JPS63313934A - Digital radio receiver - Google Patents

Abstract

PURPOSE:To enable to receive a digital signal, equal to that by using the antenna of high gain by detecting each of plural small antenna reception signals once, and deciding the digital signal after adding and synthesizing the obtained base band signals. CONSTITUTION:A first series amplifies and frequency-converts the signal received by the antenna 1a, by a high frequency part 2a, and makes it into the base band signal by a carrier synchronization circuit 3a. Phase ambiguity is removed by a phase ambiguity removing part 4a by a unique word detection, etc. A second series obtains the base band signal without any phase ambiguity similarly by 1b-5b. The two base band signals obtained by an above-mentioned way are added by an adding synthesizer 10, and furthermore, the decision of the digital signal is performed by a decider 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) This invention relates to a wireless communication device that receives digital signals.

(Conventional technology) In conventional wireless communication, lines are designed for each applicable system.
We have selected and installed an antenna of an appropriate size to perform communications. In particular, when constructing a system that assumes multiple speeds (bands) in cases where the reception power flux density is limited, such as in satellite communications, even if the system does not receive high-speed (wideband) signals at the beginning of its inception. A larger antenna must be installed for future expansion, which causes an increase in cost.

There is also a method of combining small antennas to create a high-gain antenna, but according to the conventional method, it is necessary to optimally adjust the phase of each small antenna output signal. In particular, an automatic follow-up circuit that automatically adjusts the phase is required for short-term changes due to temperature characteristics, etc., which inevitably increases the cost.

(Problems to be Solved by the Invention) An object of the present invention is to provide a radio receiver that configures a high-gain antenna subsystem by combining small antennas without particularly requiring an automatic phase tracking circuit. shall be.

[Structure of the invention]

(Means for Solving the Problems) The present invention detects signals received by a plurality of small antennas individually, adds and synthesizes the obtained baseband signals, and then determines the digital signal. This method performs the same digital signal reception as using .

Particularly, in a system using a phase modulation method, a phase ambiguity dust removal function is provided in the detection circuit, and a digital signal is determined after adding and combining baseband signals with no phase ambiguity.

Further, an error correction function is provided in the detection circuit, and a code (g reliability) is outputted as an output, and a digital value judgment is performed after addition and synthesis.

(Operation) The signals received by multiple antennas are high frequency signals,
Although these signals are amplified and frequency converted while maintaining their respective phases, there are difficulties due to the phase when synthesizing the signals.According to the configuration of the present invention, multiple high frequency or The intermediate frequency signal is converted into a plurality of baseband signals by a detection circuit, and then added and synthesized.

The main component of the noise is thermal noise generated in each high frequency amplifier, and there is no correlation between them, but the two signal components are the same and the correlation is extremely strong.

In particular, in phase modulation methods such as BPSK and QPSK, if phase ambiguity is removed, noise components are added by power and signal components are added by vectors, resulting in S of the resulting signal.
The /N ratio is equal to the S/N ratio of a signal obtained by performing optimal phase synthesis on a high frequency signal or an intermediate frequency signal.

This makes it possible to optimally combine received signals from multiple antennas without requiring a complex circuit such as an automatic phase tracking type combining circuit.

Although there is almost no need to consider the phase difference between baseband signals, it may become a problem when it comes to balancing antenna spacing and transmission bit rate. For example, the bit rate is 10M
At high speeds of the order of bps, it is necessary to set the antenna position within 1 to 2 m relative to the radio wave arrival direction, or to adjust it using a cable or the like. However, compared to combining high frequencies and intermediate frequencies, an extremely loose precision is sufficient.

(Example) Examples of the present invention will be shown below using the drawings.

FIG. 1 shows an example in which the present invention is implemented using a phase modulation method and two antennas.

In the first series, a signal received by an antenna (1a) is amplified and frequency-converted by a high frequency section (2a), and converted into a baseband signal by a carrier synchronization circuit (3a). The phase ambiguity is removed by a phase ambiguity removing unit (4a) by unique word detection or the like, but at this time, the amplitude information is maintained. A recovered clock necessary for unique word detection etc. is obtained by a clock recovery circuit (5a).

For the second series, a baseband signal without phase ambiguity is obtained using (1b) to (5b) in the same manner as above.

The two baseband signals obtained in the above manner are added by an addition combiner (10), and further by a decider (10).
The lock required for the 6-decision in which the digital signal is determined by 1) is obtained by the clock recovery circuit (12).

FIG. 2 shows a second embodiment of the invention.

This is an example in which the present invention is implemented using a frequency shift keying (FSX) modulation method and the number of antennas is two.

Since there is no phase ambiguity, a baseband signal can be obtained only by using frequency discriminators (6a, 6b) as detectors.

Hereinafter, addition and synthesis and digital determination are the same as in the first embodiment.

Above, we have explained the case where the number of antennas is 2, but the same applies to the case where the number of antennas is 3, 4, etc. Up to now, we have explained the case where the number of antennas is 3, 4, etc.
, d, and so on, and the signals of 3, 4, and 4 systems can be combined using one combining adder, thereby implementing the present invention.

Furthermore, in the embodiment shown in FIG. 1, the clock regeneration circuit is (5
Although three clock regeneration circuits are used, a), (5b), and (12), one clock regeneration circuit can be placed anywhere among the three to regenerate all necessary locks. Further, the present invention can be implemented by further adding an error correction function to the above embodiment.

The output of the detector, that is, the signals that were each input to the adder synthesizer (10), is input to the error correction circuit, and the error correction circuit uses the error-corrected code as the upper bit and information indicating the reliability of the code. Outputs a signal as the lower bit. This error correction circuit output signal is input to an addition combiner (10), and the code of the combined signal is determined to obtain transmitted code information. At this time, it is of course possible to further perform error correction when determining the sign of the composite signal.

〔Effect of the invention〕

By implementing the present invention, it is possible to optimally combine received signals from a plurality of antennas without using a special automatic control phase tracking type combining circuit.

Although a plurality of detection circuits will be used, since detection circuits are essential for communication equipment, it is clear that technologies such as LSI will lead to lower prices, smaller sizes, and lower power consumption. In this way, by combining a mass-produced circuit and a similarly mass-produced small antenna according to the present invention, it is possible to obtain the same performance as a system using a large antenna, which is extremely effective in reducing costs. It is. Doll antennas are custom-made or made to order, and are expensive.

Furthermore, compared to a method of synthesizing a plurality of signals at high frequency and intermediate frequency stages, the present invention eliminates the need for optimal phase adjustment or an automatic adjustment device.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing another embodiment. la, lb...antenna 2a, 2b...high frequency section 3a, 3b...carrier synchronization section 4a, 4b...phase ambiguity removal section 5a, 5b,
12... Clock synchronization unit 10... Addition synthesizer
11...Digital judgment device agent Patent attorney Nori Chika Ken Yudo Mitsuyuki Matsuyama

Claims (2)

[Claims] (1) A digital radio receiver comprising a plurality of antennas and a plurality of detection circuits corresponding to the antennas, and which performs digital value determination and outputs after adding and combining the outputs of the detection circuits. (2) The digital radio receiver according to claim 1, wherein the modulation method is phase modulation, and the detection circuit has a phase ambiguity removal function. (3) The detection circuit has an error correction function. 2. The digital radio receiver according to claim 1, wherein the digital radio receiver also outputs information indicating the reliability of the code after error correction.