JPS63149927A - Fading pseudo signal generator - Google Patents

Abstract

PURPOSE:To facilitate to ensure a transmission band width required for an infinite phase shifter by constituting the infinite phase shifter giving an optional phase shift to an IF signal input to be modulated to generate a signal corresponding to a reflected wave at a high frequency band of an output of a local oscillator. CONSTITUTION:An up-converter 5A frequency-converting an intermediate frequency signal of a 2nd path branched from a branch circuit 1 into a high frequency signal, a down-converter 5B frequency-converting the high frequency signal being an output of the up-converter 5A into the same frequency as the intermediate frequency signal, and a local oscillator 6 supplying a local carrier fL to both the up-converter 5A and the down-converter 5A, are provided. Then the infinite phase shifter 3 varies the phase of the local carrier fed to the up- converter 5A to give an optional phase shift to the intermediate frequency signal of the 2nd path. Thus, the circuit of the infinite phase shifter 3 in the path corresponding to the reflected wave is constituted by the high frequency band and the specific band width of the circuit is decreased and the equipment with high quality and wide transmission bend width is obtained.

Description

[Detailed Description of the Invention] [Summary] A fading pseudo signal generator used for testing intermediate frequency circuits of wireless communication receiving devices, etc., which is generated by combining a signal equivalent to a direct wave and a signal equivalent to a reflected wave. However, in order to create a signal equivalent to a reflected wave, an infinite phase shifter that applies an arbitrary phase shift to the modulated IP signal input is not constructed directly using the IP multiplied signal frequency band, but instead is constructed using a local oscillator. The device is constructed in a high output frequency band, making it easy to secure the transmission bandwidth required by the infinite phase shifter, thereby improving the quality of the device.

[Industrial application field]

The present invention relates to a fading pseudo signal generator used for testing radio communication receiving devices, that is, a pseudo signal generator for testing that simulates a received signal that fluctuates due to fading, and particularly relates to a fading pseudo signal generator used for testing wireless communication receiving devices. This invention relates to an intermediate frequency band fading pseudo signal generator used for testing frequency circuits.

A received radio wave that undergoes fading in wireless communication is a composite wave of a direct wave from the other party's transmitter and a reflected wave that is reflected from an intermediate ground or the like and reaches the receiver. Since the direct wave and the reflected wave have different propagation paths, their amplitudes and phases are different from each other and vary over time.

Therefore, as a fading pseudo signal generator for testing that simulates a received signal, it is possible not only to easily change the amplitude and phase of the input received signal, but also to change the original quality of the input received signal. not to damage, i.e.
A fading pseudo signal generator used for intermediate frequency band testing can secure the transmission bandwidth required to guarantee the signal quality multiplied by the modulated IF of the input intermediate frequency, and
It is desired that signal deterioration be reduced by a factor of two.

[Conventional technology]

FIG. 4 shows a block configuration of a conventional IF multiplied signal fading pseudo signal generator.

The input intermediate frequency modulated IF multiplied signal is divided into two by a hybrid (HYB) 1, and branched into a first path corresponding to a direct wave and a second path corresponding to a reflected wave.

The IP multiplied signal branched to the first path is input to the attenuator (ATT) 2A via the delay line DEL-a with an appropriate delay amount, and the attenuator (ATT) 2A applies a specified attenuation amount to the amplitude of the input signal. and is connected to the hybrid (HYB) 5.

The IF multiplied signal branched to the second path is also input to the infinite phase shifter (EPS) 3 via the delay line DEL-b with an appropriate delay amount, and the infinite phase shifter (HPS) 3 inputs an arbitrary signal to the input signal. Gives the specified phase delay■.

The output of infinite phase shifter (EPS) 3 is an attenuator (ATT).
) 2B, and the attenuator (ATT) 2B gives a specified amount of attenuation to the amplitude of the input signal and converts it into a hybrid (H
YB) Connected to 4.

Hybrid (HYB) 4 is an IF multiplied signal that passes through the first path equivalent to a direct wave and receives specified attenuation, and an IF multiplied signal that passes through a second path equivalent to a reflected wave and receives a specified phase shift and specified attenuation. The signals are combined and an IP signal output that simulates the fading received signal is output as the device output.

[Problem that the invention seeks to solve]

As mentioned above, the conventional fading pseudo signal generator shown in FIG.
A composite wave signal with any combination of amplitude and phase of the II' signal equivalent to the double signal reflected wave is generated, and a test signal imitating the received signal in various fading states is generated and used for testing the intermediate frequency circuit of the receiving device. can do.

However, the circuit of the conventional fading I pseudo signal generator shown in FIG. The transmission bandwidth of the attenuator 2A of the path and the infinite phase shifter 3 and attenuator 2B of the second path is, for example, 20 MHz as the transmission bandwidth ΔB required by the modulated signal of the received signal. Each of these circuits needs to satisfy a bandwidth of +2 at the center frequency of 70 MHz, since the input signal to each of these circuits is an IP multiplied signal in the intermediate frequency band of, for example, 70 MHz.
It is necessary to secure a wide transmission bandwidth of 0M) lz.
Bandwidth/center frequency of fractional bandwidth is 40MHz/70M
The large value of Hz = 4/7 makes it difficult to manufacture the circuit.

In particular, the infinite phase shifter 3 that continuously varies and applies a designated phase shift to the II2 signal of the second path is easy to manufacture with a center frequency of 70 MHz and a bandwidth of 40 MHz, with minimal level fluctuations. As a result, a problem arises in that the quality of the pseudo signal of the output signal of the fading pseudo signal generator is degraded.

[Means for solving problems]

The problem that the circuit of the infinite phase shifter 3 of the second path in the conventional fading pseudo signal generator mentioned above has a large fractional bandwidth, making it difficult to manufacture and deteriorating the quality of the pseudo signal output from the device, is as follows. The operation of the infinite phase shifter 3, which continuously varies and imparts an arbitrary phase to the second path signal, is not performed in the path of the input signal of a low frequency called the intermediate frequency of the receiving device. The configuration is such that the frequency conversion is performed using the path of an unmodulated carrier wave with a high frequency called the oscillation frequency of the local oscillator, and the infinite phase shifter 3 is operated at a single frequency without band broadening, and the ratio of the frequency conversion circuit is This is solved by the configuration of the present invention which attempts to reduce the bandwidth to a small value.

As shown in the principle block diagram of FIG. 1, the configuration of the present invention includes a branch circuit 1 that branches an input intermediate frequency modulated signal into a first path and a second path; an infinite phase shifter 3 that provides an arbitrary phase shift to the intermediate frequency signal of the two paths; a level variable means 2 provided in at least one of the first path and the second path; and an output signal of the first path. A fading pseudo signal generator comprising a synthesizer 4 for synthesizing the output signals of the second path, an up converter 5A for frequency converting the intermediate frequency signal of the branched second path of the branch circuit 1 into a high frequency signal; A down converter 5 converts the high frequency signal output from the up converter 5A to the same frequency as the intermediate frequency signal.
B, and a local oscillator 6 that supplies a local carrier fL to both the amplifier converter 5A and the down converter 5B.
and the infinite phase shifter 3 changes the phase of the local carrier wave supplied to the amplifier/converter, thereby giving an arbitrary phase shift to the intermediate frequency signal of the second path.

[Effect]

The intermediate frequency signal of the modulated signal of frequency IP input to the device is branched into a first path and a second path in a branch circuit 1, and the intermediate frequency signal branched to the second path is sent to an up converter 5A.
is mixed with the local carrier wave of frequency fL from the local oscillator 6 to generate a high frequency signal RF of frequency (fL+rF).
However, the infinite phase shifter 3 inputs the local carrier wave from the local oscillator 6, shifts the phase of the local carrier wave to an arbitrary phase, and sends the phase-shifted local carrier wave to the up converter 5A. Therefore, the up converter 5A sends out a high frequency signal RF having a frequency of fL+IF and a phase shifted to a designated phase.

The high frequency signal RF output to the amplifier/converter 5 is
In the down converter 5B, the signal is mixed with a local carrier wave of frequency fL, frequency-converted, and the frequency is returned to the original signal of intermediate frequency IF. The intermediate frequency signal whose frequency is returned to the original intermediate frequency IF and which has undergone a specified phase shift is given a specified output level by the level variable means 2 and input to the synthesizer 4, where it is passed through the first pass. It is synthesized with the intermediate frequency signal of the frequency IF that has passed through and outputs an intermediate frequency signal having a desired level and phase.

The infinite phase shifter 3 is a circuit that inputs a high-frequency local carrier wave of a single frequency fL with no band spread from the local oscillator 6 and provides a phase shift, and has a fractional band that indicates the difficulty of configuring a circuit with a band. Since the width ΔB/fLO value becomes smaller, manufacturing becomes easier. Further, the problem is solved because the up converter 5A absorbs the level fluctuations occurring in the infinite phase shifter 3 by absorbing the fluctuations in the output level of the infinite phase shifter 3.

〔Example〕

FIG. 2 is a block diagram showing the configuration of a fading pseudo signal generator according to a first embodiment of the present invention.

The intermediate frequency signal IF input to the hybrid HYB 1 of the branch circuit 1 is a modulated signal with a bandwidth ΔB of 40 MHz and a frequency of 70 M)Iz. The level variable means 2 is composed of a first attenuator 2A on the first path and a second attenuator 2B on the second path.

The 70MHz signal branched into two by the hybrid HYBI in branch circuit 1 is divided into a first path equivalent to a direct wave and a second path equivalent to a reflected wave, and the 7 Q M tl z signal in the first path is connected to a delay line with an appropriate amount of delay. First attenuator 2 via DELa
The signal A is subjected to AGC amplification by its amplifier 22A, and is given a specified amount of attenuation by its attenuator 21A.

The 70MHz signal on the second path is also connected to a delay line DE with an appropriate amount of delay.
It is input to the IF/RF converter of up converter 5A via Lb.

The IP/RF converter to the amplifier/converter 5 uses the frequency of the oscillator 61 of the local oscillator 6 (15 GHz + 70 MHz
z ) local carrier wave by hybrid 62 and infinite phase shifter 3
The signal is input through the IF signal, and is mixed with the previous IF signal input with a frequency of 70 MHz to output a high frequency signal with a frequency of 15 GHz.

At this time, the infinite phase shifter 3 shifts the phase of the local carrier wave of the frequency (15 GfIz 70 MHz) output from the oscillator 61 to an arbitrary designated phase.

Furthermore, the high frequency signal with a frequency of 15 GHz output from the IP/RF converter of the amplifier/converter 5A absorbs fluctuations in the output level of the infinite phase shifter 3 during the frequency conversion process. Unnecessary wave components accompanying frequency conversion are removed by filter 5C.

In this way, the partial level 15 from which unnecessary frequency components have been removed
G) Iz multiplied signal is input to the RF/IF converter of the down converter 5B.

In the RF/IF converter of the down converter 5B, the 15 GHz high frequency signal from the filter 5C and the local carrier wave of the frequency (15 GHz ± 70 MHz) input from the oscillator 61 of the local oscillator 6 via the hybrid 62 are mixed and converted into the original signal. The frequency is converted to a 70MHz signal with an intermediate frequency of .

The 70 MHz signal converted to the original intermediate frequency of 70 MHz is amplified by the amplifier 22B T:AGc of the second attenuator 2B, given a specified attenuation by the attenuator 21B, and inputted to the hybrid IYB 4 of the synthesis circuit 4.

The hybrid HYB of the synthesis circuit 4 receives a 70 MHz signal which has been given a specified attenuation through the first attenuator 2A of the first path, and a 70 MHz signal which has been given a specified phase shift and specified attenuation through the second path. A 70MH2 signal that simulates an arbitrary fading received signal is output by combining the signals.

Both the infinite phase shifter 3 and the amplifier/converter 5A input a high frequency carrier signal of frequency (15 GHz + 70 MHz) from the local oscillator 6, and perform phase changes and changes over a transmission bandwidth ΔB of 40 MH2 required by the device. Frequency conversion is performed, but the fractional bandwidth ΔB of the circuit
/fL value is 40MHz / (15GHz±70M
Since the value of t(z) is small, its manufacture is easy, and since the up-converter 58 absorbs fluctuations in the output level of the infinite phase shifter 3, there is no problem.

FIG. 3 is a block diagram showing the configuration of a fading pseudo signal generator according to a second embodiment of the present invention. This embodiment has almost the same circuit configuration as the first embodiment shown in FIG. 2, but
The difference is that the circuit configuration of the first path, which corresponds to the direct wave, has an IF/RF converter, a filter, and a frequency conversion circuit for the RF/IF converter, similar to the circuit of the second path, which corresponds to the reflected wave. The point is that the operating characteristics of the circuits are made the same.

That is, the 70 MHz signal of the output of the hybrid HYB l of the branch circuit 1 with the 70 MHz signal input is connected to the delay line D.
After passing through ELa, the IP/R of amplifier converter 7A
In the F converter, the frequency of the local oscillator 6 (15 GHz
+70MHz) local carrier wave to generate 15G[Iz
A doubled signal is generated, unnecessary waves are removed by a filter 7C, and a 15 GHz RF multiplied signal is extracted. The 15 GHz RF multiplied signal is returned to the original intermediate frequency 70 MHz signal in the down converter 7B, and is input to the first attenuator 2A, and is given the attenuation specified by the IF multiplied signal of the first pass to the first pass. The circuit format of the second path and the second path are made the same so that the transmission characteristics are made the same.

In this embodiment as well, the infinite phase shifter 3 poses a problem in manufacturing.
together with the up converter 5A, the value of the fractional bandwidth ΔB /fI of the circuit is 40MHz / (15GHz±
The upconverter 5A absorbs fluctuations in the output level of the infinite phase shifter 3, so there is no problem.

In the first and second embodiments, the configuration of the first attenuator 2A of the first path and the second attenuator 2B of the second path constituting the level variable means 2 is set to an intermediate frequency of 70 MHz.
However, it is of course possible to configure the first attenuator 2A and the second attenuator 2B at 15 GHz of the high frequency signal after frequency conversion.

In addition, in the above embodiment, a two-wave model fading pseudo signal generator is constructed with the second path corresponding to the reflected wave as one path, but the fading pseudo signal generator of the two-wave model is configured with a plurality of paths corresponding to the reflected wave. Needless to say, it is possible to construct an apparatus using a multiple wave model and applying the idea of the present invention.

〔Effect of the invention〕

As explained above, according to the present invention, the circuit of the infinite phase shifter in the path corresponding to the reflected wave of the fading pseudo signal generator can be configured in the received frequency band, and the fractional bandwidth of the circuit can be made small. This has the effect of facilitating the manufacture of a high-quality device with a wide transmission bandwidth. Further, since level fluctuations can be kept small over a wide transmission band, there is an effect that a high quality fading pseudo signal generator can be realized.

[Brief explanation of the drawing]

FIG. 1 is a principle block diagram showing the configuration of a fading pseudo signal generating device according to the present invention, FIG. 2 is a block diagram showing the configuration of a fading pseudo signal generating device according to the first embodiment of the present invention, and FIG. FIG. 4 is a block diagram showing the configuration of a fading pseudo signal generating device according to a second embodiment of the invention, and FIG. 4 is a block diagram of a conventional fading pseudo signal generating device. In Figures 1, 2, and 3, 1 is a branch circuit, 2A, 2B are attenuators, 3 is an infinite phase shifter, 4 is a combining circuit, 5A, 7A are up converters, 5B, 7B
is a down converter, 5G, 7C is a filter, and 6 is a local oscillator.

Claims (1)

[Claims] Two intermediate frequency modulated signals are input to the first path and the second path.
A branch circuit (1) that branches, an infinite phase shifter (3) that provides an arbitrary phase shift to the intermediate frequency signal of the branched second path of the branch circuit (1), and a level variable means (2) provided in at least one of them; and a synthesizer (4) for synthesizing the output of the first pass and the output of the second pass.
A fading pseudo signal generator comprising: an up converter (5A
), a down converter (5B) that frequency converts the high frequency signal output from the up converter (5A) to the same frequency as the intermediate frequency signal, and the up converter (5A) and the down converter (5B). Local oscillator (6) supplying local carrier wave fL
and the infinite phase shifter (3) is connected to the up converter (5A
) A fading pseudo signal generator characterized in that an arbitrary phase shift is given to the intermediate frequency signal of the second path by changing the phase of the local carrier wave supplied to the second path.