JPH04342318A - Diversity reception system - Google Patents

Abstract

PURPOSE:To realize a space diversity reception system with a pair of reception circuits, to miniaturize the device, to improve reliability and to reduce cost by periodically switching antennas one by one with an RF switching means. CONSTITUTION:Antennas 1 and 2 are respectively connected to an RF switching means 3. The RF switching means 3 selects the antenna 1 or 2 and connects it to a band filter 5. However, the selection is executed according to a selective signal from an RF switch changeover signal generating means 4 and does not depend on electric field strength received by the antennas 1 and 2 at all. According to this selective signal, the RF switching means 3 alternately connects the antennas 1 and 2 to the band filter 5 in a fixed cycle. Thus, a diversity effect equivalent to the space diversity reception system providing a received electric field strength detecting means at every antenna can be obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a space diversity reception system for a radio receiver.

0002

[Background Art] Conventionally, a space diversity reception method (Space diversity reception method) has been used.
In order to select and switch the reception system of each antenna in the antenna, one set of reception field strength detection means is connected to each antenna used for diversity reception, and the antenna and reception field strength detection means are connected to each other. Using two or more combinations, the reception field strength information from each reception field strength detection means is judged by a reception system switching controller to determine, select, and switch which antenna reception system to use. was.

0003

[Problems to be Solved by the Invention] However, the conventional method requires as many reception field strength detection means as the number of antennas used, and also requires a reception system switching controller to select the reception system. there were. In particular, the received field strength detection means must include a circuit up to the intermediate frequency stage or audio frequency stage for each antenna, which not only increases the circuit size and costs, but also causes problems such as a lack of reliability. There was a problem.

0004

[Means for Solving the Problems] In order to solve the above problems, the present invention provides an RF switch means (Radio Frequency Switch) for selecting any one of the plurality of antennas and connecting it to a receiver.
h (hereinafter simply referred to as an RF switch), the antenna is connected to a set of radio receivers, and the RF switch means periodically switches a plurality of antennas one by one to connect them to the radio receiver.

[0005]

[Operation] By doing the above, only one set of radio receivers is required, and not only is there no need for a receiving field strength detection means, but it is also necessary to select a receiving system based on the receiving field strength received by each antenna. Since the control device can be simplified, the device can be made smaller, and costs can be reduced and reliability can be improved.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the main components of a wireless receiver embodying the present invention. In the example in the figure, two antennas are used, and the receiver is a single superheterodyne reception system.The example includes a mixer that mixes the local oscillation frequency and reception frequency to create an intermediate frequency, and a mixer that mixes the local oscillation frequency and reception frequency to create an intermediate frequency. Later intermediate frequency amplifiers, intermediate frequency filters, detectors, audio circuits, etc. are omitted.

In the figure, antenna 1 and antenna 2 are
They are respectively connected to the RF switch means 3. The RF switch means 3 selects the antenna 1 or the antenna 2 and connects it to the bandpass filter 5. The selection is performed by a selection signal from the RF switch switching signal generation means 4, and the electric field received by the antenna 1 or the antenna 2 is It does not depend on strength at all. Based on the selection signal, the RF switch means 3 alternately connects the antenna 1 and the antenna 2 to the bandpass filter 5 at a constant cycle. If there are three or more antennas, antennas are switched from antenna 1 to antenna n in order. When the antenna is switched by the RF switch means 3, the switching frequency of the antenna and the reception frequency are mixed, and a frequency is generated by multiplying the two frequencies by the trigonometric function SIN.The frequency thus generated is as follows.
The switching frequency of the RF switch means 3 must be selected so as not to fall within the frequency of the local oscillator 8, intermediate frequency, image frequency, or reception band. Furthermore, as the phase difference between the carrier waves of the radio waves received by antenna 1 and antenna 2 approaches 180 degrees, the S
The amplitude of the frequency generated by the multiplication of IN increases, which causes the RF amplifier 6 to saturate.
Because the frequency that should be received may be interfered with,
Among the frequencies generated by SIN multiplication, the frequencies closest to the receiving frequency, the antenna's (switching frequency + receiving frequency) and (antenna switching frequency - receiving frequency) frequencies, are set outside the band of the bandpass filter 5. It is desirable to set the antenna switching frequency to .

Furthermore, if the receiving band and the band of the bandpass filter 5 are wide and the above-mentioned antenna switching frequency setting conditions are to be satisfied, the antenna switching frequency will become too high, making it impossible to achieve the above-mentioned antenna switching frequency setting conditions. In this case, the antenna switching frequency can be selected to be such that the pass gain of the audio filter is −20 dB or less. In this case as well, care must be taken to ensure that the frequency generated by the SIN multiplication does not become the local oscillation frequency, image frequency, or intermediate frequency of the local oscillator 8.

[0009]

Effects of the Invention This invention enables the reception electric field strength to be adjusted for each antenna by switching a plurality of antennas using an RF switch and connecting them one by one to a radio receiver by switching the antenna switching frequency as described above. It can achieve the same diversity effect as the space diversity reception method that has a detection means, requires only one set of radio receivers, does not require a reception system switching controller, eliminates the need for complex control, and can reduce the circuit size. Therefore, it is possible to downsize the device, improve reliability, and reduce the cost of the device.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main components of a wireless receiver embodying the present invention.

[Explanation of symbols]

1, 2 Antenna 3 RF switch means 4 RF switch switching signal generation means 5 Bandpass filter 6 RF amplifier 7 Mixer 8 Local oscillator

Claims (1)

[Claims] 1. A radio receiver comprising a plurality of antennas and an RF switch means for selecting and connecting any one of the plurality of antennas, wherein the RF switch means connects the plurality of antennas. A diversity reception method for wireless receivers that is characterized by periodically switching one signal at a time regardless of the strength of the received electric field.