JPS5991740A - Diversity device - Google Patents

Abstract

PURPOSE:To reduce phase noise at switching and connecting and to reduce the bit error rate by selecting outputs from plural antenna systems so that each output has a prescribed amplitude or over and the phase difference with the output of a switching device is minimized. CONSTITUTION:Antenna systems 11a-11c are three systems or over and have independent output, and an antenna system 11a is selected by a switching device 12. Amplitude phase detectors 14a-14d are connected respectively to the antenna systems 11a-11c and the output terminal of the switching device 12, a reference signal of a reference oscillator 15 is inputted to generate a phase difference signal and an amplitude signal, and its output is inputted to a comparator 16. The comparator 16 controls the switching device 12 so as to select an antenna system minimizing the phase difference with the switching device 12 from the antenna systems 11b, 11c, e.g., the 11b when the amplitude signal of the switching device 12 is decreased to a reference value or below, and when the output level of the antenna system 11b does not attain to a reference value, the system is connected and switched to the other antenna system 11c.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a diversity device for reducing the effects of fading in wireless communications.

[Technical backlogs of inventions and their problems]

Conventionally, various methods have been considered to reduce fading in wireless communications. Especially time.

If frequency redundancy is not allowed,
Space diapersity and directional diapersity are used. This space diversity or directional diversity involves arranging two or more antenna systems to receive radio waves separately, and selecting the antenna system so that the level of each output or S ratio is maximized. It is a method.

Conventional dipacity devices using this type of system are 2III! 4 waves are received by one of the antenna systems of jl, and the output level of this antenna system is
1. 111 power level is higher than the reference value (t! Switch the antenna system on the J side.

lc and 2c in Fig. 1 show the outputs of the two antenna systems that change at each time ζ as trajectories on the complex plane, and IP and 2P in Fig. 2 show the corresponding times ζ. This shows the change in the phase of . When the level (absolute value on the complex plane) of the output 1c of one antenna system falls below the tile value on a predetermined basis at time t4, the output is switched to the output 2c of the other antenna system at this point. At this time, the phase of the output of the antenna system is -6 as shown by the thick line in Figure 2.
00 to +6o.

changes rapidly.

In this way, conventional diversity devices do not take phase changes into account, so when switching antenna systems (a large phase gap may occur and position noise may occur, especially when using digital phase modulated waves) When demodulating by synchronous detection when receiving.

The disadvantage is that the large phase gap causes the digital signal data to change and cause errors.

[Purpose of the invention]

The present invention has been made in order to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a diversity device that can reduce phase noise caused by switching the diversity.

[Existing requirements of the invention]

In this invention, one of three or more antenna systems having independent outputs is switched and connected using a switch.

When the output of this switching device falls below a predetermined amplitude, select an antenna system among other antenna systems whose output has a predetermined 4-line width or more and has a minimum difference of 7 m from the output of the switching device. This suppresses the phase jump caused by the switching of the diversity to a small value.

〔Effect of the invention〕

This invention does not have any loss of diversity under fading, and is designed so that the output from among a plurality of unconnected antenna systems is at least a predetermined amplitude and has a minimum phase difference with the output of the switch. Since it is selected and connected so that 1 phase noise can be significantly reduced, it has the feature of being able to significantly reduce the bit error rate especially when demodulating phase modulated digital signals by synchronous detection. .

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 3, 11a to IIC are antenna systems having independent outputs of three or more systems (three systems in the illustrated example), and these antenna systems 118 to IIC are selected from switching k121 and switching r4 Nu. and its output is input to the receiver 13.

On the other hand, 4-width phase detectors 14a-14 (l) are connected to the output terminals of each antenna system 11a-IIC and switch 13, respectively, and each amplitude phase detector 14a-14d receives a reference signal from a reference oscillator 15. Here, the amplitude phase detectors 14a to 14d are inputted according to the output of each antenna system 11a to 11C and the switch 12.
A phase difference signal and an amplitude signal are generated, and their respective outputs are input to the comparator 16. When the amplitude (level) signal of the output of the switching device 12 falls below the reference value, this comparator 16 detects the output of the switching device 12 among the antenna systems 111) other than the currently selected antenna system 11a, The switch 12 is controlled so that the antenna system, for example, ILB, has a minimum phase difference between the two antennas. In addition, the switching device 12
The antenna system 11 whose output phase l belongs to the closest value
In two stations where the output level of 1) is less than the base 1'14 value, it is switched and connected to another antenna system 11C.

Figures 4 and 5 show the switching status of this diaperity device.
This will be further explained using figures. Antenna system 11 of now 3 leaps
Changes in each output of a-11c form a locus of improvement in the complex element as shown in FIG. 4 from 1c to 30.

A favorable assumption is made that the phases IP to 3P at that time change as shown in FIG. As a result of this swirling, the output level of the antenna system 11a currently being used changes to the base I at time t4.
It is said that the value has become lower than the IIA value. At this time, comparator 1
2 is (Tatsu) (corner phase detection ≧S) Among the output signals of 14b and 14c, the peaks are very close to the phase of the output signal of channel width phase detection ridge 14a.
1C is selected 17% - Kokiri l! The IL unit 12 is controlled.

As a result, the phase of the output of the antenna system changes as shown by the thick line in FIG. According to the conventional diaperity device, the magnitude of the output phase dip is about 1200 from the m2 diagram, but in this embodiment, the 5th
As shown in the figure (this phase jump is as low as 400).

Therefore, according to such an adjustment, the phase jump caused by the switching of the diversity under fading can be suppressed to a very low level, so that the phase noise can be significantly reduced compared to the conventional one. Special feature: When a phase modulated digital signal is demodulated by synchronous detection, disturbances in information due to phase jumps are reduced, and the error rate can be significantly reduced.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be modified in various ways without changing the gist thereof.

For example, in the above-mentioned license, each antenna system and switching device was connected to an amplitude phase generator to detect the phase difference signal and amplitude signal between each antenna system and switching device and the reference oscillator, but instead of this, one The outputs of each antenna system and switch can also be detected on a time-division basis using an amplitude phase detector.

Further, in the above embodiment, the phase difference is detected using the reference oscillator, but the present invention is not limited to this. For example, one of three or more antenna systems or switching):
It is also possible to derive the phase difference using the divine output signal as a reference.

Further, in the present invention, when the receiver is performing a phase-coherent wave, the carrier position (■) can be taken as the base phase of the carrier reproduced by the carrier reproducing section included therein.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams for explaining the switching state of a conventional diversity device. Figure 1 is a locus diagram on a complex plane of a received signal, and Figure 2 is a diagram of a phase change of a received signal. , FIG. 3 is a circuit J IIυ diagram showing one embodiment of the present invention, and FIGS. 4 and 5 are diagrams for explaining the switching states of the same embodiment. FIG. The locus diagram, FIG. 5, is a diagram of the change in position a of the received signal. ■C~3C...Antenna system output L/ /< JL
/1p~3p...-Antenna system output phase 11a-
1ie...Antenna system 12...Switcher 13...
- Receivers 148 to 14d...amplitude phase detector

Claims (6)

[Claims] (1) 1. Three or more antenna systems each having independent outputs, a switch that selects and connects these antenna systems, and the phase of the output signal of this switch and each antenna system. There is a phase difference between the amplitude detector and the output of the switch of another antenna system whose output is higher than the predetermined amplitude value when the output signal of the switch is lower than the predetermined amplitude value. A diversity device characterized in that it comprises means for selecting a minimum antenna system. (2) The diversity device according to claim 1, wherein the detector is provided corresponding to the switch and each antenna system. (3) The detector is 11 for the switch and each antenna system.
1N is provided for the above switching device and each antenna system. 2. The diversity device according to claim 1, wherein the output signal is detected in a time-division manner. (4) The detector detects the phase difference between the outputs of the switching device and each antenna system using the output signal of the basic oscillator as a reference phase. Diapersity device as described. (5) The detector detects the phase difference between the outputs of the switching device and each antenna system using the carrier phase regenerated by the carrier regeneration section of the receiver IR device that performs phase synchronized detection as a reference phase. ! i! A diversity device according to any one of claims 1 to 3. (6) The diversity device according to claim 3, wherein the detector detects a phase difference using the output signal of one of the antenna systems or the switch as a reference.