JPS589443A - Reception switching device of mobile radio station - Google Patents

Abstract

PURPOSE:To always receive selectively an electric wave in a good receiving state while avoiding a complicated operation of a switch circuit, by inserting a high frequency attenuator between an antenna and a signal receiver which is receiving the transmission from a base station which is not used at the present time point. CONSTITUTION:The signal receivers 3 and 4 receive selectively the transmission from the 1st base station that transmits the 1st frequency as a carrier wave and the transmission from the 2nd base station that transmits the 2nd frequency as a carrier wave. The output of either one of these receivers 3 and 4 is connected to an output circuit, and a high frequency attenuator 7 is inserted between an antenna 1 and the input of the other transmitter through the switching 6. In the case of this switching, the receiving level outputs are compared 5 with each other. Then a switch circuit 6 is controlled to select the receiver having the higher receiving level output.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiving device for a mobile radio station. A first base station transmits information using a first frequency as a carrier wave, and a second base station installed at a different location from the first base station transmits information using a second frequency as a carrier wave. A mobile radio station within a range that can receive both the transmission from the first base station and the transmission from the second base station uses the transmission from one of the base stations. ing. Since both base stations are generally transmitting the same information, the mobile radio station can use the base station that provides the best reception.

FIG. 1 is a block diagram showing an example of a conventional device used in such a case, in which (1) is an antenna, (2) is an Fi distributor, and (3) is a carrier wave frequency of the first frequency (hereinafter abbreviated as F1). (4) is a receiver that receives the carrier wave frequency of the second frequency (hereinafter abbreviated as F2), (5) is a comparison circuit, (6) is a switching circuit, (6-1 ) are contacts that are switched by the switching circuit (6).

Comparison circuit for Fl reception level and F2 reception level (5
), and if the received level of Fl is higher, the output of the comparison circuit (5) controls the switching circuit (6), and the contact (
6-1) selects the output of the receiver (3). If the reception level of F2 is higher, the contact (6-1) selects the output of the receiver (4). In this way, the one with the higher reception level is always selected and received, but in conventional equipment, frequent switching occurs in areas where the electric field level from both base stations is about the same, resulting in noise such as shoe sounds caused by switching. Therefore, there was a drawback that the quality of communication deteriorated. In other words, the electric field level undergoes complex minute changes due to various causes, so in an area where the electric field levels from both base stations are about the same, there will be many points where the electric field levels of both base stations intersect. This is because switching is performed each time a mobile radio station passes.

This invention was devised to eliminate the above-mentioned drawbacks of conventional devices. By inserting an attenuator, the switching circuit operates only when the reception level of the base station being used is definitely higher than that of the base station not being used, thereby avoiding frequent operation of the switching circuit. However, it is an object of the present invention to provide a reception switching device that can always selectively receive radio waves in a better reception state.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 2 is a block diagram showing an embodiment of the present invention, where the same reference numerals as in FIG. 1 indicate the same or corresponding parts, (7) is a high frequency attenuator, (6-2), (6-3) , (6-4), (6-5)
is a switching contact controlled by the switching circuit (6) and the contact (6-1
) between the input terminal of the receiver (receiver (4) in the example in Figure 2) whose output is not connected to the contact (6-1) and the antenna (1). Insert a high frequency attenuator (7) into the

FIG. 3 is a level diagram showing the relationship between the reception level at a mobile radio station and the position of the mobile radio station, in which the mobile radio station is assumed to move on a line connecting both base stations, and Pl is the first
It is assumed that the mobile radio station moves on P1P2P3P4P5, and P represents the position of the second base station. It is assumed that the curve ABCI is the reception level for transmission from the first base station, and when the high frequency attenuator (7) is inserted, the level decreases as shown by the curve FGHI'. It is also assumed that the curve GCDE is the reception level for transmission from the second base station, and when the high frequency attenuator (7) is inserted, the level decreases as shown by G'HIJ. Although the curve in Figure 3 is a simple power curve, in reality the reception level fluctuates within a small range due to various complicated causes.
There are many points other than 0 where the reception levels represented by BCI and GCDE intersect, and in the conventional device shown in FIG. 1, the switching circuit (6) operates each time.

In the circuit shown in FIG. 2 of this invention, when the output of the receiver (3) is connected to the contact (6-1), P2P3P
When the position changes to 4, the output reception level of the receiver (3) changes to BCI, and the receiver (4) has a contact point (6-4).
.

Since the high frequency attenuator (7) is inserted through (6-5), the output reception level of the receiver (4) becomes G' HI and the intersection of both levels occurs at 24 points, and the switching circuit ( 6)
works. After this operation, the output reception level of the receiver (4) becomes D9, and the output reception level of the receiver (3) becomes I', so in this vicinity the curves F'GHI' and GCD
Nothing such as crossing with E will occur. Mobile radio station is F
When moving from 4 to F2, switch circuit (6) at point G
operates, and after operation, the level is B and σ, so that defects caused by frequent switching can be reliably removed.

In the above explanation, the present invention has been explained on the premise of switching between two base stations, the first base station and the second base station. However, when the number of base stations is three or more, switching between two base stations is possible. If the present invention is applied to all combinations of stations, the base station with the highest reception level can be selected as a result.

As described above, according to the present invention, the drawback of frequent reception switching in a mobile radio station can be eliminated, and a good reception condition can always be obtained even from l-.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional device, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a level diagram showing the relationship between mobile radio station position and reception level. (1)...Antenna, (2)...Distributor, (3), (
4)...Find receiver, (5)...Comparison circuit, (6
)...Truncation circuit, (7)...High frequency attenuator. Note that the reference numbers in the figures indicate the same or equivalent parts. Agent Makoto Kuzuno − 221− Body type Δ° (ri

Claims (1)

[Claims] Transmission from a first base station that transmits a first frequency as a carrier wave, and a second frequency that is installed at a different location from the first base station and that is different from the first frequency. A reception switching device for a mobile radio station that selectively receives transmissions from a second base station that transmits as a carrier wave, a first receiver that receives transmissions from the first base station; a second receiver that receives transmission from the second base station; and a receiver that connects the output of one of the first and second receivers to an output circuit and outputs the output of the other receiver. A switching circuit that switches to insert a high frequency attenuator between the input and the antenna, compares the reception level output from the first and second receivers, and selects the receiver with the larger reception level output as one of the receivers. 1. A reception switching device for a mobile radio station, comprising: a comparison circuit for controlling the switching circuit to select a mobile radio station as a mobile radio station.