JPH0715380A - Demodulation method selection reception diversity circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] To suppress an increase in power consumption when applying a diversity reception method to a portable mobile device for mobile communication, and to obtain stable reception characteristics regardless of whether the fading change is gradual. [Structure] A detection circuit 3 which outputs a detection output and an envelope strength signal to a selection circuit 5 which switches and selects two antennas 1 and 2.
And the detection circuit 4 having the power saving mode function are connected.
The fading pitch judgment circuit 6 judges whether the fading change is slow or fast.
The received signals are detected by the two detection circuits 3 and 4, respectively, and the combined control circuit 7 combines the outputs to obtain a demodulation output. When the change is gentle, the detection circuit 4 is set to the power saving mode and rested.
The configuration is such that one antenna is selected and the detection output is obtained by the detection circuit 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity circuit used in a receiver of a portable mobile station in digital mobile communication.

[0002]

2. Description of the Related Art A demodulator used in a portable mobile device in digital mobile communication often uses diversity in order to compensate for deterioration of reception quality due to a fluctuating transmission path. As an example of the diversity method, there is a post-detection combining diversity method in which two systems from an antenna to a demodulator are prepared and two outputs after demodulation detection are combined. Also,
As another example of the diversity system, an antenna switching diversity system has been proposed in which only two systems of antennas are prepared and the received signal from the antenna with the better reception sensitivity of the two antenna outputs is demodulated. (References:
Yoshihiko Akaiwa: "Antenna selection diversity method for digital mobile communication" 1989 IEICE Spring National Convention B-856)

[0003]

Among the above-mentioned two diversity methods, the post-detection combining diversity method has a great effect of improving the reception quality, but it is necessary to always operate the two reception detection circuits. In addition to increasing power consumption, there is a problem that the weight and volume of the portable device increase as a portable mobile device using a battery as a power source. In addition, the antenna selection diversity method has a single reception detection circuit, so the circuit scale and power consumption can be reduced compared to post-detection combining diversity, but when the fading pitch is large and the transmission characteristics change drastically. However, since the switching frequency of the antenna cannot follow the change, there is a problem that the characteristic improvement effect due to diversity cannot be obtained so much.

An object of the present invention is to alleviate the drawbacks of the above-mentioned conventional mobile station portable receivers, such as the increase in power consumption or the deterioration of the reception characteristics in the transmission path where the fading changes rapidly, and the increase in power consumption. The purpose of the present invention is to provide a diversity circuit which has a small effect and has an effect of improving the reception characteristic even in a transmission line in which fading changes rapidly.

[0005]

A demodulation method selection reception diversity circuit according to the present invention includes first and second receiving antennas, and the first and second receiving antennas are connected to each other according to a switching control signal. A selection circuit that outputs a reception signal from the second output terminal, and a detection circuit that is connected to the first output terminal of the selection circuit to detect and output the reception signal from the first output terminal, and the envelope strength of the reception signal. And a first receiving and detecting circuit for detecting and outputting an envelope strength signal, and a receiving signal from the second output terminal connected to the second output terminal of the selecting circuit for detecting and outputting the received signal, and mode control A second receiving detection circuit that switches to a power saving mode to stop the detection operation only when a signal is applied, and detects a fading pitch from the envelope strength signal, and compares the detected value with a predetermined threshold value. And fae Fading pitch judgment circuit that outputs a sudden change signal indicating that fading changes rapidly when the pitch is larger than the threshold, and outputs a slow signal indicating that fading changes slowly when the fading pitch is smaller than the threshold. And a decision output from the fading pitch decision circuit and an envelope strength signal from the first reception detection circuit are provided to output a switching control signal for the selection circuit and a mode control signal for the second reception detection circuit. And the first and second
And a diversity combining control circuit for combining the detection outputs from the receiving detection circuit to obtain a demodulation output, wherein the diversity combining control circuit is provided to the selection circuit when the judgment output is a drastic change signal. Output the switching control signals such that the reception signals of the receiving antennas are output from the first and second output terminals, respectively, to perform post-detection combined diversity reception, and when the determination output is a slow signal, the second output signal is output. The mode control signal is applied to the reception detection circuit of the first detection circuit, and the first and second reception antennas are selectively switched to the selection circuit according to the envelope strength signal.
It is characterized in that the switching control signal for outputting the reception signal is output from the output terminal of (1) to perform antenna selection diversity reception.

[0006]

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, reference numerals 1 and 2 denote receiving antennas, and 3 denotes demodulation and detection of one of the outputs from the plurality of receiving antennas 1 and 2 and outputs, and the envelope strength of an input received signal is detected to detect an envelope strength signal A reception detection circuit 4 for outputting the demodulated detection output of one of the outputs from the plurality of reception antennas 1 and 2 and an operation in a low power consumption mode by a mode control signal from a diversity combining control circuit 7 described later. A reception detection circuit 5 having a function of performing the above is a selection circuit for switching the connection between the reception antennas 1 and 2 and the reception detection circuits 3 and 4 by a control signal from a diversity combining control circuit 7 described later. Reference numeral 6 is a fading pitch determination circuit that detects the fading pitch of the received signal from the envelope strength signal from the reception detection circuit 3 and determines and outputs the fading speed, and 7 also includes the determination signal from the fading pitch determination circuit 6. A switching signal for the selection circuit 5 and a mode control signal for switching the operation mode of the reception detection circuit 4 from the normal operation mode to the power saving mode are output, and the diversity detection is performed by using the outputs of the reception detection circuits 3 and 4. It is a diversity combining control circuit that operates and outputs a demodulation result.

[0007]

The diversity circuit of the present invention is configured to automatically select and switch between two types of diversity modes, that is, a post-detection combining method and an antenna selection method. First, the operation in the combined diversity mode after detection will be described. FIG. 2 is a block diagram showing the operation in the diversity mode of the post-detection combining method, and the connection of the two switching devices of the selection circuit 5 is as shown. In FIG. 2, the signal received by the antenna 1 is output to the reception detection circuit 3 from the first output terminal of the selection circuit 5. The reception detection circuit 3 receives the reception signal from the antenna 1 connected by the selection circuit 5 as an input, performs a reception detection operation, outputs a detection output to the diversity combining control circuit 7, and detects the envelope strength of the reception signal. Then, the envelope strength signal is output to the fading pitch determination circuit 6. The signal received by the antenna 2 is output to the reception detection circuit 4 from the second output terminal of the selection circuit 3. The reception detection circuit 4 includes a selection circuit 5
The reception detection operation is performed by using the reception signal from the antenna 2 connected by the above as an input, and the detection output is output to the diversity combining control circuit 7.

The fading pitch judging circuit 6 detects the fading pitch from the envelope strength signal from the reception detecting circuit 3, compares the fading pitch with a predetermined threshold value for diversity system switching, and judges the result. Is output. The diversity combination control circuit 7 performs a combination diversity for combining the two detection outputs from the reception detection circuits 3 and 4, and outputs the result as a demodulation output, and the determination output of the fading pitch determination circuit 6
The following diversity mode is judged as follows, and in accordance with the judgment, the switching control signal for the selection circuit 5 and the mode control signal for controlling the transition / exit to the power saving mode for the reception detection circuit 4 are output. (1) When the fading pitch of the received signal is larger than the predetermined threshold value and the fading of the transmission line changes rapidly, the post-detection combining diversity mode is continued. (2) When the fading pitch of the received signal is smaller than the predetermined threshold value and the change in the fading of the transmission path is slow, the mode shifts to the antenna selection diversity mode.

Next, the operation in the antenna selection diversity mode will be described. FIG. 3 is a block diagram showing the operation in the antenna selection type diversity mode,
The connection of the two switches of the selection circuit 5 is as shown.
In FIG. 3, the signals received by the antennas 1 and 2 are output to the selection circuit 5. The selection circuit 5 selectively outputs one of the antennas 1 and 2 having a larger reception intensity from the first output terminal according to the switching control signal from the diversity combination control circuit 7. The reception detection circuit 3 receives the reception signal from the antenna selected by the selection circuit 5 as an input from the first output terminal, performs a reception detection operation, outputs the detection output to the diversity combining control circuit 7, and simultaneously receives the envelope of the reception signal. The strength is detected and the envelope strength signal is output to the fading pitch determination circuit 6 and the diversity combination control circuit 7. The reception detection circuit 4 enters a power saving mode in response to a mode control signal from the diversity combination control circuit 7, and does not perform reception detection operation in the antenna selection diversity mode.

The fading pitch judgment circuit 6 detects the fading pitch from the envelope strength signal from the reception detection circuit 3, compares the detected fading pitch with a predetermined threshold value, and outputs the judgment result. . The diversity combining control circuit 7 outputs the output from the reception detection circuit 3 as a demodulation output, and determines the antenna to be selected based on the envelope strength signal from the reception detection circuit 3.
According to the determination, the selection circuit 5 is controlled to switch the antenna connected to the reception detection circuit 3 from the first output terminal. Further, the diversity combination control circuit 7 controls the subsequent transition / exit of the diversity mode based on the judgment output of the fading pitch judgment circuit 6. (1) When the fading pitch of the received signal is larger than the predetermined threshold value and the fading of the transmission line changes rapidly, the mode shifts to the selection diversity mode after detection. (2) When the fading pitch of the received signal is smaller than the predetermined threshold value and the change in fading of the transmission path is slow, the antenna selection diversity mode is continued.

Although the above embodiment is an example in which the number of antennas is two, the present invention can also be utilized when the number of antennas is three or more. FIG. 4 is a configuration diagram showing an embodiment in the case of three antennas. In this embodiment, an antenna 8 is added to the configuration of FIG. 1 and a reception detection circuit 9 is added correspondingly. The reception detection circuit 9 is a detection circuit that can be switched to the power saving mode like the reception detection circuit 4. Therefore, the selection circuit 10 inputs the reception outputs of the antennas 1, 2, and 8 to the reception detection circuits 3, 4, and 9 when the rate of fading change is rapid, and the detection outputs are combined by the diversity combination control circuit 7. Is controlled so that a demodulated output is obtained. The state of each switch of the selection circuit 10 in FIG. 4 shows the connection state when the change in fading is gradual, and the reception detection circuits 4 and 9 are controlled in the power saving mode to stop the detection operation. An antenna selection diversity mode 10 is controlled so as to selectively switch the antennas 1, 2 and 8 to give a reception signal to the reception detection circuit 3.

FIG. 5 is a block diagram showing an embodiment in which the number of antennas is further increased by 2 to make a total of 5 antennas.
In this embodiment, antennas 11 and 12 are added to the configuration of FIG. These two additional antennas 11 and 12
Does not have a corresponding reception detection circuit, and becomes an antenna to be selected in the antenna selection diversity mode.

[0013]

As described in detail above, by implementing the present invention, it is possible to realize a diversity circuit which has a small increase in power consumption and has an effect of improving reception characteristics even in a transmission line with severe fading. , Has a great effect in practice.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing an operation in a post-detection combining diversity mode of the present invention.

FIG. 3 is a block diagram showing the operation of the antenna selection diversity mode of the present invention.

FIG. 4 is a diagram showing a configuration example when the number of antennas of the present invention is increased.

FIG. 5 is a diagram showing a configuration example when the number of antennas of the present invention is increased.

[Explanation of symbols]

 1, 2 reception antenna 3, 4 reception detection circuit 5 selection circuit 6 pulley pitch determination circuit 7 diversity combination control circuit 8, 11, 12 reception antenna 9 reception detection circuit 10, 13 selection circuit

Claims (1)

[Claims] 1. A first and a second reception antenna, a selection circuit which is connected to the first and the second reception antenna, and outputs a reception signal from the first and second output terminals according to a switching control signal, A first reception connected to the first output terminal of the selection circuit to detect and output a reception signal from the first output terminal and to detect an envelope strength of the reception signal and output an envelope strength signal. A detection circuit and a second output terminal of the selection circuit, which is connected to the second output terminal to detect and output a reception signal from the second output terminal. Only when a mode control signal is given, the mode is switched to the power saving mode for detection. A fading pitch is detected from the second reception detection circuit that stops the operation and the envelope strength signal, and the detected value is compared and determined with a predetermined threshold value. When the fading pitch is larger than the threshold value, the fading changes. Speed A fading pitch determination circuit that outputs a sudden change signal indicating that the fading pitch is smaller than a threshold value, and outputs a slow signal indicating that the fading change is slow, and a determination output from the fading pitch determination circuit. The envelope strength signal from the first reception detection circuit is given to output a switching control signal for the selection circuit and a mode control signal for the second reception detection circuit, and the first and second reception detection signals are output. A diversity combining control circuit for combining the detection outputs from the circuits to obtain a demodulation output, wherein the diversity combining control circuit includes first and second receiving antennas for the selection circuit when the determination output is a drastic change signal. Output the switching control signal such that the reception signal of the above is output from the first and second output terminals respectively Diversity reception is performed, and when the determination output is a slow signal, the mode control signal is given to the second reception detection circuit, and the first and second reception antennas are supplied to the selection circuit with an envelope strength signal. A demodulation method selection reception diversity circuit configured to selectively switch according to the above and output the switching control signal for outputting a reception signal from the first output terminal to perform antenna selection diversity reception.