JPH0437334A - Radio communication equipment - Google Patents

Abstract

PURPOSE:To measure a reception electric field strength accurately by neglecting the accuracy of reception demodulation for a time slot other than that for its own equipment and processing a signal while placing highest priority on the accurate measurement of the reception electric field strength. CONSTITUTION:An input intermediate frequency input signal is amplified by an amplifier 2 and outputted to a demodulation circuit from an output terminal 3. In this case, part of the output of the amplifier 2 is detected by an AGC circuit 4 and inputted to an AGC setting circuit 6 through a changeover switch 5 thrown to the position of solid lines in figure by a control section 9. The AGC setting circuit 6 sets a gain of the amplifier 2 properly and variably in response to the input signal from the AGC detection circuit 4 to control the intermediate frequency output signal from the output terminal 3 to be constant. In this case, a level detection circuit 7 detects a level of the intermediate frequency input signal through the amplifier 2 and outputs the result of detection to an output terminal 8 as a reception electric field strength (RSSI) signal. A radio communication equipment in compliance with the communication of the TDMA system executes the reception (transmission) operation as above by a reception (transmission) time slot of its own equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a wireless communication device adapted to time division multiplexing (hereinafter referred to as TDMA) communication.

(Prior Art) Typical modulation methods used in TDMA communication include the GMSK method and the QPSK method.

Among these, the modulated wave according to the latter method particularly includes amplitude fluctuations.

In order to faithfully demodulate such modulated waves, including amplitude fluctuations, it is necessary to stabilize the intermediate frequency signal given to the demodulation circuit, and as a countermeasure to this, an automatic gain control (AGC) circuit is used. is common.

On the other hand, this type of wireless communication device is equipped with a received electric field level detection circuit for the purpose of, for example, evaluating the radio wave quality of the device itself and switching to another wireless line if the radio wave quality deteriorates.

In this type of conventional wireless communication device having such a configuration, during the reception time slot of the device itself, reception is performed with the AGC circuit operating, and at the same time, the received field strength is also measured.

At this time, the AGC circuit automatically variably controls the gain of the intermediate frequency amplifier and operates to provide a constant intermediate frequency output signal to the demodulator.

Although this so-called AGC control is extremely useful for faithfully demodulating received data, on the other hand, the gain of the intermediate frequency amplifier is set to a specific value each time, which poses an obstacle to accurately measuring the received electric field strength. It became.

To solve this problem, special structural measures are required to prevent the gain control by the AGC circuit from interfering with the measurement of the received electric field strength, and it is difficult to accurately measure the received electric field strength while performing AGC control. This could not be achieved with a simple configuration.

(Problems to be Solved by the Invention) As described above, in the conventional wireless communication device described above, data reception and measurement of the received electric field strength at that time are performed simultaneously during the reception time slot of the own device, and by controlling the AGC circuit. Since the gain of the intermediate frequency amplifier is varied each time,
There was a problem in that the received electric field strength could not be measured accurately.

An object of the present invention is to eliminate this problem and provide a wireless communication device that can contribute to accurate measurement of received electric field strength without reducing demodulation accuracy of received signals.

[Structure of the invention]

(Means for Solving the Problems) A wireless communication device of the present invention includes an automatic gain control means for automatically controlling the gain of an amplifier for an intermediate frequency signal, and is a wireless communication device adapted to time division multiplex communication. , a detection means for detecting whether or not it is a reception time slot of the own device; a control means for prohibiting gain control of the amplifier in an interval other than the reception time slot of the own device; and a received electric field level detection means for detecting the received electric field level of the intermediate frequency input signal through an amplifier.

(Operation) A wireless communication device that is compatible with the TDMA system receives signals only during its own reception time slot, and is in a standby state during other time slots, so it is required to faithfully demodulate the received signal. Not done.

In the present invention, paying attention to this point, the reception demodulation accuracy is ignored during time slots other than the own device, and processing is performed with top priority given to accurate measurement of the reception electric field strength.

Specifically, when a time slot other than the own device is recognized, the intermediate frequency amplifier is separated from the control of the AGC circuit, its gain is fixed, and the received electric field level is detected in this state.

In this way, when the gain of an intermediate frequency amplifier is fixed, the detection output of the level detection circuit connected to the amplifier corresponds one-to-one to the input signal level to the amplifier, which allows accurate reception electric field. Measurements of intensity can be made.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a block circuit diagram showing an embodiment of a wireless communication device according to the present invention.

In FIG. 1, ] is an input terminal for an intermediate frequency signal whose frequency has been converted upon reception, 2 is an amplifier for this intermediate frequency signal,
3 is the output terminal of the amplified intermediate frequency signal, 4 is the amplifier 2
A, G detecting part of its output for gain control of
C detection circuit; 5 is a changeover switch that switches between the solid line position and the dotted line position in the figure; 6 is an AGC setting circuit that variably sets the gain of amplifier 2; and 7 detects the level of the intermediate frequency input signal through amplifier 2. 8 is an output terminal of the level detection circuit 7; 9 is a control section that controls the entire operation including the changeover switch 5;

Next, the general operation will be explained.

First, a signal received by this device is converted into an intermediate frequency signal by a frequency converter (not shown) and input to the input terminal 1.

This intermediate frequency input signal is amplified by an amplifier 2 and outputted from an output terminal 3 to a demodulation circuit (not shown).

At this time, a part of the output of the amplifier 2 is detected by the AGC circuit 4, and is input to the AGC setting circuit 6 through the changeover switch 5, which is switched to the solid line position in the figure by the control section 9.

The AGC setting circuit 6 appropriately variably sets the gain of the amplifier 2 in accordance with the human input signal from the AGC detection circuit 4, and controls the intermediate frequency output signal from the output terminal 3 to a constant value.

At this time, the level detection circuit 7 detects the level of the intermediate frequency human input signal through the amplifier 2, and outputs the detection result to the output terminal 8 as a received electric field strength (R3SI) signal.

A wireless communication device adapted to TDMA communication performs the above-described reception operation in its own reception time slot.

Similarly, transmission is performed only in the transmission time slot of the own device.

FIGS. 2(a) and 2(b) schematically show the structure of a transmit (TX) frame and a receive (RX) frame related to the communication operation of the wireless communication device.

In this case, in particular, the transmission frame and the reception frame each have a configuration of three time slots #1 to #3.

Among these, regarding the received frame, the configuration of one time slot is as shown in Fig. 3.
Consists of each information element of data.

When the operating wireless communication device receives the synchronization signal in the received frame, it determines whether it is the receiving time slot of its own terminal based on the next information element, the slot number, and determines the receiving time slot of its own terminal. Responds to reception only during slot.

Conventionally, during this receiving operation, reception was performed under AGC control, and at the same time, the received electric field strength was also measured.

At that time, since the gain of the amplifier 2 is variably set each time by AGC control, it was not possible to accurately measure the received electric field strength.

In the present invention, in order to eliminate this problem, the timing of measurement of received electric field strength (R3SI) and AGC control in receiving operation are changed as shown in FIGS. 2(C) and (d), respectively. .

Note that the timing control of R35I measurement and AGC control in this case is particularly an example of the case in a terminal to which the time slot shown as #1 in FIGS. 2(a) and 2(b) is assigned.

The timing charts in Fig. 2 (c) and (d) prohibit R55I measurement in the reception time slot of the own device and only perform data reception under AGC control, and prohibit AGC control in other time slots. This indicates that the R35I measurement will be performed.

The details of this receiving operation will be explained below with reference to the flowchart of FIG.

First, in the wireless communication device to which reception time slot #1 is assigned, in the reception time slot #1, the first
The changeover switch 5 in the figure is switched to the solid line position in the figure.

In this state [ON state in FIG. 2(d)], AGC control functions, and a constant intermediate frequency output signal is obtained at the output terminal 3 by the gain appropriately set for the amplifier 2 by the AGC setting circuit 6. .

This state corresponds to 5101 in the flowchart of FIG. 4, and is maintained until the end of the receiving time slot of the own device through the processing from 5102 to 5104 by the control unit 9.

That is, when the control unit 9 detects a synchronization signal in the received frame (see FIG. 3) (S102), it refers to the next information element, the slot number, and determines whether the received time slot belongs to the own device. (3103).

Here, when it is recognized that it is the receiving time slot of the own device, it is determined whether the receiving time slot of the own device has ended while receiving data under the above-mentioned AGC control (S104).

Then, when the reception time slot of the own device ends, counting of a preset time is started, and it is monitored whether a predetermined time has elapsed after the end of the reception time slot of the own device (S105).

This set time corresponds to the length of time slots other than the own device (in this example, the total time of time slots #2 and #3 other than #1).

At this time, the control section 9 recognizes the end of the reception time slot of its own device in step 5104 and at the same time switches the changeover switch 5 to the dotted line position in FIG. 1 (S106).

At this time, the AGC setting circuit 6 is disconnected from the AGC detection circuit 4 and connected to the GND side.

As a result, the AGC control is canceled, and a constant gain is set in the amplifier 2 through the AGC setting circuit 6 according to the GND potential.

The R35I output of the level detection circuit 7 in this state (ON state in FIG. 2(C)) is taken into a received electric field level processing circuit (not shown) (S107) and processed as a normal measurement value of the received electric field strength.

In this way, when the gain of the amplifier 2 is fixed, the fidelity of the demodulated signal decreases, but on the contrary, it is convenient for accurate measurement of the received electric field strength.

Regarding the decrease in the fidelity of the demodulated signal, since the timing at which the gain of the amplifier 2 is fixed corresponds to the time slot of the device other than the device itself, this does not pose a similar problem in terms of reception operation.

Subsequently, the control unit 9 maintains control of 5106.51.07 while monitoring the time of 5105.

During this period, if the control section 9 confirms in 5105 that the time corresponding to the time slot length of the device other than the own device has elapsed, it again switches the changeover switch 5 to the solid line position in FIG. Receive the destination data.

At this time, in the received electric field level processing circuit, the level detection circuit 7
The R35I output from is not captured.

The above operation is an example of a case where the gain of the amplifier 2 is fixed and the reception field strength is continuously measured in a period other than the reception time slot of the own device.

In addition, in the present invention, the received electric field strength may be measured only in a part of the period other than the reception time slot of the own device.

For example, since there is a transmitting time slot of the own device as an interval other than the receiving time slot of the own device, the reception field strength can be measured by recognizing the transmitting time slot of the own device.

In either case, since the R55I measurement is performed with the gain of the amplifier 2 fixed during a section where reception is not required, extremely accurate received field strength measurements can be obtained.

〔Effect of the invention〕

As explained above, in the present invention, in the reception time slot of the own device, only reception is performed under gain control by the AGC circuit, and in other time slots, the above gain control is prohibited and the gain of the amplifier is fixed. Since the received electric field strength is measured, there is an excellent advantage that the received electric field strength can be accurately measured without reducing the fidelity of the demodulated signal.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing one embodiment of the wireless communication device according to the present invention, FIG. 2 is a timing chart showing each operating signal in the wireless communication device of the present invention, and FIG. 3 is the same as shown in FIG. FIG. 4 is a flowchart showing an example of the receiving operation of the wireless communication device of the present invention.

Claims (2)

[Claims] (1) In a wireless communication device that has an automatic gain control means that automatically controls the gain of an amplifier for an intermediate frequency signal and is adapted to time division multiplex communication, detects whether or not it is the receiving time slot of the own device. a detection means for detecting the received electric field level of the intermediate frequency input signal through the amplifier during the period in which the gain control is prohibited; 1. A wireless communication device comprising: electric field level detection means. (2) A changeover switch provided in the control input path of the automatic gain control means is switched from the output side of the amplifier to the constant output generation section side, thereby fixing the gain of the amplifier and inhibiting the gain control. The wireless communication device according to claim (1).