of the reception signal, so that the antenna selection and AGC processing time can be shortened. .

  That is, the reception signal is detected after step S10 (step S11), and the level determination unit 23 determines whether or not the reception level of the standby antenna 11 is higher than the first reference level Vref1 (step S12). If the reception level of the standby antenna 11 is higher than the first reference level Vref1 as a result of this determination, the antenna selection switch 13 selects the standby antenna 11 as a data reception antenna according to the control signal from the switch control unit 24 (step S13). ). At the same time, the gain control unit 25 sets a gain G2 (where G2 <G1) that allows the variable gain amplifier 16 to determine whether or not the reception level is higher than the second reference level Vref2 (step S14).

  On the other hand, if the reception level is equal to or lower than the first reference level Vref1 as a result of the determination in step S12, the antenna selection switch 13 selects the non-standby antenna 12 as the data reception antenna according to the control signal from the switch control unit 24. (Step S15). Similarly to step S14, the gain control unit 25 sets a gain G2 that can determine whether or not the reception level is higher than the second reference level Vref2 for the variable gain amplifier 16 (step S16). If the second reference level is determined, antenna selection may be performed after the gain G2 is set.

  After setting the gain G2 in step S14 or step S16, the AGC loop of the variable gain amplifier 16 → the quadrature demodulator 17 → the A / D converter 18 → the reception level measuring unit 20 → the gain control unit 25 → the variable gain amplifier 16 works. AGC processing is then performed.

  Here, the first reference level Vref1 and the second reference level Vref2 are set as shown in FIG. FIG. 3 shows the relationship between the reception level and C / N (carrier power / noise power ratio). C / N is improved as the reception level increases, but saturates at a certain reception level. The second reference level Vref2 is selected as the reception level when C / N begins to saturate. The first reference level Vref1 is set between the noise level and the second reference level Vref2.

  FIG. 4 shows how the level measurement range by the reception level measurement unit 20 changes depending on the number of gain controls of the variable gain amplifier 16. Here, R is the dynamic range of the A / D converter 18. First, during standby, the gain of the variable gain amplifier 16 is set to a relatively large value G1 (first gain control). When the gain of the variable gain amplifier 16 is G1, the level determination unit 23 can determine whether or not the reception level is higher than the first reference level Vref1 during standby, but whether or not the reception level is higher than the second reference level Vref2. It cannot be judged until.

  Therefore, when the received signal is detected, the gain of the variable gain amplifier 16 is set to G2 smaller than G1 (second gain control). As a result, the level measurement range R by the reception level measurement unit 20 is relatively shifted upward as shown in the figure, so that the level determination unit 23 can determine whether or not the reception level is higher than the first reference level Vref1, and It can also be determined whether or not it is higher than the second reference level Vref2.

  After setting the gain of the variable gain amplifier 16 to G2 in this way, the reception level determination unit 23 determines the reception level. If the reception level is less than or equal to the first reference level Vref1, the gain is increased, and the second reference level Vref2 If it is larger, the AGC is operated to lower the gain. As a result, the reception level seen at the output of the variable gain amplifier 16, in other words, the reception level seen at the input of the A / D converter 18 is held at an appropriate level within the dynamic range R of the A / D converter 18. Therefore, a good reception demodulation operation is possible.

  At this time, as shown in FIG. 4, by reducing the level difference between the first reference level Vref1 and the second reference level Vref2 below the dynamic range R of the A / D converter 18, the reception level is within the dynamic range R, That is, it does not fall within the level measurement range in the reception level measurement unit 20 and level measurement is not impossible. Further, as shown in FIG. 1, when the reception level is measured by calculating the absolute level from the relative level of the reception signal converted into the digital signal by the A / D converter 18 in the reception level measurement unit 20, the measurement is performed. The level determination unit 23 can simultaneously determine whether the reception level is greater than the first reference level Vref1 and whether it is greater than the second reference level Vref2.

  As described above, in the first embodiment, the level of the reception level of the standby antenna 11 is determined, and either the standby antenna 11 or the non-standby antenna 12 is selected as a reception antenna according to the level determination result. The reception level measurement of the antenna 12 can be omitted.

  Further, by setting a gain G2 that can determine whether or not the reception level is higher than the first reference level Vref1 when the reception antenna is selected, and whether or not the reception level is higher than the second reference level Vref2. It is possible to quickly shift to the AGC operation. Therefore, the processing time from selection of the receiving antenna at the start of reception to AGC operation can be shortened as compared with the technique described in Patent Document 1 in which selection of the receiving antenna and AGC operation are performed independently.

  Next, another operation example of the diversity receiver according to the present embodiment will be described using the flowchart shown in FIG. In FIG. 5, the processing from step S20 to step S26 is exactly the same as the processing from step S10 to step S16 in FIG. When the standby antenna 12 is selected as a receiving antenna as in step S23, the gain of the variable gain amplifier 16 is set to G2 in step S24 as in the case of FIG.

  On the other hand, when the non-standby antenna 12 is selected as in step S25, this is positioned as a temporary selection of the receiving antenna, and after the gain of the variable gain amplifier 16 is set to G2 in the next step S26, the process proceeds to step S27. . In step S27, the level determination unit 23 determines whether the reception level of the non-standby antenna 12 is higher than the first reference level Vref1. If the reception level of the non-standby antenna 12 is greater than the first reference level Vref1 as a result of this determination, the antenna selection switch 13 selects the non-standby antenna 12 as a data reception antenna according to the control signal from the switch control unit 24 (step S28).

  If the reception level of the non-standby antenna 12 is equal to or lower than the first reference level Vref1 as a result of the level determination in step S27, the antenna selection switch 13 sets the standby antenna 11 as a data reception antenna according to the control signal from the switch control unit 24. Select (step S29). That is, when both the reception level of the standby antenna 11 and the reception level of the non-standby antenna 12 are equal to or lower than the first reference level Vref1, the standby antenna 11 is selected as the reception antenna.

  Unlike a mobile communication system, in a wireless communication system in which a terminal does not move much like a wireless LAN, it may be considered that the reception level does not change significantly within a short time. As described above, the antenna that was selected as the receiving antenna until just before entering the standby state is normally selected as the standby antenna. There is a high possibility that the reception level is high. Therefore, in such a case, a better reception state can be obtained by selecting the standby antenna 11 as a reception antenna.

  Even when the reception antenna is selected in this way, it is not necessary to compare the reception levels of the standby antenna 11 and the non-standby antenna 12, so that the processing time for selecting the reception antenna can be shortened. .

  Although the case where the number of antennas is 2 has been described in the first embodiment, the same effect can be obtained when the number is 3 or more.

(Second Embodiment)
As shown in FIG. 6, the diversity receiving apparatus according to the second embodiment of the present invention includes two receiving units 10A and 10B of a selective diversity system each having a plurality of antennas.

  Similarly to FIG. 1, the receiving units 10A and 10B include antennas 11A and 11B, 12A and 12B, antenna selection switches 13A and 13B, low noise amplifiers 14A and 14B, down converters 15A and 15B, variable gain amplifiers 16A and 16B, orthogonal Demodulators 17A and 17B, A / D converters 18A and 18B, reception level measurement units 20A and 20B (relative level calculation units 21A and 21B and absolute level calculation units 22A and 22B), level determination unit (first level determination unit) 23A and 23B, switch control units 24A and 24B, and gain control units 25A and 25B.

  The receiving units 10A and 10B further include second level determination units 26A and 26B as components unique to the second embodiment. The second level determination units 26A and 26B determine whether or not the reception level is higher than the second reference level Vref2. The determination result of the second level determination unit 26A is given to the gain control unit 25A in the same reception unit 10A and the gain control unit 25B in the other reception unit 10B. Similarly, the determination result of the second level determination unit 26B is given to the gain control unit 25B in the same reception unit 10B and the gain control unit 25A in the other reception unit 10A.

  Output signals from the receiving units 10A and 10B, that is, digital received signals from the A / D converters 18A and 18B are combined into one signal by the combining unit 27 and then input to the demodulating unit 19.

  Hereinafter, the operation of the diversity receiver of FIG. 6 will be described using the flowchart shown in FIG. First, the receiving antenna is selected for each of the receiving units 10A and 10B in the same procedure as shown in FIG. 2 or FIG. 5 (step S30). That is, in the receiving unit 10A, the antenna selection switch 13A selects either the antenna 11A or 12A as a receiving antenna. Similarly, in the receiving unit 10B, the antenna selection switch 13B selects either the antenna 11B or 12B as a receiving antenna.

  Next, whether or not the reception levels of all the antennas selected as reception antennas in step S30, that is, a total of two reception antennas selected one by one by the reception units 10A and 10B, are equal to or lower than the second reference level Vref2. The determination is made by the second level determination units 26A and 26B (step S31).

  As a result of the determination in step S31, if the reception levels of all the antennas selected by the receiving units 10A and 10B are all equal to or lower than the second reference level Vref2, common control of the gain for all the antennas is performed. That is, the gain control units 25A and 25B set a gain for setting the output of the variable gain amplifier 16A or 16B corresponding to the reception signal of the maximum reception level to the specified level for the variable gain amplifiers 16A and 16B (step S32). ). Here, the specified level of the output of the variable gain amplifier is, for example, a level such that the input levels of the A / D converters 18A and 18B are within the dynamic range, and is generally approximately the center level of the dynamic range. desirable.

  In the region where the reception level of the antenna is equal to or lower than the second reference level Vref2, C / N is proportional to the reception level as shown in FIG. Accordingly, the gains of the variable gain amplifiers 16A and 16B are set so that the output corresponding to the reception signal of the maximum reception level among the reception signals from the antennas selected by the reception units 10A and 10B as described above becomes a specified level. As a result, the C / N of the received signal at the output of the combining unit 27 can be improved. In other words, when the received signal from the antenna selected by the receiving units 10A and 10B is subjected to the maximum ratio combining by the combining unit 27, the weight of the received signal having the maximum reception level is increased to be output from the combining unit 27. The C / N of the final received signal is improved.

  On the other hand, if it is determined in step S31 that the reception levels of all the antennas selected by the reception units 10A and 10B are not all lower than the second reference level Vref2, the gains for the antennas selected by the reception units 10A and 10B are individually set. To control. That is, it is determined whether the reception level of the antenna (X) selected by any of the reception units 10A and 10B is higher than the second reference level Vref2 (step S33).

  As a result of the determination in step S33, for example, if the reception level of the antenna selected in the reception unit 10A is determined to be higher than the second reference level Vref2 by the second level determination unit 26A, the gain control unit 25A determines the variable gain amplifier 16A. A gain for setting the output to a specified level is set for the variable gain amplifier 16A (step S34). Similarly, if the reception level of the antenna selected in the reception unit 10B is determined by the second level determination unit 26B to be higher than the second reference level Vref2, the gain control unit 25B sets the output of the variable gain amplifier 16B to a specified level. The gain to be set is set for the variable gain amplifier 16B.

  In the region where the reception level of the antenna is higher than the second reference level Vref2, C / N is saturated as shown in FIG. 3, and maintains a substantially constant value even when the reception level increases. Therefore, in such a case, the A / D converter is set by setting the gain that makes the output of the variable gain amplifier that amplifies the received signal of the antenna whose reception level is higher than the second reference level Vref2 as described above. The input levels of 18A and 18B are set within the dynamic range.

  On the other hand, if the reception level of the antenna selected in the reception unit 10A is determined to be equal to or lower than the second reference level Vref2 by the second level determination unit 26A, the fixed gain that makes the output of the variable gain amplifier 16A lower than the specified level. Is set for the variable gain amplifier 16A (step S35). Similarly, if the reception level of the antenna selected in the reception unit 10B is determined to be lower than the second reference level Vref2 by the second level determination unit 26B, the output of the variable gain amplifier 16B is fixed to a level lower than the specified level. The gain is set for the variable gain amplifier 16B.

  As shown in FIG. 3, C / N is proportional to the reception level in the region where the reception level of the antenna is equal to or lower than the second reference level Vref2. Therefore, by setting the gain that makes the output of the variable gain amplifier that amplifies the received signal of the antenna whose reception level is the second reference level Vref2 or lower lower than the specified level, the output signal level of the variable gain amplifier is set to the input signal level. C / N can be increased in proportion to

  As described above, according to the second embodiment of the present invention, the final gain of the variable gain amplifier is determined based on whether or not the reception level of the antenna is higher than the second reference level Vref2. The processing time can be shortened, and the C / N after the synthesis of reception signals output from a plurality of reception units can be improved.

  Although the case where the number of receiving units is 2 and the number of antennas in each receiving unit is 2 has been described in the second embodiment, these numbers may be 3 or more. Further, the number of antennas may be different between the receiving units.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The block diagram of the diversity receiver which concerns on the 1st Embodiment of this invention The flowchart for demonstrating the operation example of the diversity receiver which concerns on 1st Embodiment. The figure for demonstrating the relationship between the reception level of an antenna and C / N The figure for demonstrating the gain control operation | movement in the 1st Embodiment of this invention. The flowchart for demonstrating the other operation example of the diversity receiver which concerns on 1st Embodiment. The block diagram of the diversity receiver which concerns on the 2nd Embodiment of this invention The flowchart for demonstrating the operation example of the diversity receiver of the 2nd Embodiment of this invention.

Explanation of symbols

10A, 10B: Receiving unit 11, 11A, 11B ... Antenna 12, 12A, 12B ... Antenna 13, 13A, 13B ... Antenna selection switch 14, 14A, 14B ... Low noise amplifier 15, 15A, 15B ... Down converter 16, 16A, 16B ... Variable gain amplifier 17, 17A, 17B ... Quadrature demodulator 18, 18A, 18B ... A / D converter 19 ... Demodulator 20, 20A, 20B ... Receive level measuring unit 21, 21A, 21B ... Relative level calculator 22 , 22A, 22B ... absolute level calculation unit 23, 23A, 23B ... first level determination unit 24, 24A, 24B ... switch control unit 25, 25A, 25B ... gain control unit 26A, 26B ... second level determination unit 17 ... synthesis Part

Claims (13)

With multiple antennas;
A switch for selecting one antenna from the plurality of antennas;
A variable gain amplifier that amplifies the received signal obtained by the selected antenna;
An A / D converter for converting the received signal amplified by the variable gain amplifier into a digital signal;
A level measuring unit for measuring the reception level of the selected antenna from the digital signal;
A level determination unit for determining whether the reception level is higher than a first reference level;
Switch control for controlling the switch so that either the first antenna selected by the switch during standby or the second antenna other than the first antenna is selected as a receiving antenna according to the determination result of the level determination unit Part;
The gain of the variable gain amplifier is set to the first gain at the time of standby, and after the reception antenna is selected, the gain of the variable gain amplifier is set to the second gain smaller than the first gain. Diversity receiving apparatus comprising: a gain control unit that controls according to the reception level of the antenna.   When the reception level of the first antenna is higher than the first reference level, the switch control unit selects the first antenna as a reception antenna, and the reception level of the first antenna is equal to or lower than the first reference level. The diversity receiving apparatus according to claim 1, wherein the switch is controlled so that a second antenna other than the first antenna is selected as a receiving antenna.   The switch control unit is configured such that the reception level of the first antenna is higher than the first reference level, and the reception level of the first antenna and the reception level of the second antenna other than the first antenna are both the first reference level. In the following cases, the first antenna is selected as a receiving antenna, and the reception level of the first antenna is lower than the first reference level and the reception level of the second antenna is higher than the first reference level. The diversity receiving apparatus according to claim 1, wherein the switch is controlled so that the second antenna is selected as a receiving antenna.   The diversity receiver according to claim 1, wherein the gain control unit sets, as the first gain, a gain that allows the level determination unit to determine whether or not a reception level is higher than the first reference level.   The gain control unit can determine whether the level determination unit can determine whether the reception level is higher than the first reference level and can determine whether the reception level is higher than the second reference level as the second gain. The diversity receiver according to claim 1, wherein the diversity receiver is set.   The diversity receiver according to claim 1, wherein the first reference level and the second reference level have a level difference smaller than a dynamic range of the A / D converter. In a diversity receiver that synthesizes and outputs output signals of a plurality of receiving units, each of the plurality of receiving units includes:
With multiple antennas;
A switch for selecting one antenna from the plurality of antennas;
A variable gain amplifier that amplifies the received signal obtained by the selected antenna;
An A / D converter for converting the received signal amplified by the variable gain amplifier into a digital signal;
A level measuring unit for measuring the reception level of the selected antenna from the digital signal;
A first level determination unit that determines whether or not the reception level is higher than a first reference level;
According to the determination result of the first level determination unit, the switch is controlled so that either the first antenna selected by the switch at the time of standby or the second antenna other than the first antenna is selected as a receiving antenna. A switch controller;
A second level determination unit for determining whether or not the reception level of the reception antenna is higher than a second reference level;
According to the determination result of the second level determination unit, when the reception level of the reception antenna is higher than the second reference level, a gain for setting the output of the variable gain amplifier to a specified level is set for the variable gain amplifier. A gain control unit configured to set, for the variable gain amplifier, a gain for setting the output of the variable gain amplifier to a level equal to or lower than the specified level when the reception level of the receiving antenna is equal to or lower than the second reference level. Diversity receiving device.   The gain control unit in the plurality of receiving units has the maximum reception level when the maximum reception level among the reception levels of the reception antennas selected in the plurality of reception units is equal to or lower than the second reference level. 8. The diversity receiver according to claim 7, wherein a gain for setting the output of one variable gain amplifier corresponding to a signal to the specified level is set in common to all the variable gain amplifiers in the plurality of receiving units. In a reception method in a diversity receiver that demodulates a reception signal obtained by one antenna selected from a plurality of antennas after being amplified by a variable gain amplifier,
Setting the gain of the variable gain amplifier to a first gain when waiting;
Determining whether the reception level of the first antenna selected during the standby is higher than a first reference level when the reception signal is detected during the standby;
When the reception level of the first antenna is higher than the first reference level, the first antenna is selected as a reception antenna, and when the reception level of the first antenna is equal to or lower than the first reference level, the first antenna is selected. Selecting a second antenna other than as a receiving antenna;
And a step of setting the gain of the variable gain amplifier to a second gain smaller than the first gain after the first antenna or the second antenna is selected. In a reception method in a diversity receiver that demodulates a signal received from one antenna selected from a plurality of antennas after amplification by a variable gain amplifier,
Setting the gain of the variable gain amplifier to a first gain when waiting;
Determining whether the reception level of the first antenna selected during the standby is higher than a first reference level when the reception signal is detected during the standby;
When the reception level of the first antenna is higher than the first reference level, the first antenna is selected as a reception antenna, and when the reception level of the first antenna is equal to or lower than the first reference level, the first antenna is selected. Temporarily selecting a second antenna other than as a receiving antenna;
If the reception level of the second antenna is equal to or lower than the first reference level when the second antenna is temporarily selected, the first antenna is selected as a reception antenna, and the reception level of the first antenna is the first antenna level. Selecting the second antenna as a receiving antenna if it is below a reference level and the reception level of the second antenna is higher than the first reference level;
Determining whether the receiving level of the receiving antenna is higher than a second reference level;
When the reception level of the reception antenna is higher than the second reference level, a gain for setting the output of the variable gain amplifier to a specified level is set for the variable gain amplifier, and the reception level of the reception antenna is the first level. And a step of setting, for the variable gain amplifier, a gain for setting the output of the variable gain amplifier to a level equal to or lower than the specified level when the reference level is equal to or lower than two reference levels. In a reception method in a diversity receiver that demodulates a reception signal obtained from one antenna selected from a plurality of antennas after synthesizing reception signals from a plurality of reception units that are amplified and output by a variable gain amplifier,
Setting the gain of the variable gain amplifier to a first gain when waiting;
Determining whether the reception level of the first antenna selected during the standby is higher than a first reference level when the reception signal is detected during the standby;
When the reception level of the first antenna is higher than the first reference level, the first antenna is selected as a reception antenna, and when the reception level of the first antenna is equal to or lower than the first reference level, the first antenna is selected. Selecting a second antenna other than as a receiving antenna;
Determining whether the receiving level of the receiving antenna is higher than a second reference level;
When the reception level of the reception antenna is higher than the second reference level, a gain for setting the output of the variable gain amplifier to a specified level is set for the variable gain amplifier, and the reception level of the reception antenna is the first level. And a step of setting, for the variable gain amplifier, a gain for setting the output of the variable gain amplifier to a level equal to or lower than the specified level when the reference level is equal to or lower than two reference levels. In a reception method in a diversity receiver that demodulates a reception signal obtained from one antenna selected from a plurality of antennas after synthesizing reception signals from a plurality of reception units that are amplified and output by a variable gain amplifier,
Setting the gain of the variable gain amplifier to a first gain when waiting;
Determining whether the reception level of the first antenna selected during the standby is higher than a first reference level when the reception signal is detected during the standby;
When the reception level of the first antenna is higher than the first reference level, the first antenna is selected as a reception antenna, and when the reception level of the first antenna is equal to or lower than the first reference level, the first antenna is selected. Selecting a second antenna other than as a receiving antenna;
When the reception level of the first antenna is higher than the first reference level, the first antenna is selected as a reception antenna, and when the reception level of the first antenna is equal to or lower than the first reference level, the first antenna is selected. Temporarily selecting a second antenna other than as a receiving antenna;
If the reception level of the second antenna is equal to or lower than the first reference level when the second antenna is temporarily selected, the first antenna is selected as a reception antenna, and the reception level of the first antenna is the first antenna level. Selecting the second antenna as a receiving antenna if it is below a reference level and the reception level of the second antenna is higher than the first reference level;
Determining whether the receiving level of the receiving antenna is higher than a second reference level;
When the reception level of the reception antenna is higher than the second reference level, a gain for setting the output of the variable gain amplifier to a specified level is set for the variable gain amplifier, and the reception level of the reception antenna is the first level. And a step of setting, for the variable gain amplifier, a gain for setting the output of the variable gain amplifier to a level equal to or lower than the specified level when the reference level is equal to or lower than two reference levels.   When the maximum reception level of the reception antennas selected by the plurality of reception units is equal to or lower than the second reference level, the output of one variable gain amplifier corresponding to the signal of the maximum reception level is 13. The reception method in the diversity receiver according to claim 11 or 12, wherein the gain for setting to the specified level is set in common for all variable gain amplifiers in the plurality of reception units.

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