JP2012163423A - Signal measurement instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more reliably perform accurate inspection of a frequency band including a suddenly inputted measurement target signal, by raising the probability of detecting the measurement target signal.SOLUTION: A signal measurement instrument includes: a distribution unit 3 which distributes measurement target signals S1 in a measurement frequency band; a signal detection unit 4 which receives a measurement target signal S1a from the distribution unit 3 and detects, in parallel, intra-divided band signals S2a to S2c respectively included in three continuous frequency bands into which the measurement frequency band is divided; a reception unit 5 which sweeps a first local oscillation signal S3 with the same frequency band width as a designated divided band to detect a signal S4 generated by mixing a measurement target signal S1b from the distribution unit 3 and the first local oscillation signal S3 and generates a detection output Vd about an intra-divided band signal in the designated divided band; and a processing unit 7 which takes one of divided bands where intra-divided band signals S2 are detected by the signal detection unit 4, as a designated divided band to cause the reception unit 5 to generate the detection output Vd.

Description

  The present invention relates to a signal measuring apparatus for measuring a signal level of a signal under measurement included in a predetermined measurement frequency band.

  As this type of signal measuring apparatus, a signal measuring apparatus (microwave detector) disclosed in Patent Document 1 below is known. This signal measuring apparatus includes a superheterodyne receiving unit that repeats receiving operation of a target band (target frequency band) set in a microwave band, and a detection target frequency based on a detection output output from the receiving unit. In a microwave detector comprising a detection means for detecting a microwave and an alarm means for outputting an alarm when the detection target microwave is detected by the detection means, the reception means has a target band in a plurality of regions. The detection means is configured to repeatedly sweep and receive each divided band, and the detection means adds an addition means for adding each detection output obtained when the divided bands are repeatedly swept, and the added addition detection output And a judging means for judging the presence or absence of a microwave having a frequency to be detected based on the added detection output. Further, the receiving means further has a function of sweeping and receiving a frequency band wider than the divided band, and the detecting means is a frequency to be detected based on a detection output when sweeping a wide frequency band (whole target band). It further has a judgment function for judging the presence or absence of the microwave.

  In this signal measurement device, microwaves are detected based on the added detection output obtained by repeatedly sweeping multiple times for each divided band obtained by dividing the target band and adding the detection outputs of the same divided band based on each sweep. Therefore, even if the target microwave level is low, it can be detected reliably, and after searching for one divided band, it is swept once for a wide frequency band (whole target band). Then, since the presence / absence of a normal microwave is searched, if the level of the target microwave is high, it can be detected at the time of one sweep. Therefore, high-accuracy detection of microwaves is performed by searching based on divided bands, and high-level microwaves are detected quickly by searching based on a single sweep of a wide frequency band between the divided bands. It is possible to do.

JP 2000-75018 A (page 3-4, FIG. 1-2)

  However, the signal measuring apparatus described above has the following problems to be solved. That is, in this signal measurement device, a high-precision search based on a sweep for each divided band and a quick search for a high-level microwave based on a single sweep of a wide frequency band performed between sweeps of each divided band. And running in combination. However, in this signal measurement apparatus, even if a sudden microwave included in another divided band other than the divided band being swept is received in the former search, this microwave cannot be detected. Even in the latter search, even if a sudden microwave included in a band (band) already completed in one sweep of a wide frequency band is received, this microwave cannot be detected. Therefore, this signal measuring apparatus has a problem to be solved that it is difficult to execute a high-accuracy inspection for a divided band including the microwave as a result of the fact that the microwave input suddenly cannot be detected. ing.

  The present invention has been made to solve such a problem, and can increase the detection accuracy of a signal under measurement that is suddenly input, and more accurately perform a high-accuracy inspection for a frequency band including the signal. The main object is to provide a signal measuring device.

  In order to achieve the above object, the signal measuring apparatus according to claim 1, wherein a signal distribution unit that distributes and outputs a signal under measurement in a predetermined measurement frequency band, and the signal output from one output unit of the distribution unit. Signal detection in which signals to be measured are input and signals in each divided band included in each divided band obtained by dividing the measurement frequency band into consecutive n (n is an integer of 2 or more) frequency bands are detected in parallel And a local oscillation signal with the same frequency bandwidth as the designated frequency bandwidth of the divided band, and the signal under measurement and the local oscillation signal output from the other output unit of the distribution unit A superheterodyne receiver that generates a detection output for the signal in the specified subband by detecting the intermediate frequency signal generated by mixing, and the signal detector A processing unit that causes the receiving unit to generate the detection output using the one of the divided bands in which an in-band signal is detected as the designated divided band, and the detection output of the signal under measurement Measure as signal level.

  The signal measurement device according to claim 2 is the signal measurement device according to claim 1, wherein the signal detection unit is defined in a pass band corresponding to each of the divided bands, and the one of the distribution units is provided. N band-pass filters each having an input unit connected to an output unit, and each of the band-pass filters connected to the output unit of each band-pass filter, and the peak of the signal in the divided band output from the corresponding band-pass filter. N peak detectors to detect in parallel and each peak detector connected to each of the peak detectors, and the peak value of the peak detected by the corresponding peak detector is analog-to-digital converted in parallel and output. N A / D converters.

  The signal measuring device according to claim 3 is the signal measuring device according to claim 2, wherein the processing unit is preliminarily defined as the peak value of the signal in the divided band detected by the signal detecting unit. When the peak value is equal to or greater than the threshold value, one of the divided bands in which the signal in the divided band is detected is set as the designated divided band to the receiving unit. On the other hand, the detection output is generated.

  According to a fourth aspect of the present invention, there is provided the signal measuring apparatus according to the first or second aspect, further comprising an operation unit for selecting any one of the divided bands, and the processing unit. The detection unit detects the one divided band selected by the operation unit from among the divided bands in which the signal in the divided band is detected by the signal detection unit as the designated divided band to the receiving unit. Generate output.

  2. The signal measuring apparatus according to claim 1, wherein the signal detection unit inputs n signals to be measured output from one output unit of the distribution unit and continuously divides the measurement frequency band. Are detected in parallel.

  Therefore, according to this signal measuring apparatus, even when the signal under measurement whose frequency is included in the measurement frequency band is suddenly generated, the signals in the divided bands constituting the signal under measurement in the signal detection unit Can be reliably detected. Further, according to this signal measurement device, the processing unit causes the receiving unit to generate a detection output with one of the divided bands in which the signal in the divided band is detected by the signal detecting unit as the designated divided band. Therefore, based on this detection output and the local oscillation frequency of the local oscillation signal generated by the receiver, each frequency component included in the designated division band (for example, the division band where the signal is suddenly generated) is generated. The signal level can be displayed along the frequency axis (frequency spectrum is displayed).

  According to the signal measuring device of claim 2, n band-pass filters which are defined in the passband corresponding to each divided band and whose input unit is connected to one output unit of the distribution unit, respectively, N peak detectors connected to the output units of the bandpass filters, respectively, for detecting in parallel the peaks of the signals in the divided bands output from the corresponding bandpass filters, and connected to the respective peak detectors. The signal detector is configured to include n A / D converters that detect in parallel the peak value detected by the corresponding peak detector, so that the frequency to be measured is included in the measurement frequency band. It is possible to reliably detect sudden occurrences of signals with a simple configuration.

  According to the signal measuring device of the third aspect, when the peak value of the signal in the divided band detected by the signal detection unit is equal to or greater than a predetermined threshold value, the processing unit detects the signal in the divided band. Since one of the divided bands is designated as a designated divided band and the reception unit generates a detection output, the frequency spectrum of the designated divided band can be immediately displayed (measured). .

  5. The signal measuring apparatus according to claim 4, further comprising an operation unit for selecting any one of the divided bands, wherein the processing unit is a divided band in which the signal in the divided band is detected by the signal detecting unit. The reception unit generates a detection output for one divided band selected by the operation unit. Therefore, according to this signal measuring device, the operator can display the frequency spectrum for any of the divided bands by operating the operation unit.

1 is a configuration diagram of a signal measuring device 1. FIG. It is a frequency characteristic diagram for demonstrating the relationship with the measurement frequency band A, each division band Ba, Bb, Bc, and the intermediate frequency f4 in the receiving part 5. FIG. 3 is a front view of an operation panel 1a in the signal measuring device 1. FIG. It is a block diagram of the other receiving part 5A.

  Hereinafter, an embodiment of the signal measuring apparatus 1 will be described with reference to the accompanying drawings.

  First, the configuration of the signal measuring apparatus 1 will be described with reference to FIG.

  As shown in FIG. 1, the signal measuring apparatus 1 includes a level adjustment unit 2, a distribution unit 3, a signal detection unit 4, a reception unit 5, a first A / D conversion unit 6, a processing unit 7, a display unit 8, and an operation unit 9. And a signal under measurement (for example, microwave) Si having an arbitrary frequency fi included in a predetermined measurement frequency band A (see FIG. 2) is detected, and its signal level (in this example, RMS is taken as an example) (Root Mean Square) value) can be measured.

  The level adjustment unit 2 is composed of an attenuator or an amplifier, for example, and adjusts the signal level of the signal to be measured Si input from the outside so as to obtain an optimum input level for each component in the subsequent stage. Output as measurement signal S1. The distribution unit 3 receives and distributes the signal under measurement S1, and outputs the signals under measurement S1a and S1b from a pair of output units (not shown) as an example.

  The signal detection unit 4 includes a plurality of filters 11 (filters 11a to 11c described later), a plurality of peak detection units 12 (peak detection units 12a to 12c described later), and a plurality of second A / D conversion units 13 (second A described later). / D converters 13a to 13c). As shown in FIG. 2, the measurement frequency band A includes n consecutive frequency bands (where n is an integer of 2 or more and 3 in this example as an example) Ba, Bb. , Bc (Ba <Bb <Bc). In this case, the divided band Ba is defined with a lower limit frequency of f0 (for example, 100 kHz) and an upper limit frequency of f1 (for example, 1 GHz), and the divided band Bb has a lower limit frequency of f1 (for example, 1 GHz) and an upper limit frequency of f2 (for example, 2 GHz), and the divided band Bc is defined with a lower limit frequency of f2 (for example, 2 GHz) and an upper limit frequency of f3 (for example, 3 GHz). Each divided band Ba, Bb, and Bc can be defined to have the same bandwidth or different widths. In this example, as an example, the divided bands Ba, Bb, and Bc are defined to have substantially the same bandwidth as described above.

  The plurality of filters 11 are each configured as a band-pass filter (band-pass filter), and the number of pass bands corresponding to each of the divided bands Ba, Bb, and Bc (three in this example (filter 11a, 11b, 11c)). In this case, as shown in FIG. 2, the filter 11a has a pass band PBa corresponding to the divided band Ba and is defined to be equivalent to the divided band Ba, and the filter 11b has a pass band PBb corresponding to the divided band Bb. The filter 11c is defined to be equivalent to the divided band Bb, and the pass band PBc is defined to be equivalent to the divided band Bc corresponding to the divided band Bc.

  Further, as shown in FIG. 1, each of the filters 11 a, 11 b, and 11 c has an input unit connected to one output unit of the pair of output units in the distribution unit 3, and is output from this one output unit. Each of the frequency components included in each of the passbands PBa, PBb, and PBc among the frequency components included in the signal under test S1a is selectively passed. Different signals S2a, S2b, and S2c (corresponding to signals in the divided band and are also referred to as “signal S2” unless otherwise distinguished) are output.

  The plurality of peak detectors 12 are arranged in the same number as the respective filters 11 (three in this example (peak detectors 12a, 12b, 12c)), and are connected to the corresponding filters 11 on a one-to-one basis. In this example, the peak detector 12a is connected to the filter 11a, the peak detector 12b is connected to the filter 11b, and the peak detector 12c is connected to the filter 11c. Each peak detector 12 is supplied to the second A / D converter 13 so that the peak of the signal S2 output from the corresponding filter 11 can be reliably sampled by the second A / D converter 13 at the subsequent stage. In each period of the common sampling clock (not shown), in synchronization with the beginning of the period (specifically, a reset period starting from this beginning (which is also the end described later) (a period shorter than the period of the sampling clock) In synchronization with the completion timing of the signal P2, detection of the peak P for the signal S2 is started. Thereafter, each peak detector 12 updates and holds the maximum peak P while detecting the peak P of the signal S2 generated within the same period, and synchronizes with the end of the period (during the reset period). The operation of resetting (clearing) the held peak P is executed. With this configuration, the peak detector 12a detects and outputs the peak P (Pa) of the signal S2a, the peak detector 12b detects and outputs the peak P (Pb) of the signal S2b, and the peak detector 12c The peak P (Pc) of S2c is detected and output.

  The plurality of second A / D converters 13 are arranged in the same number n as each filter 11 (three in this example (second A / D converters 13a, 13b, 13c)), and the corresponding peak detectors 12 are provided. Connected one-on-one. In this example, the second A / D converter 13a is connected to the peak detector 12a, the second A / D converter 13b is connected to the peak detector 12b, and the second A / D converter 13c is connected to the peak detector 12c. Has been. In the present example, each of the second A / D converters 13a, 13b, 13c is synchronized with the end of each period of the sampling clock, and the peaks Pa, Pb, Pc output from the corresponding peak detectors 12a, 12b, 12c. , The peak values of peaks Pa, Pb, Pc (data indicating peak voltage values) PVa, PVb, PVc are output.

  With this configuration, the signal detection unit 4 is connected to one output unit of the distribution unit 3 to obtain peak values PVa, PVb, and PVc for the signals S2a, S2b, and S2c included in the respective divided bands Ba, Bb, and Bc. In the period of the sampling clock of each second A / D conversion unit 13, it is detected and output in parallel. Note that the period of the sampling clock is defined in a very short time with respect to the sweep time described later.

  As shown in FIG. 1, the reception unit 5 includes a first local oscillation unit 21, a sweep signal generation unit 22, a first mixer 23, a first bandpass filter (first BPF) 24, and a detection unit 25. It is configured as a system receiver. Although not shown, it is possible to employ a configuration in which an amplifier is arranged between the components as necessary.

  The first local oscillating unit 21 is configured by a VCO (Voltage Controlled Oscillator) as an example, and forms one frequency converting unit together with the sweep signal generating unit 22, the first mixer 23, and the first BPF 24. The first local oscillator 21 generates and outputs a first local signal S3 having a frequency (first local frequency) fL1 corresponding to the sweep voltage Vs as an input control voltage. The sweep signal generation unit 22 is a sweep voltage in which the voltage value changes linearly from the lower limit voltage value set by the processing unit 7 to the upper limit voltage value (or from the upper limit voltage value to the lower limit voltage value) within the set sweep time. (Voltage signal that changes in a sawtooth or triangular shape) Vs is generated and output to the first local oscillator 21. With this configuration, the first local oscillation unit 21 allows the sweep voltage Vs from the lower limit frequency fmin defined by the lower limit voltage value to the upper limit frequency fmax defined by the upper limit voltage value (or from the upper limit frequency fmax to the lower limit frequency fmin). Until the first local oscillation frequency fL1 linearly changes in the set sweep time.

  In this example, the first local oscillating unit 21 sets the intermediate frequency of the first BPF 24 to f4 when the processing unit 7 defines the lower limit voltage value and the upper limit voltage value of the sweep voltage Vs output from the sweep signal generation unit 22. (> F3. For example, 7 GHz) When detecting the divided band Ba (lower limit frequency f0, upper limit frequency f1), the first station where the lower limit frequency fmin is (f4 + f0) and the upper limit frequency fmax is (f4 + f1). A first local oscillation signal S3 having an oscillation frequency fL1 is output. Further, when the first local oscillator 21 detects the divided band Bb (lower limit frequency f1, upper limit frequency f2), the first local oscillator frequency where the lower limit frequency fmin is (f4 + f1) and the upper limit frequency fmax is (f4 + f2). A first local signal S3 of fL1 is output. Further, when the first local oscillation unit 21 detects the divided band Bc (lower limit frequency f2, upper limit frequency f3), the first local oscillation frequency where the lower limit frequency fmin is (f4 + f2) and the upper limit frequency fmax is (f4 + f3). A first local signal S3 of fL1 is output.

  The first mixer 23 is connected to the other output unit of the distribution unit 3, inputs the signal under test S 1 b output from the other output unit, and outputs the first station output from the first local oscillation unit 21. By inputting the signal S3 and mixing the signal under measurement S1b and the first local signal S3, the sum of the frequency fi of the signal under measurement S1b and the first local frequency fL1 of the first local signal S3 And an intermediate frequency signal S4 (hereinafter, also referred to as “signal S4”) composed of signals having different frequencies (| fi ± fL1 |).

  As shown in FIG. 2, the first BPF 24 has a pass band whose frequency band is sufficiently higher than the measurement frequency band A and whose bandwidth C matches the resolution bandwidth of the signal measurement device 1. Has been. The first BPF 24 selectively selects a signal on the low frequency side | fi−fL1 | (in this example, (fL1−fi)) among the signals of the frequencies (| fi ± fL1 |) included in the signal S4. Output as signal S5.

  With this configuration, when the frequency component included in the divided band Ba (lower limit frequency f0, upper limit frequency f1) is detected for the signal under measurement S1b, the lower limit frequency fmin is detected from the first local oscillator 21 to the first mixer 23. A first local signal S3 whose frequency is swept from (= f4 + f0) to the upper limit frequency fmax (= f4 + f1) is output. For this reason, from the first BPF 24, the frequency components included in the divided band Ba are frequency-converted to the band of the frequency f4 as the frequency fL1 of the first local oscillation signal S3 is swept. The signal is output as a signal S5 in a band-limited state.

  Similarly, when the frequency component included in the divided band Bb (lower limit frequency f1, upper limit frequency f2) is detected for the signal S1b to be measured, the lower limit is applied from the first local oscillator 21 to the first mixer 23. A first local signal S3 whose frequency is swept from the frequency fmin (= f4 + f1) to the upper limit frequency fmax (= f4 + f2) is output. For this reason, from the first BPF 24, the frequency components included in the divided band Bb are frequency-converted into the band of the frequency f4 in accordance with the sweep of the frequency fL1 of the first local oscillation signal S3, and the band width C is changed by the first BPF 24. The signal S5 is output in a limited state. When the frequency component included in the divided band Bc (lower limit frequency f2, upper limit frequency f3) is detected for the signal S1b to be measured, the lower limit frequency fmin (= A first local signal S3 whose frequency is swept from f4 + f2) to the upper limit frequency fmax (= f4 + f3) is output. For this reason, from the first BPF 24, the frequency components included in the divided band Bc are frequency-converted into the band of the frequency f4 in accordance with the sweep of the frequency fL1 of the first local oscillation signal S3, and the band width C is changed by the first BPF 24. The signal S5 is output in a limited state.

  The detector 25 detects the signal S5 output from the first BPF 24 and outputs, for example, a detection output (detection voltage) Vd indicating an RMS (Root Mean Square) value of the signal S5. With the above configuration, the receiving unit 5 has one signal level of each frequency component included in the signal under test S1b output from the distributing unit 3 designated from the above-described divided bands Ba, Bb, and Bc. Detection is performed for each divided band, and the detection output Vd is output.

  The first A / D conversion unit 6 samples the detection output Vd output from the reception unit 5, converts it to data Dd indicating the voltage value, and outputs the data Dd. In this example, the first A / D converter 6 samples the detection output Vd at the same sampling period as each of the second A / D converters 13a, 13b, and 13c. The processing unit 7 is configured using a CPU, a DSP for FFT calculation, and a memory (all not shown), and executes a peak value display process and a spectrum display process.

  The display unit 8 is constituted by a display device such as an LCD (Liquid Crystal Display) as an example, and is disposed on the operation panel 1a of the signal measuring device 1 as shown in FIG. The display unit 8 has a display screen divided into a peak value display region 8a and a spectrum display region 8b. The display unit 8 displays, in the peak value display area 8a, peak values PVa, PVb, PVc (for each sampling period) of each frequency band included in each divided band Ba, Bb, Bc for each divided band Ba, Bb, Bc. (Maximum peak value) is displayed (in this example, it is displayed as a bar graph as an example). The display unit 8 displays the signal level of each frequency included in one divided band selected from the divided bands Ba, Bb, and Bc along the frequency axis in the spectrum display area 8b (frequency spectrum). Is displayed).

  For example, the operation unit 9 includes switches SWa, SWb, and SWc as many as the number of the divided bands Ba, Bb, and Bc, and is disposed on the operation panel 1a. Further, the switches SWa, SWb, SWc are arranged corresponding to the display positions of the peak values PVa, PVb, PVc for the divided bands Ba, Bb, Bc displayed on the display unit 8. Specifically, as an example, the switch SWa corresponding to the divided band Ba is disposed below the display position of the peak value PVa, and the switch SWb corresponding to the divided band Bb is positioned below the display position of the peak value PVb. A switch SWc corresponding to the divided band Bc is disposed below the display position of the peak value PVc. Further, when any one of the switches SWa, SWb, and SWc is operated, the operation unit 9 outputs a selection signal S11 indicating the operated switches SWa, SWb, and SWc to the processing unit 7.

  Next, the operation of the signal measuring apparatus 1 will be described.

  In the signal measuring apparatus 1, the level adjusting unit 2 inputs the signal to be measured Si, converts the signal level and outputs it to the distribution unit 3, and the distribution unit 3 outputs the signal to be measured Si to be measured signals S1a and S1b. The signal under measurement S1a is supplied to the signal detector 4 and the signal under measurement S1b is supplied to the receiver 5.

  The signal detection unit 4 parallelizes the peak values PVa, PVb, and PVc of the signals S2a, S2b, and S2c included in the respective divided bands Ba, Bb, and Bc at the sampling clock period of each second A / D conversion unit 13. And output to the processing unit 7. In this case, as described above, the peak value PVa is the peak value of the maximum peak P among the frequency components included in the divided band Ba, and the peak value PVb is the frequency value included in the divided band Bb. The peak value PVc is the peak value of the maximum peak P among the frequency components included in the divided band Bc.

  The processing unit 7 inputs the peak values PVa, PVb, and PVc output from the signal detection unit 4 at a constant cycle (sampling clock cycle) in this way, and executes a peak value display process. In this peak value display process, each time the peak value PVa, PVb, PVc is input, the processing unit 7 displays the peak value PVa, PVb, PVc in the peak value display area 8a of the display unit 8 as shown in FIG. Band information indicating each divided band Ba, Bb, Bc in the form of a bar graph while being updated (in this example, the symbol “Ba” indicating the divided band Ba, the symbol “Bb” indicating the divided band Bb, and the divided band Bc) Symbol “Bc”). Thus, the peak values PVa, PVb, PVc (the changes in the peak values PVa, PVb, PVc) for the signals S2a, S2b, S2c included in the respective divided bands Ba, Bb, Bc, that is, the measurement frequency band A It is possible to simultaneously confirm in real time what level of peak value PV is generated and in what frequency band.

  In this case, each time new peak values PVa, PVb, and PVc are input, the peak values PVa, PVb, and PVc displayed immediately before are immediately cleared, and the new peak values PVa, PVb, and PVc are displayed. In the configuration, when the sampling period of each second A / D conversion unit 13 is extremely fast, the display update is too early, and it may be difficult to determine the state of each peak value PVa, PVb, PVc. In this case, for example, the maximum of the predetermined number (for example, 10) of the past peak values PVa, PVb, PVc including the peak values PVa, PVb, PVc displayed immediately before, It is also possible to employ a configuration in which the new peak values PVa, PVb, and PVc are displayed (simultaneously).

  In this state, for example, as shown in FIG. 3, when the switch SWb corresponding to the divided band Bb whose peak value PVb is higher than the other divided bands Ba and Bc is operated, FIG. As shown in FIG. 4, the operation unit 9 outputs a selection signal S11 indicating the operated switch SWb to the processing unit 7, and the processing unit 7 that has received the selection signal S11 executes a spectrum display process.

  In this spectrum display process, the processing unit 7 first detects the detection output Vd of each frequency component included in the divided band (the divided band Bb in this example) indicated by the selection signal S11 with respect to the receiving unit 5. Start operation. Specifically, the processing unit 7 first causes the sweep signal generation unit 22 to have a lower limit voltage value corresponding to the lower limit frequency f1 of the division band Bb, an upper limit voltage value corresponding to the upper limit frequency f2 of the division band Bb, And information indicating the sweep time. As a result, the sweep signal generating unit 22 performs a sweep voltage (sawtooth waveform) in which the voltage value linearly changes from the lower limit voltage value to the upper limit voltage value within the set sweep time based on the lower limit voltage value, the upper limit voltage value, and the sweep time. Or a voltage signal whose voltage changes like a triangular wave) Vs is generated and output to the first local oscillator 21. In this case, when the sweep voltage Vs reaches the upper limit voltage value, the sweep signal generator 22 returns the sweep voltage Vs to the lower limit voltage value in a short time, and repeats the operation of changing the sweep voltage Vs linearly again.

  Further, the first local oscillating unit 21 is based on the sweep voltage Vs, and the upper limit frequency fmax (= f2) defined by the upper limit voltage value from the lower limit frequency fmin (= f1) defined by the lower limit voltage value of the sweep voltage Vs. ), The first local oscillation signal S3 in which the first local oscillation frequency fL1 changes linearly in the set sweep time is generated and output to the first mixer 23. In this case, when the first local oscillation frequency fL1 reaches the upper limit frequency fmax (= f2), the first local oscillation unit 21 returns the first local oscillation frequency fL1 to the lower limit frequency fmin (= f1) in a short time. Again, the operation of changing the frequency of the first local oscillation signal S3 to the first local oscillation frequency fL1 is repeated.

  The first mixer 23 mixes the first local signal S3 and the signal S1b to be measured, and the sum and difference between the frequency fi of the signal S1b to be measured and the first local frequency fL1 of the first local signal S3. A signal S4 composed of signals of each frequency (| fi ± fL1 |) is output. Next, the first BPF 24 is a signal on the low frequency side | fi−fL1 | (in this example, the frequency (fL1−fi)) of the signals of the frequencies (| fi ± fL1 |) included in the signal S4. The signal included in its own pass band (bandwidth C) is selectively output as the signal S5. With this configuration, from the first BPF 24, each frequency component included in the divided band Bb is frequency-converted to the band of the frequency f4 in accordance with the sweep of the frequency fL1 of the first local oscillation signal S3, and the bandwidth is increased by the first BPF 24. The signal is output as the signal S5 in a state where the band is limited to C. The detector 25 detects this signal S5 and outputs a detection output Vd.

  Subsequently, the first A / D conversion unit 6 samples the detection output Vd output from the reception unit 5 (for example, samples at the same sampling period as that of the second A / D conversion unit 13), and calculates the voltage value. It converts into the data Dd shown, and outputs to the process part 7. FIG. Next, the DSP of the processing unit 7 inputs the data Dd in synchronization with the sampling period, and at the same time, the data Dd and the first local oscillation frequency fL1 of the first local oscillation signal S3 (the sweep voltage Vs by the sweep signal generation unit 22). The first local oscillation frequency fL1 can be calculated from the sweep time, the lower limit voltage value, and the upper limit voltage value), and the signal level for each frequency component included in the divided band Bb is calculated. Further, as shown in FIG. 3, the CPU of the processing unit 7 displays the signal level of each frequency included in the divided band Bb along the frequency axis in the spectrum display region 8b of the display unit 8 (displays the frequency spectrum). ) At this time, as shown in the figure, the CPU of the processing unit 7 identifies the identification code (“Bb” in this example) of the selected divided band Bb, the peak value PVa of the maximum peak P, and the selected divided band. The lower limit frequency f1 and the upper limit frequency f2 of the band Bb are also displayed. Thereby, the spectrum display process is completed.

  Thereafter, the processing unit 7 repeatedly executes the peak value display process while detecting the output of the selection signal S11 from the operation unit 9. When the selection signal S11 is input, the processing unit 7 executes the spectrum display process and displays The display content of the spectrum display area 8b in the unit 8 is updated to one of the frequency spectra of the divided bands Ba, Bb, and Bc indicated by the selection signal S11.

  Thus, in this signal measuring apparatus 1, the signal detection unit 4 receives the signal under test S1a output from one output unit of the distribution unit 3, and continuously divides the measurement frequency band A. Peak values PVa, PVb, and PVc of signals (divided band signals) S2a, S2b, and S2c included in the divided bands Ba, Bb, and Bc are detected in parallel.

  Therefore, according to the signal measuring apparatus 1, even when the signal under measurement Si whose frequency is included in the measurement frequency band A is suddenly generated, the signal detection unit 4 configures the signal under measurement Si. The signal S2 (the peak value PV of the signal S2) can be reliably detected. Further, according to the signal measuring apparatus 1, the processing unit 7 is assigned with one of the divided bands Ba, Bb, and Bc in which the signal S2 (peak value PV) is detected by the signal detecting unit 4. In order to cause the receiving unit 5 to generate a detection output Vd, a designation is made based on the detection output Vd and the first local oscillation frequency fL1 of the first local oscillation signal S3 output from the first local oscillation unit 21. The signal level of each frequency component included in the divided band (for example, the divided band where the signal is suddenly generated) can be displayed along the frequency axis (frequency spectrum is displayed).

  Further, according to the signal measuring apparatus 1, the signal detection unit 4 is defined in the pass band corresponding to each of the divided bands Ba, Bb, and Bc, and the input unit is connected to one output unit of the distribution unit 3. The n filters (3 in this example) 11a, 11b, 11c and the outputs of the filters 11a, 11b, 11c are respectively connected to the peaks of the signals S2 output from the corresponding filters 11. N (three in this example) peak detectors 12 to be detected in parallel, and connected to each peak detector 12 to detect in parallel the peak value PV detected by the corresponding peak detector 12 By providing the n second A / D converters 13a, 13b, and 13c, it is possible to reliably detect sudden occurrence of a signal including a frequency within the measurement frequency band A with a simple configuration. it can.

  In addition, the signal measuring apparatus 1 includes an operation unit 9 for selecting any one of the divided bands Ba, Bb, and Bc, and the processing unit 7 receives the signal S2 (peak) by the signal detection unit 4. The reception unit 5 is caused to generate a detection output Vd for one divided band selected by the operation unit 9 among the divided bands Ba, Bb, and Bc in which the value PV) is detected. Therefore, according to this signal measuring apparatus 1, the operator can operate the operation unit 9 to display a frequency spectrum for an arbitrary divided band among the divided bands Ba, Bb, and Bc.

  In the signal measuring apparatus 1 described above, an example in which the measurement frequency band A is divided into three divided bands Ba, Bb, and Bc is described. However, if there are a plurality of measurement frequency bands A, three are used. Besides, it is possible to divide by any number of 2 or 4 or more.

  Further, in the signal measuring apparatus 1, the receiving unit 5 is configured by a superheterodyne method. However, like the other receiving unit 5A illustrated in FIG. 4, the second mixer is provided between the first BPF 24 and the detecting unit 25. 32, another frequency converter 31 composed of the second local oscillator 33 and the second BPF 34 may be arranged to constitute a double superheterodyne system. In this case, as an example, the second local oscillating unit 33 has a second fixed frequency (second local oscillation frequency) fL2 lower than the frequency f5 when the frequency (fL1-fi) of the signal S5 is f5. A local signal S6 is generated and output. The second mixer 32 receives the signal S5 output from the first BPF 24 and the second local oscillation signal S6 output from the second local oscillation unit 33, and receives the signal S5 and the second local oscillation signal S6. , The second intermediate frequency composed of signals of the sum and difference frequencies (| f5 ± fL2 |) of the frequency f5 of the signal S5 and the second local frequency fL2 of the second local signal S6. A signal S7 (hereinafter also referred to as “signal S7”) is output. The second BPF 34 selectively outputs the signal on the low frequency side | f5-fL2 | of the signals of the frequencies (| f5 ± fL2 |) included in the signal S7 as the signal S8. Therefore, in this configuration, the detection unit 25 detects the down-converted signal S8 output from the second BPF 34, and outputs a detection output Vd.

  In the signal measuring apparatus 1 described above, the operation unit 9 is provided, and the operation unit 9 is operated when one divided band B is selected from the divided bands Ba, Bb, and Bc. Further, it is possible to adopt a configuration in which this one divided band B is selected without operating the operation unit 9. For example, a threshold value for the peak value PV is set in advance for the processing unit 7, and when the processing unit 7 detects a peak value PV that is equal to or greater than the threshold value, the peak value PV is detected. It is possible to adopt a configuration in which the receiving sections 5 and 5A are operated with the divided band B as one divided band B described above. In this case, when there are a plurality of divided bands B in which the peak value PV equal to or greater than the threshold is detected, a configuration in which the divided band B having the largest peak value PV is the one divided band B may be employed. Further, a predetermined number of occurrences (5 times, 10 times, etc.) for the peak value PV is set in advance, and the processing unit 7 counts the number of occurrences while detecting the peak value PV, and this count value is the prescribed number of occurrences. When it becomes above, the structure which operates the receiving parts 5 and 5A can be employ | adopted by making the division | segmentation zone | band B in which peak value PV more than the frequency | count of generation | occurrence | production occurs is said one division | segmentation zone | band B. Further, the subband B to be monitored is defined in advance, and when the peak value PV detected in the subband B becomes equal to or more than the above threshold, or the occurrence of the detected peak value PV is generated. It is possible to adopt a configuration in which when the number of times becomes equal to or more than the above-mentioned specified number of occurrences, the reception units 5 and 5A are operated with the divided band B to be monitored as the one divided band B.

  As described above, when the detection state of the peak value PV for each divided band B in the signal detection unit 4 (the generation state of the peak value PV in each divided band B) satisfies a predetermined condition, the processing unit 7 By adopting a configuration that automatically identifies (selects) the divided band B and operates the receiving units 5 and 5A with the identified divided band B as the one divided band B described above, The frequency spectrum can be immediately displayed (measured) for one divided band B in which the detection state of the peak value PV for the divided band B satisfies a predetermined condition.

DESCRIPTION OF SYMBOLS 1 Signal measuring device 3 Distribution part 4 Signal detection part 5 Reception part 7 Processing part 9 Operation part 11 Filter 12 Peak detection part 13 2nd A / D conversion part Ba, Bb, Bc Divided band Vd Detection output

Claims (4)

A distribution unit that distributes and outputs a signal under measurement in a predetermined measurement frequency band; and
Included in each divided band obtained by inputting the signal under measurement output from one output unit of the distributing unit and dividing the measurement frequency band into consecutive n (n is an integer of 2 or more) frequency bands A signal detector for detecting signals in each divided band in parallel;
The local oscillation signal is swept with the same frequency bandwidth as the frequency bandwidth of the designated division band, and the measured signal and the local oscillation signal output from the other output unit of the distribution unit are mixed. A superheterodyne receiver that generates a detection output for the signal in the divided band within the designated divided band by detecting the generated intermediate frequency signal;
A processing unit that causes the receiving unit to generate the detection output using the one of the divided bands in which the signal in the divided band is detected by the signal detection unit as the designated divided band; A signal measuring device for measuring an output as a signal level of the signal under measurement. The signal detector is
N band-pass filters, each of which is defined in a pass band corresponding to each of the divided bands and has an input unit connected to the one output unit of the distribution unit;
N peak detectors connected to the output units of the respective bandpass filters, and detecting in parallel the peaks of the signals in the divided bands output from the corresponding bandpass filters;
N number of A / D converters connected to each of the peak detectors and outputting the peak values of the peaks detected by the corresponding peak detectors in parallel by analog-to-digital conversion. The signal measuring device according to claim 1.   The processing unit compares the peak value of the signal in the divided band detected by the signal detection unit with a predetermined threshold value, and when the peak value is equal to or greater than the threshold value, The signal measuring apparatus according to claim 2, wherein the receiving unit generates the detection output by using one of the divided bands in which a signal in a divided band is detected as the designated divided band. An operation unit for selecting any one of the divided bands;
The processing unit sets the one divided band selected by the operation unit among the divided bands in which the signal in the divided band is detected by the signal detection unit as the designated divided band to the receiving unit. The signal measuring apparatus according to claim 1, wherein the detection output is generated.

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