JP3156111B2 - Gain control method for wireless communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gain control method for a radio communication device having an AGC circuit for controlling a gain of a receiving section by a gain control voltage.

[0002]

2. Description of the Related Art Conventionally, a portable radio communication device using an AM wave or an SSB wave in the MF band or the like has been known. This type of wireless communication device includes a transmission unit and a reception unit, and can perform mutual communication with another wireless communication device by switching with a switching control unit.

An AGC circuit (automatic gain control circuit) that controls the gain (total gain) of the receiving unit when the strength of the radio wave fluctuates, thereby maintaining a constant audio output. It has. FIG. 5 shows the characteristics of the audio output P with respect to the radio wave intensity E in the AGC circuit. As shown by the characteristic line M3-Ms in FIG. 7, when the radio wave intensity E does not reach the specified audio output Ps in the receiving unit, the maximum (set) gain is maintained, and the magnitude of the audio output P becomes It changes almost in proportion to the strength E of the radio wave,
Is greater than or equal to the specified strength Es, the AGC circuit operates, the gain of the receiving unit is reduced, and the audio output P is kept constant. Note that Mn indicated by a dotted line is a characteristic line when an AGC device is not provided.

[0004] Further, the receiving section is provided with a gain setting circuit capable of arbitrarily setting the start point (Es point) of the AGC operation in the AGC circuit by changing the gain control voltage. This type of gain setting circuit is, for example, when the gain control voltage is arbitrarily changed by manually operating a variable attenuator or the like with an operation knob or the like.
The gain of the receiving unit, which is the starting point of the GC operation, can be set to an arbitrary value. M1 and M2 shown in FIG. 5 are characteristic lines when the start point of the AGC operation is changed and set by the gain setting circuit.

[0005]

By the way, in the case of a radio communication device having such an AGC circuit, the magnitude of the gain control voltage is changed in the reception mode in accordance with the intensity of the received radio wave. Is also controlled, but when the mode is switched from the reception mode to the transmission mode, the gain of the receiving unit is maximized due to the disappearance of the received radio wave. Therefore, when the transmission mode ends and the mode is switched to the reception mode, the AGC operation starts from the state where the gain (sensitivity) is maximum, and converges to the original gain to be controlled after a predetermined transition time. Thus, there is a problem that the voice quality is remarkably deteriorated, for example, a loud voice is output immediately at the moment of switching, or the voice is distorted. In the case of data communication, a malfunction may be caused.

The present invention has been made to solve the problems existing in the prior art, and has achieved a stable operation by eliminating the deterioration and malfunction of the sound quality (volume and sound quality) when switching from the transmission mode to the reception mode. It is an object of the present invention to provide a gain control method for a wireless communication device capable of performing mode switching.

[0007]

A gain control method for a radio communication device according to the present invention comprises the steps of:
In controlling the gain of the wireless communication device including the AGC circuit 12 for controlling the magnitude of the gain, the magnitude of the gain control voltage Vc for obtaining the optimal gain for each channel is detected in advance,
And gain setting data De for obtaining the detected gain control voltage Vc, reading the stored gain setting data De corresponding to the selected reception channel in the reception mode, and performing gain based on the read gain setting data De. The control voltage Vc is set, and in the transmission mode, the gain data Da corresponding to the magnitude of the gain control voltage Vc in the immediately preceding reception mode is stored in the storage unit 13, and is stored when switching from the transmission mode to the reception mode. Gain data D
AGC circuit 1 based on the magnitude of gain control voltage Vc based on a
2 is operated. In this case, in implementation, the gain control voltage Vc based on the gain data Da stored in the storage unit 13 is applied to the reception unit 11 during the transmission mode, and the gain control voltage Vc is switched when the transmission mode is switched to the reception mode. Cancel the grant and return to normal AG
The operation is switched to the operation of the C circuit 12.

[0008]

According to the gain control method of the present invention, basically, the gain of the receiving section 11 in the receiving mode is controlled by the AGC circuit 1
2, controlled by the magnitude of the gain control voltage Vc,
If the strength of the radio wave is too strong, the gain of the receiving unit 11 is reduced, so that the sound output is controlled to be constant. At this time, a gain control voltage Vc for obtaining an optimum gain is set in advance. First, a gain control voltage Vc for optimizing the gain of the receiving unit 11 for each channel is detected, and gain setting data De for obtaining the detected gain control voltage Vc is stored. Then, in the reception mode, the stored gain setting data De corresponding to the selected reception channel is read, and the gain control voltage Vc is set based on the read gain setting data De.
Is set.

On the other hand, in the transmission mode during communication,
According to the present invention, the gain data Da corresponding to the magnitude of the gain control voltage Vc in the immediately preceding reception mode is stored in the storage unit 13, whereby the magnitude of the gain control voltage Vc is maintained, and the gain control voltage Vc is maintained. Vc is applied to the receiver 11 during the transmission mode, instead of the gain control voltage based on the original AGC operation.

When the mode is switched from the transmission mode to the next reception mode, the application of the gain control voltage Vc based on the stored gain data Da is released, and at the same time, the normal A
The operation of the GC circuit 12 starts. Therefore, the operation of the AGC circuit 12 is started not from the state where the gain (sensitivity) is maximum but from the magnitude of the gain control voltage Vc in the immediately preceding reception mode, so that no transient fluctuation of the gain control voltage Vc occurs. . Therefore, the deterioration of the sound quality (volume and sound quality) and malfunction at the time of switching between the transmission mode and the reception mode are eliminated, and stable mode switching is performed.

[0011]

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

First, an outline of a wireless communication device used in the present invention will be described with reference to FIGS.

FIG. 4 shows a portable wireless communication device 5 according to the present embodiment.
Indicates 0. The wireless communication device 50 includes a transmission unit 51 and a reception unit 11, and can perform mutual communication with another wireless communication device by being switched by the switching control unit 52. FIG.
Reference numeral 53 denotes a microphone, 54 denotes a speaker, 55 denotes a changeover switch, and 56 denotes an antenna.

FIG. 3 shows the receiving section 11 more specifically. Reference numeral 21 denotes a high-frequency circuit, which has a function of performing variable gain amplification on a high-frequency signal received by the antenna 56 and can receive a plurality of channels. Reference numeral 22 denotes a detection circuit that detects an output signal of the high-frequency circuit 21, and reference numeral 23 denotes an audio amplification circuit (low-frequency amplification circuit) that amplifies the output signal of the detection circuit 22 to obtain an audio output. 23d is a digital demodulation circuit used for data communication.

On the other hand, a block surrounded by a two-dot chain line indicates the AGC circuit 12. Next, the configuration of the AGC circuit 12 will be described.

Reference numeral 24 denotes an AG from the output signal of the high-frequency circuit 21.
An AGC detection circuit 25 for obtaining a C control voltage is an AGC amplification circuit for amplifying the AGC control voltage. The AGC amplification circuit 25 outputs a main gain control voltage Vco. Therefore, the main gain control voltage Vco is applied to the high frequency circuit 21 via the adding circuit 26. Thereby, the addition circuit 2
AGC in which the gain (amplification degree) of the high-frequency circuit 21 is variably controlled in accordance with the magnitude of the gain control voltage Vc which is the output of the AGC
The basic circuit of the circuit 12 is configured. In this case, when the other input (gain adjustment voltage Vr) to the addition circuit 26 is zero, the main gain control voltage Vco is used as it is as the gain control voltage Vc.
Becomes

Reference numeral 30 denotes a gain setting circuit. The gain setting circuit 30 has a computer unit X, executes a variety of control processing and arithmetic processing, a CPU 31, an analog-digital converter (A / D converter) 32, a digital-analog converter (D / A converter) 33 RAM managed by CPU 31
34 (storage unit 13), ROM storing a control program
35, an input unit such as an input key 36, a rewritable nonvolatile memory (EE-PROM) 37, and an analog-to-digital converter (A / D converter) for performing an analog-to-digital conversion of the gain control voltage Vc output from the adding circuit 26. ) 38.
The output signal of the AGC amplifier circuit 25 is output from the A / D converter 3
2 to the CPU 31 and the CPU 3
From 1 the gain adjustment voltage Vr is applied to the addition circuit 26 via the D / A converter 33.

Next, a gain control method according to the present embodiment including the operation of the AGC circuit 12 will be described with reference to the flowchart shown in FIG. 1 and FIGS. 2 and 3.

First, the gain of the receiving unit 11 is the gain control voltage V
Since the value of c is set to an arbitrary value by changing the value of c, first, a gain control voltage Vc for making the gain of the receiving unit 11 an optimum value is detected and stored for each channel. That is, first, an SN ratio (for example, about several tens dB) of a target reception signal and a noise signal is set. This S / N ratio is input from the input unit 36 and stored in an empty area of the EE-PROM 37. Next, when there is no received signal, AG
While activating the C circuit 12, the CPU 31 scans the channel. When one channel is detected, the output signal of the AGC amplifier circuit 25 supplied from the A / D converter 32 is monitored by the CPU 31 to obtain the gain control voltage Vc which is the preset target SN ratio. The magnitude of the gain adjustment voltage Vr is detected. The detected gain adjustment voltage Vr is supplied to the EE-PROM 3 by the CPU 31.
7, the gain setting data D is stored in the first memory cell 37a.
Write as e. The above processing is similarly executed up to n channels. When all the n channels have been completed, the setting is completed. The above control processing is automatically executed according to the control program stored in the ROM 35. Note that such a gain adjustment voltage Vr may be detected manually by operating a variable attenuator or the like with an operation knob or the like.

On the other hand, in FIG. 1, in the reception mode (step 1), if a selected reception channel, for example, two channels is selected, the gain setting data De corresponding to the two channels is stored in the memory cell 37 of the EE-PROM 37.
b, and the read gain setting data De
Conversion is performed by the A converter 33 to obtain the gain adjustment voltage Vr.
This gain adjustment voltage Vr is applied to the addition circuit 26,
It is added to the main gain control voltage Vco provided from the C amplifier circuit 25 to obtain a gain control voltage Vc (= Vco + Vr). That is, the target gain control voltage Vc is automatically set.
As a result, troublesome setting operations are not required, and unnecessary noise output, extreme reduction in reception sensitivity, and malfunction are prevented. Moreover, quick and accurate communication can be performed even during emergency communication.

In FIG. 2, point C0 indicates the timing at which the two channels are selected. Therefore, C
After point 0, gain setting data De corresponding to two channels
, And the magnitude of the gain A is set accordingly. FIG. 7A shows a state where a gain As smaller than the maximum gain is set. Then, as shown in FIG. 3B, when the radio wave is received at the point Eo and the intensity E of the radio wave is increased, the sound output P (FIG. 3C) is correspondingly increased. On the other hand, if the strength E of the radio wave exceeds the specified strength Es at the point C1, A
The GC circuit 12 operates, the gain A is reduced, and the sound output P
Is made constant.

In the reception mode, the gain control voltage Vc output from the adder circuit 26 is converted into a digital signal by the A / D converter 38 according to the present invention to obtain gain data Da, and is stored in the RAM 34 by the CPU 31.

On the other hand, if the changeover switch 55 shown in FIG. 4 is operated to switch from the reception mode to the transmission mode, the mode is shifted to the transmission mode, and the RAM is issued by the hold command.
The gain data Da is read from 34, and the gain data Da is given to the addition circuit 26 via the D / A converter 33. As a result, the output of the adding circuit 26 is held at the gain control voltage Vc in the immediately preceding reception mode (steps 2, 3, and 4).

When the transmission mode ends and the mode is switched from the transmission mode to the reception mode by operating the changeover switch 55, the control based on the gain data Da stored in the RAM 34, that is, the control from the D / A converter 33 is performed. Gain control voltage V
The output of c is released, and at the same time, the operation of the AGC circuit 12 returns to the normal state, and shifts to the normal reception mode (steps 5, 6, 7). Therefore, in this case, the operation of the AGC circuit 12 does not start from the state where the gain (sensitivity) is maximum, but starts from the magnitude of the gain control voltage Vc in the immediately preceding reception mode. The above processing is similarly executed each time the reception mode and the transmission mode are switched (step 8).

In FIG. 2, point C2 indicates a switching point from the reception mode to the transmission mode, and point C3 indicates a switching point from the transmission mode to the reception mode. In this case, according to the present invention, during the transmission mode period, the gain control voltage Vc in the immediately preceding reception mode is applied to the reception unit 11, so that the gain A of the reception unit 11 ((a) in the figure) is kept constant. . By the way, when control by the method of the present invention is not performed, when switching from the reception mode to the transmission mode (point C2).
Since the gain of the receiving unit 11 is maximized, the gain A of the receiving unit 11 changes like a gain Am indicated by a virtual line. Thereby, at the time of switching from the transmission mode to the reception mode (C3
At this point, the AGC circuit 12 operates from the state where the gain (sensitivity) is maximum, and converges on the gain to be controlled after the transient time ti (see the virtual line Am). As a result, FIG.
As shown by a virtual line Pm in (c), the sound output suddenly increases at the moment of switching, or the sound distortion W deteriorates like a distortion Wm shown by a virtual line as shown in FIG. In addition, a remarkable decrease in voice quality is caused, and a malfunction occurs in the case of data communication. However, by controlling according to the method of the present invention, the gain A of the receiving unit 11 is kept constant even during the transmission mode period, so that such an adverse effect is eliminated.

Although the embodiment has been described in detail, the present invention is not limited to such an embodiment. For example, the addition circuit of the embodiment may be configured by a subtraction circuit according to signal processing. The wireless communication device can be applied to both analog communication and digital communication. In addition, it is possible to arbitrarily change the detailed configuration, method, and the like without departing from the gist of the present invention.

[0027]

As described above, in the gain control method for a radio communication device according to the present invention, the magnitude of the gain control voltage for obtaining the optimum gain for each channel is detected in advance, and the detected gain control voltage is obtained. For storing gain setting data for the selected reception channel in the reception mode, and setting the gain control voltage based on the read gain setting data. The gain data corresponding to the magnitude of the gain control voltage in the reception mode is stored in the storage unit, and when switching from the transmission mode to the reception mode, the AGC circuit is operated from the magnitude of the gain control voltage based on the stored gain data. As a result, when switching between the transmission mode and the reception mode, the voice quality (volume and sound quality) is prevented from deteriorating and malfunctioning, and a stable mode is eliminated. A marked effect of being able to perform de switching.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a gain control method according to the present invention;

FIG. 2 is a timing chart of signals and operations in each unit using the gain control method according to the present invention;

FIG. 3 shows an AGC capable of implementing the gain control method according to the present invention.
Block diagram of the circuit,

FIG. 4 is a schematic block diagram of a wireless communication device capable of implementing the gain control method according to the present invention;

FIG. 5 is a characteristic diagram showing a relationship between radio wave intensity and audio output;

[Explanation of symbols]

 Reference Signs List 11 receiving unit 12 AGC circuit 13 storage unit Vc gain control voltage De gain setting data Da gain data

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/40 H04B 1/16

Claims (2)

(57) [Claims] 1. A gain control method for a wireless communication device including an AGC circuit for controlling the magnitude of a gain of a receiving unit by a gain control voltage, the magnitude of a gain control voltage for obtaining an optimum gain for each channel is detected in advance. And stores gain setting data for obtaining the detected gain control voltage, reads out the stored gain setting data corresponding to the selected reception channel in the reception mode, and controls the gain control voltage based on the read gain setting data. In the transmission mode, gain data corresponding to the magnitude of the gain control voltage in the immediately preceding reception mode is stored in the storage unit, and when switching from the transmission mode to the reception mode, gain control based on the stored gain data is performed. A gain control method for a wireless communication device, wherein an AGC circuit is operated based on a magnitude of a voltage. 2. In a transmission mode, a gain control voltage based on gain data stored in a storage unit is applied to a reception unit. When switching from the transmission mode to the reception mode, the application of the gain control voltage is canceled to perform normal operation. 2. The gain control method for a wireless communication device according to claim 1, wherein the operation is switched to an operation of an AGC circuit.