JPH07226706A - Fading pitch detector - Google Patents

Abstract

PURPOSE:To provide a fading pitch detector detecting a fading pitch with higher precision. CONSTITUTION:A receiver 3(4) detects a radio wave reception level L1(L2), a comparison control means 7 using a difference between the reception levels L1, L2 causing a level fluctuation due to a cause other than fading to a branch switching signal S1 as a threshold and providing a level difference monitor signal S2 whose level is an H level when the level difference is below a threshold level and whose level is an L level when the level difference exceeds the threshold level and an L level, a mask means 13 provides an output of the signal S1 as a switching signal S3 as it is when the level of the signal S2 is an L level and holding and outputting a level of the switching signal S3 when the level of the signal S2 is an H level, and a switching number detection means 10 counts a level change of the switching signal S3 to obtain the number of times of switching, and a fading pitch detection means 11 detects a fading pitch based on the number of switching times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fading pitch detecting apparatus in a radio receiver which performs post-detection selection diversity or antenna switching diversity in a mobile communication system.

In the field of mobile communication, a phenomenon called fading in which the reception level fluctuates significantly is observed. The temporal fluctuation pitch (fading pitch) of the reception level due to fading is proportional to the moving speed of the mobile station.

The fading pitch detecting device is mounted on a mobile station typified by a car phone and a mobile phone, and is necessary for detecting the moving speed of the mobile station by detecting the fading pitch. There is a demand for obtaining the fading pitch with high accuracy.

[0004]

2. Description of the Related Art FIG. 8 is a block diagram of a conventional fading pitch detecting device. The fading pitch detecting device shown in FIG. 8 is provided in a mobile station,
To receive the reception level of communication radio waves sent from a base station by two uncorrelated reception systems (two branches) and compare the reception levels to count the number of times each branch is switched. The fading pitch is detected by. However, the fading pitch corresponds to the number of times of branch switching.

In the figure, 1 and 2 are antennas, 3 and 4 are first and second receivers, 5 and 6 are first and second demodulators, 7 is a reception level comparison control circuit, 8 is a selection circuit, and 9 is a selection circuit. Is a data processing circuit, 10 is a switching frequency detector, and 11 is a fading pitch detection circuit.

Communication radio waves transmitted from a base station (not shown) are received by the first and second receivers 3 and 4 via the first and second antennas 1 and 2, and the received signals thus received are It is demodulated by the first and second demodulators 5 and 6.

The reception level comparison control circuit 7 includes demodulators 5 and 5.
6 receive levels L1 and L with different phases
2 is compared and the branch switching signal S1 is output. FIG. 9 shows the reception levels L1 and L2 and the branch switching signal S1. Since the reception levels L1 and L2 are obtained by mutually uncorrelated reception systems, their phases are different as shown in FIG. The reception level comparison control circuit 7 detects the level switching position indicated by the arrow Y in FIG. 9 by comparing the reception levels L1 and L2, and “H” is detected at the switching position.
The branch switching signal S1 (FIG. 9) for switching to the level or the "L" level is output.

The switching number detecting circuit 10 detects the number of branch switchings by counting the rising edge and the falling edge of the branch switching signal S1. The fading pitch detection circuit 11 detects the fading pitch based on the number of times of branch switching.

The selection circuit 8 selects the demodulation signal with the higher reception level, which is the branch switching signal S1.
When the level is "L", the demodulated signal output from the first demodulator 5 is selected, and when the level is "H", the demodulated signal output from the second demodulator 6 is selected.

The data processing circuit 9 is adapted to perform processing such as converting the demodulated signal sent through the selection circuit 8 into a voice signal.

[0011]

By the way, in the above-mentioned conventional fading pitch detecting apparatus, when the reception levels L1 and L2 between both branches are close to each other, the receivers 3 and 4 are provided.
Branch switching is performed due to another factor that does not depend on fading, such as variation in the level detection function. That is, as shown in FIG. 9, when the reception levels L1 and L2 are close to a predetermined level, the "L" level and the "H" level of the branch switching signal are switched at high speed at that location as shown by the reference sign S1 '. Therefore, there is a problem that the fading pitch cannot be accurately detected.

The present invention has been made in view of the above points, and an object of the present invention is to provide a fading pitch detecting apparatus capable of detecting a fading pitch with higher accuracy.

[0013]

FIG. 1 shows a principle diagram of a fading pitch detecting apparatus of the present invention. This fading pitch detecting device detects a fading pitch from the number of times of branch switching obtained from a change in "L" level and "H" level of a branch switching signal in a radio device that performs either post-detection diversity or antenna switching diversity. Is.

In the figure, 3 and 4 are a plurality of receivers for detecting the reception levels (L1, L2) of radio waves. Reference numeral 7 is a comparison control means, which uses a level difference between the reception levels L1 and L2 that causes a level change in the branch switching signal S1 due to factors other than fading as a threshold value, and if the level difference is less than or equal to the threshold value, an "H" level, It outputs the level difference monitor signal S2 which becomes "L" level when the threshold value is exceeded.

Reference numeral 13 is a masking means, which is a branch switching signal S1 when the level difference monitor signal S2 is at "L" level.
Is output as the switching signal S3 as it is, and in the case of "H" level, the level of the switching signal S3 is held as it is and output.

Reference numeral 10 denotes a switching number detecting means, which obtains the number of branch switchings by counting the level change of the switching signal S3. Reference numeral 11 is a fading pitch detecting means for detecting the fading pitch from the number of times of branch switching.

[0017]

According to the above-described present invention, the masking means 13 outputs the branch switching signal S1 as it is as the switching signal S3 when the level difference monitor signal S2 is at "L" level, and switches it when it is at "H" level. The level of the signal S3 is held as it is and output.

When the level difference monitor signal S2 is at "L" level, it means that the level difference between the reception levels L1 and L2 exceeds the threshold value, which is because the branch switching signal S1 changes in level due to fading. When the level difference monitor signal S2 is at the "L" level, if the branch switching signal S1 is used as it is as the switching signal S3 for counting the number of times of branch switching, an accurate number of times of branch switching can be obtained.

When the level difference monitor signal S2 is at "H" level, it means that the level difference between the reception levels L1 and L2 is less than the threshold value, which is the branch switching signal S1.
Is a level change due to factors other than fading, so if the level difference monitor signal S2 is at "H" level,
By holding the level of the switching signal S3 as it is and outputting it, it is possible to remove a portion whose level has changed due to factors other than fading of the branch switching signal S1.

Since the number of times of branch switching can be accurately obtained by the switching signal S3 thus obtained, the fading pitch can be detected with high accuracy from the number of times of branch switching.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram of a fading pitch detecting apparatus according to the first embodiment of the present invention. This Figure 2
In FIG. 8, the parts corresponding to the respective parts of the conventional example shown in FIG.

The characteristic of the fading pitch detecting apparatus of the first embodiment shown in FIG. 2 is that "H" level is set when the difference between the reception levels L1 and L2 of both is less than a predetermined threshold value, and "L" level is set when the difference is larger than the threshold value. The level difference monitor signal S2 which becomes the level
Is output from the reception level comparison control circuit 7,
Further, the reception level comparison control circuit 7 and the switching number detection circuit 1
When the reception levels L1 and L2 of both are approaching a predetermined value with respect to 0, the switching point of the branch switching signal S1 which is switched by a factor other than fading is set to the level difference monitor signal S.
The point is that the mask circuit 13 for masking by 2 is connected.

The above-mentioned threshold value is applied to the branch switching signal S1.
It is a value corresponding to the level difference between the reception levels L1 and L2 that causes a portion to be switched due to factors other than fading.
For example, the threshold value is 3 dB.

That is, the reception level comparison control circuit 7 compares the reception levels L1 and L2 with each other, and if the level difference is less than or equal to the threshold value, the "H" level, and if the level difference is greater than the threshold value, the "L" level difference monitor. The signal S2 is output.

As shown in FIG. 3, the mask circuit 13 directly outputs the branch switching signal S1 as the switching signal S3 when the level difference monitor signal S2 is at the "L" level,
In the case of "H" level, the level of the switching signal S3 is held and output.

The level change of the switching signal S3 output from the mask circuit 13 will be described with reference to the timing chart shown in FIG. When the branch switching signal S1 becomes "H" level at the time t1, the level difference monitor signal S2 is "L" level at this time, so the branch switching signal S1 is used as it is and the switching signal S3 becomes "H" level.

At time t2, the level difference monitor signal S
2 becomes "H" level, and the branch switching signal S1 becomes "L" level at time t3. At the timing of this time t3, the level difference monitor signal S2 is at "H" level, so the branch switching signal S1 immediately before this is
"H" level is used, and the switching signal S3 remains at "H" level.

From time t4 to t7, the level of the branch switching signal S1 finely changes. At this time, since the level difference monitor signal S2 is at "H" level, the switching signal S3 remains at "H" level.

At time t8, the level difference monitor signal S
When 2 goes to the “L” level, the branch switching signal S1 is used as it is, so the switching signal S3 goes to the “L” level.

At time t9, the level difference monitor signal S
When 2 goes to the "H" level, the branch switching signal S1 immediately before this is used, so that the switching signal S3 remains at the "L" level. Thereafter, the level of the switching signal S3 is similarly determined.

The switching signal S3 thus obtained is
As can be seen from FIG. 3, when the reception levels L1 and L2 of both sides approach a predetermined value, the switching location of the branch switching signal S1 that switches due to a factor other than fading is masked, so that the rising edge of this signal S3 and By counting the number of falling edges by the switching number detection circuit 10, the number of branch switchings depending on fading can be accurately obtained.

Therefore, the fading pitch detection circuit 11
The fading pitch can be detected with high accuracy. Next, a fading pitch detecting device according to the second embodiment will be described with reference to FIG. However, in FIG.
The same reference numerals are given to the portions corresponding to the respective portions of the first embodiment shown in, and the description thereof will be omitted.

A characteristic of the fading pitch detecting apparatus of the second embodiment shown in FIG. 4 is that a clock signal used for generating the branch switching signal S1 between the reception level comparison control circuit 7 and the switching number detection circuit 10. The point is that CK is used and a mask circuit 15 for masking the switching location of the branch switching signal S1 that is switched by a factor other than fading is connected.

The mask circuit 15 has a branch switching signal S1.
When the same level continues for a certain time from the time when the level changes, the level is set as the level of the switching signal S4, and when the level of the branch switching signal S1 changes within the certain time, the level of the switching signal S4 is the same as the previous time. It is something to hold at the level.

That is, if the level of the branch switching signal S1 is the same for a certain number of consecutive clock signals CK synchronized with the branch switching signal S1 from the time when the branch switching signal S1 changes, then the branch switching signal S1 The level is used as the level of the switching signal S4, and the clock signal C
If the level of the branch switching signal S1 changes while K is less than a certain number, the level of the switching signal S4 is maintained at the same level as the previous time.

This operation will be described with reference to the timing chart shown in FIG. However, in the mask circuit 15, the clock signal CK becomes 1 from the time when the branch switching signal S1 changes.
It is determined whether or not the level of the branch switching signal S1 is used as the level of the switching signal S4 after six consecutive times.

When the branch switching signal S1 changes to the "H" level at time t1, the mask circuit 1 starts from this point.
5 counts the falling edges of the clock signal CK and grasps the level of the branch switching signal S1. If the count value is 16 times at time t2 and the level of the branch switching signal S1 is "H" level during this period, the mask circuit 15 sets the "H" level to the switching signal S4.
Used as a level. That is, the switching signal S4 becomes "H" level.

When the branch switching signal S1 changes to the "L" level at time t3, the mask circuit 1 starts from this point.
5 counts the falling edges of the clock signal CK and grasps the level of the branch switching signal S1. If the branch switching signal S1 changes to "H" level at time t4 when the count value is less than 16 times, the switching signal S
The level of 4 is maintained at the "H" level similar to the previous time.
Thereafter, the level of the switching signal S4 is similarly determined.

The switching signal S4 thus obtained is
As can be seen from FIG. 5, the switching location of the branch switching signal S1 that is switched by a factor other than fading is masked, so that the switching frequency detection circuit 10 counts the rising edge and the falling edge of this signal S4. , The number of branch changes depending on fading can be accurately obtained, and the fading pitch detection circuit 11 can detect the fading pitch with high accuracy.

Next, a fading pitch detecting device according to the third embodiment will be described with reference to FIG. However, in FIG. 6, parts corresponding to the respective parts of the first and second embodiments shown in FIGS. 2 and 4 are designated by the same reference numerals, and description thereof will be omitted.

A characteristic of the fading pitch detecting apparatus of the third embodiment shown in FIG. 6 is that it has both masking functions described in the first and second embodiments. That is, between the reception level comparison control circuit 7 and the switching number detection circuit 10, as shown in FIG.
And the mask circuit 15 shown in FIG.
It is configured by connecting and in series.

In FIG. 6, in order to distinguish each mask circuit, its name is given as a first mask circuit 13 and a second mask circuit 15. Further, the branch switching signal S1 and the level difference monitor signal S2 are input to the first mask circuit 13, the switching signal S3 output from the first mask circuit and the clock signal CK output from the reception level comparison control circuit 7 are input.
Are input to the second mask circuit 15, and the second mask circuit 1
The switching signal S5 output from the switch 5 is the switching number detection circuit 10
It is configured to be input to.

With such a configuration, as described in the first embodiment by the first mask circuit 13, when the level difference monitor signal S2 is at the "L" level, the branch switching signal S1 is directly used as the switching signal S3. When it is output and is at "H" level, the level immediately before the branch switching signal S1 is held and output as the switching signal S3.

The second mask circuit 15 sets the level of the switching signal S5 to the level of the switching signal S3 when the same level continues for a certain period of time after the level of the switching signal S3 changes, and the level of the switching signal S3 is set within the certain period of time. Is changed, the level of the switching signal S5 is held at the same level as the previous time.

This operation will be described with reference to the timing chart shown in FIG. Branch switching signal S at time t1
When 1 goes to "H" level, the level difference monitor signal S2 is at "L" level at this time, so the branch switching signal S1 is used as it is as the switching signal S3 by the first mask circuit 13. As a result, the switching signal S3 becomes "H" level. When the switching signal S3 changes to the “H” level, the second mask circuit 15 counts the falling edges of the clock signal CK and grasps the level of the switching signal S3.

At time t2, the level difference monitor signal S
It is assumed that 2 has reached the “H” level. If the count value of the clock signal CK reaches 16 times at this time, the level of the switching signal S3 is "H" level during this period, so the second
The mask circuit 15 uses the "H" level as the level of the switching signal S5. As a result, the lunch signal S5 becomes "H" level.

At time t3, the branch switching signal S1
Is at the “L” level. At this timing, the level difference monitor signal S2 is at the “H” level, so the branch switching signal S1 immediately before that is set by the first mask circuit 13.
“H” level of is used as the level of the switching signal S3.

From time t4 to t7, the level of the branch switching signal S1 is finely changed. At this time, since the level difference monitor signal S2 is at "H" level, the switching signal S3 remains at "H" level.

At time t8, the level difference monitor signal S
When 2 becomes "L" level, the branch switching signal S1 is used as it is by the first mask circuit 13, so that the switching signal S3 becomes "L" level. In addition, the switching signal S3
Is changed to the “L” level, the second mask circuit 15
Counts the falling edges of the clock signal CK and grasps the level of the switching signal S3.

At time t10, assuming that the count value of the clock signal CK reaches 16 times, the switching signal S
Since the level of 3 is "H" level, the second mask circuit 15
Uses the "L" level as the level of the switching signal S5. As a result, the lunch signal S5 becomes "L" level. Thereafter, the level of the switching signal S5 supplied to the switching number detection circuit 10 is similarly determined.

According to such an operation, first, the switching portion of the branch switching signal S1 which is switched by a factor other than fading when both reception levels L1 and L2 approach a predetermined value is masked by the first mask circuit 13, Here, as shown between times t11 and t12 in FIG.
In addition, even if a switching portion due to a factor other than fading remains, the second mask circuit 15 further removes the remaining portion.

Therefore, by counting the rising edge and the falling edge of the switching signal S5 output from the second mask circuit 15 by the switching number detecting circuit 10, the number of branch switchings depending on fading can be more accurately obtained. Therefore, the fading pitch detection circuit 11 can detect the fading pitch with higher accuracy.

[0053]

As described above, according to the present invention,
There is an effect that the fading pitch can be detected with higher accuracy.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a block diagram of a fading pitch detecting device according to a first embodiment of the present invention.

FIG. 3 is a timing chart for explaining an operation of a main part of the fading pitch detection device shown in FIG.

FIG. 4 is a block diagram of a fading pitch detecting device according to a second embodiment of the present invention.

5 is a timing chart for explaining a fading pitch detecting operation of the fading pitch detecting device shown in FIG.

FIG. 6 is a block diagram of a fading pitch detecting device according to a third embodiment of the present invention.

7 is a timing chart for explaining a fading pitch detecting operation of the fading pitch detecting device shown in FIG.

FIG. 8 is a block diagram of a conventional fading pitch detecting device.

9 is a timing chart for explaining a fading pitch detecting operation of the fading pitch detecting device shown in FIG.

[Explanation of symbols]

 3, 4 receiving means 7 comparison control means 10 switching number detecting means 11 fading pitch detecting means L1, L2 reception level S1 branch switching signal S2 level difference monitor signal S3 switching signal

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuo Obuchi 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited (72) Inventor Kensuke Sawada 1015 Kamedota, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited

Claims (3)

[Claims] 1. A fading pitch detection for detecting a fading pitch from the number of times of branch switching obtained from a change in the "L" level and "H" level of a branch switching signal in a radio device that performs either post-detection diversity or antenna switching diversity. In the device, multiple receiving means to detect the reception level (L1, L2) of the radio wave
(3,4) and the level difference of the reception level (L1, L2) that causes the level change in the branch switching signal (S1) due to factors other than fading, as a threshold, and if the level difference is less than or equal to the threshold, Comparison control means (7) that outputs a level difference monitor signal (S2) that becomes "L" level if it exceeds the "H" level and the threshold value, and the branch if the level difference monitor signal (S2) is "L" level. The switching signal (S1) is output as it is as the switching signal (S3), and when it is at "H" level, the masking means (13) for holding the level of the switching signal (S3) as it is and outputting it, and the switching signal (S3). ), A switching number detecting means (10) for obtaining the number of branch switchings by counting the level change, and a fading pitch detecting means (11) for detecting the fading pitch from the number of branch switchings. Fading pitch detecting device. 2. Fading pitch detection for detecting a fading pitch from the number of times of branch switching obtained from changes in the "L" level and "H" level of a branch switching signal in a radio device that performs either post-detection diversity or antenna switching diversity. In the device, multiple receiving means to detect the reception level (L1, L2) of the radio wave
(3,4) and the level difference of the reception level (L1, L2) that causes the level change in the branch switching signal (S1) due to factors other than fading, as a threshold, and if the level difference is less than or equal to the threshold, The comparison control means (7) for outputting the level difference monitor signal (S2) which becomes the "H" level and the "L" level when the threshold value is exceeded, and the same level are determined from the time when the level of the branch switching signal (S1) changes. If the level of the branch switching signal (S1) is changed within the predetermined time, the level of the switching signal (S4) is output when the switching time (S4) of the switching signal (S4) is changed. A masking means (15) for holding and outputting the level as it is, a switching number detecting means (10) for obtaining the branch switching number by counting the level change of the switching signal (S4), and Fading pitch for detecting fading pitch A fading pitch detecting device comprising a switch detecting means (11). 3. A fading pitch detection for detecting a fading pitch from the number of times of branch switching obtained from a change in “L” level and “H” level of a branch switching signal in a radio device which performs either post-detection diversity or antenna switching diversity. In the device, multiple receiving means to detect the reception level (L1, L2) of the radio wave
(3,4) and the level difference of the reception level (L1, L2) that causes the level change in the branch switching signal (S1) due to factors other than fading, as a threshold, and if the level difference is less than or equal to the threshold, Comparison control means (7) that outputs a level difference monitor signal (S2) that becomes "L" level if it exceeds the "H" level and the threshold value, and the branch if the level difference monitor signal (S2) is "L" level. The first masking means (13 ′) for outputting the switching signal (S1) as it is as the first switching signal (S3) and, in the case of “H” level, holding the level of the first switching signal (S3) as it is and outputting it.
), And if the same level continues for a predetermined time from the time when the level of the first switching signal (S3) changes, the second level of that level is changed.
The switching signal (S5) is output, and if the level of the first switching signal (S3) changes within the predetermined time, the second signal is output.
The second which holds the level of the switching signal (S5) as it is and outputs it
A masking means (15 ') and a switching number detecting means (10) for obtaining the branch switching number by counting the level change of the second switching signal (S5).
And a fading pitch detecting means (11) for detecting the fading pitch based on the number of times of branch switching.