JPH10135887A - Receiving attenuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an attenuation amount which is needed for a receiving signal and also to prevent receiving sensitivity from degrading when the attenuation of a receiving signal is not needed by consisting of at least two antennas whose antenna gains that receive a signal are different and a switch that switches the antennas. SOLUTION: When a receiving signal level is small and the receiving signal does not have to be attenuated, a switch 10 performs connection to a 1st antenna 8 side that has the better antenna gain. In such cases, because an attenuator which attenuates a receiving signal and a switch which switches attenuators are not used, loss that is caused by a frequency does not occur and receiving sensitivity is not degraded. Also, when a receiving signal level is large and the attenuation of the receiving signal is needed, the switch 10 connects a circuit to a 2nd antenna 9 side that has the worse antenna gain. If the antenna gain of the antenna 9 is bad by 20db, naturally, the attenuation of 20db signal is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving attenuator in a radio device used for mobile communication and the like.

[0002]

2. Description of the Related Art Generally, in a radio device used for mobile communication or the like, when a high-frequency circuit is saturated, the signal is amplified in a non-linear region of an amplifier for amplifying a received signal. When the received signal is amplified in the non-linear part as described above, a signal having a lower level is amplified more than a desired received signal, and the amplified signal has a great influence on demodulation of the received signal. Will wake up. Therefore, it is necessary to suppress the reception signal to an appropriate reception signal level so as not to amplify the reception signal in the nonlinear region of the amplifier.

FIG. 3 shows an example of a conventional reception attenuator device.
Shown in This will be described below with reference to the drawings. As shown in the figure, the reception attenuator device has a through (0 dB), 10
Attenuators 3, 4, and 5 having three kinds of attenuation amounts of 20 dB and 20 dB, and switches 1 and 2 for selecting the attenuators 3, 4, and 5 to obtain a desired attenuation amount, and attenuation by the selected attenuator. Switches 6 and 7 for connecting the received signals.

Next, the operation of the receiving attenuator will be described. The received signal received from the antenna is first determined by a switch 1 and a switch 2 that select the received signal to pass through which attenuator. When the received signal level is small and the received signal does not need to be attenuated, the attenuator 3 that passes through the received signal (0 dB) is selected. The switch 1 for selecting the attenuator of the received signal is connected to the attenuator 3 which passes through the received signal (0 dB). After the received signal is passed through (0 dB) by the attenuator 3 that passes through the received signal (0 dB), the circuit is connected to the attenuator 3 that passes through the received signal (0 dB) by the switch 7 that connects the received signal. , And the received signal is output to a subsequent circuit.

[0005]

However, in the conventional reception attenuator device, when the received signal level is small and the received signal does not need to be attenuated, the received signal is connected to the switch 1 for selecting the attenuator and the received signal. Pass through two of the switches 7 to be performed. Therefore, although it is desired to select an attenuator having a small received signal level and a small amount of attenuation, attenuation occurs due to the insertion loss of the two switches 1 and 7, and the reception sensitivity deteriorates accordingly.

As described above, in the reception attenuator having the conventional configuration, although it is desired to select an attenuator having a small reception signal level and a minimum attenuation, attenuation occurs by an insertion loss of a switch for switching the attenuator. However, the reception sensitivity is deteriorated. That is, in the conventional reception attenuator, there is a problem that the sensitivity in a through state (a state without attenuation) is deteriorated because the switch on the signal path has a loss.

In view of the above-mentioned problems, the present invention can obtain a required attenuation of a received signal without providing an attenuator changeover switch on a signal path. It is an object of the present invention to provide a receiving attenuator device which does not deteriorate.

[0008]

According to the present invention, there is provided a receiving attenuator comprising at least two antennas having different antenna gains for receiving signals and a switch for switching the antennas. .

According to the present invention, required attenuation can be obtained by selecting at least two antennas having a desired antenna gain, instead of providing a switch on the signal path to change the amount of attenuation. When no attenuation is required, a receiving attenuator device can be provided in which the loss due to the switch does not occur and the receiving sensitivity does not deteriorate.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises an antenna for receiving a received signal, an antenna having a lower gain than the antenna, and a switch for switching each of the antennas. This is a reception attenuator device that attenuates a received signal by selecting an antenna according to its strength. By selecting an antenna according to the strength of the received signal, it obtains a desired amount of attenuation for the received signal. It has the effect of being able to.

According to a second aspect of the present invention, there are provided at least two antennas for receiving a received signal, a switch for switching between the antennas, an attenuator for attenuating the received signal of the antenna, and a switch for the attenuator. This is a reception attenuator device having a switch for performing the above-described operations, and has an effect that diversity can be achieved and a desired amount of attenuation can be obtained for a received signal by selecting an antenna.

An embodiment of the receiving attenuator according to the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is a block diagram showing a circuit configuration of a reception attenuator according to Embodiment 1 of the present invention.

The receiving attenuator includes a first antenna 8 for receiving a signal as shown, a second antenna 9 having an antenna gain lower than that of the first antenna 8, and the first and second antennas. Switch 1 for switching between 8 and 9
0.

Next, the operation will be described. The amount of attenuation for the received signal is the Received Signal Strength Indicator
(Hereinafter referred to as RSSI), the required attenuation is determined from information obtained from the signal. After determining the required attenuation, the switch 10 connects the circuit to a desired one of the first and second antennas 8 and 9 according to the switching signal.

That is, when the received signal level is low and there is no need to attenuate the received signal, the switch 10 connects to the first antenna 8 having the better antenna gain.
In this case, unlike the conventional method, an attenuator for attenuating the received signal and a switch for switching the attenuator are not used, so that there is no loss due to the switch and the reception sensitivity does not deteriorate.

When the received signal level is large and the received signal needs to be attenuated, the required attenuation is determined based on information obtained from the RSSI signal, and the switch 10 is connected to the second antenna 9 having a poor antenna gain. Make circuit connections.
Here, if the antenna gain of the second antenna 9 is lower than that of the first antenna 8 by, for example, 20 dB, the signal is naturally attenuated by 20 dB.

As described above, the reception signal can be attenuated by connecting a circuit to the second antenna 9 having a poor antenna gain. In addition, compared to the case where attenuation of the received signal is performed using an attenuator, a switch for switching the attenuator is not necessary.Therefore, there is no loss or deterioration in reception sensitivity due to the switch. Since a bad one is sufficient, a reception attenuator device excellent in cost can be realized.

(Embodiment 2) FIG. 2 shows a circuit configuration of a receiving attenuator apparatus according to Embodiment 2 of the present invention.

This receiving attenuator device includes at least two first and second antennas 8 and 9 for receiving a received signal, a switch 10 for switching the antenna, and an attenuator for attenuating the received signal of the antenna as shown in the figure. 12 and switches 11 and 13 for switching the attenuator 12.

Next, the operation will be described. The required attenuation is determined based on information obtained from the RSSI signal for the received signal. After the necessary attenuation has been determined, the switching signal is switched according to the switching signal. Switch 11
And 13 are controlled.

When there is no need to attenuate the received signal, a circuit is normally connected to the first antenna 8 by the switch 10 for switching the antenna. In this case, similar to the first embodiment, unlike the conventional method, the attenuator 12 that attenuates the received signal and the switch that switches the attenuator 12 are not used, so that there is no loss due to the switch 10 and the reception sensitivity is reduced. There is no deterioration.

When the first antenna 8 and the second antenna 9 for receiving a signal have the same antenna gain, the difference between the gains of the first antenna 8 and the second antenna 9 is determined by the attenuator. Switches 11 and 1 for selecting 12
Only three losses. Since the loss of the switch is not so large, the signal level received by the second antenna 9 may be higher than the signal level received by the first antenna 8 due to space diversity. In this case, the switch 10 selects the second antenna 9 and the switch 1 that selects the attenuator 12.
Attenuator 1 for attenuating a received signal by 1 and 13
Connect the circuits so that they do not pass through the two sides. Therefore,
In the circuit configuration shown in FIG. 2, the effect of space diversity can be obtained.

If the signal level of the received signal is large and the received signal needs to be attenuated, the switching signal selects the second antenna 9 side. The attenuator 12 is switched by the switching signal.
Are connected to the attenuator 12 side. Further, a circuit is connected to the second antenna 9 by a switch 10 for switching the antenna. In this case, when the attenuator 12 that attenuates the received signal has an attenuation amount of 30 dB, the attenuation is naturally performed by 30 dB. This amount of attenuation is sufficient.
Further, the attenuator 1 is different from that of the first embodiment.
2, the amount of signal attenuation can be freely and easily performed, and by increasing the number of attenuators 12,
It is possible to control complicated reception signal attenuation.

Although two antennas are used in each of the above embodiments, the number of antennas may be three or more, and a switch may be used.

[0026]

As is apparent from the above description, according to the present invention, a required amount of attenuation of a received signal can be obtained by switching antennas having different gains. Further, even when it is not necessary to attenuate the received signal, it is possible to realize a reception attenuator device capable of obtaining a desired attenuation without deteriorating the reception sensitivity.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a circuit configuration of a reception attenuator according to a first embodiment of the present invention;

FIG. 2 is a circuit block diagram of a reception attenuator device according to a second embodiment of the present invention;

FIG. 3 is a circuit configuration block diagram of a conventional reception attenuator device.

[Explanation of symbols]

 8 first antenna 9 second antenna 10 switch 11 switch 12 attenuator 13 switch

Claims (2)

[Claims] An antenna for receiving a received signal, an antenna having a lower gain than the antenna, and a switch for switching between the antennas, wherein the antenna is selected according to the strength of the received signal to reduce the attenuation of the received signal. A receiving attenuator device characterized in that the receiving attenuator device is used. 2. An antenna comprising: at least two antennas for receiving a received signal; a switch for switching between the antennas; an attenuator for attenuating the received signal of the antenna; and a switch for switching the attenuator. A receiving attenuator device capable of obtaining a desired amount of attenuation by selecting an antenna.