JP2872142B2 - 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, and more particularly to switching control of a diversity receiver which determines and selects a good system signal from a demodulated and output baseband signal.

[0002]

2. Description of the Related Art In a diversity receiving apparatus, it is necessary to switch from a plurality of received signals to signals of a good receiving system, and various diversity reception switching control methods have been proposed. For example, Japanese Patent Application Laid-Open No. 4-111621 discloses a diversity receiving apparatus that performs switching control using a voltage corresponding to deterioration of an eye pattern of a demodulator. In this receiving apparatus, as shown in FIG. 4, a window is formed by providing upper and lower thresholds (A determination points) in addition to the center threshold of the eye pattern, and a received signal falls into this window. Switching control is performed based on the voltage corresponding to the ratio.

[0003]

However, in the above-mentioned conventional apparatus, since the decision points, which are the upper and lower thresholds, are fixed, the reception quality of the two systems is degraded and the amplitude of the signal is smaller than the decision point. In the case of a received signal, it is only necessary to make a selection based on the voltage corresponding to the deterioration of the eye pattern of the demodulator, and it is not possible to make a system selection by judging whether a bit error is true or not.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a diversity receiving apparatus which enables accurate quality judgment even when the quality of a receiving system is all degraded.

A diversity receiving apparatus according to the present invention comprises a desired number of receiving systems, and a demodulating means provided for each of the receiving systems, and an eye of a demodulated output of the demodulating means provided for each of the demodulating means. Judging means for judging the pattern aperture using the judging reference value, judging selecting means for selecting one of the demodulated outputs based on the judging result of the judging means, And determination criteria setting means for sequentially changing the determination criteria.

Thus, even when all the reception qualities are deteriorated, the judgment reference value can be changed according to the deterioration, and the system can be selected by judging whether the bit error is true or not.

Preferably, when the determination means determines that all of the eye pattern openings are degraded from the determination reference value, the determination reference setting means changes the determination reference value in a stepwise manner. More specifically, when the determination means determines that all of the eye pattern openings are degraded below the determination reference value, the determination reference setting means decreases the determination reference value stepwise. As a result, even when all the reception qualities are degraded, the bit error can be reduced by switching to a system with a good reception quality at least a little.

[0008]

FIG. 1 is a block diagram showing one embodiment of a diversity receiving apparatus according to the present invention. In the figure, two receiving inputs # 1 and # 2 are demodulator 1
Reception baseband signals # 1 and # 2, which are demodulated by 01 and 201, respectively, and are demodulated outputs, are input to a changeover switch 301, and a baseband signal having a better reception quality is selected.

[0009] Also, received baseband signals # 1 and # 2
Are input to the comparison circuits 102 and 202, where a pair of determination voltages + V _L generated by the determination voltage setting circuit 302.
And -V _L respectively are compared. However, the pair of determination voltage + V _L and -V _L received baseband signals # 1 and #
It is a notation when the center level of No. 2 is set as the reference voltage.

The comparison circuit 102 is a clock recovery circuit 103
And an eye pattern level comparator 104. The clock recovery circuit 103 recovers a clock from the received baseband signal # 1 and supplies the clock to the eye pattern level comparator 104. According to the clock from the clock recovery circuit 103, the eye pattern level comparator 104 and the eye pattern aperture of the received baseband signal # 1 and a pair of determination voltages +
Compared V _L and a -V _L, respectively, the comparison result V
_COMP1 is output to the determiner 303 and the simultaneous deterioration detector 304, respectively. Similarly, the comparison circuit 202 includes a clock recovery circuit 203 and an eye pattern level comparator 204. The clock recovery circuit 203 recovers a clock from the received baseband signal # 2 and supplies the clock to the eye pattern level comparator 204. Eye pattern level comparator 204
According to the clock from the clock recovery circuit 203,
Received baseband signal # 2 of eye pattern opening of the pair of determination voltage + V _L and a -V _L respectively compared, determination unit 303 and the simultaneous degradation detector 30 and the comparison result V _COMP2
4 respectively. Comparison result V _COMP1 and V
_COMP2 is a determination result indicating the quality of the received baseband signals # 1 and # 2 of the eye pattern relative to the pair of determination voltage + V _L and -V _L. That is, if the eye pattern aperture of the received baseband signal is larger than the determination voltage, it is determined to be good, and if it is smaller, it is determined to be deteriorated.

The decision unit 303 compares the comparison results V _COMP1 and V _COMP
COMP2 is input to determine which reception system is good, and output a switching control signal to the changeover switch 301 so as to select a reception baseband signal of a good reception system.
However, if both of the receiving systems are good, one of the determined systems is selected. When both the comparison results V _COMP1 and V _COMP2 indicate eye pattern deterioration, the simultaneous deterioration detector 304 determines that both reception systems are both deteriorated, and outputs a first detection signal indicating simultaneous deterioration. Voltage control circuit 3
Output to 05. Conversely, when both the receiving systems are good, the simultaneous deterioration detector 304 outputs a second detection signal indicating good at the same time to the voltage control circuit 305.

When the voltage control circuit 305 receives the first detection signal indicating the simultaneous deterioration, the voltage control circuit 305 lowers the judgment voltage value _VL generated by the judgment voltage setting circuit 302 by a predetermined voltage to generate a pair of judgment voltages + V _L and Genchijimi the potential difference -V _L. Therefore, the pair of judgment voltages + V _Li and −V _Li which are narrowed by one step are set as judgment points, and the eye pattern level comparator 10
Nos. 4 and 204 determine the eye pattern deterioration of the received baseband signals # 1 and # 2, respectively. Accordingly, the determination of reception baseband signals # 1 and # also be degraded to the extent that both of the two is comprised between the initial determination voltage + V _L and -V _L, narrowed determined voltage + V _Li and -V _Li The comparison as points makes it possible to clearly determine the deterioration. Of course, by further reducing the determination voltage to reduce the determination voltage difference, accurate degradation determination can be performed even on a more deteriorated received signal.

Conversely, when the voltage control circuit 305 receives the second detection signal indicating good at the same time, the voltage control circuit 305
By a predetermined voltage determination voltage value V _Li 2 produces raised, extending the potential difference between the pair of determining the voltage + V _Li and -V _Li. Therefore, a pair of judgment voltages + V _L extended one step
And -V _L as determined point, eye level comparator 104 and 204 receive the baseband signals # 1 and # 2
The eye pattern deterioration determination is performed. Therefore, the judgment voltage for judging eye pattern deterioration is set to the most appropriate level, and the total bit error of the diversity receiver can be reduced.

FIG. 2 is an eye pattern diagram of a reception baseband for explaining an example of the present embodiment. The determination voltage setting circuit 302 controls the voltage control circuit
The types of judgment voltages V _L1 and V _L2 (V _L1 > V _L2 ) can be set. First, comparison is made by the eye pattern comparator 104 and 204 a pair of determination voltage + V _L1 and -V _L1 as the decision point. If both of the comparison results V _COMP1 and V _COMP2 indicate eye pattern deterioration, the voltage control circuit 305 controls the judgment voltage setting circuit 302 by the simultaneous deterioration detection signal of the simultaneous deterioration detector 304 to change the judgment voltage to V. _Lower from _L1 to _VL2 . As a result, the eye pattern comparators 104 and 204 compare the pair of determination voltages + V _L2 and −V _L2 with the reduced potential difference as the determination points.

FIG. 3 is an eye pattern diagram of a reception baseband for explaining another example of the present embodiment. The determination voltage setting circuit 302 controls two or more determination voltages V _{L1 to} V _LN (V _L1 > V _L2 >...> V) under the control of the voltage control circuit 305.
_LN ) Can be set. First, a pair of determination voltages + V
Eye pattern comparator 104 _L1 and -V _L1 as the decision point
And 204 make a comparison. Comparison result V _COMP1
When both V _COMP2 and V _COMP2 indicate eye pattern deterioration, the voltage control circuit 305 controls the judgment voltage setting circuit 302 by the simultaneous deterioration detection signal of the simultaneous deterioration detector 304 to change the judgment voltage from _VL1 to _VL2. To. As a result, the pair of determination voltages + V _L2 and −V with a reduced potential difference
The eye pattern comparators 104 and 20 are determined using V _L2 as a judgment point.
4 makes a comparison. In the same manner, the counter-constant voltage is sequentially reduced until a meaningful comparison determination result is obtained. Therefore, accurate switching determination can be performed even for a received signal in which eye pattern deterioration is severe.

As described above, according to the present embodiment, when the reception quality of the two systems is deteriorated, it is possible to switch to a system with a good reception quality without fixing to either one of the systems. In addition, by changing the determination point in a stepless manner, it is possible to switch to a system having better reception quality. Therefore, when the input reception quality of the two systems is degraded, the bit error can be reduced by changing the reception quality to a good system and switching to a system with a good reception quality even a little.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a diversity receiving apparatus according to the present invention.

FIG. 2 is an eye pattern diagram of a reception baseband for explaining an example of the present embodiment.

FIG. 3 is an eye pattern diagram of a reception baseband for explaining another example of the present embodiment.

FIG. 4 is an eye pattern diagram of a reception baseband for explaining switching control in a conventional diversity receiving apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 101 Demodulator 102 Comparator 103 Clock recovery circuit 104 Eye pattern level comparator 201 Demodulator 202 Comparator 203 Clock recovery circuit 204 Eye pattern level comparator 301 Changeover switch 302 Judgment voltage setting circuit 303 Judge 304 Simultaneous deterioration detector 305 Voltage control circuit V _L1 ~V _LN decision point

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 7/08 H04B 7/02-7/12 H04L 1/02-1/06

Claims (5)

(57) [Claims] 1. A diversity receiving apparatus comprising a desired number of receiving systems, a demodulating means provided for each of the receiving systems, and a demodulating means provided for each of the demodulating means. Determining means for respectively determining the eye pattern aperture of the output using a determination reference value; determination selecting means for selecting any of the demodulated outputs based on the determination result of the determining means; And a criterion setting means for sequentially changing the criterion value based on the criterion value. 2. The criterion setting means changes the criterion value stepwise when the deciding means determines that all of the eye pattern openings are degraded from the criterion value. The diversity receiving apparatus according to claim 1, wherein: 3. The criterion setting means decreases the criterion value stepwise when the deciding means determines that all of the eye pattern openings are degraded from the criterion value. 3. The diversity receiving apparatus according to claim 2, wherein: 4. A diversity receiving apparatus comprising a desired number of receiving systems, a demodulating means provided for each of the receiving systems, and for judging a deterioration of an eye pattern aperture of a demodulated output of the demodulating means. A determination voltage generating means for generating a pair of determination voltages, and a determination provided corresponding to each of the demodulation means, wherein an eye pattern aperture of a demodulated output of the demodulation means is respectively determined using the pair of determination voltages. Means, a determination selecting means for selecting one of the demodulated outputs based on a determination result of the determination means, and a determination voltage control means for sequentially changing an interval between the pair of determination voltages based on a determination result of the determination means And a diversity receiver. 5. The determination voltage control unit increases the interval between the pair of determination voltages in a stepwise manner when the determination unit determines that all of the eye pattern openings are degraded from the determination reference value. 5. The diversity receiving apparatus according to claim 4, wherein: