JP2007103991A - Method and apparatus of controlling phase of diversity reception - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the influence, on a poststage demodulator, of the phase fluctuation of a composite signal in a diversity receiver of equal gain composition or maximum ratio composition when a reception signal level is reduced. <P>SOLUTION: In a diversity reception system in which at least two antennas are arranged, when the reception level is reduced even in one of a plurality of received high-frequency signals, the control of the phase shifter of a converter for downconverting the plurality of received high-frequency signals is stopped. When the control is started again, the continuity of a phase is maintained, the amount of change in the phase is suppressed, and then the plurality of received high-frequency signals are synthesized. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to phase control of a radio receiver such as an equal gain combining or maximum ratio gain combining diversity receiver and an array antenna applied to a radio transmission apparatus.

  FIG. 7 is a block diagram of a conventional equal gain combining diversity receiver. Both phase difference information is detected by the combining unit 101 from the received signal # 1 and the received signal # 2. The phase difference information is a DC voltage, and takes a higher value as it is closer to the in-phase. Based on this phase difference information, the phase shifter control unit 102 outputs a phase shifter control voltage that increases the combined signal level of the received signal # 1 and the received signal # 2 to the phase shifter 103. In this configuration, the phase of the received signal # 2 is changed. The control to make the received signal # 1 and the received signal # 2 in phase is repeated infinitely, and the combined output level is always maximized.

FIG. 8 shows a block diagram of the conventional synthesis unit 101. The mixer 201 detects the combined output and the phase difference voltage from the received signal # 3 and the received signal # 4 down-converted to the IF band.
The phase shifter control unit 103 in FIG. 7 is configured by a microcomputer. FIG. 3 shows a schematic diagram for each condition of microcomputer control. In FIG. 3, c represents the control value of the microcomputer, and PD (c) represents the phase difference voltage. 3A shows a condition in which PD (c) increases when the control value is incremented by 1 (received signal # 3 and received signal # 4 approach the same phase). FIG. 3B shows PD (c) even if the control value is incremented by +1. c) does not change (received signal # 3 and received signal # 4 are substantially in phase). FIG. 3C shows that PD (c) decreases when the control value is increased by 1 (received signal # 3 and received signal #). 4 is a condition for moving away from the same phase). In the condition (A), the microcomputer maintains the control direction so as to change from (1) to (2) in the figure. When the condition (B) is satisfied, the output phase shifter control voltage is fixed, and when the condition (C) is satisfied, the control direction is reversed so as to change from (1) to (2) in the figure.
JP-A-6-303171

  When the received signal (received signal # 1 in FIG. 7) that is not subjected to the phase shifter control input to the equal gain combining diversity receiver is not received, the DC voltage output from the mixer 201 in FIG. Adds a lot of noise. At this time, the phase shifter control unit (microcomputer) 102 shown in FIG. 7 is always operated in an unstable manner because the phase difference voltage with noise is input, and as a result, the combined signal of the equal gain combining diversity receiver has a phase fluctuation. May affect the demodulator at the later stage. In the maximum ratio gain combining, the received signal is weighted in proportion to each antenna signal level. Therefore, the low-level received signal has a small contribution ratio to the combined signal. However, sudden fluctuations in the low-level received signal become noise of the combined signal, which may affect the demodulator and the like at the subsequent stage.

  It is an object of the present invention to reduce the influence on the demodulator and the like of the subsequent stage due to the phase fluctuation of the combined signal of equal diversity combining or maximum ratio gain combining of the diversity receiver when the received signal level is lowered.

  In order to achieve the above object, the present invention provides a diversity receiving apparatus in which at least two or more antennas are arranged, and when the reception level is reduced even in one of the received signals, the received signals When the control of the phase shifter that stops the phase is stopped and the control is started again, the continuity of the phase is maintained and the amount of change in the phase is suppressed, and then the received signals are synthesized.

  That is, in the diversity reception method of equal gain combining or maximum ratio gain combining, the phase of the combined signal is not disturbed even in a situation where neither of the diversity receivers receives the received signal.

  As described above, by using the diversity receiver of the present invention, it is possible to generate a composite signal of equal gain synthesis or maximum ratio gain synthesis that has a stable phase regardless of the level of any received signal among a plurality of received signals. It becomes possible to output.

  In addition, when returning from stoppage of phase shifter control, phase shifter control with extreme changes will greatly change the phase of the composite signal in a short time, and the demodulator at the subsequent stage can follow the phase change. Therefore, the demodulation characteristic is deteriorated. However, even after the phase shifter control is stopped and returned, the phase shifter control voltage always maintains continuity and suppresses the amount of phase change per time to some extent. Thereby, it is possible to avoid the phase of the combined signal from changing extremely in a short time, and the demodulator at the subsequent stage can demodulate without deteriorating the characteristics.

  FIG. 1 shows a block diagram of an equal gain combining diversity receiver according to one embodiment of the present invention. The combining unit and the phase shifter control unit are different from the block diagram of the conventional equal gain combining diversity receiver of FIG. FIG. 2 shows a block diagram of the combining unit and phase shifter control unit of the equal gain combining diversity receiver according to one embodiment of the present invention. 2, in addition to the phase difference voltage output in the conventional method, AGC 401 and AGC 402 output AGC voltages for reception signal # 3 and reception signal # 4, and adjust the respective AGC voltages to adjust the power. The received power # 1 and the received power # 2 representing are output to the phase shifter control unit 403. The phase shifter control unit 403 stops phase control when the value of either received power # 1 or received power # 2 is equal to or lower than a predetermined level.

  A schematic diagram illustrating the control of one embodiment of the present invention is shown in FIG. FIG. 4 shows a case where phase shifter control is performed over time t. When the received power falls to a predetermined level, for example, 1/4 or less of the normal power, the phase shifter control is stopped.

  In addition, when returning from the stoppage of the phase shifter control, as shown in FIG. 4, the phase shifter control of extreme change greatly changes the phase of the synthesized signal in a short time, and the demodulator at the subsequent stage changes the phase. Unable to follow, leading to degradation of demodulation characteristics. In order to avoid this, as another embodiment of the present invention, the amount of phase change per time is suppressed to some extent while the phase shifter control voltage always maintains continuity even after the phase shifter control is stopped and returned. A schematic diagram of a control example of another embodiment of the present invention is shown in FIG. 5, and a control block diagram of the phase shifter control unit 403 is shown in FIG. Thereby, it is possible to avoid the phase of the combined signal from changing extremely in a short time, and the demodulator at the subsequent stage can demodulate without deteriorating the characteristics.

  FIG. 5 of the control example of the phase shifter control unit of another embodiment of the present invention shows that the phase difference changes during the control stop period (decrease in the phase difference voltage PD (c)) and is not in phase when the control is resumed. In the state, the control starts from the phase state before stopping the control and then decreases the phase rotation speed until the phase difference becomes maximum.

  FIG. 6A is a control block diagram of the phase shifter control unit 403 when the reception level is lowered. FIG. 6A is a control block diagram of the phase shifter control unit 403 according to another embodiment of the present invention. Received power level drop detectors 701 and 702 monitor received power # 1 and # 2, and send a control stop command and a phase hold command to phase shifter control voltage generator 703 when the level drops. FIG. 6B is a control block diagram of the phase shifter control unit 403 when the reception level returns to the threshold value or more. At this time, the phase shifter control voltage generation unit 703 restarts the control and generates a voltage for phase rotation by the phase shifter, but the rotation speed is sufficiently low so as not to affect the subsequent demodulator. Control it to become something.

  By the way, in the above embodiments, only the equal gain combining diversity receiver has been described. However, the present invention is not limited to the equal gain combining diversity receiver, and may be a maximum specific gain combining diversity receiver. .

In the above embodiment, a method of using a local oscillator (LOC) 106 and a mixer 201 to synthesize a plurality of received high-frequency signals after down-converting them into low-frequency signals has been described. A method of directly synthesizing received high-frequency signals may be used.

1 is a block diagram of an equal gain combining diversity receiver according to an embodiment of the present invention. The block diagram of the synthetic | combination part and phase shifter control part of one Example of this invention Schematic diagram of control example of phase shifter controller The schematic diagram of the control example of the phase shifter control part of one Example of this invention The schematic diagram of the control example of the phase shifter control part of another Example of this invention The control block diagram of the phase shifter control part of the control example of another Example of this invention Block diagram of conventional equal gain combining diversity receiver Block diagram of conventional synthesis unit

Explanation of symbols

101, 404: synthesis unit, 102, 403: phase shifter control unit, 103: phase shifter 104, 105, 201: mixer, 106: local oscillator (LOC),
401, 402: AGC, 701, 702: reception level decrease detection unit,
703: Phase shifter control voltage generator

Claims (2)

In a diversity receiver in which at least two or more antennas are arranged,
If the reception level drops even in one of the received signals,
Stop the control of the phase shifter that phase the received multiple signals, and maintain the continuity of the phase when starting the control again, and further suppress the amount of phase change before synthesizing the received multiple signals A phase control method characterized by the above. In a diversity receiving apparatus in which at least two or more antennas are arranged, if even one of a plurality of received signals has a reduced reception level, control of the phase shifter that phases the plurality of received signals is stopped. When starting control again, the function of synthesizing a plurality of received signals after maintaining the continuity of the phase and further suppressing the amount of phase change,
A diversity receiver having a gain combining function such as diversity or a diversity maximum ratio gain combining function.

Images