JPH0486038A - Radio channel testing circuit - Google Patents

Abstract

PURPOSE:To reduce a mounting space by extracting only a desired reception frequency component from synthesized transmitted signals. CONSTITUTION:A first oscillation signal (frequency fL1) is applied from a first oscillation circuit 38 to a first mixer circuit 82. The first mixer circuit 82 mixes the first oscillation signal into the synthesized transmitted signals. In this case, the transmission frequency component of a second channel is converted to a frequency component. Namely, in this case, the first oscillation signal frequency fL1 is adjusted so that the frequency component of the second channel can be fN, and the mixed signal from the first mixer circuit 82 is applied to a filter circuit 84 and filtered in this circuit 84 so as to extract only the frequency component fN. Thus, the return test of the desired channel can be executed with simple configuration.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a wireless channel test circuit, and more particularly to a test circuit for a wireless channel loopback test.

(Prior Art) Generally, in a wireless system (transmission/reception system) having n wireless channels (n is an integer of 2 or more), first to nth transmitters 11 to 1n and It includes first to nth receivers 21 to 2n.

Referring to FIG. 4, in this type of transmission/reception system, the first
The transmission signals from the nth transmitters 11 to 1n are filtered by the first to nth channel filtering circuits 31 to 3n, respectively, and then filtered by the transmission combining circuit 40 for each radio channel (first to nth channel). and is transmitted from the transmitting antenna 41 as a combined transmit signal.

On the other hand, the combined transmission signal received by the reception antenna 42 is
After being filtered by the reception filter circuit 43, the reception common amplifier circuit 4
4, and is separated into first to nth received signals by a reception distribution circuit 45, and distributed to first to nth receivers 21 to 2n, respectively.

In the above-mentioned transmission/reception system, a test circuit shown in FIG. 4 is connected to perform a loopback test of a radio channel. That is, the first to n-th high frequency switching devices 51 to 5n are arranged between the first to n-th transmitters 11 to 1n and the first to n-th channel filter circuits 31 to 3n, respectively. 1st to nth high frequency switching devices 51 to 5
n is connected to the mixer circuit 60. An oscillator 61 is connected to this mixer circuit 60.

A receiving coupling circuit 63 is connected to the output side of the mixer circuit 60 via a filtering circuit 62, and this receiving coupling circuit 63 is connected to the input side of the receiving filtering circuit 43.

Here, with reference to FIG. 4, a case will be described in which the second channel is the channel to be tested for loopback.

When testing the second channel by loopback, the transmission signal (frequency f2) from the second transmitter 12 is applied to the mixer circuit 60 by the second high frequency switch 52.

At this time, the oscillation circuit 61 outputs the transmission/reception interval frequency (f a 2
An oscillation signal having fR□) is output, and the mixer circuit 60 mixes the second transmission signal and the oscillation signal.
A received signal of the second channel (received wave second layer wave number f R2) is generated.

This second received wave fR2 is filtered by a filtering circuit 62, and is given to a receiving input coupling circuit 63 as a filtered received wave. Then, it is input to the reception filter circuit 43 with a predetermined (preset) coupling amount.

The output (filtered signal) from the reception filtering circuit 43 is given to the second receiver 22 via the reception common amplifier circuit 44 and the reception distribution circuit 45.

(Problems to be Solved by the Invention) Conventionally, for a loopback test of a transmitting/receiving system, first to n-th high frequency switchers 51 to 52, a mixer circuit 60, an oscillator 61, a filter circuit 62, and a receiving coupling circuit 63 are used. A test circuit consisting of is arranged in the transmitting/receiving system, and in particular, it is necessary to insert first to nth high frequency switchers 51 to 5n on the output sides of the first to nth transmitters 11 to 1n, respectively. There is.

For this reason, not only is a large amount of mounting space taken up due to the arrangement of the first to nth high frequency switching devices 51 to 50 and the increase in the number of connection cables, but also the first to nth high frequency switching devices 51 to 5n are mechanically Since switching operations are performed periodically, there is a problem in that reliability decreases significantly over time.

An object of the present invention is to provide a folding test circuit that requires less mounting space and is highly reliable.

(Means for Solving the Problems) According to the present invention, there is provided a transmitter that has a plurality of radio channels and transmits a composite transmission signal to which transmission signals of different transmission frequencies are assigned to each of the radio channels; It is used when performing a loopback test of the radio channel in a wireless system having a receiving unit that receives a composite reception signal to which reception signals of different reception frequencies are assigned to each channel, and receives the composite transmission signal and receives a preset signal. a first conversion means for converting a transmission signal of a transmission frequency corresponding to a radio channel to be set into a predetermined intermediate frequency component; and a second conversion means for converting the intermediate frequency component into a reception frequency component corresponding to the set radio channel. and supply means for supplying the received frequency component to the receiving section.

(Example) The present invention will be explained below with reference to Examples.

Referring to FIG. 1, the wireless channel test circuit according to the invention includes an input terminal T-71 and an output terminal 72. A wireless channel test section 8 is arranged between the input terminal 71 and the output terminal 72.

Here, the operation of the radio channel test circuit shown in FIG. 1 will be explained with reference also to FIGS. 2 and 3. Here, the same reference numerals are given to the same components as those shown in FIG. 4, and the description thereof will be omitted, and a case will be described in which a loop test is performed on the second channel.

The output (combined transmission signal) from the transmission (8) combining circuit 40 is given to the input terminal 70 via the transmission output terminal 40a.The combined transmission signal is then input to the radio channel test section 8.

A combined transmission signal is input to a first mixer circuit 82 via a transmission coupling circuit 81 . A first oscillation circuit 83 is connected to the @1 mixer circuit 82, and a first oscillation signal (frequency fLl) is applied from the first oscillation circuit 83 to the first mixer circuit 82. The first mixer circuit 82 mixes the composite transmission signal and the first oscillation signal. At this time, the transmission frequency component T2 of the second channel is converted to the frequency component N (fN-f72 ft+).

That is, here, the first oscillation signal frequency fL+ is adjusted so that the frequency component in the second channel becomes fN. The mixed signal (mixed component) from the first mixer circuit 82 is given to a filter circuit 84, where it is filtered and
Only N frequency components are extracted.

This fN frequency component is given to a second mixer circuit 85, where it is mixed with a second oscillation signal (frequency f L2) given from a second oscillation circuit 86. At this time, the second oscillation signal frequency fL2 is determined by the second mixer circuit 85.
The output signal frequency is adjusted to be the receiving frequency fR2 in the second channel. The fR2 reception frequency component is given to the output terminal 72 by the reception input coupling circuit 87, and input to the reception filtering circuit 43 via the reception input/output terminal 43a.

The output from the reception filter circuit 43 is transmitted to a reception common amplifier circuit 44,
The signal is input to the second receiver 22 via the reception distribution circuit 45, and a loopback test of the second channel is executed.

When conducting a loopback test for the n-th channel, the frequency fLI of the first oscillation signal is adjusted to convert the n-th transmission signal frequency fTo to a predetermined frequency fN (fN=fT-fz), It is only necessary to extract only the fN frequency component by filtering with a filtering circuit, and then adjust the second oscillation signal frequency fL2 and convert it to the n-th reception frequency fRfi.

In this manner, the present invention allows a desired channel folding test to be performed.

Margins below (effects of the invention) As explained above, in the present invention, only the desired reception frequency component is extracted from the composite transmission signal, so the high frequency switch that was conventionally required for each channel is no longer necessary, and as a result, This has the effect of requiring less mounting space and increasing reliability.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a radio channel test circuit according to the present invention, FIG. 2 is a block diagram showing a transmitting section of a radio system in which the radio channel test circuit shown in FIG. 1 is used, and FIG. FIG. 1 is a block diagram showing a receiving section of a radio system in which the radio channel test circuit shown in FIG. 1 is used, and FIG. 4 is a block diagram showing the conventional radio channel test circuit together with the radio system. ]1 to 1n...first to nth transmitters, 21 to 2
n...first to nth receivers, 3] to 3n...channel filtering circuits, 40...transmission combining circuits, 41...transmission antennas, 2...reception antennas, filtering circuits, 44...・Reception common amplifier circuit, 3...Reception 5...Reception distribution circuit Figure 2 Figure 3 Figure

Claims (1)

[Claims] 1. A transmitter having a plurality of radio channels and transmitting a composite transmission signal to which transmission signals of different transmission frequencies are assigned to each of the radio channels, and a receiving frequency that is different for each of the radio channels. used when performing a return test of the wireless channel in a wireless system having a receiving unit that receives the received signal as a combined received signal to which the received signal is assigned, and receives the combined transmitted signal and transmits corresponding to a preset wireless channel. a first conversion means for converting a frequency transmission signal into a predetermined intermediate frequency component; a second conversion means for converting the intermediate frequency component into a reception frequency component corresponding to the set wireless channel; and supply means for supplying the signal to the receiving section. 2. In the radio channel test circuit according to claim 1, the first conversion means is a first oscillation device that outputs a first oscillation signal of a first channel frequency determined for each set radio channel. means, first generation means for mixing the first oscillation signal and the composite transmission signal to generate a mixed signal having a predetermined intermediate frequency component, and selection means for selecting only the intermediate frequency component. and the second conversion means includes a second oscillation means that outputs a second oscillation signal of a second channel frequency determined for each set wireless channel, and a a second generating means for generating a reception frequency component corresponding to the set wireless channel by mixing the received frequency component with an oscillation signal.