JP2000031842A - Reception equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide reception equipment capable of avoiding the degradation of a bit error rate caused by an interference radio wave while keeping the required reception sensitivity. SOLUTION: In a step S6, an attenuator (ATT) value is added to a variable ATT and the ATT value is changed continuously. In a step S8, an intra-received frame error (FER) is measured and the state of making the FET better or worse or no change with the change of the ATT value is discriminated. When the FER gets better, further, the processing of S6 is continuously performed for improving the FER, the loop of steps S6-S8 is repeated and the ATT value of the variable ATT s changed. As a result, when the FER is not changed any more even after the ATT value of the variable ATT is changed, at that time point, processing is advanced from the step S8 to a step S9. Then, the ATT value of variable ATT control is determined (step S9) and the variable ATT is set to the relevant ATT value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a receiving apparatus for receiving a signal.

[0002]

2. Description of the Related Art Conventionally, a communication device, for example, a PHS,
Is provided. That is, the radio wave received by the antenna 1 is band-limited to a band of 1.9 GHz by a BPF (Band Pass Filter) 2, connected to the receiving side by switching an antenna switch 3, and connected to the LNA ( Low N
oise Amplifier 4. Next, BPPF
5, the band is limited to the 1.9 GHz band,
The frequency is converted to a 240 MHz band by X (Mixer) 6. Further, the band is limited to a 240 MHz band by BP F7, the frequency is converted to a 10.8 MHz band by 2nd MIX8, the band is limited to a 10.8 MHz band by BP F9, and the modem is Output to IC (demodulator) 11.

FIG. 5 shows an example of a reception level diagram in the PHS. The configuration of the level diagram shown in FIG. 1 enables a reception sensitivity of -102 dBm.

[0004]

However, in such a configuration, when a large signal is input from the antenna 1, the LNA 4 and the 1st MIX 6 are distorted, and as a result, bit errors are worsened. The causes of the bit error deterioration include deterioration of the C / N due to the saturation of the LNA 4 and the 1st MIX 6 and the device operating point fluctuating due to a large signal, resulting in the fluctuation of the input impedance. It is considered that the P.F7 pass band characteristic is deteriorated.

In order to avoid such bit error deterioration, the TX / RX (transmission / transmission) of the antenna switch 3 is currently used.
The level of the input signal is attenuated by ATT (Attenuator) control by switching of reception. However, when the ATT control is performed by switching the TX / RX of the antenna switch 3 in this manner, the sensitivity of the ATT is degraded. That is, in the case of the example of FIG. 5, if the ATT value of the antenna switch 3 is 20 dB, -10
The reception sensitivity value of 2 dB becomes the reception sensitivity value of -82 dB.

[0006] As described above, the TX /
When the ATT control is performed by switching the RX, a certain AT
The reception sensitivity value is attenuated by the T value, and accordingly, the reception sensitivity value also decreases. At this time, if the reception level of the desired frequency is sufficiently high, there is no problem even if the reception sensitivity value decreases. However, when a large signal interfering wave (adjacent CH (Channel) or the like) is input in a state where the reception level of the desired frequency is low, the ATT (TX) is switched by the TX / RX switching of the antenna switch 3. 20 dB) When control is performed, distortion and impedance fluctuation of LNA 4 and 1st MIX 6 due to a large signal interference wave can be improved, but the receiving sensitivity is greatly reduced, and the necessary receiving sensitivity cannot be secured. .

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and has as its object to provide a receiving apparatus capable of maintaining a required receiving sensitivity and avoiding bit error deterioration due to an interference wave. It is the purpose.

[0008]

According to a first aspect of the present invention, there is provided a receiving apparatus for receiving a signal, comprising: a level changing means for sequentially changing a level of the signal; A judgment means for judging the presence or absence of an interference wave in a signal, and an attenuation control means for attenuating the signal by the level varying means when the judgment means judges that an interference wave is present, are provided. Therefore,
If it is determined that there is an interfering wave in the received signal, the received signal is attenuated by level varying means capable of sequentially changing its level. Therefore, without causing an excessive decrease in reception sensitivity due to an excessive level decrease of the received signal,
Deterioration of reception errors due to interference waves is avoided.

Further, in the invention according to claim 2, the determination means determines that an interference wave is present when the reception error rate of the signal fluctuates. Therefore, when the reception error rate of the received signal fluctuates, the received signal is attenuated by the level varying means that can sequentially change the signal level, so that the deterioration of the reception error due to the interference wave is effectively avoided. .

According to a third aspect of the present invention, the attenuation control means attenuates the signal by the level varying means until the reception error rate of the signal becomes substantially minimum. Therefore, since the error rate is substantially minimized, the influence of interference waves on reception is almost completely avoided.

According to a fourth aspect of the present invention, the attenuation control means attenuates the signal by the level varying means within a range where the reception level of the signal does not fall below a predetermined reception sensitivity. . Therefore, the reception error can be improved within a range where the reception sensitivity does not extremely decrease.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the present invention
Is applied to a terminal for use as shown in FIG.
The radio wave received by the antenna 1 is band-limited to the 1.9 GHz band by BPF2 and connected to the receiving system by switching the antenna switch 3. In this receiving system,
L.N.A.4 and B.P.F. similar to those shown in FIG.
5, 1st MIX 6, BP F7, 2nd MIX 8,
A BP F9, an IF amplifier 10, and a modem IC (demodulator) 11 are provided. Further, in this receiving system, between the BP F5 and the first MIX 6, the BP.
A variable ATT 12 that can attenuate the level of the signal input from F5 to the first MIX 6 steplessly is provided.
The variable ATT 12 is controlled by the CPU 13, and the CPU 13 is connected to the modem IC 11.

On the other hand, MOD14, MIX1
5, BPPF16 and HPA17 are provided in order.
The MOD 14 is connected to the modem IC 11 and to the second MIX 8 via the second LOCAL 18. MIX15 is 2nd LOCAL
19 is connected to the first MIX 6, and the HPA 17 is connected to the antenna switch 3.

The CPU 13 has the following (1) to
Each data of (3) is supplied from each unit.

(1) Data for estimating the level of an interfering wave from the relationship between FER (error in a received frame) and RSSI (reception level) (2) Data for judging that the deterioration of the bit error is an interfering wave (3) Based on (1) and (2), data for estimating the quality of the radio wave condition. In the present embodiment according to the above configuration, the CPU 13
Operates according to the flowchart shown in FIG.
Is measured and it is determined whether or not the value is larger than a predetermined level (step S1). Here, if the ATT value of the antenna switch 3 is 20 dB, the predetermined level is a reception level at which an appropriate reception sensitivity can be ensured even if the ATT control is performed at this 20 dB. Therefore, in this case, when it is necessary to avoid the deterioration of the bit error, the control of attenuating the level of the input signal by 20 dB by the ATT control by switching the TX / RX (transmission / reception) of the antenna switch 3 ( Step S2), that is, the same control as the above-mentioned conventional one is executed.

However, as a result of the determination in step S1, R
If the SSI is equal to or lower than a predetermined level, if the same processing as in the related art is performed, as described above, it becomes impossible to secure an appropriate reception sensitivity. Therefore, from step S1 to step S
Proceed to 3 to measure FER and measure this measured FE
R to determine whether the radio wave condition is good or bad (step S
3). If the result of this determination indicates that the radio wave condition is good, there is no need to operate the variable ATT 12
The current set value is maintained without operating the TT 12 (step S4).

However, if the result of the determination in step S3 indicates that the radio wave condition is poor, it is determined whether or not there is an interfering wave (step S5), and it is assumed that there is an interfering wave. That is, FE
When the R value deteriorates and the error value of the FER value fluctuates and is irregular, it is assumed that an interference wave is input at this time, and otherwise, it is assumed that no interference wave is input. Then, when it is assumed that no interfering wave has been input, the process of step S4 described above is executed, and when it is assumed that an interfering wave has been input, the process proceeds to step S6.

Next, in step S6, the variable ATT12
Is executed, and the ATT value is added to the variable ATT 12 to change the ATT value steplessly. Continue with this ATT
After confirming that the RSSI level decreases with the change in the value,
It is determined whether or not the SSI level is equal to or higher than a predetermined lower limit level (step S7). If the SSI level has reached the lower limit level, the process proceeds to step S9 described below.

If the RSSI level is maintained at or above the predetermined lower limit level, the FER is measured, and it is determined whether the FER is in a good state, a bad state, or no change with a change in the ATT value. (Step S8). If the FER is improved, it is concluded that an interfering wave is input, and the process of step S6 is continuously performed to further improve the FER, and the loop of steps S6 to S8 is repeated to obtain the ATT value of the variable ATT12. To change. As a result, the FER becomes the minimum value and the variable ATT12
If the FER does not change even if the ATT value of
At that time, the process proceeds from step S8 to step S9 to determine the ATT value of the variable ATT12 control (step S9),
The variable ATT 12 is set to the ATT value.

Therefore, by the processing in steps S6 to S9, when the RSSI is equal to or higher than the predetermined lower limit level and F
The variable ATT12 can be set to the ATT value that can minimize the ER. Thus, it is possible to effectively prevent the bit error from being deteriorated due to the interference wave while maintaining the RSSI at or above the predetermined lower limit level. Moreover,
In step S7, it is confirmed that the RSSI level has decreased due to the change in the ATT value. If the RSSI level has reached the lower limit level, the process proceeds to step S9, so that it may not be possible to secure the necessary reception sensitivity. Absent.

If the FER does not change (improve) even if the ATT value of the variable ATT 12 is changed as a result of the determination in step S8, it is determined that the fluctuation of the radio wave level such as fading is large. AT of variable ATT12
The T value is returned to the original set value (step S10), and the state of the maximum receiving sensitivity is maintained.

FIG. 3 shows a variable ATT according to the present embodiment.
12 is an experimental result showing a relationship between an ATT value set to 12, reception sensitivity, intermodulation, and the like. In this experimental result, (A) shows that the ATT value of the input to the first MIX is 0 to 1 in the case of FIG. 5, that is, in the reception level diagram of FIG.
This is the case where it is changed to zero. (B) shows a case where the 1st MIX is changed in the reception level diagram of FIG. 5 (N
F = 7 dB, gain = 6 dB). In this experiment, an appropriate receiving sensitivity was set to a receiving sensitivity of -99 dB or more.

As a result, in the case of (A), an appropriate reception sensitivity can be secured even if the ATT value is changed to "4" (arrow A), and in the case of (B), the ATT value is changed to "8". However, it was found that appropriate reception sensitivity could be ensured (arrow b). Therefore, in the case of (A), by changing the ATT value to “4”, appropriate reception sensitivity can be ensured while avoiding the bit error deterioration caused by the interfering wave as effectively as possible. In this case, it has been found that by changing the ATT value to “8”, it is possible to secure the appropriate reception sensitivity while avoiding the bit error deterioration caused by the interference wave as effectively as possible. In the case of (A), by changing the ATT value to “4”, “2.
7 dB "can be improved, and in the case of (B), by changing the ATT value to" 8 "," 5.
4 dB "has been found to be possible.

In the above embodiment, the present invention is applied to the PHS. However, the present invention is not limited to this. The present invention can be applied to a communication device having a receiving device, such as a mobile phone and a pager.

[0025]

As described above, according to the present invention, when it is determined that an interfering wave is present in the received signal, the signal is attenuated by the level varying means capable of sequentially changing the signal level. It is possible to avoid a reception error from being deteriorated due to an interference wave without causing an excessive decrease in reception sensitivity due to an excessive decrease in the level of the signal.

Further, since it is determined that there is an interference wave when the reception error rate of the received signal fluctuates, the fluctuation of the reception error rate when it is determined that there is an interference wave is sequentially changed by the level varying means. The signal level can be effectively suppressed by the change in the signal level, and the deterioration of the reception error due to the interference wave can be effectively avoided.

Also, since the signal is attenuated by the level varying means until the reception error rate of the signal is substantially minimized, the influence on the reception by the interference wave is reduced by the error rate being substantially minimized. Can be avoided almost completely.

Further, the signal is attenuated by the level varying means within a range where the reception level of the signal to be received does not fall below a predetermined reception sensitivity. Thus, the reception error can be improved, and thus the reception error can be improved while properly maintaining the reception sensitivity.

[0029]

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a circuit configuration of a PHS terminal to which an embodiment of the present invention is applied.

FIG. 2 is a flowchart showing a control procedure according to the embodiment.

FIG. 3 is a view showing experimental results of the example.

FIG. 4 is a block diagram showing a circuit configuration of a conventional PHS terminal.

FIG. 5 is a diagram showing a reception level diagram of the terminal.

[Explanation of symbols]

 3 Antenna switch 4 LNA 5 BPF 6 1st MIX 12 Variable ATT 13 CPU

Claims (4)

[Claims] 1. A receiving apparatus for receiving a signal, a level varying means for sequentially changing a level of the signal, a determining means for determining the presence or absence of an interference wave in the signal, An attenuation control means for attenuating the signal by the level varying means when it is determined that there is an interfering wave. 2. The receiving apparatus according to claim 1, wherein said determining means determines that an interference wave is present when a reception error rate of said signal fluctuates. 3. The receiving apparatus according to claim 1, wherein said attenuation control means attenuates said signal by said level varying means until a reception error rate of said signal becomes substantially minimum. 4. The reception apparatus according to claim 1, wherein said attenuation control means attenuates said signal by said level varying means within a range in which a reception level of said signal does not fall below a predetermined reception sensitivity. apparatus.