JPH04130829A - Diversity receiver - Google Patents

Abstract

PURPOSE:To realize stable reception by fixing an antenna system to be selected to one antenna system when the intensity of an input electric field for plural antenna systems is a strong electric field whose intensity is more than a prescribed value or a weak electric field or when the difference of the output levels in plural antenna systems is less than the prescribed value. CONSTITUTION:When a signal meter S1 is larger than a signal meter S2, and when S2 is larger than S1 but the difference is less than the prescribed value, a signal is inputted from a first level comparator 2 to a change-over switch 6 through an OR circuit 5. The change-over switch 6 does not execute change- over and it maintains the selection of a group A. When S1 is more than the prescribed value and it is judged to be the strong electric field even if the signal meter S2 is larger than S1 by the prescribed value, the change-over switch 6 does not execute change-over by a signal from a second level comparator 3 but it maintains connection for the group A. Even if S2 is larger than S1 by the prescribed value, connection for the group A is maintained. Thus, the occurrence of noise at the time of switching can be prevented and stable reception can be realized.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a diversity receiver.

<Prior art> A diversity receiver is equipped with multiple antenna systems consisting of an antenna, a front end section, an intermediate frequency amplification section, a detection section, etc., and compares the input electric field strength level of each antenna system to determine which field strength level is higher. By configuring the receiver to select an antenna system for reception, it is configured to obtain the effect of reducing multipath distortion.

<Problem to be solved by the invention> However, when the input electric field strength difference between each antenna system is very small, or when the electric field is weak or strong, the noise generation due to antenna switching is more important than the multipath distortion reduction effect. However, there were drawbacks such as instability of reception operation.

The present invention was made in order to solve the above-mentioned drawbacks of the prior art, and it provides diversity in which antenna switching is not performed when the difference in input electric field strength between each antenna system is very small, or when the electric field is weak or strong. The purpose is to provide a receiver.

Means for Solving the Problems> To achieve the above object, the present invention provides a diversity receiver including a plurality of antenna systems and means for selecting the antenna system with the highest medium output level among these antenna systems.
Means for detecting that the input electric field strength to the plurality of antenna systems is a strong electric field of a predetermined value or more, and detection means for detecting that the input electric field strength of the plurality of antenna systems is a weak electric field of a predetermined value or less. means for detecting that the difference in output level of the plurality of antenna systems is less than or equal to a predetermined value; and when the input electric field strength to the plurality of antenna systems is a strong electric field of a predetermined value or more, When the input electric field strength to the antenna system is a weak electric field below a predetermined value, or when the difference in the output level of the plurality of antenna systems is below a predetermined value, the antenna system to be selected is one antenna system. The basic feature is that the device is provided with a means for fixing the device.

<Operation> According to the detection results from each detection means, when the input electric field strength to multiple antenna systems is a strong electric field greater than a predetermined value, or when the input electric field strength to multiple antenna systems is a weak electric field less than a predetermined value. When , or when the difference between the output levels of the plurality of antenna systems is less than or equal to a predetermined value, the antenna system to be selected is fixed to one antenna system. As a result, noise caused by antenna switching can be removed and stable reception can be achieved.

<Example> An embodiment of the present invention will be described below based on the drawings.

FIG. 1 shows an embodiment of a diversity receiver having two antenna systems, A and B, including an antenna 50ab, a front end section 51ab, an intermediate frequency amplification section 52ab, and a detection section 53ab.

The series A and B are selectively connected to the stereo demodulation section 54 and the low frequency amplification section 55 by the changeover switch 6.

The intermediate frequency amplifying section 52ab outputs a signal meter S1 and a signal meter S2 representing the input electric field strength, respectively, which are configured to be subtracted and compared in the subtracter 1.

The output of the subtractor 1 is input to the second rubel comparator 2, and if the signal meter S1 is larger than the signal meter S2, and if the signal meter S2 is larger than the signal meter S1,
It is configured to output a signal to the changeover switch 6 via the OR circuit 5 when the difference is smaller than a predetermined value.

The selector switch 6 selectively selects series A or B as described above.
However, when there is a signal from the OR circuit 5, the series A is selected. Therefore, if the signal meter S1 is larger than the signal meter S2 due to the signal from the second rubel comparator 2, the signal meter S2
Even if S1 is larger than signal meter S1, if the difference is smaller than a predetermined value, selection of series A is maintained and switching to series B is not executed.

The second level comparator 2 is also configured to send a signal to the second level comparator I13 and the third level comparator 4 if the signal meter S2 is larger than the signal meter S1 and the difference is greater than a predetermined value. .

The second level comparator 3 receives the value of the signal meter S1 from the intermediate frequency amplifying section 52a, and the third level comparator 4 receives the value of the signal meter S2 from the intermediate frequency amplifying section 52b. The second level comparator 3 determines whether the signal meter S1 is larger than a predetermined value and indicates a strong electric field, and the signal meter S1 is determined based on the signal from the second level comparator 2.
2 is larger than the signal meter S1 by a predetermined value or more and is a strong electric field, a signal is sent to the changeover switch 6 via the OR circuit 5. Even if the signal meter S2 is larger than the signal meter S1 by a predetermined value or more due to the signal from the second level comparator 3, if there is a strong electric field, the changeover switch 6 maintains the connection to series A and switches to series B. No switching is performed.

The third level comparator 4 determines whether the signal meter S2 is smaller than a predetermined value and indicates a weak electric field, and the third level comparator 2
OR if the signal from signal meter S2 is larger than signal meter S1 by a predetermined value and the electric field is weak.
It is configured to send a signal to a changeover switch 6 via a circuit 5.

If the signal from the third level comparator 4 indicates that the electric field in the signal meter S2 is 1 weak even if the signal meter S2 is larger than the signal meter S1 by a predetermined value or more, the changeover switch 6 maintains the connection to the series A and switches it to the series B. The configuration is such that switching is not performed.

In the above configuration, if the signal meter S1 is larger than the signal meter S2, or if the signal meter S2 is larger than the signal meter S1 but the difference is smaller than a predetermined value, the signal is sent from the second level comparator 3 via the OR circuit 5. A signal is input to the changeover switch 6, and the changeover switch 6 does not perform the changeover and maintains the selection of series A.

Further, even if the signal meter S2 is larger than the signal meter S1 by a predetermined value or more, if the signal meter S1 is determined to be a strong electric field because the signal meter S1 is larger than the predetermined value, the changeover switch 6 is switched by the signal from the second level comparator 3. without running
Maintain connection to series A.

Furthermore, even if the signal meter S2 is larger than the signal meter S1 by a predetermined value or more, if the signal meter S2 is less than the predetermined value and it is determined that the electric field is weak, the changeover switch 6 will not switch based on the signal from the third level comparator 4. Do not execute and maintain connection to series A.

As described above, when the difference between the input electric field strengths of series A and B is small below a predetermined value, when there is a strong electric field, and when there is a weak electric field, switching of the antenna system is not executed, so it is possible to prevent the generation of noise at the time of switching. Stable reception is possible.

Next, FIG. 2 shows a more specific embodiment.

This embodiment is also a diversity receiver equipped with series A and B, and is connected to signal meter S from intermediate frequency amplification section 52a b.
1 and a signal meter S2. The difference signal from the subtracter 10 is sent to the inverting amplifier 11 and the first
input to Schmitt trigger circuit 12;
is configured to send a signal to the OR circuit 17 via the diode D when the signal meter S1 is larger than the signal meter S2. The output side of the OR circuit 17 is connected to a switching circuit 18. The switching circuit 18 is composed of a pair of transistors Tri, 2 and an inverter NV, and is configured to selectively ground the series AB and connect only one series to the stereo demodulator 54 and the low frequency amplifier 55. ing. When the output side of the OR circuit 17 is H, the transistor Tr1 is turned off and the transistor Tr2 is turned on, so that the series A is connected to the stereo demodulation section 54 and the low frequency amplification section 55, and the series B is connected to the ground. ing. Therefore, the switching circuit 18 is configured to select the series A while there is an output from the OR circuit 17.

As a result, while the signal meter S1 is larger than the signal meter S2 and the inverting amplifier 11 is out, the switching circuit 1
8 is configured to maintain selection of series A without performing a switching operation.

The second Schmitt trigger circuit 12 is a signal meter S2
When the difference between the signal meter S2 and the signal meter S1 is smaller than a predetermined value, a signal is output from the inverted output to the OR circuit 17. is now being sent. Therefore, even if the signal meter S2 is larger than the signal meter S1, if the difference is smaller than a predetermined value, a signal is sent to the switching circuit 18, and the switching circuit 18 maintains the connection of series A without performing a switching operation. It is configured as follows.

If the difference between the signal meter S2 and the signal meter s1 is greater than or equal to a predetermined value, the first Schmitt trigger circuit 12 turns on the transistors 13 and 14, and turns on the second
The signal meter S1 is input to the Schmitt trigger circuit 15, and the signal meter s2 is input to the third Schmitt trigger circuit 16.

The second Schmitt trigger circuit 15 is a signal meter S1
When the electric field is larger than a predetermined value and the electric field is 1 strong, a signal is sent to the OR circuit 17 and the switching circuit 18 to maintain the connection of the series A.

On the other hand, the inverted output of the third Schmitt trigger circuit 16 is O when the signal meter S1 is smaller than the predetermined value and the electric field is weak.
It is configured to send a signal to the R circuit 17 and the switching circuit 18 to maintain the connection of series A.

As described above, when the difference between the input electric field strengths of series A and H is small below a predetermined value, when there is a strong electric field, and when there is a weak electric field, the switching circuit 18 does not perform a switching operation and switching of the antenna system is not performed.

Next, FIG. 3 shows another embodiment. This example is also series AB
It is equipped with

Signal meters S1, 2 from intermediate frequency amplification section 52ab
is subtracted by a subtracter 20, and the result is output to the first Schmitt trigger circuit 21. The first Schmitt trigger circuit 21 is a signal meter S
2 is larger than the signal meter S1 by a predetermined value or more, a signal is output to the switching circuit 22.

The switching circuit 22 is composed of a pair of transistors T r 1.2 and an inverter INV, and is configured to selectively ground the series AB and connect only one series to the stereo demodulation section 54 and the low frequency amplification section 55. It has become. When the output side of the first Schmitt trigger circuit 21 is H, the transistor Tr1 is turned on, the transistor Tr2 is turned off, and the series B is connected to the stereo demodulator 54 and the low frequency amplifier 55, and the series A is connected to the stereo demodulator 54 and the low frequency amplifier 55. Therefore, when there is an output from the first Schmitt trigger circuit 21, the switching circuit 22 performs a switching operation to
The configuration is such that the connection is switched from series B to series B.

Signal meter S1.2 from intermediate frequency amplification section 52ab
The output is also sent to a second Schmitt trigger circuit 23 and a third Schmitt trigger circuit 24. The second Schmitt trigger circuit 23 is configured to output a signal to the transistor 26 via the OR circuit 25 when the signal meter S1 has an electric field of 1 strength greater than a predetermined value. On the other hand, in the third Schmitt trigger circuit 24, the signal meter S
2 is smaller than a predetermined value and the electric field is weak, the signal is output to OR circuit 2.
The signal is configured to be output to the transistor 26 via S.

The transistor 26 is provided between the output side of the first Schmitt trigger circuit 21 and ground, and is connected to the second Schmitt trigger circuit 21.
Trigger circuit 23. When turned on by a signal from the third Schmitt trigger circuit 24, the output side of the first Schmitt trigger circuit 21 is grounded.

In the above configuration, when the signal meter s2 is larger than the signal meter S1 by a predetermined value or more, the first system
Even if there is a signal output from the trigger circuit 21, if there is an output from the second Schmitt trigger circuit 23 or the third Schmitt trigger circuit 24 in a weak electric field or a strong electric field, the transistor 26 is turned on and the first Schmitt trigger circuit 24 is turned on. - Since the output of the trigger circuit 21 is grounded, the switching circuit 22 does not perform any switching operation.

As described above, when the difference between the input electric field strengths of series A and B is smaller than a predetermined value, no signal is output from the first Schmitt trigger circuit 21, and when there is a strong electric field or a weak electric field, the first Schmitt trigger circuit 21 outputs no signal. Since the output of antenna 21 is grounded, switching circuit 22 does not perform a switching operation, and switching of the antenna system is not performed.

According to the configuration described above, when the difference between the input electric field strengths of series A and H is small below a predetermined value, or when there is a strong electric field and a weak electric field, antenna system switching is not performed. The antennas are not switched frequently, the generation of noise caused by antenna switching is suppressed, and stable reception is possible.

<Effects of the Invention> As explained above, the present invention provides a diversity receiver including a plurality of antenna systems and means for selecting the antenna system with the highest medium output level among these antenna systems. means for detecting that the electric field intensity input to the antenna system is a strong electric field greater than a predetermined value; and detecting means for detecting that the electric field intensity input to the plurality of antenna systems is a weak electric field less than a predetermined value; means for detecting that the difference in output levels of the plurality of antenna systems is less than or equal to a predetermined value;
When the input electric field strength to the plurality of antenna systems is a strong electric field of a predetermined value or more, or when the input electric field strength to the plurality of antenna systems is a weak electric field of a predetermined value or less, or the plurality of antenna systems and means for fixing the antenna system to be selected to one antenna system when the difference in the output levels of the two is less than a predetermined value, based on the detection results from each detection means.

When the input electric field strength to multiple antenna systems is a strong electric field greater than a predetermined value, or when the input electric field strength to multiple antenna systems is a weak electric field less than a predetermined value, or the output level of multiple antenna systems When the difference is less than a predetermined value, the antenna system to be selected is fixed to one antenna system, which has the effect of eliminating noise caused by antenna switching and achieving stable reception.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment, and FIG. 3 is a block diagram showing still another embodiment. 1: Subtractor, 2: Second level comparator, 3: Second level comparator, 4: Third level comparator, 5: OR circuit, 6: Changeover switch, 10: Subtractor, 11: Inverting amplifier , 12: first Schmitt trigger circuit, 13: transistor, 14
: transistor, 15: second Schmitt trigger circuit,
16: Third Schmitt trigger circuit, 17: OR circuit,
18: switching circuit, 20: subtracter, 21: first Schmitt trigger circuit, 22: switching circuit, 23: second Schmitt trigger circuit, 24: third Schmitt trigger circuit, 2
5: OR circuit, 26: transistor, 50: antenna,
51: Front end section, 52: Intermediate frequency amplification section, 53
: Detection section, 54 Nstereo demodulation section, 55: Low frequency amplification section. Patent applicant: Clarion Co., Ltd. Representative: Patent attorney Kiyoshi Takahashi

Claims (1)

[Claims] A diversity receiver comprising a plurality of antenna systems and means for selecting the antenna system with the highest intermediate output level among these antenna systems, wherein the input electric field strength to the plurality of antenna systems is a predetermined value. means for detecting that the electric field is strong than a predetermined value; detecting means for detecting that the electric field intensity input to the plurality of antenna systems is a weak electric field less than a predetermined value; means for detecting that the difference is less than or equal to a predetermined value; means for fixing the antenna system to be selected to one antenna system when the electric field is weak or when the difference in output level of the plurality of antenna systems is less than a predetermined value. diversity receiver.