JPH05172866A - Spectrum measurement device - Google Patents

Abstract

PURPOSE:To permit the signals in a wide band region to be measured at a same time, by obviating the need of the readjustment of the synchronous cycle of a variable band-pass filter for suppressing the unnecessary signal even if the measurement cycle is varied. CONSTITUTION:A measured signal is distributed into two parts by a distributor 1. One signal is inputted into a variable BPF 2, and only the unnecessary signal is extracted and inputted into a synthesizing device 5. As for the other output of the distributor 1, the amplitude is adjusted by a variable attenuator 4 and inputted into the synthesizing device 5. Two signals are adjusted by a phase shifter 3 and the variable attenuator 4 so that the amplitude of the unnecessary signal component is equal and the phase is different by 180 deg., only the unnecessary signal components can be deleted by the synthesizing device 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectrum measuring apparatus, and more particularly to a spectrum measuring apparatus for measuring a wide band spectrum.

[0002]

2. Description of the Related Art Conventionally, a spectrum measuring apparatus selects a desired signal from signals under measurement by a variable bandpass filter 7 (hereinafter referred to as "variable BPF") as shown in FIG. It was to measure with the analyzer 8.

[0003]

However, in the conventional spectrum measuring apparatus, when the signal to be measured has a wider band than the variable BPF 7, the measurement frequency cannot be changed unless the tuning of the variable BPF 7 is sequentially changed. However, there is a problem that a wideband signal cannot be measured at the same time.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a spectrum measuring apparatus capable of simultaneously measuring a wideband signal without re-adjusting it.

[0005]

In order to achieve the above object, a spectrum measuring apparatus of the present invention includes a divider for dividing a signal under measurement into two and only an unnecessary signal included in one output signal divided by the divider. Of the variable bandpass filter for selecting, the phase shifter for controlling and outputting the output signal of the variable bandpass filter so that the phase thereof has a phase difference of 180 ° from the unnecessary signal, and the other output distributed by the distributor. A variable attenuator that outputs a signal so that the amplitude of the unwanted signal matches the amplitude of the unwanted signal of the output signal of the phase shifter, and a combiner that combines the output signal of the variable attenuator and the output signal of the phase shifter And a spectrum analyzer for measuring the spectrum of the output signal of the combiner.

[0006]

According to the spectrum measuring apparatus having the above structure, the variable BPF is tuned to the unnecessary signal contained in one of the output signals distributed by the distributor and passed through, and the phase of the output signal of the variable BPF is phase-shifted. Is controlled to have a phase difference of 180 ° with the unwanted signal, while the variable attenuator matches the amplitude of the unwanted signal of the output signal of the phase shifter and the other output of the distributor, and the variable attenuation is performed by the combiner. The output signal of the phase shifter and the output signal of the phase shifter are combined. At the combiner output of this combiner, the unwanted signals will cancel each other out.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram showing a spectrum measuring apparatus according to an embodiment of the present invention.

In the figure, 1 is a divider for dividing the signal under test into 2 and 2 is a variable band pass filter (hereinafter referred to as "variable BPF 2") for selecting only unnecessary signals included in one of the output signals divided by the divider. ) 3 is a phase shifter for controlling and outputting the output signal of the variable BPF 2 so that the phase thereof is 180 ° out of phase with the unnecessary signal.

Reference numeral 4 is a variable attenuator for outputting the other output signal distributed by the distributor 1 such that the amplitude of the unwanted signal matches the amplitude of the unwanted signal of the output signal of the phase shifter 3.
Is a combiner for combining the output signal of the variable attenuator 4 and the output signal of the phase shifter 3. A spectrum analyzer 6 measures the spectrum of the output signal of the combiner 5.

Therefore, according to the spectrum measuring apparatus of this embodiment, the signal under measurement is divided into two by the divider 1. One of the distributed signals is input to the variable BPF 2. Only the unnecessary signal is selected by the variable BPF 2, and the phase of the unnecessary signal is made variable by the phase shifter 3.

The amplitude of the other signal of the distributor 1 is made variable by the variable attenuator 4. Then, the combiner 5 combines the signals from the phase shifter 3 and the variable attenuator 4. In this case, the output signal of the phase shifter 3 and the output signal of the variable attenuator 4 have the same unnecessary signal component amplitude and a phase of 180 °.
Since they are adjusted in the phase shifter 3 and the variable attenuator 4 so as to be different, unnecessary signals cancel each other out at the output end of the combiner 5. Therefore, the spectrum analyzer 6
A signal from which unnecessary signals have been removed is input to.

The phase shifter 3 and the variable attenuator 4 do not need to be readjusted even if the measurement frequency is changed, and can simultaneously measure a wideband signal.

[0013]

As described above, according to the spectrum measuring apparatus of the present invention, the variable attenuator, the variable bandpass filter, and the phase shifter are adjusted so that the unwanted signals cancel each other at the input of the spectrum analyzer. Even if the frequency is changed, it is not necessary to readjust these. Therefore, it is possible to simultaneously measure a wideband signal without retuning the variable bandpass filter.

[Brief description of drawings]

FIG. 1 is a block diagram showing a spectrum measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional spectrum measuring apparatus.

[Explanation of symbols]

 1 divider 2 variable bandpass filter (variable BPF) 3 phase shifter 4 variable attenuator 5 combiner 6 spectrum analyzer 7 variable bandpass filter (variable BPF) 8 spectrum analyzer

Claims (1)

[Claims] 1. A divider for dividing a signal under test into two, a variable bandpass filter for selecting only an unnecessary signal included in one of the output signals divided by the divider, and an output signal for the variable bandpass filter. The phase shifter for controlling and outputting the phase so as to have a phase difference of 180 ° with the unnecessary signal and the other output signal distributed by the distributor have the amplitude of the unnecessary signal of the unnecessary signal of the output signal of the phase shifter. Equipped with a variable attenuator that outputs to match the amplitude, a combiner that combines the output signal of the variable attenuator and the output signal of the phase shifter, and a spectrum analyzer that measures the spectrum of the output signal of the combiner A spectrum measuring device characterized in that