JP3442249B2 - Diversity receiver - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity receiver, for example, a diversity receiver that suppresses reception deterioration due to fading in mobile radio communication.

[0002]

2. Description of the Related Art Spatial diversity systems for separating two antennas include a post-detection selection diversity system and an antenna switching diversity system. On the other hand, the post-detection selection diversity method selects the antenna that receives the received data according to the reception level detected by each antenna at the same time, and the antenna switching diversity method uses the reception level detected by one antenna and a predetermined threshold value. The antenna is switched alternately according to the relationship with.

Next, each spatial diversity system will be described in detail. First, the post-detection selection diversity method will be described. FIG. 7 is a block diagram showing a configuration example of a diversity receiving apparatus to which the post-detection selection diversity method is applied in the conventional example.

The diversity receiver shown in FIG.
Antennas 71 and 72 for capturing radio waves, and antennas 71 and 72,
Receiving circuits 73 and 7 that are respectively connected to 72 and perform detection.
4, a receiving level determining circuit 75 connected to the receiving circuits 73 and 74 for determining the receiving level obtained by detection, and a receiving level determining circuit 75 and receiving circuits 73 and 74,
A switch 76 for switching the input between the receiving circuits 73 and 74
It has and.

The operation will now be described. In this diversity receiver, when the radio waves are captured by the antennas 71 and 72, the received signals obtained by the capture are received circuits 73 and 74 corresponding to the antennas 71 and 72.
Is output to.

Each of the receiving circuits 73 and 74 carries out detection from the input received signal. In the reception circuit 73, the reception level LA at the time of detection is output to the reception level determination circuit 75, and the data portion is received by the switch 76 as reception data DTA.
Is output to. Similarly, in the reception circuit 74, the reception level LB at the time of detection is output to the reception level determination circuit 75, and the data portion is received by the switch 76 as reception data DTB.
Is output to.

Each reception level L is applied to the reception level determination circuit 75.
When A and LB are input, level comparison is performed there. Then, when the determination result that the reception level input from the reception circuit 73 is higher is obtained, the reception level determination circuit 75 instructs the switch 76 to receive the reception circuit 73.
Input switching to the side is instructed. On the other hand, the receiving circuit 74
When the determination result that the reception level input from is higher is obtained, the reception level determination circuit 75 instructs the switch 76 to switch the input to the reception circuit 74 side.

At this time, when the switch 76 is switched to the receiving circuit 73 side, the input received data DTA becomes the received data DT taken into the inside of the device, while the switch 7
When 6 is switched to the receiving circuit 74 side, the input received data DTB becomes the received data DT taken into the inside of the device.

That is, in the diversity receiving apparatus shown in FIG. 7, a receiving path having a higher level is selected from the receiving level LA and the receiving level LB detected by the receiving circuit 73 and the receiving circuit 74, respectively, and switched by the switch 76. The reception data on the reception path is finally output.

Next, the antenna switching diversity system will be described. FIG. 8 is a block diagram showing a configuration example of a diversity receiving apparatus to which an antenna switching diversity system is applied in the conventional example.

The diversity receiving apparatus shown in FIG.
Antennas 81 and 82 for capturing electric waves, and antennas 81 and
A switch 83 connected to the antenna 82 and switching the input between the antennas 81 and 82, a receiving circuit 84 connected to the switch 83 for performing detection, and a reception level obtained by the detection and a predetermined threshold Th. And a threshold value determination circuit 85 for determining the magnitude relationship between them.

The threshold value judging circuit 85, when the reception level L is equal to or higher than a predetermined threshold value Th, is higher than the threshold value Th, and the antenna selection signal Asel for switching to the antenna 81 side.
Is supplied to the switch 83, and the reception level L is a predetermined threshold value T
When it is lower than h, it has a logic for supplying the antenna selection signal Asel for switching to the antenna 82 side to the switch 83.

The operation will now be described. In this diversity receiver, when the radio waves are captured by the antennas 81 and 82, the received signal obtained by the capture is output to the switch 83 in the subsequent stage. This switch 83
As will be described later, is switched to either one of the antennas 81 and 82 in advance by the antenna selection signal Asel supplied from the threshold value judgment circuit receiving circuits 73 and 74.

By selecting the antenna of the switch 83, a receiving path between one of the antennas 81 and 82 and the receiving circuit 84 is formed. For example, when the switch 83 has already been switched to the antenna 81 side, the received signal of the radio wave captured by the antenna 81 is supplied to the receiving circuit 84. In the receiving circuit 84, detection is performed based on the reception signal of the antenna 81, and the reception level L and the reception data DT obtained at that time are output to the threshold value determining circuit 85 and the inside of the device, respectively.

If the threshold value judgment circuit 85 obtains the judgment result that the reception level is lower than the predetermined threshold value Th, the threshold value judgment circuit 85 inputs the switch 83 to the antenna 81 side to the antenna 82 side. An antenna selection signal Asel for switching is output.

When the input of the switch 83 is switched by the antenna selection signal Asel, a receiving path is formed by the antenna 82 and the receiving circuit 84 this time.
Therefore, the antenna 8 is provided inside the device from the receiving circuit 84.
The received data DT of 2 is fetched.

After that, each time the magnitude relationship between the reception level L and the predetermined threshold Th is switched, the input switching operation of the switch 83 is repeatedly performed according to the instruction of the threshold determination circuit 85.

[0018]

As described above, in the diversity receiver according to the conventional example, in the case of the post-detection selection diversity system, the receiving circuits 73 and 74 are provided corresponding to the antennas 71 and 72, respectively. Since it is necessary to prepare a receiving circuit for each antenna, there have been problems such as an increase in current consumption and an increase in the price of the entire device depending on the number of receiving circuits.

On the other hand, in the case of the antenna switching diversity system, since the configuration in which only one receiving circuit 84 is provided corresponding to the antennas 81 and 82 is adopted, the power consumption becomes the minimum necessary and Although the device configuration is low in cost, the predetermined threshold Th supplied to the threshold determination circuit 85 has a fixed value, and the correlation between the fixed value and the reception level becomes insufficient. Therefore, there is a problem that the diversity effect is significantly inferior to the above-mentioned post-detection selection diversity method.

As an approximation technique to which the antenna switching diversity system is applied, Japanese Patent Laid-Open No. 6-303219 is used.
And Japanese Patent Laid-Open No. 57-10542.

Japanese Unexamined Patent Publication No. 6-303219 discloses a technique in which the timing of threshold value judgment is performed within the range between the preamble and the sync word. Also, JP-A-57-1
Japanese Patent No. 0542 discloses a technique in which a plurality of thresholds are prepared and the thresholds are changed together with the switching of antennas. In any of the publications, the threshold value is prepared as a fixed value, and therefore, the correlation between the fixed value threshold value and the reception level remains insufficient.

The present invention has been made to solve the above problems, and in the antenna switching diversity system, it is possible to suppress the deterioration of the diversity effect by sufficiently correlating the threshold value and the reception level. The purpose is to obtain a versatile diversity receiver.

[0023]

[Means for Solving the Problems]
To achieve the object, a diversity receiver according to the present invention uses a plurality of antennas and one receiving circuit.
However, by switching the antenna,
A datum forming a receiving path with one of the shifts and the receiving circuit.
Diversity receiver applying the diversity method
The reception level at the time of reception in the receiving circuit.
Reception level storage means for storing each reception, and the reception circuit
Reception level at the time of current reception and the reception level memory
Antenna based on past reception levels stored in the stage
Threshold setting means for setting a threshold for switching determination,
Reception level at the time of current reception in the reception circuit and the threshold setting
Antenna switching based on threshold set by means
Judgment means for judging whether or not the
If the judgment result that the antenna can be switched is obtained,
Antenna off to switch antennas in multiple antennas
Replacement means, the threshold value setting means
Every time switching by the tena switching means, that switching
The previous reception level which is the previous reception level and its cutoff
And the reception level at the time of the current reception, which is the reception level after replacement
Comparing means for comparing the present reception by the comparing means
If the comparison result that the reception level at time is higher is obtained,
In this case, the threshold set last time is set to the past reception level.
Correction so that it is higher than
The comparison result that the reception level at the time of the current reception is lower
If it is obtained, the previously set threshold value will
Correction means for correcting the signal level to be lower than the signal level,
It is characterized by having.

[0024] Accordingly, stores the past reception level, to perform the antenna switching based on the threshold set on the basis of the current reception level and the past reception levels and the current receiving level, threshold setting When receiving the current
If the reception level is higher than the past reception level, previous
Set the threshold to be higher than the past reception level
The received level at the current reception is higher than the past received level.
If it is lower than the threshold, the previously set threshold is set to the past reception level.
Because be corrected to be lower than, Rutotomoni threshold Do is sufficient correlation between the reception level and the threshold value is die
It will be changed to namic, and this will change the threshold
Since the correlation between the reception level and the reception level is increased, it is possible to improve the diversity effect.

In the diversity receiving apparatus according to the next invention, the average value for calculating the reception level average value is further calculated based on the reception level at the time of the current reception in the reception circuit and the past reception level stored in the reception level storage means. The threshold value setting means has a calculating means, and when the threshold value is set in the current reception, obtains a difference between the reception level average value calculated by the average value calculating means and the threshold value set this time, and the difference is predetermined. If it is within the level fluctuation compensation width of, the threshold set this time is validated for the judging means, while if the difference is other than the predetermined level fluctuation compensation width, the threshold set this time for the judging means. It is characterized by disabling.

Therefore, if the difference between the average value of the reception levels based on the current reception level and the past reception level and the threshold value set this time is within the predetermined level fluctuation compensation range, the threshold value set this time is validated. On the other hand, if the difference is outside the level fluctuation compensation range, the threshold set this time is made invalid, so the threshold is set according to the large fluctuation of the reception level caused by the adverse effect of external waves. It is possible that a proper threshold value can be adopted.

The diversity receiver according to the next invention further has a counting means for counting the number of times of antenna non-switching based on the judgment result of the judging means, and the threshold setting means has the antenna non-switching counted by the counting means. When the number of times exceeds the predetermined number of antenna non-switching monitoring stages, the threshold value is reset asynchronously with the switching operation by the antenna switching means.

Therefore, when the number of antenna non-switching times exceeds the predetermined number of antenna non-switching monitoring stages, the threshold value is reset asynchronously with the switching operation by the antenna switching means. Even if the state continues, the threshold value will change periodically, which makes it possible to return the inactive state of diversity during use of the same antenna to the active state.

A diversity receiving apparatus according to the next invention uses a plurality of antennas and one receiving circuit,
By changing the tenor, one of the antennas
Diversity that forms a receiving path with the receiving circuit
In the diversity receiver applying the T-method,
The reception level at the time of reception in the reception circuit
And a receiving level storing means for storing the
Stored in the reception level at the time of the current reception and the reception level storage means
For each antenna based on the past received level
Multiple thresholds to set the threshold for antenna switching determination
The setting means and the reception level at the time of the current reception in the reception circuit.
And the threshold set by the threshold setting means.
Based on the threshold value corresponding to the currently switched antenna
And a determination means for determining whether or not the antenna can be switched.
The determination result indicates that the antenna can be switched.
Therefore, within the threshold values set by the respective threshold value setting means,
Corresponds to the antenna used for reception after this switch
Threshold switching means for switching to a threshold for
According to the judgment result that the antenna can be switched depending on the stage
Antenna that switches antennas among multiple antennas
Switching means, and each of the threshold value setting means,
Every time the antenna switching means switches,
The past reception level which is the reception level before the replacement and its
The reception level at the time of the current reception, which is the reception level after switching
Comparing means for comparing the current
The comparison result that the reception level at the time of reception is higher is obtained.
If the threshold value set last time is set to the past reception level,
Correction so that it is higher than
A comparison result that the reception level at the time of current reception is lower than
If the result is obtained, the previously set threshold is
Correcting means for correcting so as to be lower than the reception level of
And are included.

Therefore, the past reception level is stored, the threshold value is set for each antenna based on the present reception level and the past reception level, and the threshold value corresponding to the antenna currently in use and the present reception level are set. When setting the threshold corresponding to each antenna, the antenna switching and the switching to the threshold corresponding to the antenna are performed based on
The current reception level is higher than the past reception level.
If it is not, the threshold set last time is lower than the past reception level.
Correct so that the reception level at the current reception is higher than that of the past.
If it is lower than the reception level, the previously set threshold is
Changes since to correct so as to be lower than the reception level, Rutotomoni threshold such that the threshold that is suitable for the antenna to be used after the switching is employed is dynamically
Is now being, thereby, also the reception levels of a plurality of antennas a heterogeneous, Ri Do a sufficient correlation between the reception level and the threshold value at each antenna used, the threshold for each antenna
From the high or Rukoto correlation value between a reception level, it is possible to perform an optimum diversity by improving the diversity effect.

In the diversity receiving apparatus according to the next invention, the average value for calculating the reception level average value is further calculated based on the reception level at the time of current reception in the reception circuit and the past reception level stored in the reception level storage means. Each of the threshold value setting means has a calculating means, and when the threshold value is set in the current reception, the difference between the reception level average value calculated by the average value calculating means and the threshold value set this time is calculated, and the difference is calculated. If it is within the predetermined level fluctuation compensation width, the threshold value set this time for the judging means is validated, while if the difference is other than the predetermined level fluctuation compensation width, it is set for the judging means this time. It is characterized in that the threshold is invalidated.

Therefore, among the plurality of threshold value setting means, in the threshold value setting means in which the threshold value is set by the current reception, the reception level average value based on the current reception level and the past reception level, and the threshold value set this time. If the difference is within the predetermined level fluctuation compensation width, the threshold value set this time is validated, while if the difference is outside the predetermined level fluctuation compensation width, the threshold value set this time is invalidated. Because I did
In reception of each antenna, the threshold value is not set in accordance with a large change in the reception level caused by the adverse effect of an external wave or the like, whereby it is possible to adopt an appropriate threshold value for each antenna.

The diversity receiving apparatus according to the next invention further has counting means for counting the number of times of antenna non-switching based on the judgment result of the judging means, and each threshold value setting means has the antenna uncounted by the counting means. When the number of times of switching exceeds the predetermined number of antenna unswitched monitoring stages, the threshold value is reset asynchronously with the switching operation by the antenna switching means.

Therefore, when the number of times of antenna non-switching exceeds the predetermined number of antenna non-switching monitoring stages, the threshold value corresponding to the antenna currently in use is reset asynchronously with the switching operation by the antenna switching means. Therefore, the threshold value changes periodically even if the unswitched state of the antennas continues, which makes it possible to return the inactive state of diversity during the use of the same antenna to the active state.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the diversity receiving apparatus according to the present invention will be described in detail below with reference to the accompanying drawings.

(Embodiment 1) FIG. 1 is a block diagram showing an internal configuration of a diversity receiving apparatus according to Embodiment 1 of the present invention.

The diversity receiving apparatus shown in FIG.
A pair of antennas 1 and 2, an antenna switch 3 for switching between the antennas 1 and 2, a single receiving circuit 4, a receiving level storage circuit 5, a threshold determining circuit 6, a threshold setting circuit 7, a receiving level average value calculating circuit 8, An antenna unswitched monitoring counter 9 and the like are provided. A diversity system in which the antennas 1 and 2 and the receiving circuit 4 form a two-system receiving path by switching the antennas is applied to this diversity receiving apparatus. Therefore, the pair of antennas 1 and 2 are
These are units that are spatially separated and that capture radio waves.

The antenna switch 3 is connected to the pair of antennas 1 and 2, the receiving circuit 4, and the threshold value judging circuit 6, and switches between the antennas 1 and 2 in accordance with an antenna selection signal Asel described later output from the threshold value judging circuit 6. I do. The switching of the antenna has a function of alternately switching between two receiving paths formed between the antennas 1 and 2 and the receiving circuit 4.

The receiving circuit 4 receives a received signal from either one of the antennas 1 and 2 via the antenna switch 3 and performs detection based on the received signal. The reception level and the reception data are acquired from this detection. The reception level supplied from this reception circuit 4 to other circuits is L (0) because it is the reception level at the time of the current reception. The received data supplied from the receiving circuit 4 to an internal circuit (not shown) is represented by DT.

The reception level storage circuit 5 is connected to the reception circuit 4 and receives the reception level L supplied from the reception circuit 4.
Store (0) every time it is received. In this reception level storage circuit 5, for example, the reception levels of the past two receptions can be stored. The reception levels supplied from the reception level storage circuit 5 to other circuits are past reception levels. Therefore, the reception level at the previous reception is L (-1), and the reception level at the previous reception is L (-). 2).

The threshold judgment circuit 6 is connected to the reception circuit 4 and the threshold setting circuit 7, and has a reception level L (0) supplied from the reception circuit 4 and a threshold Lth described later supplied from the threshold setting circuit 7. Antenna switching is determined according to the size relationship. In this determination result, the antenna selection signal Asel is valid when the antenna switching is performed, while the antenna selection signal Asel is invalid when the antenna switching is not performed. This antenna selection signal As
el is output to the antenna switch 3, the threshold value setting circuit 7, and the antenna non-switching monitoring counter 9.

The threshold value setting circuit 7 is connected to the receiving circuit 4, the receiving level storage circuit 5, the threshold value judging circuit 6, the receiving level average value calculating circuit 8 and the antenna non-switching monitoring counter 9, and is supplied from the threshold value judging circuit 6. The antenna selection signal Asel to be used is fetched as the threshold correction instruction flag Cflg, and the antenna switching valid is judged to be the threshold correction valid, and the threshold suitable for the switched antenna is set.

Further, the threshold value setting circuit 7 includes therein a comparison circuit 7a and a correction circuit 7b. Comparison circuit 7
a compares the reception level L (0) at the current reception with the reception levels L (-1) and L (-2) in the past to determine which reception level is higher. The correction circuit 7b is the comparison circuit 7a.
If the reception level at the current reception is higher, the threshold value Lth is set or corrected so as to be higher than the reception level at the past, while if the reception level at the current reception is lower, the threshold value Lth is set at the past. That is, it is set or corrected to be lower than the reception level of.

Further, the threshold setting circuit 7 inputs a predetermined antenna non-switching monitoring stage number Nnch and a predetermined level fluctuation compensation width COMW from a unit (not shown), and outputs a predetermined antenna non-switching monitoring stage number Nnch and antenna non-switching monitoring. A threshold value Lth is set when the antenna is inactive and a predetermined level fluctuation compensation width COM is set based on an after-mentioned antenna non-switching number Cnch supplied from the counter 9.
Based on W and a reception level average value Lav (described later) supplied from the reception level average value calculation circuit 8, the setting of the threshold value at the time of a large level change is invalidated.

The reception level average value calculation circuit 8 is connected to the reception circuit 4 and the reception level storage circuit 5, and receives the current reception level L (0) and the past reception levels L (-1), L.
The reception level average value Lav is calculated based on (-2). The reception level average value Lav is output to the threshold setting circuit 7 and is used as one of the criteria for judging a large fluctuation in the reception level.

The antenna non-switching monitoring counter 9 is connected to the threshold value judgment circuit 6, counts the number of times of antenna non-switching Cnch according to the antenna selection signal Asel supplied from the threshold value judgment circuit 6 at each reception, and causes the threshold value setting circuit 7 to do so. Supply.

Next, the principle of threshold value correction will be described. FIG. 2 is a graph showing an example of correcting a threshold value according to a change in reception level, and FIG. 3 is a graph showing another example of correcting a threshold value according to a change in reception level. It is a figure.

First, the case where the reception level after switching the antenna is high will be described with reference to FIG. In FIG. 2, 101A indicates the locus of the reception level of the antenna 1,
102A shows the locus of the reception level of the antenna 2. 103A indicates the threshold level before correction, and 104A
Indicates the threshold level after correction. LA (-1) shows the reception level at the time of the previous reception as the sample value at the antenna 1, and LA (-2) shows the reception level at the time of the reception two before as the sample value at the antenna 1.
LB (0) indicates the reception level at the time of the current reception as a sample value in the antenna 2. S1 indicates the direction of change of the reception level due to antenna switching, and S2 indicates the direction of change of the threshold. P1 indicates the intersection of the loci 101A and 102A.

In the example of FIG. 2, the antenna 1 is bounded by the intersection P1.
However, the reception state of the antenna 2 becomes good. The locus 101A of the antenna 1 is the threshold value Lth.
When the level becomes lower than the level 103A, the antenna switching from the antenna 1 to the antenna 2 is performed (see the transition direction S1).

Therefore, in accordance with this antenna switching, the threshold value Lth is corrected so as to approach the reception level at the intersection P1 of the loci 101A and 102A of the antenna 1 and the antenna 2, respectively.

Specifically, since the reception level LB (0) at the current reception after the antenna switching is higher than the past reception level LA (-1) before the antenna switching, the level of the intersection P1 is the reception level. The level is higher than LA (-1). Therefore, at the threshold Lth, the level changes from level 103A to level 10 in accordance with the transition direction S1.
Increased to 4A.

In this case, the level 1 used for the threshold value Lth
As an example of 04A, the reception level LA (-2) at the time of reception two before can be used.

Next, the case where the reception level after the antenna switching is low will be described with reference to FIG. In FIG. 3, 101B shows the locus of the reception level of the antenna 1, and 102B shows the locus of the reception level of the antenna 2. 103B indicates a threshold level before correction, and 104
B indicates the threshold level after correction. LA (-
1), LA (−2) and LB (0) have the same meanings as in FIG. 2, and LA (0) indicates the reception level at the time of the current reception as a sample value in the antenna 1. S3 indicates the direction of change of the reception level due to antenna switching, and S4 indicates the direction of change of the threshold. P2 is loci 101B and 10
The intersection with 2B is shown.

In the example of FIG. 3, the antenna 1 is bounded by the intersection P2.
However, the reception state of the antenna 2 becomes good. The locus 101B of the antenna 1 is the threshold value Lth.
When the level becomes lower than the level 103B, the antenna switching from the antenna 1 to the antenna 2 is performed (see the transition direction S3).

Therefore, in accordance with this antenna switching, the threshold value Lth is corrected so as to approach the reception level at the intersection P2 of the loci 101B and 102B of the antenna 1 and the antenna 2, respectively.

However, since the reception level LB (0) at the current reception after the antenna switching is lower than the past reception level LA (-1) before the antenna switching, the level at the intersection P2 is the reception level LA (- It is a lower level than 1). Therefore, at the threshold Lth, the level changes from level 103B to level 104 in accordance with the transition direction S4.
Lowered to B.

In this case, the level 1 used for the threshold Lth
As an example of 04B, the reception level LA (0) at the time of current reception when the antenna is switched can be used.

Next, the circuit operation according to the first embodiment will be described. FIG. 4 is a flowchart explaining the diversity receiving operation according to the first embodiment.

In the diversity receiving apparatus shown in FIG. 1, the receiving circuit 4 detects the receiving level L (0) at the time of the current reception at each reception (step S1). The detected reception level L (0) is output to the threshold determination circuit 6, the reception level storage circuit 5, the threshold setting circuit 7, and the reception level average value calculation circuit 8.

In the reception level storage circuit 5, the reception level L (0) received last time is shifted to the reception level L (-1) at the previous reception at each reception, and similarly, The reception level L (-1) at the time of the previous reception is shifted to the reception level L (-2) at the time of the previous reception.

In the threshold determination circuit 6, the threshold correction instruction flag Cflg (antenna selection signal Asel) is off (invalid).
In the "0" state (step S2), the reception level L (0) and the threshold Lt are respectively received from the reception circuit 4 and the threshold setting circuit 7.
When h is input, the threshold value Lth is compared with the reception level L (0) (step S9).

If the comparison result that the reception level L (0) is higher is obtained, it is judged that the reception state of the antenna currently in use is good, and the antenna selection signal A
sel is output as invalid “0”. Therefore, in the antenna non-switching monitoring counter 9, the antenna non-switching number Cn is determined according to the antenna selection signal Asel “0”.
ch is incremented by 1 (step S13).

At this time, the number of times the antenna is not switched Cnc
h is supplied to the threshold value setting circuit 7, and the threshold value setting circuit 7 compares the antenna non-switching number Cnch with a predetermined antenna non-switching monitoring stage number Nnch (step S14).

If the comparison result that the antenna non-switching frequency Cnch is higher is obtained, first, the antenna non-switching monitoring counter 9 is cleared of the antenna non-switching frequency Cnch (step S15), and the threshold Lth of the threshold Lth is set. Reset is performed (step S16).

That is, the threshold value setting circuit 7 determines the inactive state of diversity based on the number of times Cnch of antenna non-switching. In this case, the threshold value Lt is an example.
The reception level average value Lav supplied from the reception level average value calculation circuit 8 is adopted for h.

In this way, after the threshold value Lth is corrected to take the value of the reception level average value Lav, antenna switching is forcibly performed (step S17).

Further, by comparing the reception level L (0) with the threshold value Lth (step S9), if the reception level L
When the comparison result that (0) is lower is obtained,
It is determined that the reception state of the antenna currently in use has deteriorated, and the antenna selection signal Asel is output as valid "1". As a result, the antenna switch 3 switches the antenna between the antennas 1 and 2 (step S10).

Thereafter, the antenna non-switching monitoring counter 9 clears the antenna non-switching number Cnch according to the antenna selection signal Asel (valid) (step S11). Further, when the antenna is switched, the antenna selection signal Asel (valid) is supplied to the threshold setting circuit 7 as the threshold correction instruction flag Cflg (ON “1”).

When the reception level L (0) at the current reception is detected again by the reception circuit 4, the reception level L (0) at the previous reception is the reception level L (-1) immediately before. Become.

This time, since the threshold correction instruction flag Cflg is in the ON state (step S2), the threshold value setting circuit 7 first controls the threshold value judgment circuit 6 to turn off the threshold value correction instruction flag Cflg to "0". (Step S3),
Reception level L (0) at the time of current reception and reception level L in the past
Comparison with (-1) is performed (step S4).

If a comparison result that the reception level L (0) at the current reception is higher is obtained by this comparison, the threshold value Lth needs to be raised compared to the current state, and therefore, in FIG. 2 described above. According to the principle described, the reception level L (-2) at the time of reception two before is set to the temporary threshold LLth (step S5).

When the comparison result that the reception level L (0) at the current reception is lower is obtained, the threshold value Lth is set.
Since it is necessary to lower than the current value, the sample value on the trajectory of the antenna used before the antenna switching is set to the temporary threshold LLth according to the principle described in FIG. The formula for obtaining this sample value is 2 × L (−
1) -L (-2), and the sample value is set to the temporary threshold value LLth (step S6).

In this way, when the temporary threshold value LLth is obtained in step S5 or step S6, this time, the difference between the temporary threshold value LLth and the reception level average value Lav supplied from the reception level average value calculation circuit 8 is calculated. It is calculated.
Then, the difference is compared with a predetermined level fluctuation compensation width COMW supplied from the outside (step S7).

As a result of this comparison, if the difference is larger than the predetermined level fluctuation compensation width COMW, the provisional threshold value LLth set as the provisional threshold value this time is the reception level average value L.
This means that the provisional threshold value LLth is not adopted, and the current threshold value Lth is held with the correction of the threshold value disabled because it means that the temporary threshold value LLth has changed significantly.

On the other hand, if the difference is a predetermined level fluctuation compensation width COM
If it is within W, it means that the provisional threshold LLth set as the provisional threshold this time is within the normal variation range with respect to the reception level average value Lav. Therefore, the provision of the provisional threshold LLth is adopted. The threshold value Lth is recognized as valid and the threshold value Lth is corrected to the value of the temporary threshold value LLth (step S8).

As described above, according to the first embodiment, when the threshold value is corrected in the threshold value setting circuit 7, if the reception level at the current reception is higher than the past reception level, the threshold value set last time is set. To be higher than the past reception level, and if the reception level at the current reception is lower than the past reception level, the previously set threshold value should be corrected to be lower than the past reception level. As a result, the threshold is dynamically changed, which increases the correlation between the threshold and the reception level.
It is possible to improve the diversity effect.

If the difference between the average value of the reception levels based on the current reception level and the past reception level and the threshold value set this time is within the predetermined level fluctuation compensation range, the threshold value set this time is validated. On the other hand, if the difference is outside the level fluctuation compensation range, the threshold set this time is made invalid, so the threshold is set according to the large fluctuation of the reception level caused by the adverse effect of external waves. It is possible that a proper threshold value can be adopted.

Further, in the threshold setting circuit 7, when the number of times of antenna non-switching supplied by the antenna non-switching monitoring counter 9 exceeds the predetermined number of antenna non-switching monitoring stages, the switching operation by the antenna switching means is asynchronous. Since the threshold value is reset, the threshold value is changed periodically even if the unswitched state of the antenna 1 or 2 continues, and thus the inactive state of diversity during the use of the same antenna is maintained. It is possible to return to the active state.

(Embodiment 2) Now, in Embodiment 1 described above, a pair of antennas 1 and 2 is used.
However, one threshold value Lth is shared, but as in the second embodiment described below, a threshold value that can be corrected for each antenna is prepared and even if the reception level of each antenna is uneven. Alternatively, optimum diversity control may be obtained. In the second embodiment, components having the same configurations and functions as those of the circuits and switches shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

Only the parts different in structure and operation from the first embodiment will be described below. 5 is a block diagram showing an internal configuration of a diversity receiving apparatus according to Embodiment 2 of the present invention.

The diversity receiving apparatus shown in FIG.
A pair of antennas 1 and 2, an antenna switch 3 for switching between the antennas 1 and 2, a receiving circuit 4, a receiving level storage circuit 5, a threshold value judging circuit 6, and a pair of threshold value setting circuits corresponding to the antennas 1 and 2. 10 and 11, a reception level average value calculation circuit 8, an antenna non-switching monitoring counter 9, a threshold switch 12, and the like.

Each of the threshold value setting circuits 10 and 11 is connected to the receiving circuit 4, the receiving level storage circuit 5, the threshold value judging circuit 6, the receiving level average value calculating circuit 8 and the antenna non-switching monitoring counter 9 and the threshold value judging circuit. The antenna selection signal Asel supplied from 6 is used as a threshold correction instruction flag Cf.
This is taken in as lg and the antenna switching validity is judged to be the threshold correction validity, and the threshold value suitable for the antenna after switching is set.

The threshold value setting circuit 10 includes therein a comparison circuit 10a and a correction circuit 10b. The comparison circuit 10a compares the reception level L (0) at the time of the current reception with the reception levels L (-1) and L (-2) in the past to determine which reception level is higher. The correction circuit 10b is
From the comparison result of the comparison circuit 10a, if the reception level at the current reception is higher, the threshold value Lth is set or corrected so as to be higher than the past reception level. On the other hand, if the reception level at the current reception is lower, the threshold value Lth is set. Lth is set or corrected so as to be lower than the past reception level.

Similarly, the threshold value setting circuit 11 includes therein a comparison circuit 11a and a correction circuit 11b. The comparison circuit 11a compares the reception level L (0) at the current reception with the reception levels L (-1) and L (-2) in the past to determine which reception level is higher. The correction circuit 11b is
From the comparison result of the comparison circuit 11a, if the reception level at the current reception is higher, the threshold value Lth is set or corrected so as to be higher than the past reception level, while if the reception level at the current reception is lower, the threshold value is set. Lth is set or corrected so as to be lower than the past reception level.

Further, the threshold value setting circuits 10 and 11 both input a predetermined antenna non-switching monitoring stage number Nnch and a predetermined level fluctuation compensation width COMW from a unit (not shown) to obtain a predetermined antenna non-switching monitoring stage number Nnch. The threshold value Lth is set in the antenna inactive state based on the antenna non-switching count Cnch, which will be described later, supplied from the antenna non-switching monitoring counter 9, and is supplied from the predetermined level fluctuation compensation width COMW and the reception level average value calculation circuit 8. The setting of the threshold value at the time of a large level change is invalidated based on the reception level average value Lav described later.

The threshold switch 12 includes a threshold judgment circuit 6,
And threshold value setting circuits 10 and 11, and switches between the threshold value to be supplied to the threshold value determination circuit 6 and the threshold value ALth of the threshold value setting circuit 10 and the threshold value BLth of the threshold value setting circuit 11 according to the determination result of the threshold value determination circuit 6. .

Next, the main part of the operation will be described. FIG. 6 is a flowchart for explaining a main part of the diversity receiving operation according to the second embodiment.

The second embodiment is the same as the first embodiment described above.
Similarly to the above, the circuit operation is mainly performed according to the flowchart shown in FIG. 4, but since the threshold value setting circuit corresponds to the antenna, a threshold value switching operation (step S18) is newly added between step S10 and step S11. .

That is, the threshold switching operation in step S18 is synchronized with the antenna switching operation in step S10. The validity / invalidity of the antenna selection signal Asel output from the threshold determination circuit 6 is input to the threshold switch 12 as valid / invalid of the threshold selection signal THsel.

Therefore, the threshold switch 12 switches to the threshold setting circuit corresponding to the antenna after antenna switching according to the threshold selection signal THsel (valid). For example, when the threshold setting circuit 10 is selected before the antenna switching, the threshold switching to the threshold setting circuit 11 is performed in synchronization with the antenna switching. As a result, the threshold used by the threshold determination circuit 6 is changed from the threshold ALth of the threshold setting circuit 10 to the threshold BLth of the threshold setting circuit 11.

As described above, according to the second embodiment, when the threshold values corresponding to the antennas 1 and 2 are set, if the reception level at the current reception is higher than the past reception level, the previous setting is performed. If the received level at the current reception is lower than the past received level, the previously set threshold is corrected to be lower than the past received level. As a result, the threshold value is dynamically changed. Therefore, even if the reception levels of the plurality of antennas 1 and 2 are not uniform, the correlation between the reception level and the threshold value is sufficient when each antenna is used, so that the optimal diversity can be performed by improving the diversity effect. It will be possible.

Further, in the threshold value setting circuit in which the threshold value is corrected by the current reception among the plurality of threshold value setting circuits 10 and 11, the reception level average value based on the current reception level and the past reception level and the current reception level are calculated. If the difference from the set threshold value is within the predetermined level fluctuation compensation width, the threshold value set this time is validated, while if the difference is other than the predetermined level fluctuation compensation width, the threshold value set this time is set. Since it is disabled, the threshold value will not be set in accordance with the large fluctuation of the reception level caused by the adverse effect of external waves when receiving each antenna 1 and 2, and the appropriate threshold value will be set for each antenna. Can be adopted.

Further, in each of the threshold value setting circuits 10 and 11, when the number of antenna non-switching times supplied by the antenna non-switching monitoring counter 9 exceeds a predetermined number of antenna non-switching monitoring stages, the switching operation by the antenna switch 3 is performed. Since the threshold value corresponding to the antenna currently in use is reset asynchronously with, the threshold value will change periodically even if the unswitched state of the antenna 1 or 2 continues. It is possible to return the diversity inactive state to the active state while using the same antenna.

[0094]

As described above, according to the present invention, the past reception level is stored and the threshold value set based on the present reception level and the past reception level and the present reception level are set. to perform the antenna switching based on the time of the threshold setting, the reception level at the current reception past
If it is higher than the reception level of, the previously set threshold is exceeded.
Corrected so that it will be higher than the previous reception level, and during the current reception
If the reception level of is lower than the past reception level,
Set the threshold to be lower than the past reception level
Since so as to correct, satisfactory and Do Rutotomoni threshold correlation of the reception level and threshold is changed dynamically
The threshold value and the reception level.
Since the relationship is increased, it is possible to obtain the diversity receiving device capable of improving the diversity effect.

According to the next invention, if the difference between the reception level average value based on the current reception level and the past reception level and the threshold value set this time is within the predetermined level fluctuation compensation range, the current setting level is set. On the other hand, if the difference is outside the predetermined level fluctuation compensation width, the threshold set this time is made invalid, so that there is a large fluctuation in the reception level caused by the adverse effect of external waves, etc. The threshold value is not set at the same time, which brings about an effect that a diversity receiving apparatus capable of adopting an appropriate threshold value can be obtained.

According to the next invention, when the number of antenna non-switching times exceeds the predetermined number of antenna non-switching monitoring stages, the threshold value is reset asynchronously with the switching operation by the antenna switching means. , The threshold value is periodically changed even if the antenna is not switched, and thereby the diversity receiver capable of returning the inactive state of diversity to the active state while using the same antenna is obtained. Has the effect.

According to the next invention, the past reception level is stored, the threshold value is set for each antenna based on the present reception level and the past reception level, and the threshold value corresponding to the antenna currently in use is set. Based on the current reception level and the current reception level, the antenna switching and the switching to the threshold value corresponding to the antenna are performed, and the threshold value corresponding to each antenna is changed.
When setting, the reception level at the current reception is the past reception level.
If the threshold is higher than the
The reception level at the time of current reception
Is lower than the past reception level, the previously set threshold
Correct the value so that it is lower than the past reception level.
Because it was Unishi, Rutotomoni threshold such that the threshold that is suitable for the antenna to be used after the switching is employed is dynamic
Now is changed to click, whereby, even in the reception levels of a plurality of antennas uneven, Ri Do is sufficient correlation between the reception level and the threshold value at each antenna used, Ante
From the high or Rukoto correlation by Na threshold and the reception level, an effect that is capable of diversity receiving apparatus to perform an optimum diversity by improving the diversity effect can be obtained.

According to the next invention, in the threshold value setting means in which the threshold value is set by the current reception among the plurality of threshold value setting means, the reception level average value based on the current reception level and the past reception level and the current reception level. If the difference from the set threshold value is within the predetermined level fluctuation compensation width, the threshold value set this time is validated, while if the difference is other than the predetermined level fluctuation compensation width, the threshold value set this time is set. Since it is disabled, the threshold will not be set according to the large fluctuation of the reception level caused by the adverse effect of external waves when receiving each antenna, and thus the appropriate threshold will be adopted for each antenna. An effect is obtained that a diversity receiving device capable of being obtained can be obtained.

According to the next invention, when the number of antenna non-switching times exceeds the predetermined number of antenna non-switching monitoring stages, the threshold value corresponding to the antenna currently in use is re-synchronized with the switching operation by the antenna switching means. Since the setting is executed, the threshold value will change periodically even if the unswitched state of the antenna continues, which can return the inactive state of diversity to the active state while using the same antenna. The effect that a possible diversity receiver can be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an internal configuration of a diversity receiving apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a graph showing an example of a case where a threshold value is corrected according to a change in reception level.

FIG. 3 is a diagram illustrating another example of a case where a threshold value is corrected according to a change in a reception level in a graph.

FIG. 4 is a flowchart illustrating a diversity receiving operation according to the first embodiment.

FIG. 5 is a block diagram showing an internal configuration of a diversity receiving apparatus according to Embodiment 2 of the present invention.

FIG. 6 is a flowchart illustrating a main part of diversity reception operation according to the second embodiment.

FIG. 7 is a block diagram showing a configuration example of a diversity receiver according to a conventional example.

FIG. 8 is a block diagram showing another configuration example of the diversity receiver according to the conventional example.

[Explanation of symbols]

1, 2 antennas, 3 antenna switch, 4 reception circuit, 5 reception level storage circuit, 6 threshold value judgment circuit,
7, 10, 11 threshold setting circuit, 7a, 10a, 11a
Comparison circuit, 7b, 10b, 11b correction circuit, 8 reception level average value calculation circuit, 9 antenna non-switching monitoring counter, 12 threshold value switch.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04B ⁷ /02-7/12 H04L 1/02-1/06

Claims (6)

(57) [Claims] 1. A diversity receiver using a diversity system, which uses a plurality of antennas and one receiving circuit, and forms a reception path between any one of the plurality of antennas and the receiving circuit by switching antennas. A reception level storage unit that stores a reception level at the time of reception in the reception circuit for each reception, a reception level at the time of current reception in the reception circuit, and a past reception level stored in the reception level storage unit. Threshold setting means for setting a threshold for antenna switching determination based on the above, and determination means for determining whether or not antenna switching is possible based on the reception level at the time of current reception in the receiving circuit and the threshold set by the threshold setting means. When the determination result that the antennas are switchable is obtained by the determination unit, the plurality of antennas are An antenna switching unit that performs antenna switching within the antenna, and the threshold setting unit, each time the switching is performed by the antenna switching unit, the past reception level that is the reception level before the switching and the reception level after the switching. Comparing means for comparing the reception level at the time of the current reception, which is, when the comparison result that the reception level at the time of the current reception is higher by the comparison means, the previously set threshold value When the comparison result is obtained that the reception level at the current reception is lower, the threshold value set last time is set to the past threshold value. A diversity receiving device comprising: a correction unit that corrects the reception level to be lower than the reception level. 2. An average value calculation means for calculating a reception level average value based on a reception level at the time of current reception in the reception circuit and a past reception level stored in the reception level storage means, When the threshold is set in this reception, the threshold setting means obtains a difference between the reception level average value calculated by the average calculation means and the threshold set this time, and the difference is a predetermined level fluctuation compensation. If it is within the width, the threshold value set this time is validated for the judgment means, while if the difference is other than the predetermined level fluctuation compensation width, the threshold value set this time is set for the judgment means. The diversity receiver according to claim 1, wherein the threshold value is invalidated. 3. The antenna further comprises counting means for counting the number of times of antenna non-switching based on the judgment result of the judging means, and the threshold value setting means has an antenna with a predetermined number of times of antenna non-switching counted by the counting means. The diversity receiver according to claim 1, wherein when the number of unswitched monitoring stages is exceeded, the threshold value is reset asynchronously with the switching operation by the antenna switching unit. 4. A diversity receiving apparatus using a diversity system, wherein a plurality of antennas and one receiving circuit are used, and a receiving path is formed by any one of the plurality of antennas and the receiving circuit by switching antennas. A reception level storage unit that stores a reception level at the time of reception in the reception circuit for each reception, a reception level at the time of current reception in the reception circuit, and a past reception level stored in the reception level storage unit. A plurality of threshold value setting means for setting a threshold value for antenna switching determination for each of the antennas based on the above, and the reception level at the time of current reception in the receiving circuit and the threshold value currently set by the threshold value setting means. Determination means for determining whether or not the antenna can be switched based on a threshold value corresponding to the existing antenna; According to the determination result that the antenna can be switched by the means, the threshold switching means for switching to the threshold value corresponding to the antenna used for reception after the current switching among the threshold values set by the threshold setting means, and the determination means for the antenna An antenna switching unit that performs antenna switching in the plurality of antennas according to the determination result that switching is possible, and each threshold setting unit, each time the switching by the antenna switching unit, the reception level before the switching Comparison means for comparing the reception level in the past with the reception level at the current reception which is the reception level after the switching, and the comparison result that the reception level at the current reception is higher by the comparison means were obtained. In this case, the previously set threshold will be higher than the past reception level. On the other hand, if the comparison means obtains a comparison result that the reception level at the current reception is lower, the threshold value set last time is corrected to be lower than the past reception level. A diversity receiving device, comprising: 5. An average value calculation means for calculating a reception level average value based on a reception level at the time of current reception in the reception circuit and a past reception level stored in the reception level storage means, Each of the threshold value setting means, when a threshold value is set in the current reception, obtains a difference between the reception level average value calculated by the average value calculation means and the threshold value set this time, and the difference is a predetermined level fluctuation. If it is within the compensation width, the threshold set this time is validated for the judging means, while if the difference is other than the predetermined level fluctuation compensation width, the threshold is set this time for the judging means. The diversity receiving apparatus according to claim 4, wherein the threshold that has been set is invalidated. 6. The counter further comprises counting means for counting the number of times of antenna non-switching based on the judgment result of the judging means, and each of the threshold value setting means has a predetermined number of times of antenna non-switching counted by the counting means. 5. The diversity receiver according to claim 4, wherein when the number of antenna non-switching monitoring stages is exceeded, the threshold value is reset asynchronously with the switching operation by the antenna switching unit.