JP2822752B2 - Signal synthesizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal synthesizing apparatus applied to a space diversity receiving apparatus, and more particularly to a signal synthesizing apparatus for in-phase synthesizing two IF receiving signals whose frequency spectrum distributions are vertically symmetric with respect to a center frequency. .

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing an example of a conventional signal synthesizer.

In order to combine the two IF reception signals S1 and S2, the phases must be matched. For this reason, the phase comparator 6 detects the phase difference between the two IF reception signals,
After controlling the infinite phase shifter 7 in accordance with the detected phase difference and adjusting the phase of one IF reception signal S2, the in-phase 2
The three IF received signals are combined by the combiner 3 and the combined signal S
I got 3.

By the way, in order to detect the phase difference between the two IF received signals and to make the phases coincide, the signals are branched by the demultiplexers 1 and 2, respectively. A phase control loop is configured to detect the phase difference by supplying the phase difference to the phase comparator 6 and control the infinite phase shifter 7 according to the phase difference.

[0005]

In the conventional signal synthesizer described above, the phase is controlled at the point that the phase control loop first holds after the operation starts. However, due to the width of the control range of the phase control loop, a slight phase shift occurs in the state where the phase is held first. Therefore, there is a problem that the synthesis cannot be performed in an optimum state in which the phases of the two IF reception signals completely match.

It is an object of the present invention to provide a signal synthesizing apparatus capable of synchronizing two IF reception signals in an optimum state.

[0007]

A signal synthesizing apparatus according to the present invention is a signal synthesizing apparatus for in-phase synthesizing two IF reception signals whose frequency spectrum distributions are vertically symmetrically distributed with respect to a center frequency. Phase shifting means for changing one of the phases of the IF reception signal in accordance with the control signal;
Control means for generating the control signal; means for detecting a phase difference between the two IF reception signals and outputting data indicating the phase difference; A means for detecting the symmetry of the lower spectral distribution and outputting data indicating the symmetry, and storage means for receiving and storing the data indicating the phase difference and the data indicating the symmetry, respectively, Means for setting the phase shift amount of the phase shift means to 0 at predetermined intervals.
After changing the data indicating the phase difference and the data indicating the symmetry by changing the data by 360 ° in the storage means, the control signal is controlled so that the stored data has the best symmetry. Is configured to generate

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, and the same reference numerals are assigned to the same parts as those of the conventional signal synthesizing apparatus shown in FIG. Here, the difference from FIG. 2 is that a frequency characteristic detection unit 8, a data storage unit 9, and a control unit 10 are provided.

In general, the frequency spectrum distribution of a quadrature modulated signal such as a 16QAM signal is uniformly distributed above and below the center frequency. Therefore, by detecting the symmetry of the frequency spectrum distribution of the synthesized signal and controlling it to the most symmetrical point, that is, the point where the frequency characteristic becomes the flattest, the phase can be controlled to the optimum state.

Now, the frequency characteristic detecting section 8 outputs the synthesized signal S
3, the frequency spectrum distribution is detected, and the symmetry of the upper and lower spectrum distributions with respect to the center frequency is detected to generate data Ds indicating the symmetry.

The data storage unit 9 stores data Dp indicating the phase difference between the two IF reception signals output from the phase comparator 6 and data D indicating the symmetry output from the frequency characteristic detection unit 8.
s is received and stored. Further, the control unit 10 generates a control signal C for controlling the amount of phase shift and sends it to the infinite phase shifter 7.

Next, the operation will be described.

First, the control unit 10 sends a control signal for changing the phase shift amount of the infinite phase shifter 7 at a predetermined interval by 0 to 360 °, and outputs data Dp indicating the phase difference between the two IF reception signals.
Then, data Ds indicating the symmetry of the composite signal is stored in the data storage unit 9.

Thereafter, the control unit 10 checks the data stored in the data storage unit 9 and determines that the synchronous synthesis point is 1
In the case of two, a control signal is generated and transmitted to the point. When there are a plurality of synchronous synthesis points, a control signal is generated such that the frequency spectrum distribution becomes the most symmetrical point.

In this manner, even if there are a plurality of synchronous combining points, the IF receiving signal S1 and the IF receiving signal S2 can be synchronously combined in an optimum state.

[0017]

As described above, according to the present invention, 2
When detecting the phase difference between the two IF reception signals and controlling the phase shifter to perform in-phase synthesis, first, the phase shift amount of the phase shifter is changed by 0 to 360 ° at a predetermined interval, and the two IF reception signals are changed. The data indicating the phase difference and the data indicating the symmetry of the synthesized signal are respectively stored.After that, the stored data is checked.If there are a plurality of synchronous synthesis points, the frequency spectrum distribution is set to the most symmetrical point. By generating such a control signal, the two IF reception signals can be synchronously combined in an optimal state.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating an example of a conventional signal synthesis device.

[Explanation of symbols]

 Reference Signs List 3 synthesizer 6 phase comparator 7 infinite phase shifter 8 frequency characteristic detection unit 9 data storage unit 10 control unit S1, S2 IF reception signal S3 synthesized signal C control signal Ds signal indicating symmetry of frequency spectrum distribution Dp phase difference Signal

Claims (1)

(57) [Claims] 1. An in-phase combination of two IF reception signals whose frequency spectrum distributions are vertically symmetrically distributed with respect to a center frequency.
A signal synthesizing device, comprising: a phase shifter that changes a phase of one of the two IF reception signals in accordance with a control signal; a controller that generates the control signal; and the two IF reception signals. Means for detecting the phase difference and outputting data indicating the phase difference, and detecting the frequency spectrum distribution of the synthesized signal to detect the symmetry of the upper and lower spectrum distributions with respect to the center frequency, indicating the symmetry. Means for outputting data, and storage means for receiving and storing the data indicating the phase difference and the data indicating the symmetry, respectively, wherein the control means sets the phase shift amount of the phase shift means at predetermined intervals. After changing the data indicating the phase difference and the data indicating the symmetry by changing the angle by 0 to 360 ° in the storage unit, the stored data has the best symmetry among the stored data. A signal synthesizing apparatus for generating the control signal as described above.