JP2838996B2 - Automatic gain control device and method for mobile radio - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio such as a radio selective call receiver and a portable telephone of a time division multiplex communication system, and more particularly to a mobile radio having a receiving unit provided with an automatic gain control circuit.

[0001]

2. Description of the Related Art Generally, a mobile radio is provided with an automatic gain control circuit for controlling the level of a received signal within a predetermined level when demodulating and decoding a received signal. In particular, mobile radios are often used in situations where the electric field level is apt to change, so that the reception level greatly varies, and an automatic gain control circuit is indispensable. Conventionally, such an automatic gain control circuit is configured to detect the electric field strength of a received signal, adjust the amplification based on the electric field strength, and maintain the output level at a predetermined level.

As a radio having such an automatic gain control circuit, for example, an automatic gain control device disclosed in Japanese Patent Application Laid-Open No. 1-170165 is known.

In this automatic gain control device, when a burst-like signal is received, the automatic gain control circuit is operated substantially simultaneously with the reception of the burst-like signal.

[0004]

However, in this automatic gain control device, in order to adapt to a burst signal,
Since the amplification degree of the amplifier circuit may fluctuate rapidly and greatly depending on the reception state, the fluctuation of the amplification degree may affect the demodulator and the decoder at the subsequent stage of the wireless device, and may cause the reception signal to be erroneous. The problem that occurs.

On the other hand, if the followability to the level of the received signal is reduced in order to avoid the occurrence of such an error,
It becomes impossible to follow the level of the received signal, and it becomes impossible to suitably receive a burst signal.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide an automatic gain control device and an automatic gain control method for a mobile radio, which can effectively reduce the number of reception errors by effectively exhibiting the original function of the automatic gain control device.

[0007]

Means for Solving the Problems To achieve the above object, an automatic gain control device for a mobile radio device according to the present invention receives a transmission signal of a time division multiplex system and detects an electric field strength of the reception signal. Detection means, and an amplification coefficient indicating the followability of the automatic gain control with respect to the electric field strength are variable .
Automatic gain control amplifying means for automatically controlling the gain of a received signal based on a control signal indicating whether or not a communication timing and an amplification coefficient controlled by the detection result of the detecting means; and amplification of the automatic gain control amplifying means. Control means for outputting the control signal for controlling the coefficient . Further, the automatic gain control device for a mobile wireless device according to the present invention includes a step of detecting an electric field strength RSSI (t) of a received signal at time t;
A step of determining whether or not the transmitting station is transmitting a signal based on the detected electric field strength RSSI (t); a case where the transmitting station is not transmitting a signal; and a case of communication timing of its own mobile radio device Setting the amplification coefficient k (t) to a predetermined value; and, when the transmitting station is transmitting a signal and other than the communication timing of its own mobile radio device, the amplification coefficient k (t) is set. ) Is set to a value larger than the predetermined value, and Ag (t) is set to an amplification value of time t, Ag
Ag (t) = Ag (t-1) -k, where (t-1) is the amplification value at time t-1 and V1 is the ideal value of the electric field strength.
And (a) amplifying the received signal based on the amplification value represented by (t) × (RSSI (t) -V1) . By adopting the above configuration and method, in the present invention, the electric field strength of the received signal is detected and the amplification coefficient of the automatic gain control amplification unit is controlled based on the detection result. The automatic gain control amplifier can be operated by setting the amplification coefficient. When the detected electric field strength is sufficiently small and the base station is determined to be OFF, and when it is the communication timing of its own mobile wireless device defined by the time division multiplexing method, the amplification coefficient is set to a predetermined value. Value, and when the base station is ON and performing communication with a mobile radio device other than its own mobile radio device by the time-division multiplexing method, the amplification coefficient is made larger than a predetermined value. It is possible to obtain sufficient follow-up to the variation of the received signal, to enable reception in a suitable state, and to avoid occurrence of communication error of the mobile wireless device due to a large variation of the amplification factor.

[0008]

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a first embodiment in which the present invention is applied to a reception-only automatic radio such as a radio selective calling receiver or a radio receiver.
FIG. 4 is a block diagram of an embodiment of FIG. In FIG. 1, a solid line indicates a signal line, and a broken line indicates a control line.

[0010] The mobile radio 100 receives a radio wave received by an antenna 101 from a receiving unit 1 including an automatic gain control amplifier 102.
03, and the received signal is received by the automatic gain control amplifier 10
After being amplified by 2, demodulation is performed by the demodulation unit 104. Then, the demodulated signal is decoded by decoding section 106, and the decoded signal is input to detecting section 107. Detecting section 107 detects whether or not the communication signal is for the own mobile wireless device, and inputs the detection signal to control section 109. If the signal is a communication signal for the own mobile wireless device, the control unit 109 operates the notification unit 108 to notify it.

On the other hand, the signal received by the receiving unit 103 is also input to an RSSI (field strength detecting unit) 105 at the same time.
The received electric field strength is detected. The detection output of the RSSI 105 is input to the automatic gain control amplifier 102 and the control unit 109, respectively. Here, the automatic gain control amplifier 102
The automatic gain control operation is performed based on the detection output of the SSI 105, and the amplification coefficient is changed under the control of the control circuit 109. The amplification coefficient is a coefficient indicating the followability of the automatic gain control with respect to the electric field strength,
In general, the larger the amplification coefficient, the better the tracking.

When the control unit determines that the base station is in a state in which the transmission operation is stopped (OFF) because the detection signal of the RSSI 105 is lower than a certain level, and when the communication timing is addressed to itself, a predetermined value is set. For example, the amplification coefficient is set to “0”. Note that the amplification coefficient is “0” when the amplification of the automatic gain control amplifier 102 is maintained at a fixed amplification (fixed).
Is to be done.

On the other hand, a state in which the base station is performing a transmission operation because the detection signal of the RSSI 105 is sufficiently large (ON)
When it is determined that the communication timing is not the communication timing addressed to itself, the amplification coefficient is set to the predetermined value described above, for example, the amplification coefficient is set to a value larger than “0”, for example, “0.2”.
5 "is controlled.

FIG. 2 is a timing chart for explaining the operation of the above-mentioned mobile radio.

It is assumed that a base station (not shown) performs time division transmission as shown in FIG. Here, OFF is a state in which the base station does not transmit, PR is a synchronization signal, DATAA
To D are transmission data for the four individual mobile radios A to D. Each mobile radio A to D is P
By receiving R, the communication timing of data addressed to itself can be grasped. In this case, it is possible to perform a receiving operation of a power saving measure such as battery saving as needed.

Here, the operation of the mobile radio B is shown, and (b) the communication timing of the mobile radio is shown in (b). When the above-described receiving operation is performed in the mobile radio B, the detection signal of the RSSI 105 becomes, for example, as shown in (c). The detection output becomes an output of a certain level VR or more when the base station is ON, and becomes an output when the base station is OFF. Is output below a certain level. Thereby, the mobile radio B can determine the transmission state in the base station.

Assuming that the control unit 109 of the mobile radio B controls the amplification coefficient of the automatic gain control amplifier 102 based on the detection output of the RSSI 105 as described above, (d) As described above, when the message reception timing of the own receiver is not set and the base station is not in the transmission OFF state, the amplification coefficient is set to a constant value NA which is a relatively large value, and the automatic gain control amplifier 102 is operated. Communication timing of mobile radio, base station is 0F
At the time of F, an operation is performed in which the amplification coefficient is set to NB (here, “0”) smaller than the constant value NA to keep the amplification value of the automatic gain control amplifier constant.

Therefore, when the base station is off, the operation of the automatic gain control amplifier 102 is unnecessary, so that the amplification coefficient is set to "0", but until the mobile radio starts receiving. By setting the amplification coefficient to a relatively large constant value NA, for example, “0.25”, the automatic gain control amplifier is operated with a relatively large amplification value when reception of the own mobile radio is started. Therefore, it is possible to cope with a change in the signal level when a received signal is input, and in that case, it is possible to receive at a suitable reception level.

After the reception by the own radio receiver is started, the amplification factor is set to "0" to fix the amplification value of the automatic gain control amplifier 102 to the value set at the start of the reception. , The occurrence of a large change in the amplification degree is prevented, and the change in the signal level of the received signal is prevented.

As a result, it is possible to prevent a reception error from occurring due to a change in the reception signal level.

As described above, in the present mobile radio device, the amplification coefficient is set to a relatively large value at a timing other than the time of communication of the own mobile radio device, and the amplification coefficient is reduced at the time of its own communication. It is possible to obtain sufficient followability to fluctuations to enable reception in a suitable state, and on the other hand, to avoid occurrence of communication errors of the mobile radio device due to large fluctuations in amplification.

In the above-described embodiment, the automatic gain control may be operated only for a predetermined time immediately before the reception timing of the own mobile radio.

For example, when the RSSI is lower than a certain level, that is, when the base station is in the transmission OFF state, the mobile radio B sets the amplification coefficient to “0” to keep the amplification degree of the automatic gain control constant. On the other hand, even when the RSSI is higher than a certain level and the base station is in the transmission ON state, if the communication timing of the own mobile wireless device is not the predetermined time immediately before the communication timing of the own mobile wireless device, the amplification coefficient is changed. The automatic gain control operation is performed by setting to “0”.

In the case of FIG. 2 (e), the amplification coefficient is set to "N" only for a predetermined time immediately before the communication timing of the mobile radio B, that is, a time for receiving the synchronization signal and the DATA of the mobile radio A.
The gain is set to "A" to perform the automatic gain control operation, and the amplification factor is set to "0" at the communication timing of the mobile radio B to keep the gain of the automatic gain control constant.

This operation is performed by a built-in counter included in the control unit 109. That is, since the mobile radio B can know the next communication timing of the own mobile radio after the synchronization is established, the fixed time to be counted is changed from the communication timing of the own mobile radio to the communication timing of the next mobile radio. Set a time slightly shorter than the time until. And
The counting is started from the communication timing of the own mobile radio B, and the amplification coefficient is set to “0” for a certain time. Next, when a certain period of time has elapsed and counted up, the amplification coefficient becomes a certain value N
A, which continues until immediately before the communication timing of the own mobile wireless device. By this operation, the operation time when the amplification coefficient is changed can be shortened, and the power consumption accompanying this operation can be reduced.

FIG. 3 is a block diagram of a second embodiment in which the present invention is applied to a mobile radio of a portable telephone. In the figure, a solid line indicates a signal line, and a broken line indicates a control line.

The mobile radio device 300 converts the sound input to the microphone 301 into an electric signal, and then converts the sound into an A / D converter 30.
2 to be converted into a digital signal and encoded by the encoding unit 303,
The signal is modulated by the modulator 304 and transmitted from the transmitter 305 to the antenna 3
07 is transmitted through the duplexer 306 for transmission / reception sharing.

On the other hand, the radio wave output from the base station 200 is received by the antenna 307 and received by the receiving unit 310 through the duplexer 306. In the receiving unit 310, first, the signal is amplified by the automatic gain control amplification unit 308, and further, a signal is output through another amplification unit 309 such as superheterodyne, and demodulated by the demodulation unit 311. The demodulated data is further demodulated by the demodulation unit 314.
, And converted into an analog audio signal by the D / A converter 315, and then output as audio from the speaker 316.

The output signal from the receiving section 310 is also input to the RSSI 312 at the same time, and the received electric field strength is detected. Then, the output of the RSSI 312 is input to the automatic gain control amplification unit 308, and the automatic gain control operation is performed. The output of the RSSI 312 is output from the comparator 318.
Is compared with the constant value VR, and the result is input to the CPU 317.

Further, the demodulated signal from the demodulation unit 311 is input to the detection unit 313, and the detection unit 313 detects synchronization. The result of the synchronization detection is input to the CPU 317 together with the demodulated reception data of the mobile radio. CPU3
Reference numeral 17 denotes synchronization detection, reception data of the own mobile radio, and RSS.
Based on the output of I312, the status of the own mobile radio is determined, and when it is the communication timing addressed to itself, or when it is determined that the base station is OFF because the output of RSSI312 is lower than VR, The amplification coefficient of gain control amplification section 308 is set to a predetermined relatively small value NB (here, “0”).

On the other hand, the output of the RSSI 312 is VR
Since it is larger than the base station, it is determined that the base station is ON, and if it is not its own communication timing, the amplification coefficient of the automatic gain control amplification unit 308 is set to a predetermined NA.
At this time, NA is set to a value larger than NB. It is assumed that these values NA and NB are stored in advance in, for example, a built-in memory unit provided in the CPU 317.

FIG. 4 is a flowchart showing the operation of the mobile radio of FIG. After the power is turned on, first, the CPU 317 sets the amplification coefficient in the automatic gain control amplification section 308 to NA. At this time, as a result of detecting the electric field of the received signal, RS
If the output of the SI 312 is larger than the fixed value VR and the communication timing is not the communication timing of the own mobile radio device, the amplification coefficient remains NA.

On the other hand, the output of the RSSI 312 is a constant value VR.
If smaller, the CPU 317 sets the amplification coefficient of the automatic gain control amplification unit 308 to “NB (=“ 0 ”)” and holds the amplification value of the automatic gain control amplification unit 308 at the value at that time.
When the output of the RSSI 312 is larger than the constant value VR and the communication timing of the own mobile radio is set, the amplification coefficient is set to “0” and the amplification value of the automatic gain control amplification unit 308 is held at the value at that time. After that, the CPU 317 drives a built-in timer to count time for a certain period of time, and keeps this state shortly before the next communication timing of the own mobile radio.

Since the mobile radio device knows the communication timing of the next mobile radio device after the synchronization is established, the fixed time counted at this time is determined from the communication timing of the mobile radio device by the next mobile radio device. It is smaller than the time until the communication timing. Therefore, shortly before the communication timing of the next mobile radio device, the output of the RSSI 312 becomes a constant value V
If it is larger than R, the automatic gain control amplification unit 308 sets the amplification coefficient to NA and starts the operation again.

Therefore, also in this embodiment, FIG.
2 and the timing operation shown in FIG. 2, the amplification coefficient is set to a relatively large value NA immediately before the own mobile radio device starts receiving, and the amplification coefficient is set to “NA” after the reception starts. Since the reception is performed with the fixed amplification coefficient set to 0 ”, the reception level can be suitably set instantaneously at the start of reception, and thereafter, the fluctuation of the reception level due to a large fluctuation of the amplification degree can be avoided. Can be realized without the occurrence of the error.

FIG. 5 shows an example of the relationship between the amplification coefficient and the amplification degree in the automatic gain control amplification section 308. Here, the relationship between the amplification coefficient (k (t) in the figure) and the amplification value of the automatic gain control amplifier (Ag (t-1), Ag (t) in the figure) is shown. The output value of the RSSI 312 at time t is RSSI (t), and the amplification coefficient is k (t). At this time, the relationship between the amplification value Ag (t) of the automatic gain control amplifier 308 at time t and the amplification value Ag (t-1) of the automatic gain control amplifier 308 at time t-1 is as follows.

Ag (t) = Ag (t−1) −k (t) ×
[RSSI (t) -V1] where V1: ideal value of RSSI At this time, RSSI (t) approaches ideal value V1 quickly when amplification coefficient k (t) is large, and slowly when amplification coefficient k (t) is small. When k (t) = "0", the amplification value of the automatic gain control amplifier keeps a constant value. k (t) is NA or NB (NA> NB).

Here, in each of the above embodiments, the amplification coefficient is set to “0” as the value when the amplification coefficient is reduced. However, the present invention is not limited to this, and a small value close to “0” is set. May be set. When the amplification coefficient is increased, it may be set to the maximum value.

[0039]

As described above, the gain control device and the gain control method for a mobile radio according to the present invention detect the electric field strength of a received signal received, and based on the detection result, the automatic gain control amplification unit. Since the amplification coefficient is controlled, the automatic gain control amplification unit can be operated by setting the amplification coefficient to an appropriate amplification coefficient according to the reception state. When the detected electric field strength is sufficiently small and the base station is determined to be OFF, and when it is the communication timing of its own mobile wireless device defined by the time division multiplexing method, the amplification coefficient is set to a predetermined value. Value, and when the base station is ON and performing communication with a mobile radio device other than its own mobile radio device by the time-division multiplexing method, the amplification coefficient is made larger than a predetermined value. It is possible to obtain sufficient follow-up to the variation of the received signal, to enable reception in a suitable state, and to avoid occurrence of communication error of the mobile wireless device due to a large variation of the amplification factor.

When the AGC amplification coefficient is reduced, the AGC amplification coefficient is set to "0" and the amplification degree of the AGC amplification section is kept constant. Prevent occurrence.

Further, by increasing the AGC amplification coefficient at the timing immediately before reception by the own mobile radio,
While the above-described effects can be obtained, unnecessary control operation of the AGC amplification coefficient is not required, which is preferable in terms of low power consumption.

Further, by setting the timing for reducing the AGC amplification coefficient by the timer operation, control of the AGC amplification coefficient accurately corresponding to the reception timing of the mobile radio can be realized.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an embodiment in which the present invention is applied to a reception-only mobile wireless device.

FIG. 2 is a timing chart for explaining the operation of the embodiment of FIG. 1;

FIG. 3 is a functional block diagram of an embodiment in which the present invention is applied to a communication device.

FIG. 4 is a flowchart for explaining the operation of the embodiment in FIG. 3;

FIG. 5 is a diagram showing a relationship between an AGC amplification coefficient and an AGC amplification degree.

[Explanation of symbols]

 100 mobile radio 102 AGC amplifier 103 receiving unit 104 demodulating unit 105 RSSI 106 composite unit 107 detecting unit 108 reporting unit 109 ··· Control unit 200 ··· Base station 300 ··· Mobile radio 310 ··· Receiving unit 311 ··· Demodulation unit 312 ··· RSSI 313 ··· Detection unit 314 ··· Composite unit 317 CPU

Claims (15)

(57) [Claims] 1. Receiving a time division multiplex transmission signal,
Detection means for detecting the electric field strength of the received signal; and control for indicating whether or not it is the communication timing of its own device , wherein the amplification coefficient indicating the followability of the automatic gain control for the electric field strength is variable
Signal and an increase controlled by the detection result of the detection means.
Automatic gain control amplification means for automatically controlling the gain of the received signal based on the width coefficient, and control means for outputting the control signal for controlling the amplification coefficient of the automatic gain control amplification means, Automatic control device. Wherein said control means, when it is determined that the detection result There transmitting station that is transmitting a signal based on said detection means, and / or of the own mobile radio if it is determined that the communication timing Sets the amplification coefficient to a predetermined value, determines that the transmitting station is transmitting a signal based on the detection result of the detection means, and determines that it is other than the communication timing of its own mobile radio. 2. An automatic control apparatus for a mobile radio according to claim 1, further comprising means for setting said amplification coefficient to a value larger than said predetermined value. 3. The automatic control apparatus for a mobile wireless device according to claim 2, wherein said predetermined value is zero. 4. The apparatus according to claim 2, wherein said control means includes means for detecting its own communication timing. Wherein said control means, a detection result when the transmission station determines that you have not to transmit a signal based, and / or self predetermined before the communication timing of the mobile radios of the detection means The predetermined time, the amplification coefficient is set to a predetermined value, it is determined that the transmitting station is transmitting a signal based on the detection result of the detection means, and the amplification coefficient is determined only for the predetermined time. 2. The automatic control device for a mobile wireless device according to claim 1, wherein the control unit sets a value of the first value to a value larger than the predetermined value. 6. The automatic control apparatus for a mobile wireless device according to claim 5, wherein said predetermined value is zero. 7. The automatic control apparatus for a mobile radio according to claim 5, wherein said control means has means for detecting its own communication timing. 8. Receiving a time division multiplex transmission signal,
Detecting means for detecting the electric field strength of the received signal; and an amplification coefficient indicating the followability of the automatic gain control with respect to the electric field strength detection is variable, and based on the amplification coefficient controlled by the control signal and the detection result of the detection means. an automatic gain control amplification means for automatically gain controlling an amplification degree of a received signal, of the case where the transmitting station based on a detection result of the detecting means determines that you have not transmitted the signal, and / or the host mobile radio If it is determined that the communication timing has been reached, the amplification coefficient is set to a predetermined value, it is determined that the transmitting station is transmitting a signal based on the detection result of the detection means, and the communication of the own mobile wireless device is performed. Control means for outputting a control signal for setting the amplification coefficient to a value larger than the predetermined value when it is determined that the timing is other than the timing. Location. 9. The automatic control apparatus for a mobile wireless device according to claim 8, wherein said predetermined value is zero. 10. A mobile radio device for receiving a time division multiplexed transmission signal, wherein a detection means for detecting an electric field intensity of the received signal, and an amplification coefficient indicating a followability of automatic gain control for the electric field intensity detection are variable. Automatic gain control amplification means for automatically controlling the gain of a received signal based on the amplification coefficient controlled by a control signal and the detection result of the detection means, and transmitting based on the detection result of the detection means. If the station determines that you have not transmitted the signal, and / or otherwise predetermined time set in advance before the communication timing of the own mobile radio sets said amplification coefficient to a predetermined value, A control means for determining that the transmitting station is transmitting a signal based on the detection result of the detection means, and outputting a control signal for setting the amplification coefficient to a value larger than the predetermined value only for the predetermined time. An automatic control device for a mobile radio, comprising: a step; 11. The automatic control apparatus for a mobile wireless device according to claim 10, wherein said predetermined value is zero. 12. The RSSI of the received signal at time t
(T) detecting; determining whether or not the transmitting station is transmitting a signal based on the detected field strength RSSI (t); and if the transmitting station is not transmitting a signal, and / or Or, in the case of the communication timing of its own mobile radio, the amplification coefficient k
Setting (t) to a predetermined value; and when the transmitting station is transmitting a signal and at a time other than the communication timing of its own mobile radio, the amplification coefficient k (t)
Setting A to a value greater than the predetermined value;
g (t) is the amplification value at time t, and Ag (t-1) is the time t-
When the amplification value of V1 and V1 are the ideal values of the electric field strength, A
g (t) = Ag (t−1) −k (t) × (RSSI
(T) amplifying the received signal based on the amplification value represented by -V1). 13. The method according to claim 12, wherein the predetermined value is zero. 14. The RSSI of the received signal at time t
(T) detecting a signal, and determining whether the transmitting station is transmitting a signal based on the detected electric field strength RSSI (t). Setting the amplification coefficient k (t) to a predetermined value if the transmission time is other than the predetermined time before the communication timing of the mobile radio device; Setting the amplification coefficient k (t) to a value larger than the predetermined value only for a predetermined time, Ag (t) being the amplification value of time t, and Ag (t-1) being time t.
When an amplification value of −1 and V1 are an ideal value of the electric field strength,
Ag (t) = Ag (t−1) −k (t) × (RSSI
And (a) amplifying the received signal based on the amplification value represented by (t) -V1). 15. The method according to claim 14, wherein the predetermined value is zero.