JP2008224306A - Spectrum analysis system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spectrum analysis system which stably measures a high-frequency signal. <P>SOLUTION: The spectrum analysis system converts a received high-frequency analog signal a0(t) into a digital signal d0(t) at a sampling period T1, stores it into a memory section 104 as signal data and sequentially reads the signal data from the memory section 104, at a period T2 longer than the period T1. Hence, a low-frequency narrow-bandwidth digital signal d1(t) can be obtained. Furthermore, the digital signal d1(t) is converted into a signal A1(f) of a frequency region, and the frequency of the signal A1(f) is multiplied by T2/T1 in the frequency region, whereby a signal A2(f) equivalent to the spectrum of the received analog signal a0(t) can be obtained in the frequency region. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for analyzing a spectrum of an electric signal.

A sweeping spectrum analyzer is known as a conventional frequency analyzer (see Non-Patent Document 1). In this method, a signal having the same frequency as the frequency to be measured is generated inside the measuring device, and is multiplied as a voltage value at a desired frequency by multiplying the measurement signal by a multiplier.
Masao Nagano, “Signal Processing of Sweep Spectrum Analyzer”, Journal of High Speed Signal Processing Applied Technology, December 2000, Vol.3, No.4

  However, since it is necessary to generate a signal having the same frequency as the frequency to be measured, a complicated high-frequency analog circuit is required, and there is a problem that it is difficult to realize a stable frequency characteristic in a wide band.

  The present invention has been made in view of the above, and it is an object of the present invention to provide a spectrum analyzer that measures high-frequency / broadband electrical signals with a simpler configuration than before.

  The spectrum analysis apparatus according to the present invention includes a signal receiving means for receiving a high-frequency signal, a first clock generating means for generating a first timing signal having a period T1, and a received high-frequency signal as a first timing signal. A / D conversion means for converting to the first digital signal at period T1, writing means for storing the first digital signal as signal data in the storage means, and a period T2 longer than the period T1 of the first timing signal Second clock generating means for generating a second timing signal having the second timing signal, signal data is read from the storage means based on the second timing signal, and the sampling period becomes the period T2 of the second timing signal. Read means for generating a digital signal, conversion means for converting the second digital signal into a frequency domain signal, and the frequency of the frequency domain signal as T And output means for outputting the converted / T1 times, and having a.

  In the present invention, the received high-frequency signal is converted into a first digital signal at the sampling period T1 and stored in the storage means as signal data, and the signal data is stored from the storage means at a period T2 longer than the sampling period T1. By reading, generating a second digital signal of sampling period T2, converting the second digital signal into a frequency domain signal, converting the frequency of the frequency domain signal to T2 / T1 times, and outputting it, Since a spectrum equivalent to the spectrum of the received high-frequency signal can be obtained, it can be limited to a place where a complex high-frequency circuit is required to be converted into the first digital signal, and it is an inexpensive and stable spectrum analyzer. Can be provided.

  The spectrum analyzing apparatus includes D / A conversion means for converting the second digital signal into an analog signal, and the conversion means converts the analog signal converted by the D / A conversion means into a frequency domain signal. To do.

  In the present invention, an inexpensive low-frequency spectrum analyzer can be used by converting the second digital signal into an analog signal.

  The spectrum analyzer has a reproducing means for outputting an analog signal as sound.

  In the present invention, by outputting the obtained analog signal as a sound that can be heard by humans, the characteristics of the received high-frequency signal can be heard, and humans can listen to subtle changes in the characteristics of the high-frequency signal. Can be detected.

  According to the present invention, a spectrum analyzing apparatus for measuring a high-frequency / broadband electric signal is provided with a simpler configuration than the conventional one.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram showing the configuration of the spectrum analysis apparatus according to the first embodiment. The spectrum analysis apparatus shown in FIG. 1 includes a signal receiving unit 101, an A / D conversion unit 102, a writing unit 103, a storage unit 104, a reading unit 105, a writing clock generation unit 106, a reading clock generation unit 107, a D / A. A conversion unit 108, a spectrum conversion unit 109, and a display unit 110 are provided.

  The signal receiving unit 101 receives an analog signal a 0 (t) having a finite frequency bandwidth and outputs the analog signal a 0 (t) to the A / D conversion unit 102.

  The A / D converter 102 converts the input analog signal a0 (t) into a digital signal d0 (t) using the period T1 of the timing signal generated by the write clock generator 106 as a sampling period.

  The writing unit 103 causes the storage unit 104 to store the sampling value (signal strength) of the digital signal d0 (t) as signal data in chronological order based on the timing signal of the cycle T1.

  The reading unit 105 reads the signal data from the storage unit 104 in time series based on the timing signal of the cycle T2 generated by the read clock generation unit 107, and the D / A conversion unit 108 as a digital signal d1 (t) of the sampling cycle T2. Output to. The cycle T2 of the timing signal generated by the read clock generator 107 is longer than the cycle T1 of the timing signal generated by the write clock generator 106. Thus, the digital signal d0 (t) can be converted into a digital signal d1 (t) having a lower frequency.

  The D / A converter 108 converts the input digital signal d1 (t) into an analog signal a1 (t).

  The spectrum converter 109 receives the analog signal a1 (t) and converts it into a frequency domain signal A1 (f).

  The display unit 110 receives the signal A1 (f) in the frequency domain, converts the frequency to T2 / T1 times, and displays it.

  FIG. 2 is a diagram illustrating an analog signal a0 (t) input to the A / D conversion unit 102 and an analog signal a1 (t) output from the D / A conversion unit 108. The horizontal axis represents time, and the vertical axis represents signal strength. The analog signal a0 (t) is sampled at a sampling period T1 between time t0 and time t1, converted into a digital signal d0 (t), and stored in the storage unit 104 as signal data. On the other hand, the reading unit 105 reads the signal data from the storage unit 104 at an interval of the period T2 longer than the period T1 from the time t0, and generates the digital signal d1 (t). Thus, the digital signal d0 (t) is extended by T2 / T1 times in the time axis direction, and a digital signal with a lower frequency and a narrow band is obtained. Accordingly, the D / A converter 108 that converts the digital signal d1 (t) into the analog signal a1 (t) and the spectrum converter 109 that converts the time-series domain signal into the frequency-domain signal have complicated high-frequency circuits. No need to use.

  Note that the writing unit 103 does not write the signal data to the storage unit 104 from time t1 shown in FIG. 2 to time t2 when the reading unit 105 completes reading of the signal data, and passes the time t2. After that, the signal data writing is resumed. Since the signal data is read out until time t2, the display of the spectrum is updated at the interval of t2-t0 on the display unit 110.

  FIG. 3 is a diagram illustrating the spectrum of the analog signal a1 (t). The analog signal a1 (t) converted into the frequency domain signal A1 (f) has a low frequency and narrow band as shown in FIG. The frequency domain signal A1 (f) is input to the display unit 110, and the display unit 110 displays the frequency domain signal A2 (f) converted to T2 / T1 times, thereby obtaining a frequency domain signal A2 (f). As shown, a spectrum display equivalent to the spectrum of the high-frequency / wideband analog signal a0 (t) received by the signal receiving unit 101 can be obtained.

  Since the digital signal d1 (t) is obtained by extending the digital signal d0 (t) by T2 / T1 times in the time axis direction, the received analog signal a0 (t) is converted into the digital signal d0 (t). Since all of the sampled values (signal strength) are included in FIG. 4, the frequency of the signal A1 (f) in the frequency domain is converted to T2 / T1 times, so that a high-frequency / wideband analog signal a0 (t A spectrum equivalent to that of) can be obtained.

  Therefore, according to the present embodiment, the received high-frequency analog signal a0 (t) is converted into the digital signal d0 (t) at the sampling period T1, and is stored as signal data in the storage unit 104, and at the same time as the period T1. By sequentially reading the signal data from the storage unit 104 with a long period T2, a digital signal d1 (t) having a lower frequency and a narrower band can be obtained. Further, the digital signal d1 (t) is converted into a frequency domain signal A1 (f), and the frequency of the frequency domain signal A1 (f) is multiplied by T2 / T1, so that the received analog signal a0 (t) Since the signal A2 (f) in the frequency domain equivalent to the spectrum can be obtained, it is possible to provide a spectrum analysis apparatus with a reduced number of complicated high-frequency circuits.

  Note that the digital signal d1 (t) is not converted into the analog signal a1 (t), and the digital signal d1 (t) is converted into, for example, a fast Fourier transform (FFT) or discrete cosine transform (DCT). The signal A1 (f) in the frequency domain may be acquired by performing signal processing such as (Transform).

[Second Embodiment]
FIG. 5 is a block diagram showing the configuration of the spectrum analysis apparatus according to the second embodiment. The spectrum analysis apparatus shown in the figure is different from that shown in FIG. 1 in that it includes a plurality of storage units 504a, 504b,... 504n and an acoustic reproduction unit 511. The sound reproducing unit 511 outputs the input analog signal as sound.

  As shown in FIG. 6, the writing unit 503 sequentially selects the storage units 504a, 504b,..., 504n, and stores them so that the input digital signal d0 (t) is not interrupted. Similarly, the reading unit 505 reads signal data in order from the storage unit 504a. As described above, a plurality of storage units 504a, 504b,..., 504n are provided so that the input digital signal d0 (t) is stored without interruption, and the storage units 504a, 504b,. By reading the data, the digital signal d1 (t) can be acquired as a continuous waveform.

  Further, the period T2 is adjusted by controlling the read clock generator 107 so that the bandwidth F1 of the signal A1 (f) in the frequency domain of the analog signal a1 (t) is about 20 kHz which is a human audible range, and D The analog signal a1 (t) output from the / A conversion unit 108 is input to the sound reproduction unit 511. Thereby, a human can listen to the characteristics of the received analog signal a0 (t) as an audible signal.

  Therefore, according to the present embodiment, a plurality of storage units 504a, 504b,..., 504n are provided, and the sampled digital signal d0 (t) is sequentially stored in each storage unit, and data is sequentially read from each storage unit. The digital signal d1 (t) is generated and converted into the analog signal a1 (t), whereby the analog signal a1 (t) can be acquired as a continuous waveform.

  According to the present embodiment, the read clock generator 107 is controlled so that the bandwidth of the signal A1 (f) in the frequency domain of the generated analog signal a1 (t) is about 20 kHz, and the analog signal a1 (t ) Is input to the sound reproducing unit 511, the human can listen to the characteristics of the received analog signal a0 (t) as an audible signal.

It is a block diagram which shows the structure of the spectrum analyzer in 1st Embodiment. 3 is a graph showing an analog signal a0 (t) input to the spectrum analysis apparatus shown in FIG. 1 and a generated analog signal a1 (t). It is a figure which shows the spectrum of the analog signal a1 (t) produced | generated with the spectrum analyzer shown in FIG. It is a figure which shows the spectrum displayed in the display part of the spectrum analyzer shown in FIG. It is a block diagram which shows the structure of the spectrum analyzer in 2nd Embodiment. It is explanatory drawing which shows a mode that the spectrum analyzer shown in FIG. 5 reads and writes signal data in a memory | storage part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Signal receiving part 102 ... Conversion part 103 ... Writing part 104 ... Memory | storage part 105 ... Reading part 106 ... Write clock generation part 107 ... Read clock generation part 108 ... Conversion part 109 ... Spectrum conversion part 110 ... Display part 503 ... Writing unit 504a, 504b, 504n ... storage unit 505 ... reading unit 511 ... sound reproducing unit

Claims (3)

Signal receiving means for receiving a high-frequency signal;
First clock generating means for generating a first timing signal having a period T1,
A / D conversion means for converting the received high-frequency signal into a first digital signal in a cycle T1 of the first timing signal;
Writing means for storing the first digital signal as signal data in a storage means;
Second clock generating means for generating a second timing signal having a period T2 longer than the period T1 of the first timing signal;
Reading means for reading the signal data from the storage means based on the second timing signal and generating a second digital signal whose sampling period is the period T2 of the second timing signal;
Conversion means for converting the second digital signal into a frequency domain signal;
Output means for converting the frequency of the frequency domain signal to T2 / T1 times and outputting it;
A spectrum analyzer characterized by comprising: D / A conversion means for converting the second digital signal into an analog signal;
2. The spectrum analyzing apparatus according to claim 1, wherein the converting means converts the analog signal converted by the D / A converting means into a frequency domain signal.   3. The spectrum analyzing apparatus according to claim 2, further comprising reproducing means for outputting the analog signal as sound.

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