JP2625846B2 - In-phase combined space diversity receiver - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-phase combined space diversity receiver, and particularly to setting a dead zone for improving noise characteristics when detecting a phase difference. The present invention relates to an in-phase combined space diversity receiver that does not set a dead zone when a received input is in the vicinity of an inverted phase.

[Prior Art] In general, an in-phase combined space diversity receiving apparatus includes a phase comparator for detecting a phase difference between two reception inputs, and receives a signal by determining a lead or lag of a phase by two voltage comparators based on the output. The in-phase synthesis is performed by controlling the phase difference between the input signals.

FIG. 3 is a block diagram of a conventional in-phase combined space diversity receiver.

In the figure, 1 is an infinite phase shifter (EPS), 2 is a power combiner, the phase of a second received input signal is controlled by the infinite phase shifter 1, and the power combiner 2 always receives the first received signal. They are combined in phase with the input signal. Then, the synthesized signal is sent to a demodulator (DEM) (not shown) and demodulated into a baseband signal.

The two input signals are input to the power combiner 2 and, at the same time, are input to narrow-band bandpass filters (BPFs) 3 and 4 for extracting only components near the center frequency of the modulated wave, respectively. The signal is input to automatic gain control (AGC) amplifiers 5 and 6 that keep the signal level constant. Then, the output of the automatic gain control amplifier 5 is left as it is, and the phase comparator 7
The output of the automatic gain control amplifier 6 is input to the phase comparator 7 through the 90 ° phase shifter 8 which changes the phase by 90 °.

Here, the phase characteristics of the phase comparator 7 are as shown in FIG. 4 (a), and the output becomes 0 when the two signals to be compared are in phase.

The output voltage V ₀ of the phase comparator 7 is input to two voltage comparators 9 and 10 having different fixed threshold voltages, and a detection signal for the delay of one input phase and a detection signal for the delay of one input phase A detection signal is obtained (FIGS. 4 (b) and (c)).

Then, based on the two control signals having this phase information, the EPS control circuit 11 controls the amount of phase shift of the infinite phase shifter 1,
In-phase synthesis is performed by changing the phase of the second received input signal.

By the way, when the output voltage V ₀ of the phase comparator 7 is V ₁ > V ₀
> Of the time V _2, is not detected at all phase lead and lag the at two voltage comparators 9 and 10 (Figure 4). That is, there is a range in which the phase difference is not detected, and there is a dead zone in which the phase control is not performed.

This is because, if the phase control of the received input signal is always performed by the infinite phase shifter 1, the combined wave becomes a factor of noise and the fluctuation of the phase deteriorates the error rate characteristic of the entire receiving apparatus. It is.

As described above, the conventional in-phase combined space diversity receiving apparatus stabilizes the output by setting the dead zone in the phase control.

[Problems to be Solved] The conventional in-phase combined space diversity receiving apparatus described above only sets the dead zone of two voltage comparators with respect to the output voltage of one phase comparator. A dead zone occurs not only when the input signal is in phase but also when the input signal is out of phase.If the phase relationship of the received input jumps into the dead zone near the opposite phase for some reason, the phase control is performed in the opposite phase synthesis state. Had to be stopped.

The present invention has been made in view of the above problems,
When the two reception inputs are near the in-phase, a dead zone for improving noise characteristics is set, and when the two reception inputs are near the opposite phase, the phase control can be performed without setting the dead band. For the purpose of providing.

[Means for Solving the Problems] In order to achieve the above object, the in-phase combined space diversity receiving apparatus of the present invention detects a phase difference between received signals input from two antennas and determines whether the phase is advanced or delayed. (1) a phase difference judging means, a synthesizing means for changing one phase of the received signals based on an output of the first phase difference judging means, and synthesizing a phase difference between the received signals as the same phase; It is configured to determine whether the phase difference between the signals is near the in-phase or near the opposite phase, and to provide a second phase difference determining means for controlling the dead zone of the first phase difference determining means based on the result.

Here, specifically, in order to determine whether the phase difference between the two received input signals is near the same phase or near the opposite phase, a state where the phase difference is 90 ° different from the phase difference when determining the delay and advance of the phase. And the phase of the two received input signals is compared. From the result, the phase difference (Δθ + 90 °) between the two received input signals is close to the same phase (−90 ° <Δθ <90 °) or close to the opposite phase (90 ° <Δθ < 270
゜) is determined. Then, the threshold voltage of the voltage comparator that determines the delay and advance of the phase based on the determination is controlled.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an in-phase combined space diversity receiver according to one embodiment of the present invention. . In addition,
Portions common or corresponding to the conventional example are denoted by the same reference numerals.

In the figure, reference numeral 12 denotes a phase comparator, and the phase comparator 7
Compares two signals with a phase difference of 90 °. Reference numeral 13 denotes a voltage comparator that determines the output voltage of the phase comparator 12,
The threshold voltage of the voltage comparators 9, 10 can be changed by the output of the voltage comparator 13.

In the above configuration, the phase comparator 12 has a phase comparison characteristic (second
As shown in FIG. 3A, the voltage comparator 13 determines whether the output voltage of the phase comparator 12 is positive or negative. And its output (second
In FIG. 4D, the threshold voltages V ₁ and V ₂ of the voltage comparator 9 and the voltage comparator 10 are controlled. That is, the phase difference (Δθ + 90 °) between two received input signals is V ₁ = V ₂ = 0 when 90 ° ≦ Δθ + 90 ° ≦ 270 °, and V ₁ = V ₂ = 0 when −90 ° ≦ Δθ ≦ 90 °. ₁ = V ₂ = constant voltage.

By doing so, a dead zone does not occur near the reverse phase. Therefore, unlike the conventional in-phase combined space diversity receiver, the phase control does not stop near the opposite phase.

As described above, in this embodiment, the first phase comparator 7 that compares the phases of the two received input signals is controlled by controlling the phase difference between the received input signals coming from the two antennas and combining them in phase. A first voltage comparator 9 for detecting a phase delay between received input signals from an output of the first phase comparator 7, a second voltage comparator 10 for detecting a phase advance, A phase control circuit for controlling a phase difference between received input signals based on phase control information obtained as outputs of the second voltage comparators, and the two signals whose phases are controlled are synthesized. In the in-phase combining space diversity receiving apparatus including the power combiner 2, the second phase comparator 12 differs from the first phase comparator 7 in phase comparison characteristics with respect to the phase difference between two reception inputs by approximately 90 °. Received from the output of the second phase comparator 12. And a third voltage comparator 13 for detecting whether the phase relationship of the input signal is near the in-phase or near the reverse phase. The output of the third voltage comparator 13 outputs the first and second voltage comparators 9. Change the threshold voltage of
The dead zone of the phase control is controlled.

[Effects of the Invention] As described above, the present invention eliminates the dead zone of phase control when the phase relationship between two received input signals is near anti-phase, and stops phase control during in-phase synthesis. At the time of out-of-phase synthesis, it is possible to perform phase control such that the phase difference becomes 0 °, minimize degradation due to controlling the infinite phase shifter, and always combine two received input signals near the same phase. There is an effect that it is possible to provide an in-phase combining space diversity receiving apparatus capable of performing the above-mentioned steps.

[Brief description of the drawings]

FIG. 1 is a block diagram of an in-phase combined space diversity receiver according to one embodiment of the present invention, and FIG.
FIG. 2B shows a phase comparison characteristic of a phase comparator in the in-phase combined space diversity receiver shown in FIG.
(C) and (d) are diagrams showing output characteristics of the voltage comparator, FIG. 3 is a block diagram of a conventional in-phase combined space diversity receiver, and FIG. 4 (a) is a conventional in-phase combined space diversity receiver. And FIG. 4B and FIG. 4C are diagrams showing the output characteristics of the voltage comparator. 1: Infinite phase shifter (EPS) 2: Power combiner 7, 12: Phase comparator 8: 90 ゜ phase shifter 9, 10, 13: Voltage comparator 10: Voltage comparator 11: EPS control circuit

Claims (1)

(57) [Claims] 1. A first phase difference judging means for detecting a phase difference between received signals input from two antennas and judging a lead / lag of a phase, and based on an output of the first phase difference judging means. And changing the phase of one of the received signals, and synthesizing the phase difference between the received signals as in-phase, and determining whether the phase difference between the received signals is near the in-phase or near the opposite phase. An in-phase combined space diversity receiving apparatus, comprising: a second phase difference judging means for controlling a dead zone of the first phase difference judging means.