JPH03190331A - Data receiver - Google Patents

Abstract

PURPOSE:To prevent a data error due to doppler effect by detecting the speed of a mobile body and generating and outputting the signal of a local oscillating frequency corrected by the doppler frequency in response to the speed to a mixer corresponding to an antenna receiving the effect of the doppler effect. CONSTITUTION:A synthesizer 13 outputs a signal of a local oscillating frequency adding a carrier frequency and a maximum doppler frequency fD in response to the speed V detected by a speed measuring instrument 12 to a mixer 14A, the signal of the local oscillation frequency resulting from the maximum doppler frequency fD subtracted from the carrier frequency is outputted to a mixer 14C and the signal of the same local oscillating frequency the same as the carrier frequency is outputted to mixers 14B, 14D. Thus, the local oscillating frequency of the mixers 14A, 14C corresponding to antennas 11A, 11C receiving the effect of the doppler effect due to the movement of a moving body M is corrected by the maximum doppler frequency. Thus, even when the signal added by the adder 16 is demodulated, the production of a data error is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a data receiving device used in digital mobile communications and the like.

Conventional technology FIG.
) are, for example, the forward direction A1 and the right direction B1 of the moving body M.
It is arranged so as to have directivity in the rear direction c1 and left direction.

FIG. 5 shows the configuration of a conventional data receiving device.

In FIG. 5, antennas LA, IB, and IC.

The branch signals received via the ID are mixed with the same local oscillation frequency from the synthesizer 3 by mixers 2A, 2B, 2C, and 2D, respectively, to produce an intermediate frequency (IF).
The signals of each branch are adjusted in phase and amplitude and weighted by synthesis amplifiers 4A, 4B, 4C, and 4D, respectively.

The output signals of the synthesis amplifiers 4A, 4B, 4C, and 4D are added by an adder 5, and the synthesis gain is adjusted by the adder 5 so that the amplitude of the added signal is maximized and the distortion is minimized. The amplifier 6 is a composite amplifier 4A, 4B, 4C.
, adjust the 4D complex gain.

Therefore, in the above conventional example, a plurality of directional antennas I
By adjusting the complex gains of A, IB, IC, and LD, the level of the received signal can be controlled to be maximized, and the distortion can be controlled to be minimized.

Problems to be Solved by the Invention However, in the conventional data receiving device described above, the branch signals received via the antennas IA, IB, IC, and ID are mixed with the same local oscillation frequency from the synthesizer 3. This is affected by the Doppler effect that occurs when the body M moves at high speed, and therefore, there is a problem in that data errors occur when the signals added by the adder 6 are demodulated.

The present invention solves the above-mentioned conventional problems, and aims to provide a data receiving apparatus that can prevent data errors caused by the Doppler effect.

Means for Solving the Problems In order to achieve the above object, the present invention detects the speed of a moving object and corrects the mixer corresponding to the antenna affected by the Doppler effect using a Doppler frequency corresponding to this speed. This system generates and outputs a signal at a local oscillation frequency.

According to the above configuration, the local oscillation frequency of the antenna mixer, which is affected by the Doppler effect, is corrected in accordance with the speed of the moving body, and therefore data errors due to the Doppler effect can be prevented.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a data receiving device according to the present invention, FIG. 2 is a graph showing the frequency spectrum of an antenna due to the Doppler effect, and FIG. 3 is a block diagram showing an embodiment of a data receiving device according to the present invention. It is a graph showing the frequency spectrum of an antenna.

In FIG. 1, IIA, IIB, IIC, and 11D are antennas each having directivity in, for example, the forward direction A1 rightward direction B1 rearward direction C1 leftward direction of the moving object M, as shown in FIG. 11A, IIB, IIC, I
The frequency of the branch signal received via the ID is affected by the Doppler effect that occurs when the mobile body M moves at high speed.

12 is a speed measuring device that measures the speed of the moving object M; 13 is a method for measuring the speed detected by the speed measuring device 12 and the antenna 1;
A synthesizer that generates signals of four types of local oscillation frequencies according to the directivity of 1A111B111C111D, 14
A, 14B, 14C, and 14D are antenna II, respectively.
This is a mixer that mixes the branch signals received via A, 11B, IIC, and IID and the local oscillation frequency signal from the synthesizer 13, and converts it into an intermediate frequency (IF) band and a baseband band.

15A, 15B, 15C, and 15D are mixer 1, respectively.
A synthesis amplifier 16 adjusts and weights the phase and amplitude of the signals converted by the synthesis amplifiers 15A, 14B, 14C, and 14D, and an adder 17 adds the signals amplified by the synthesis amplifiers 15A, 15B, 15C, and 15D. is adder 16
combining amplifiers 15A, 15B so that the amplitude of the summed signals is maximized and the distortion is minimized.

This is a composite gain adjuster that adjusts the complex gains of 15C and 15D, and the signals added by the adder 16 are demodulated into digital data.

Next, the operation of the above embodiment will be explained.

In FIG. 1, when a moving body M is moving forward A at a speed V, antennas IIA, 11B111C111
The branch signals received via D are respectively input to the mixer 14
When the same local oscillation frequency is mixed by A, 14B, 14C, and 14D, the baseband spectrum S (f) becomes the maximum Doppler frequency fD proportional to the speed V of the moving object M, as shown in FIG. only spreads.

That is, since the antenna 11A has directivity in the front direction of the moving body M, the spectrum S (f) of the received signal is expanded by the maximum Doppler frequency + fD, and similarly, the antenna 11C has directivity in the rear direction C of the moving body. The spectrum S (f) of the received signal is spread by the maximum Doppler frequency −fo, and the antenna II has directivity in the horizontal direction B1D.
The spectrum S (f) of the received signal of B, IID does not widen.

Therefore, the synthesizer 13 outputs a signal of a local oscillation frequency obtained by adding the carrier frequency and the maximum Doppler frequency fo to the mixer 14A in accordance with the speed V detected by the speed measuring device 12, and converts the carrier frequency to the maximum Doppler frequency fo. The signal of the local oscillation frequency obtained by subtracting the signal is sent to the mixer 14C.
A signal having the same local oscillation frequency as the carrier frequency is output to the mixers 14B and 14D.

When the mixers 14A, 14B, 14C, and 14D mix the branch signals received via the antennas IIA, IIB, IIC, and IID, respectively, and the signal at the local oscillation frequency, the spectrum of each branch signal is generated as shown in FIG. S
(f) is the frequency f.

/2 spread, and the composite signal also has a frequency fD
/2 spread.

Therefore, according to the above embodiment, the antenna 11A111C is affected by the Doppler effect due to the movement of the mobile object M.
Since the local oscillation frequency of the mixers 14A and 14c corresponding to 1 is corrected by the maximum Doppler frequency, no data error occurs even when the signals added by the adder 16 are demodulated.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention detects the speed of a moving object;
A signal with a local oscillation frequency corrected by the Doppler frequency corresponding to this speed is generated and output to the mixer corresponding to the antenna affected by the Doppler effect, so it is possible to mix antennas affected by the Doppler effect. The local oscillation frequency of the device is corrected according to the speed of the moving body, and therefore data errors due to the Doppler effect can be prevented.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a data receiving device according to the present invention, FIG. 2 is a graph showing the frequency spectrum of an antenna due to the Doppler effect, and FIG. 3 is a block diagram showing an embodiment of a data receiving device according to the present invention. FIG. 4 is a graph showing the frequency spectrum of the antenna. FIG. 4 is an explanatory diagram showing the directivity of the antenna. FIG. 5 is a block diagram showing a conventional data receiving device. 118-11D... Antenna, 12... Speed measuring device, 1... Synthesizer, 14A-14D... Mixer, 15A-15D... Synthesis amplifier, 16... Adder, 17. ...Synthetic gain adjuster.

Claims (3)

[Claims] (1) a plurality of antennas each having directivity in different directions; a plurality of mixers that mix signals received via the antennas and signals of a local oscillation frequency; and means for detecting the speed of a moving object; A synthesizer that generates and outputs a signal of a local oscillation frequency corrected by the Doppler frequency according to the speed to a mixer corresponding to an antenna affected by the Doppler effect, and a synthesizer that synthesizes the signal mixed by the mixer. A data receiving device having means. (2) The plurality of antennas have antennas each having directivity in the front, rear, left and right directions of the moving body, and the synthesizer has a carrier frequency and a mixer corresponding to the antenna having directivity in the forward direction. It is characterized by outputting a signal with a local oscillation frequency obtained by adding the maximum Doppler frequency, and outputting a signal with a frequency obtained by subtracting the maximum Doppler frequency from the carrier frequency to a mixer corresponding to an antenna having directivity in the backward direction. The data receiving device according to claim (1). (3) The data according to claim (2), wherein the synthesizer outputs a signal having the same local oscillation frequency as the carrier frequency to a mixer corresponding to an antenna having directivity in the left and right directions. Receiving device.