JPH10233815A - Gain controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the bit errors and also to operate a phase controller only in a least necessary time for reduction of its power consumption by making a variable gain amplifier perform the proper automatic gain control processing in response to each receiving phase based on the receiving phase signal that instructs the receiving phases of the base station search, base station acquisition, call, carrier sense, etc. SOLUTION: A receiving phase instruction part 8 produces the base station search phase, base station acquisition phase, call phase and carrier sense signals based on the transmission/reception processing of both mobile and base stations and instructs them to a receiving timing processing part 9, a gain control part 5 and a level detection part 6. In the gain control processing carried out in the base station search phase, for example, no gain control is performed for a period including the detection of a unique word through the end of reception of a slot. Then the part 5 is operated once in twice of the output of the part 6. However, the gain control operations are not thinned as long as the detection level is higher than a reference level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gain control device in a PHS using a quadrature demodulation system.

[0002]

2. Description of the Related Art FIG. 14 is a block diagram showing an example of a conventional gain control device. In FIG. 14, 1 is a variable gain amplifier for increasing or decreasing the power level of a received signal, 2 is a quadrature mixer for converting the received signal output from the variable gain amplifier into I and Q analog baseband signals having phases different from each other by 90 degrees, 3 Is a variable gain amplifier that amplifies the levels of I and Q analog baseband signals output from the quadrature mixer, 4 is an A / D converter that samples the signal output from the variable gain amplifier, and 5 is an A / D converter. A level detector for detecting the power level from the output of the A / D converter; 6 a gain controller for controlling the gain of the variable gain amplifier based on the level detected by the level detector; and 7 a demodulator for the output from the A / D converter. It is a demodulation unit. With such a configuration, level control is always performed irrespective of the presence or absence of a burst signal, and control is performed so that the signal input to the A / D converter has a predetermined level. Note that the level control is performed so that the signals of the control channel and the communication channel are all at a constant level. This constant level is the same level in both channels.

[0003] In mobile communications, the received signal power changes due to the temporal change or fading of the distance between the base station and the mobile station. In digital mobile communications using quadrature modulation, quadrature demodulated I and Q analog signals are converted into digital signals by A / D conversion, and then demodulation processing is performed from the amplitude values. Automatic gain control for making the input power to the A / D converter constant is required. PHS uses π / 4 shift QPSK for modulation and TDMA / T for communication.
This is a system using DD, and using quadrature demodulation,
Automatic gain control is required.

[0004] The burst signal used in the PHS has a control channel and a speech channel. Both of them have a start symbol (SS) and a preamble (P) as shown in FIG.
R), a unique word (UW) and subsequent data. Here, SS and PR are used for bit timing reproduction required for demodulation, and UW is used for correcting slot timing and recognizing slots.

The difference between the control channel and the speech channel is PR
And UW bit length, and the control channels are 64
Bit and 32 bits, the communication channel is 6 bits and 16 bits, respectively, and the control channel is longer than the communication channel. This is because the transmission interval of the control channel transmitted by the base station is longer than 100 ms, which is longer than the transmission interval of the communication channel of 5 ms, and the control channel received by the mobile station varies in reception level and slot timing for each slot due to movement or fading. Is increased, and it becomes necessary to take the timing again for each slot. The call channel has a short transmission interval,
The influence of movement and fading as compared with the previous slot is small, and the reception level and timing of the previous slot can be used.

In the automatic level control device disclosed in Japanese Patent Application Laid-Open No. H5-236044, by providing a reception judgment circuit for judging whether or not a slot is being received, gain control is performed only during a slot reception, and in a no-signal state, No gain control is performed.

[0007]

In the conventional gain control device shown in FIG. 14, the circuit is always operated to control the level of the burst signal. In this case, since there is no signal between burst signals, the variable amplifier has the maximum gain at the start of burst reception, and the level control amount is large, so that the convergence time is long. When applied to the PHS receiver circuit, the PR
There is little problem in the control channel with a long channel, but in the speech channel, the PR is short and the level control cannot be performed in time.
A burst signal reception error will result.

In addition, since gain control is performed even during data reception after UW, when the gain of the variable amplifier is switched by switching a resistor, instantaneous interruption occurs when the gain is switched, so that data may be lost. There is. Further, when the gains of the variable amplifiers are simultaneously switched by a gain control circuit in which two or more variable amplifiers are combined, even if they are simultaneously switched in time, there is a difference in the path through which the signal passes, so that the amplitude of the signal is variable. The amplitude does not become the set amplitude by the delay time between the amplifiers, but becomes larger or smaller. In these cases,
There is a high possibility that a bit error will occur during demodulation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for preventing a reception error of a burst signal and an increase in a bit error rate, and reducing power consumption by shortening an operation time of a gain control circuit as much as possible. .

[0010]

According to a first aspect of the present invention, there is provided a gain control device for variably controlling an amplitude level of a received signal based on a gain, and for controlling a signal whose gain is controlled by the variable gain device. A / D conversion means for sampling, level detection means for averaging the amplitude of an output signal of the A / D conversion means for a designated symbol and detecting and outputting a signal level, and a reception phase for outputting a reception phase instruction signal Instruction means; reception timing processing means for generating and outputting a timing signal such as an aperture signal which is a timing for detecting a reception timing signal of a slot of the reception signal and a unique word of the reception signal; and a signal level of the level detection means. And a timing signal of the reception timing processing unit and reception of the reception phase instruction unit Based on the Phase signal is obtained by a gain control means for controlling the gain of the variable gain means.

In the gain control apparatus according to a second aspect of the present invention, in the base station search phase of the gain control means, when a signal of a certain level or more is received from a no-signal state or a converged state, a delay of the previous gain setting is set. The following gain setting is performed without consideration, and control is stopped after UW detection.

According to a third aspect of the present invention, in the gain control unit, when a signal of a certain level or more is received from a no-signal state in the base station acquisition phase of the gain control means, the delay of the previous gain setting is not considered. The following gain settings are made to UW
It is provided to stop the control before receiving.

According to a fourth aspect of the present invention, there is provided a gain control apparatus, wherein a certain value is set in a gain variable means in a carrier sense phase of the gain control means, and a signal level at that time is compared with a reference value. It is.

According to a fifth aspect of the present invention, in the talk phase of the gain control means, the gain is not set during the slot reception, and the gain is set from the level detection result of the previous slot before receiving the next slot. It is provided with that.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. As a general operation of the PHS mobile station, it can be divided into four reception phases. As the four phases, a base station search, a base station acquisition, a call, and a carrier sense can be considered. The base station search is a phase for searching for a control channel broadcast by the base station, and the receiving operation is continued until a control channel is received or a timer for monitoring the base station search period times out. The base station acquisition is a phase in which, among the control channels broadcast by the base station at intervals of 100 msec, the control channel at intervals of 1.2 sec, which must be received by the mobile station, is received. The call is a phase in which the base station and the mobile station transmit and receive a call channel every 5 ms. Carrier sense is a phase of detecting the signal level of a slot to be used to check whether the slot is available. To determine whether the slot is usable, three phases before, during, and after one slot are used. Four levels must be measured and all must be below the reference value. In the above four receiving phases, the power level of the received signal is controlled by a method corresponding to each phase.

That is, the variable gain amplifier performs appropriate processing for the phase as automatic gain control by the reception phase signal output from the reception phase instructing section for instructing the reception phase, thereby receiving a burst signal reception error or a bit error. The power consumption of the gain control circuit is reduced by preventing errors and operating only for the minimum necessary time. The receiving phase is not determined from the received data, but is determined before starting the receiving operation.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a mobile station. 1 is a variable gain amplifier that varies the power level of a received signal, 2 is a quadrature mixer that converts the received signal into I and Q analog baseband signals, and 3 is a quadrature mixer. The variable gain amplifier 4 amplifies the levels of the I and Q analog baseband signals output from the mixer, and the A 4 samples the I and Q analog baseband signals output from the variable gain amplifier 3 and converts them into digital signals. / D converter,
5 is a level detector for detecting the level from the output of the A / D converter 4, 6 is a gain controller for judging the magnitude of the signal from the output result of the level detector and controlling the gains of the variable gain amplifiers 1 and 3, 7 Is a demodulation unit for demodulating data from I and Q digital baseband signals output from the A / D converter, and 8 is a reception phase signal (base station search phase signal, base station acquisition phase signal, speech phase signal, carrier A reception phase instructing unit 9 for generating a slot reception timing signal, an aperture signal for detecting a unique word from the demodulated reception data,
This is a reception timing processing unit that generates a unique word detection signal and a carrier sense timing signal.

Note that, based on the signal output from the reception phase processing section, the level detection section and the gain control section operate properly in the reception phase. In addition, the reception phase instructing unit 8 stores the above four reception phase signals in advance. The reception phase is determined by the transmission / reception processing of the communication information between the mobile station and the base station, and the reception phase instructing unit 8 sends a predetermined reception phase signal to the reception timing processing unit 9 and the gain control unit based on the determined reception phase. 5 and output to the level detector 6. The reception timing processing unit 9, the gain control unit 5, and the level detection unit 6, which have received the reception phase signal, perform processing corresponding to a predetermined phase.
The determination of the reception phase by the transmission / reception processing of the communication information between the mobile station and the base station is a processing generally performed in the conventional mobile station and the base station, and the communication between the mobile station and the base station is performed. Each station determines the phase based on the control channel signal and the communication channel signal to be transmitted.

FIG. 2 is a conceptual operation flow of the level detector 5 in FIG. Although not described in FIG. 2, this processing is started when a reception timing signal is output from the reception timing processing unit. 100, 101, 102,
Reference numeral 103 denotes processing for determining the reception phase from the output of the reception phase processing unit. If none of the above applies, a default cycle is set. 104, 105, 106,
Reference numeral 107 denotes processing for setting the number of samples of the output from the A / D converter 4 necessary for level detection in the base station search phase, base station acquisition phase, carrier sense phase, and speech phase. 109 receives the output from the A / D converter only for the set number of level detection samples,
This is the process of calculating the level.

FIG. 3 is an operation flow of the level calculation 109 in FIG. Reference numeral 110 denotes initialization processing of a variable LEVEL for storing a level detection result. Reference numeral 111 denotes initialization processing of a counter that counts the number of times that the output of the A / D conversion has been acquired. Reference numeral 112 denotes processing for determining whether or not a slot reception timing signal has been output. If no reception timing signal has been output, the level detection processing ends. If the reception timing signal is output, the A / D conversion output ADOI, ADOQ 113
To get. 114 is the acquired ADOI and ADOQ
Is added to the detection level LEVEL. 115
Is a process for counting how many times the A / D conversion output is obtained. Reference numeral 116 denotes processing for determining whether the number of acquisitions of the A / D conversion output counted in 115 has reached the number required for level calculation.
If it is not equal to the number set in 5, 106, 107,
Returning to step 112, the above operation is repeated. If equal, 11
In step 7, LEVEL is divided by twice the number of times of obtaining the A / D conversion output and averaged to obtain a detection level. Reference numeral 118 denotes a process for outputting the level detection result LEVEL obtained in 117.
In short, this is a process of detecting the signal level by averaging the output signal of the analog / digital conversion for the designated symbol. Expression (1) represents the level detection result.

[0021]

(Equation 1)

FIG. 4 is a conceptual operation flow of the gain control in FIG. Reference numerals 119, 120, 121, and 122 denote reception phase determination processing, which performs distribution to gain control processing suitable for the reception phase. 119 is a process for determining whether or not the current phase is a base station search phase. If it is determined that the reception phase is a base station search process,
The process proceeds to the gain control process performed at the time of searching for the 23 base stations. If it is determined in step 119 that the reception phase is not the base station search process, the process proceeds to step 120 to determine whether or not the phase is the carrier sense phase. Thereafter, the same determination process is performed, and the gain control process 1 in the carrier sense phase is performed.
23, a gain control process 124 during the base station acquisition phase and a gain control process 125 during the call phase. When the gain control processing in each of the phases 123 and 124 ends, the process returns to the reception phase determination again. If the receiving phase does not match any of the phases,
That is, if no reception phase signal has been output, this flow is terminated. When the gain control process in each of the phases 125 and 126 ends, this flow ends.

As described above, the gain control unit and the level detection unit switch the processing method according to the reception phase signal.
Since the operation suitable for the reception phase can be performed and the operation period can be minimized, the power consumption is reduced, and the gain control is not performed during data reception, thereby reducing slot reception errors and bit errors. be able to.

Next, what kind of gain control is performed for each of the above four phases will be described in detail. First, the gain control process in the base station search phase will be described with reference to FIG. Reference numeral 127 denotes a wait process for not performing gain control from the time of UW detection to the end of slot reception, during which the process waits for a reception end signal from the reception timing processing unit. This wait process is a process that is performed when UW is detected once and this process is performed again, regardless of the initial startup. Reference numeral 128 denotes initialization processing of the variable gain amplifiers 1 and 3 of FIG. 1, and sets the maximum gain to each variable gain amplifier. Reference numeral 129 denotes a flag used in the present process, which is a process for initializing a convergence flag which indicates that the received signal can be set to an appropriate value for the variable gain amplifier and indicates that the received signal has converged to an appropriate level. Is set to ON to indicate that Next, it is determined at 130 whether or not a UW detection signal has been output. If a UW detection signal has been output, this processing ends. If the UW detection signal is not output, the process proceeds to the process of acquiring the level detection result from the level detection unit 5 shown in FIG. If no level detection result is output at this time, the process returns to the determination process of whether a UW detection signal has been output at 130, and the processes of 130 and 131 are repeated until a UW detection signal is output or a level detection result is output. If the level detection result has been obtained, the process proceeds to a process of determining whether it is the gain setting timing of 130. Here, before describing the gain setting timing, the relationship between the operations of the level detection unit and the gain control unit will be described.

There is a delay time from when the gain is set to the variable gain amplifier by the gain control unit to when the signal amplified by the gain reaches the level detection unit. Further, several level samples are required before the level detection section outputs the level detection result. That is,
After the gain control unit sets the gain in the variable gain amplifier, and checks the signal level control result based on the setting, the signal delay time from the variable gain amplification to the level detection unit and the level detection unit can be set to set the next gain. This means that sample time is required.

Here, assuming that the signal delay time from the variable gain amplification to the level detection unit is 2 symbols and the number of samples required for level detection is 2 symbols, the period in which the gain control unit can set the gain in the variable gain amplifier is 4 It is a symbol, and the gain is set at the timing of output of the level detection result twice. The process of determining whether the timing is the gain setting timing of 132 in FIG. 5 is a process of determining whether to set the gain based on the acquired level detection result. If it is determined in 132 that there is a gain setting timing, the process proceeds to a gain setting process of 135, but if not, the process proceeds to a process of determining whether the convergence flag of 133 is ON. Here, when the convergence flag is OFF, the process returns to the process 130, and the above process is repeated. If the convergence flag is ON, that is, if the level of the received signal is converged, the process proceeds to a process of determining whether the level detection result of 134 is equal to or greater than a certain reference value. Move on to the processing for determining the set gain. If the detection level result is determined to be equal to or less than the reference value, the process returns to step 130 and the above processing is repeated. Here, the meaning of the processes of 133 and 134 will be described in detail. If you are receiving without a signal,
Consider the case of receiving a control channel. When the gain control unit and the level detection unit operate at the timing of the above example, the level detection result of the level detection unit is not used for the gain control unit once every two times. When the head of the channel comes, the time until convergence is delayed by two symbols compared to the case where the head comes to the part to be used. The countermeasure against the delay is the processing of 133 and 134. Even if the level is not used, if the level is higher than a certain reference value, it is considered that a signal has been received, and the set gain is determined based on the level detection result. It moves to.

Next, 135 is a process for determining a gain to be amplified to the gain set in the variable gain amplifier based on the level detection result. Specifically, a table is prepared in which the level detection result and the gain to be increased / decreased are set, and the value is extracted from the table. 136 is processing for determining whether or not convergence has been achieved from the gain to be increased or decreased determined in 135. If the gain to be increased or decreased is within a certain range, it is determined that convergence has been achieved.
At 137, the convergence flag is turned ON. If the gain to be increased or decreased does not fall within a certain range, it is determined that convergence has not occurred, and the convergence flag is turned off. After the operation of the convergence flag, the process proceeds to a set gain calculation process of 139, and the set gain is obtained by increasing or decreasing the gain determined in 135 to the currently set gain. At 140, the gain determined at 139 is set in the variable gain amplifier, and the process returns to 130 again to repeat the above operation.

FIG. 9 shows the above operation timing.
become that way. FIG. 9A is an overall view, and FIG. 9B is an enlarged view of a slot portion. As shown in (a), the level detection unit and the gain control unit are activated when the reception timing signal is output, and the gain control unit stops the gain control from UW detection to the end of the slot. Also,
162 of (b) shows the gain control operation when the processes of 133 and 134 in FIG. 5 work.

As described above, in the base station search phase, the gain control unit does not perform gain control from UW detection to the end of slot reception, thereby reducing power consumption and
Also, by not performing gain control during data reception,
Slot reception errors and bit errors can be reduced.

Next, the gain control process in the base station acquisition phase will be described with reference to FIG. Most of the processing is the same as that of the base station search phase in FIG. 5, but the gain control is performed for the control channel whose reception timing is unknown in the base station search phase, whereas the reception timing is changed in the base station acquisition phase. The processing is as shown in FIG. 6 in consideration of controlling the gain for the known control channel. Only different points from FIG. 5 will be described. First, the 130 UW detection determination process of FIG.
This is a three-aperture signal detection determination process. The aperture signal is a signal indicating a period during which the UW is detected, and the position of the UW can be determined by looking at this signal. In FIG. 6, when an aperture signal is output, that is, when U
The gain control is terminated before receiving W. Next, the convergence determination process (136 in FIG. 5, 149 in FIG. 6) is a process when it is determined that the convergence has occurred. In FIG. Is stopped without performing the gain control.

The above operation timing is shown in FIG.
It will be like 0. FIG. 10A is an overall view, and FIG. 10B is an enlarged view of a slot portion. As shown in (a), the level detection unit and the gain control unit are activated when the reception timing signal is output, and the gain control unit stops the gain control when the aperture signal is output. As described above, in the base station acquisition phase, the gain control unit performs gain control from the start of slot reception to the start of the UW detection period.
By reducing power consumption and not performing gain control during data reception, slot reception errors and bit errors can be reduced.

Next, the gain control process in the carrier sense phase will be described with reference to FIG. 153 is an initial setting of the variable gain amplifier, and sets an appropriate gain for level determination. In this processing, the gain set here is not changed in the subsequent processing. 15 after gain setting
4 is a wait process until a carrier sense timing signal is output, and this process is stopped until a carrier sense timing signal is output from the reception timing processing unit.
When the carrier sense timing signal is output, the process proceeds to a detection level result acquisition process of 155, and the detection level result output from the level detection unit is acquired. Reference numeral 156 denotes a level determination process for comparing the detection level result with the carrier sense bell. There are two levels of the carrier sense, a first level and a second level below the first level. The determination is smaller than the first level, larger than the first level but smaller than the second level, and smaller than the second level. It is performed in three stages of being large. At 157, the result of the determination at 156 is output to the register, and the process ends.

The above operation timing is illustrated in FIG.
It looks like 1. 11A is an overall view, and FIG. 11B is an enlarged view of a slot portion. As shown in (a), the level detector is activated while the reception timing signal is being output. The gain control unit acquires the level detection result when the carrier sense timing signal is output, and outputs the carrier sense result. As described above, in the carrier sense phase, carrier sense is performed using the gain control unit.
Power consumption can be reduced without a circuit dedicated to carrier sense.

Finally, the gain control process in the talk phase will be described with reference to FIG. 158 is a process for acquiring a level detection result output from the level detection unit. In the call phase, since the level is detected over the entire communication channel, the level detection result is output only once at the end of the slot reception. Reference numeral 159 denotes processing for acquiring, from a table, a gain to be increased or decreased from the gain set from the level detection result acquired in the same processing as 139 in FIG. 160
5 is a process for obtaining the gain to be set by increasing or decreasing the gain obtained in 159 from the current gain similar to 140 in FIG.
161 is a process for setting the gain obtained in 160,
When the gain is set, the process ends.

The above operation timing is illustrated in FIG.
It looks like 2. FIG. 12A is an overall view, and FIG. 12B is an enlarged view of a slot portion. As shown in (a), the level detector is activated while the reception timing signal is being output, and outputs a level detection result for one slot. The gain control unit acquires the level detection result and performs gain control.
As described above, since the gain control unit performs gain control only once at the end of slot reception in the call phase, power consumption is reduced, and gain control is not performed during data reception. And bit errors can be reduced.

[0036]

As described above, according to the present invention, the gain control section and the level detection section perform an operation suitable for the reception phase according to the reception phase, thereby reducing the operation period.
By reducing power consumption and not performing gain control during data reception, slot reception errors and bit errors can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an automatic gain control circuit according to the present invention.

FIG. 2 is a main operation flow of a level detection unit.

FIG. 3 is a level detection flow of a level detection unit.

FIG. 4 is a main operation flow of the gain control means.

FIG. 5 is an operation flow of a gain control unit in a base station search phase.

FIG. 6 is an operation flow of the gain control means in a base station acquisition phase.

FIG. 7 is an operation flow in the carrier sense phase of the gain control means.

FIG. 8 is an operation flow of the gain control means in a call phase.

FIG. 9 is a timing chart in the base station search phase of the gain control means.

FIG. 10 is a timing chart in a base station acquisition phase of the gain control means.

FIG. 11 is a timing chart in the carrier sense phase of the gain control means.

FIG. 12 is a timing chart of the gain control means in a call phase.

FIG. 13 is a block diagram showing a configuration of a conventional automatic gain control circuit.

FIG. 14 is a configuration diagram of a control channel and a communication channel.

[Description of Signs] 1 variable gain amplifier, 2 quadrature mixer, 3 variable gain amplifier, 4 A / D changer, 5 level detection unit, 6 gain control unit, 7 demodulation unit, 8 reception phase instruction unit, 9 reception timing processing Department.

Claims (5)

[Claims] 1. A gain varying means for variably controlling an amplitude level of a received signal based on a gain, an analog / digital converting means for sampling a signal whose gain is controlled by the gain varying means, and an output signal of the analog / digital converting means. Level detecting means for detecting and outputting a signal level by averaging a designated symbol for the amplitude of the received signal, receiving phase indicating means for outputting a receiving phase indicating signal, a receiving timing signal of a slot of the received signal, and a unique Reception timing processing means for generating and outputting a timing signal such as an aperture signal which is a timing for detecting a word; a signal level of the level detection means; a timing signal of the reception timing processing means; The gain of the variable gain means is controlled based on the phase instruction signal. Gain control means for controlling the gain. 2. In the base station search phase of the gain control means, when a signal of a certain level or more is received from a no-signal state or a converged state, the next gain setting is performed without considering the delay of the previous gain setting, 2. The gain control device according to claim 1, wherein the control is stopped after UW detection. 3. In the base station acquisition phase of the gain control means, when a signal of a certain level or more is received from a no-signal state, the next gain setting is performed without considering the delay of the previous gain setting, and the UW reception is performed. 2. The gain control device according to claim 1, wherein the control is stopped. 4. A method according to claim 1, wherein a certain value is set in the gain variable means in a carrier sense phase of the gain control means, and a signal level at that time is compared with a reference value.
The gain control device according to any one of the preceding claims. 5. In the talk phase of the gain control device,
2. The gain control apparatus according to claim 1, wherein the gain is not set during the slot reception, and the gain is set from the level detection result of the previous slot before receiving the next slot.