JPH0488729A - Space diversity reception system - Google Patents

Abstract

PURPOSE:To attain frequency conversion under the same condition at plural antenna terminals and to eliminate complicated wiring between receivers by generating a reference oscillating frequency signal from one of the antenna terminals and using the signal so as to make frequency conversion under the same condition at the other antenna terminal. CONSTITUTION:Antennas 1A, 1B parted spatially in antenna terminals 7A, 7B receive a radio wave respectively. A frequency conversion signal is fed to signal branch circuits 9A, 9B via coaxial cables 4A, 4B and fed to a signal selection circuit 5 in a receiver, in which a reception signal with a more excellent characteristic is selected. In this case, only the antenna terminal 7A being a master is provided with a reference frequency signal oscillation circuit 8 and a reference oscillation frequency signal fc outputted from the reference frequency signal oscillation circuit 8 is used to make frequency conversion in the antenna terminals 7A, 7B, then the frequency conversion is implemented entirely under the same condition.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a space-based frequency reception system, and in particular, to a space-based frequency reception system that performs frequency conversion at a plurality of antenna ends under the same conditions using one reference oscillation frequency signal. This article relates to a space-based digital reception system.

[Conventional technology]

In a spatial diversity reception system, a method is adopted in which the frequency of the signal from the antenna is frequency-converted to a lower frequency at the antenna end to reduce signal propagation loss in the coaxial cable installed between the antenna end and the receiving device. There is.

For this frequency conversion, each antenna end is provided with an oscillator that generates a reference oscillation frequency signal.

However, if an oscillator that generates a reference oscillation frequency signal is provided in each antenna end individually, there will be a difference between the reference frequencies due to changes or differences in the characteristics of those oscillators, especially the crystal oscillator installed inside the oscillator. However, we have encountered a problem in which there is a difference in the frequency conversion results.

In order to improve this problem, a frequency converter for diversity reception solves the problem of providing one reference oscillation frequency signal from the receiving device to multiple antenna ends and having a separate reference oscillation frequency signal oscillator at each antenna end. is known (for example, Japanese Patent Application Laid-Open No. 1-279639).

[Problem II to be Solved by the Invention] However, in the method of providing the reference oscillation frequency signal from the receiving device, there is a problem that the device configuration and wiring connections become complicated depending on the system configuration.

The issues are detailed below. Generally, when constructing a single-aircraft diversity receiving system, the receiving apparatus is modularized into a block assembly configuration so that it can accommodate various system configurations. For example, as shown in FIG. 5, a system is configured using a plurality of modular receiving devices 17, 18, 19 and a receiving device side distribution device 16.

In the figure, IIA, IIB, 12A, and 12B collectively represent the antenna and the antenna end, respectively. A frequency conversion circuit is provided at each antenna end.

FIG. 5 is a configuration diagram when output is performed for each channel in a 6-channel diver single reception system.

The receiving devices 17, 18, and 19 each have an oscillator capable of providing a reference frequency for driving circuits within the receiving device and providing a reference oscillation frequency signal at the antenna end. Receiving device 17~
Similar to the conventional case where a reference oscillation frequency signal oscillator is provided at each antenna end, a slight error in characteristics occurs between the oscillators in the antenna 19. Therefore, any one oscillator in the receiving device 17, 18, 19 is used to provide one reference oscillation frequency signal for frequency conversion at the antenna end. Therefore, in order to exclude the oscillator that is not used for the antenna end, connect the receiving device f to the cable 30A.
Wire using ~30D. Therefore, there is the problem of system configuration complexity in that such cable wiring connections must be made, and also the system configuration dependence problem in that the connections change depending on the number of receiving devices. Furthermore, since wiring connections are made using cables, there is a problem in that the cost increases.

In view of the above, the present invention performs frequency conversion at a plurality of antenna ends using a common reference oscillation frequency signal without depending on the system configuration.

The purpose of the present invention is to realize an open-air diversity reception system that has a simple circuit configuration and can be realized at low cost.

[Means for Solving the Problems] In order to solve the above problems and achieve the above objects, the present invention provides an oscillation circuit that generates a reference oscillation frequency signal at one of the plurality of antenna ends. A reference oscillation frequency signal is provided from the base to the other antenna ends, and the other antenna ends also perform frequency conversion based on this reference oscillation frequency signal.

(Function) An oscillation circuit that generates a reference frequency signal is built into one of the plurality of antenna ends, and the reference oscillation frequency signal is branched from this antenna end to another antenna end via a signal branching section. It becomes possible to provide the reference oscillation frequency to other antenna ends at the signal branching section without performing wiring for oscillator activation/deactivation processing on the device side.

〔Example〕

FIG. 1 shows the configuration of one embodiment of the spatial diversity reception system of the present invention.

In FIG. 1, two spatially separated antennas L
A and IB receive radio waves from, for example, a wireless microphone, and apply the received radio waves to two antennas $7A and 7B, respectively. Antenna ends 7A and 7B transmit signals obtained by converting radio waves to a lower frequency via a coaxial cable 4A.

4B, it is applied to, for example, signal branch circuits 9A and 9B that have built-in filters. The frequency-converted reception signals from the signal branch circuits 9A and 9B are as follows.

The signal is applied to a signal selection circuit 5 in the receiving device, and the signal selection circuit 5 selects the manually input received signal which has better characteristics.

The antenna end 7A includes a nine frequency conversion circuit 2A, a local oscillation circuit 3A, an antenna side mixing branch circuit 10A, and a reference frequency oscillation circuit 8 that generates a reference oscillation frequency signal fc. The antenna @7B also has the same configuration as the antenna end 7A, or the reference frequency oscillation circuit 8 is not provided.Therefore, the reference oscillation frequency signal f applied to the local oscillation circuit 3B at the antenna end 7B is The reference oscillation frequency signal fC output from the reference frequency oscillation circuit 8 in the antenna side mixing branch circuit 10A
- Coaxial cable 4A - Signal branch circuit 9A/9B - Coaxial cable 4B - Antenna side mixing branch circuit 10B) and is applied to the local oscillation circuit 3B. Frequency conversion is also performed at one antenna end 7B using the same reference oscillation frequency signal fc as at the antenna end 7A. That is, the signal branch circuits 9A and 9B are connected to the antenna ends 7A and 7B, respectively.
While outputting the frequency-converted reception signal from the antenna end 7A to the receiving device side, the reference oscillation frequency signal f from the antenna end 7A,
is branched to the antenna end 7B side.

The details of the circuit of the antenna end 7A including the frequency conversion according to FIG. 2 are shown. In the figure, the 5 frequency conversion circuit 2A includes an RF amplifier 21. It consists of a mixer 22° filter 23. In addition, the local oscillator circuit 3A is a voltage controlled oscillator (VC
O)31. Loop filter 329 Frequency divider 333 Phase-locked loop (PLL) A local oscillation circuit 3A consisting of an integrated circuit 34 and a reference frequency signal oscillation circuit 8 constitute a PLL to generate a stable local frequency signal FL○.

The reference frequency signal oscillation circuit 8 is, for example, 240KH,
This frequency oscillation signal is divided by 1/M by the PLL integrated circuit 34, and is combined with the signal from the frequency divider 33 which divides the frequency of the output signal of the VCO 31 by 1/N. The phases are compared in the PLL integrated circuit 34 and outputted from the PLL integrated circuit 34 as a loop error signal.

The loop error signal is input to the loop filter 32, and V
The CO 31 is applied to the mixer 22 as a local frequency signal PLO of, for example, 480 MH, and mixed with a signal of a frequency, for example, 800 MH2, received by the antenna IA, which is input via the RF amplifier 21, to obtain a reception frequency of 8.
Frequency conversion is performed from 00MH2 to the lower frequency 320MH2. This frequency-converted signal is outputted to the antenna side mixer 10A via the filter 23, and then outputted to the signal selection circuit 5 of the receiving device.

The frequency conversion operation at the antenna end 7B is also 240KH.
This is the same as the antenna end 7A described above, except that the reference oscillation frequency signal fC of No. 2 is obtained from the reference frequency oscillation circuit 8 to the antenna end 7.

As described above, the reference frequency signal oscillation circuit 8 is provided only at the antenna end 7A serving as a mask, and the reference oscillation frequency signal fC output from the reference frequency signal oscillation circuit 8 is used to generate signals within the antenna ends 7A and 7B. Since frequency conversion is performed, frequency conversion is performed under exactly the same conditions. Also,
Since the reference oscillation frequency r is set as low as 240KH, even if the signal is propagated from the reference frequency signal oscillation circuit 8 in the antenna end 7A to the local oscillation circuit 3B in the antenna end 7B, a high frequency signal will be propagated. The accompanying problems, such as signal loss and distortion in the coaxial cables 4A and 4B, do not occur. Furthermore, antenna ends 7A and 7
In the example of FIG. 1, the reference oscillation frequency signal fc is transmitted from the antenna end 7A to the antenna end 7B at the position where the coaxial cables 4A and 4B are connected to the signal branch circuits 9A and 9B.
Since the branching is performed, the system can be configured without being influenced by the configuration of the receiving circuit (corresponding to the receiving units 17 to 19 in FIG. 5) disposed after the signal branching circuits 9A and 9B. I can do it.

FIGS. 3 and 4 show the configuration and connections of a diversity reception system based on the present invention, which corresponds to the conventional configuration described with reference to FIG. 5.

FIG. 3 shows the antenna section 11A, IIB or.

A configuration is shown in which the antenna portions 12A and 12B with better characteristics are selected and output. Antenna section 11A, I
IB, 12A, and 12 collectively represent the antenna and the antenna end, respectively. Antenna section 11A, II
B, 12A 12B and signal branch circuit 19A in the receiving device
, 19B. Coaxial cables 4A to 4D are wired between the antenna parts 11A, 1IB12A, 12B and the antenna distribution device 14. The antenna distribution device 14 includes a signal branch circuit 1
41,142. Distribution circuit 143. and a signal branch circuit 15. 146. A distribution circuit 147 is provided. Outputs from distribution circuits 143 and 147 are coaxial cables 4E and 4F.
The signal is inputted to the signal branching circuits 19A and 19B in the receiving device via.

In FIG. 3, the reference frequency signal oscillation circuit 8 shown in FIG. antenna part 1
．． It is applied to the local oscillation circuit at the antenna end in 1B, 12A, and 12B.

FIG. 4 shows an example in which the received signal of each channel is applied to the signal branching circuit 19Al 19A2.19B1.19B2 in the receiving device. For this reason.

An antenna distribution device 15 is provided. The antenna distribution device 15 includes signal branch circuits 161 to 164 and a distribution circuit 1.
51. Amplification circuit 1522 distribution circuit 153, and 2 distribution circuit 155. It has an amplifier circuit 156 and a distribution circuit 157. In this case as well, the reference frequency signal oscillation circuit 8 is provided at the antenna end in the antenna section 11A, and the reference frequency signal [,] is transmitted to the signal branching circuits 161 to 1 of the antenna distribution device 15.
64 to the local oscillation circuits at the antenna ends in the antenna sections 11A, 12A, and 12B.

As is clear from the configuration of the digital reception system shown in FIGS. 3 and 4, the frequency is converted at each antenna end using a common reference oscillation frequency signal fc. In addition, the antenna distribution device 1 where the coaxial cables 4A to 4D are closest
The reference oscillation frequency signal fc is branched at 4 or 15, and is not affected by the configuration of the receiving device signal branching circuits 19A, 19B, or 19A1.19A2.19B1.19B2.

〔Effect of the invention〕

As described above, according to the present invention, one of the antenna ends
Since a reference oscillation frequency signal is generated from one antenna and this reference oscillation frequency signal is used to perform frequency conversion under the same conditions at other antenna ends, frequency conversion can be performed under the same conditions at a plurality of antenna ends.

In particular, in the present invention, a reference frequency signal is generated at one of the plurality of antenna ends, and this reference oscillation frequency signal is branched to the other antenna end at the position where it is most likely to branch.
The reference oscillation frequency signal can be branched without depending on the configuration of the receiving device, and complicated wiring between the receiving devices becomes unnecessary.

Furthermore, in the present invention, since a low-frequency reference oscillation frequency signal is generated, the problem that occurs when a high-frequency reference oscillation frequency signal is branched does not occur.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of a spatially diharstic reception system of the present invention. FIG. 2 is a partial circuit diagram of FIG. 1. 3 and 4 show signal branches of a reference oscillation frequency signal according to an embodiment of the present invention, and FIG. 5 is a diagram showing the configuration of a conventional spatial die-hard reception system. (Explanation of symbols) IA IB...Antenna 2A 2B ・ 3A 3B ・ 4A 4B ・ 5 ・ 7A 7B ・ 8 ・ 9A 9B ・ 10A, 1OB ・ 11A, 1IB. Frequency conversion circuit local oscillator circuit coaxial cable. Signal selection circuit. antenna end. Reference frequency signal oscillation circuit. Signal branch circuit/antenna side mixing branch circuit 2A, 12B...antina part 14°/antenna distribution device. Patent Issuer Co., Ltd. Tamura Manufacturing Co., Ltd. Tamura Electronics Co., Ltd.

Claims (1)

[Claims] 1. In a diversity reception system in which frequency conversion is performed at each of a plurality of antenna ends connected to a plurality of antennas to a frequency lower than the frequency received by the antenna, the frequency is transmitted to one of the plurality of antenna ends. A signal oscillation circuit that generates a reference oscillation frequency signal used for conversion is provided, the reference frequency signal is provided from the antenna end to another antenna end, and frequency conversion at the plurality of antenna ends is performed based on the reference oscillation frequency signal. A spatial diversity reception system characterized by being configured as follows.