JP4543370B2 - Power line frequency characteristic measurement device - Google Patents

Description

  The present invention relates to an apparatus for measuring frequency characteristics of a power line, and in particular, an oscillator that transmits a measurement signal and a measuring instrument that measures the frequency characteristic of a received measurement signal are separated, and an oscillator is connected to one of the power lines via a coupling unit. The present invention relates to a measuring apparatus that can easily measure the frequency characteristics of a power line by connecting a measuring instrument to the other end.

  In recent years, power line carrier systems that use high-frequency signals using power lines such as outdoors and indoors are widely used because they can reduce costs, such as no need to install new transmission lines. It is being done. In high-frequency signal transmission using a power line, the transmission side and the reception side are not directly connected one-to-one like transmission using a general communication cable, It is affected by the presence of transformers, distribution boards, watt-hour meters, etc., or various household electrical appliances connected to a power outlet, resulting in attenuation of high-frequency signals and changes in transmission line impedance. In addition, there are countless combinations of causes that cause attenuation of high-frequency signals and changes in impedance of the transmission line, and in order to operate the power line carrier equipment, line design and field investigation according to the condition of the transmission line is indispensable. is there.

  Therefore, at present, a plurality of power line carrier devices set to different high-frequency signal frequencies in a power line section in which power line carrier devices are to be installed after carrying out an approximate circuit design from power line wiring diagrams and equipment installation drawings. The power line carrier device having the most suitable high-frequency signal frequency has been determined by performing a transmission test using the above.

On the other hand, a general communication line generally uses a general-purpose network analyzer when measuring the characteristics of a transmission line. Therefore, it is possible to measure the characteristics of a transmission line using a power line using a general-purpose network analyzer. FIG. 10 shows a case where the characteristics of a transmission line using a power line are measured using a general-purpose network analyzer. The example of a structure is shown. FIG. 10 includes a general-purpose network analyzer 1, an injector 2 that injects a measurement signal into a power line, and an extractor 3 that extracts the measurement signal from the power line. The network analyzer 1 includes a temperature controlled crystal oscillator (hereinafter referred to as TCXO) 4 that functions as a reference frequency signal source, a ramp voltage generator 5 that generates a triangular wave voltage for sweeping the measurement frequency, and a lamp voltage generator. A sweeper 6 that is controlled by the unit 5 to sweep the measurement frequency with a predetermined frequency width, an amplifier 7 that amplifies the received measurement frequency signal to a predetermined level, and a level of the received measurement frequency signal is measured and analyzed. The frequency analysis unit 8 calculates the frequency characteristics, the display unit 9 displays the calculated frequency characteristics, and the control unit 10 controls the operation of the frequency analysis unit.
Therefore, in the measurement system configured as described above, the required frequency characteristic can be obtained by setting the sweep range of the measurement frequency of the network analyzer to a desired frequency range.
No. 2003-273815 No. 2003-244033 JP-A-6-37676 Japanese Patent Laid-Open No. 1-212367

  However, the conventional method for measuring the frequency characteristics of the power line is that the network analyzer uses a single device for both the transmission side and the reception side, so this is a long transmission (about 10 m to 300 m) like a power line carrier system. When adapted to the system, it is necessary to draw either a transmission signal for measurement or a reception signal to a network analyzer using a coaxial cable. FIG. 11 is a diagram showing how a network analyzer is installed in a conventional method for measuring frequency characteristics of a power line. FIG. 11 shows a case where the network analyzer 1 is installed on the receiving end side of the power line, and the injector 2 installed at the transmitting end of the power line and the network analyzer 1 are connected using a coaxial cable 11. Therefore, with such a measurement method, the measurement range of the power line is limited by the length of the coaxial cable, or an amplifier is required in the middle of the coaxial cable, resulting in an increase in the size of the measurement equipment. .

On the other hand, in the measurement of the frequency characteristics of a general communication line using a network analyzer, the same problem occurs for a long transmission line, and therefore, prior art for measuring without using a network analyzer has been proposed. For example, as disclosed in Japanese Patent Application Laid-Open Nos. 6-37676 and 2003-244033, white noise is used in the method of measuring the frequency characteristics of the CATV transmission path, but it is not suitable for a power line with a lot of noise. It is. Also, as the measurement equipment for the transmission line, many models such as an arbitrary waveform generator, digital oscilloscope, personal computer are used, and it is not suitable for simple measurement during installation work.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a power line frequency characteristic measuring apparatus that is convenient to carry without restriction of the measurement range.

In order to achieve the above object, a power line frequency characteristic measuring apparatus according to the present invention has the following configuration. Take.
The frequency characteristic measurement method for a power line according to claim 1 is for measuring the frequency characteristic of a power line. An oscillator that outputs a measurement signal, and a first coupling unit that injects the measurement signal into a power line. A second coupling unit for extracting the measurement signal from the power line, and the extracted measurement A measuring instrument that measures the frequency characteristics of the power line by measuring the level of the constant signal, The measuring instrument has a sweep timing signal generating means for generating a sweep timing signal, Measurement signal input from the second coupling unit based on the sweep timing signal And the oscillator includes a sweep type supplied from the measuring instrument. Synchronous hold that generates its own sweep timing signal based on the timing signal And a predetermined sweep based on a unique sweep timing signal generated by the synchronization holding means. A signal obtained by sweeping the sweep frequency range with a predetermined sweep time is used as the measurement signal. Power using the frequency characteristic measurement device of the power line that is output to one coupling unit A method for measuring frequency characteristics of a force line, wherein the oscillator and the measuring device are connected by a coaxial cable, The sweep timing signal output from one sweep timing signal generator is synchronized with the other Supplying the holding means to obtain synchronization; removing the coaxial cable; and Pair the first coupling unit with the measuring instrument and the second coupling unit. Installing each of them at a predetermined position on the power line, and generating the sweep timing signal The sweep timing signal output from the generating means and the unique sweep output from the synchronization holding means. And performing a measurement based on the timing signal.

The power line frequency characteristic measuring apparatus according to claim 2 is a measurement signal for measuring the frequency characteristic of the power line. An oscillator that outputs a signal, and a first coupling unit that injects the measurement signal into a power line; A second coupling unit for extracting the measurement signal from the power line, and the extracted measurement signal Measuring the level of the power line to measure the frequency characteristics of the power line, and the oscillator Has a sweep timing signal generating means for generating a sweep timing signal. Sweeps within a predetermined sweep frequency range at a predetermined sweep time based on the sweep timing signal Is output to the first coupling unit as the measurement signal. The measuring instrument is synchronized with the sweep timing signal supplied from the oscillator. Synchronization holding means for generating a unique sweep timing signal, which is generated by the synchronization holding means Input from the second coupling unit based on its own sweep timing signal Power line frequency measurement device that measures the level of the measurement signal A frequency characteristic measuring method, wherein the oscillator and the measuring device are connected by a coaxial cable, The sweep timing signal output from the sweep timing signal generating means Supplying the stage to obtain synchronization; and removing the coaxial cable to connect the oscillator and the first Pair the coupling unit with the measuring device and the second coupling unit. Installing each at a predetermined position of the power line, and the sweep timing signal generating means The sweep timing signal output from the signal and the unique sweep type output from the synchronization holding means. And measuring based on the timing signal.

The frequency characteristic measurement apparatus for a power line according to claim 3 is the frequency characteristic measurement apparatus according to claims 1 and 2. In the method for measuring the frequency characteristics of a power line using an apparatus, the measuring device comprises a timer means. The timer means stops supplying the sweep timing signal to the synchronization holding means. Is configured to start timing and issue a warning signal when a preset time has elapsed. The

In the first aspect of the present invention, since the frequency characteristic measuring device is separated into the oscillator and the measuring instrument, it is possible to easily measure the frequency characteristic by setting a desired sweep time and measurement frequency point without being restricted by the measurement range. Is possible. In addition, since the device can be made small, it is convenient to carry, and by using multiple oscillators, it is possible to measure 1 to N, and it is possible to measure multiple transmission lines in a short time, and to measure the frequency characteristics of power lines. Great effect when using the device.

In the second aspect of the invention, since the frequency characteristic measuring device is separated into the oscillator and the measuring instrument, it is possible to easily measure the frequency characteristic by setting a desired sweep time and measurement frequency point without being restricted by the measurement range. Is possible. In addition, since the oscillator does not require a synchronization circuit, the oscillator can be further miniaturized, and it is convenient when moving the oscillator for measurement, and it can reduce power consumption. In addition, the battery life can be prolonged, and a great effect is exhibited when using the frequency characteristic measuring device of the power line.

The invention described in claim 3 is provided with a timer that warns the measuring device of the synchronization deviation, and exhibits a great effect in operating the frequency characteristic measuring apparatus.

Hereinafter, the present invention will be described in detail based on illustrated embodiments.
FIG. 1 is a block diagram showing a first embodiment of a power line frequency characteristic measuring apparatus according to the present invention. In this embodiment, the measuring device is divided into an oscillator 12 and a measuring instrument 13, a coupling unit 14 for injecting a signal output from the oscillator 12 into the power line is connected to the transmission end of the power line, and a signal input by the measuring instrument 13 Is coupled to the receiving end of the power line.
The oscillator 12 receives a synchronization command signal from the outside and synchronizes the PLL with a sweep timing signal inputted from the outside, and sets a sweep time and a sweep frequency range of the measurement signal from the outside, and an output interface of the oscillator 12 A control unit 16 that receives a signal for switching the condition and controls a predetermined functional block, and generates a unique sweep timing signal that is synchronized with the sweep timing signal that is input from the outside under the control of the control unit 16 The PLL 17 to be held, the VCXO 18 that outputs the reference frequency signal of the PLL 17, and the sweep timing signal output from the PLL 17 under the control of the control unit 16 are input, and a predetermined sweep time is synchronized with the sweep timing signal. The lamp power that repeatedly generates a triangular wave voltage in a predetermined voltage range with a constant frequency. A generator 19; and a sweeper 20 that receives the triangular wave voltage and controls a voltage-controlled oscillation circuit to generate a measurement signal in which a frequency signal in a predetermined range synchronized with the sweep timing signal is swept in a predetermined sweep time; The amplifier 21 is configured to amplify the measurement signal to a predetermined level, and the control unit 16 controls the output interface condition of the oscillator to be 50Ω balanced or 50Ω unbalanced.

  On the other hand, the measuring instrument 13 is a signal for setting the sweep time, the measuring time, the measuring interval time, the number of measuring frequency points, and the sweep frequency range from the outside, and a signal for setting the input interface condition of the measuring instrument 13 to be switched. TCXO 24 for controlling a predetermined functional block, TCXO 24 for outputting a reference frequency signal, and switching for switching the input interface condition of the measuring instrument 13 to 50Ω balanced or 50Ω unbalanced under the control of the controller 23 Unit 25, an amplifier 26 for amplifying the received measurement signal to a predetermined level, and a measurement frequency obtained by generating a sweep timing signal under the control of the control unit 23 and sweeping in synchronization with the sweep timing signal Frequency analysis unit that measures the level of the received measurement signal for a predetermined time and obtains the frequency characteristics of the power line. 27 and a display unit 28 for displaying the obtained frequency characteristics.

  The frequency analyzing unit 27 divides the reference frequency signal output from the TCXO 24 under the control of the control unit 23 and outputs a sweep timing signal and a measurement timing signal, and the frequency dividing unit 29 outputs the frequency dividing unit 29. In addition to inputting the sweep timing signal and the measurement timing signal, the control unit 23 receives condition control of the sweep time, the measurement interval time, the number of measurement frequency points, and the sweep frequency range, and in a predetermined voltage range synchronized with the sweep timing signal. A VCO control voltage generator 30 that repeatedly generates a stepped triangular wave voltage, and a stepped triangular wave voltage output from the VCO control voltage generating unit 30 are input, and predetermined in a predetermined sweep time in synchronization with the sweep timing signal. Output a stepped frequency signal with measurement frequency points swept in the frequency range VCO 31, a mixer unit 32 that mixes a frequency signal output from the VCO 31 and a measurement signal output from the amplifier 26, an LPF 33 that extracts a DC component of the mixed signal output from the mixer unit 32, and the LPF 33 The level measuring unit 34 measures the level of the DC voltage to be output at a predetermined timing.

  Next, the operation of the first embodiment shown in FIG. 1 will be described. In the present embodiment, the frequency characteristic measuring apparatus is separated into the oscillator 12 and the measuring instrument 13, and it is necessary to always maintain the synchronization of the sweep timing for sweeping the measurement frequency signal between the oscillator 12 and the measuring instrument 13. is there. Therefore, the measuring instrument 13 always generates a predetermined sweep timing signal, and the oscillator 12 and the measuring instrument 13 are collected in one place in advance before starting the measurement, and the sweep timing signal output terminal and the oscillator of the measuring instrument 13 are collected. Twelve sweep timing signal input terminals are connected using a coaxial cable or the like. The oscillator 12 receives the sweep timing signal output from the measuring instrument 13 and holds the phase of the PLL 17 in synchronization with the phase of the received sweep timing signal in accordance with a synchronization command signal input to the oscillator 12 from outside. The signal is used as the sweep timing signal of the oscillator 12. Therefore, since the synchronization of the sweep timing signal between the oscillator 12 and the measuring instrument 13 is maintained, the oscillator 12 and the measuring instrument 13 are installed at predetermined measurement points and measurement is started. Therefore, the following description is based on the premise that the sweep timing signal between the oscillator 12 and the measuring instrument 13 is synchronized and kept synchronized even if the oscillator 12 and the measuring instrument 13 are separated. .

  First, the operation of the oscillator 12 will be described. The oscillator 12 has a function for setting a sweep time and a sweep frequency range of the measurement signal, and a function for setting the output interface condition of the oscillator 12 to 50Ω balanced or 50Ω unbalanced. The lamp voltage generator 19 and the switching unit 22 can be controlled via the controller 16. These settings are made before starting the measurement and before establishing the synchronization of the above-described sweep timing signal between the oscillator and the measuring instrument. Next, as described above, the PLL 17 is phase-synchronized with the sweep timing signal generated by the measuring instrument 13. Therefore, when the sweep timing signal output from the PLL 17 is input to the ramp voltage generation unit 19, the ramp voltage generation unit 19 is based on the control signal from the control unit 16 in a predetermined repetition time in synchronization with the sweep timing signal. A triangular wave voltage in a predetermined voltage range is formed.

FIG. 2 shows an example of the output voltage waveform of the ramp voltage generator according to the present invention, and a triangular wave voltage in the voltage range from Va to Vb is output at a predetermined repetition time (sweep time).
Next, the triangular wave voltage output from the ramp voltage generator 19 is input to the sweeper 20, and the measurement signal is swept in a predetermined repetition time (sweep time) in a preset frequency range in synchronization with the sweep timing signal. Is output. The sweeper 20 is composed of a voltage controlled oscillation circuit, and outputs a generated frequency signal that is uniquely determined by the inputted triangular wave voltage.

FIG. 3 shows an example of the output waveform of the sweeper according to the present invention, and outputs a measurement signal which is a sweep frequency signal in a frequency range from fa to fb at a predetermined repetition time (sweep time).
Next, the measurement signal output from the sweeper 20 is input to the amplifier 21, amplified to a predetermined level, and input to the switching unit 22. In this embodiment, the output interface condition of the oscillator 12 can be selected to be 50Ω balanced or 50Ω unbalanced. This is because the expansion is provided when the coupling unit is connected. The cable connected to the ring unit can cope with a case where a twisted pair cable (50Ω balanced) is used or a case where a coaxial cable (50Ω unbalanced) is used. Therefore, the switch 22 switches the output interface of the oscillator 12 in accordance with the connection interface conditions of the coupling unit 14, switches to a desired interface, outputs a measurement signal to the coupling unit 14, and outputs the measurement signal to the power line. Inject.

The coupling unit 14 has a function of injecting a measurement signal into the power line. In this embodiment, the coupling unit 14 is inserted into an AC outlet such as a power line using a plug.
FIG. 4 shows a structural example of a coupling unit according to the present invention. A plug 35 is connected to the coupling unit 14 and is inserted into an AC outlet 36. The coupling unit 14 includes DC cut capacitors 37a and 37b and a transformer 38. As for the configuration of the coupling unit, other applicable ones, for example, an indirect connection method using a current transformer (CT) can be used.

Next, the operation of the measuring device 13 will be described. The measuring device 13 has a function for setting a sweep time, a measurement time, a measurement interval time, a measurement frequency point, and a sweep frequency range of a frequency signal for measurement, 13 has a function of setting 50 Ω balanced or 50 Ω unbalanced, and through a control unit 23, a frequency dividing unit 29, a VCO control voltage generating unit 30, a display unit 28, a level measuring unit 34, The switching unit 25 can be controlled. These settings are made before starting the measurement and before establishing the synchronization of the above-described sweep timing signal between the oscillator and the measuring instrument.
The measurement signal extracted by the coupling unit 15 installed at the measurement point of the power line is input to the switching unit 25, amplified to a predetermined level by the amplifier 26, and then input to the mixer unit 32 constituting the frequency analysis unit 27. The coupling unit 15 is the same as the coupling unit 14 connected to the oscillator 12, and the connection interface condition is 50Ω balanced (connected by a twisted pair cable) or 50Ω unbalanced (connected by a coaxial cable). In some cases, the switching unit 25 switches the input interface of the measuring instrument 13 in accordance with the connection interface condition of the coupling unit 15.

  On the other hand, the output of the TCXO 24 serving as a reference frequency oscillator is frequency-divided by the frequency divider 29 under the control of the control unit 23 to generate a desired sweep timing signal and output it as a synchronization sweep timing signal to the outside. At the same time, it is input to the VCO control voltage generator 30. The frequency divider 29 also outputs a measurement timing signal that is a timing for measuring the level of the measurement signal, and inputs the measurement timing signal to the VCO control voltage generation unit 30 and the level measurement unit 34. The VCO control voltage generator 30 under the control of the control unit 23 generates a control voltage for controlling the oscillation frequency of the VCO 31 at the next stage, and has a predetermined sweep time and sweep in synchronization with the sweep timing signal. A stepped triangular wave voltage that satisfies the conditions of interval, measurement frequency point, and sweep range is output.

FIG. 5 shows an example of the output waveform of the VCO control voltage generator according to the present invention. Each value of V1, V2, V3, and V4 shown in FIG. 5 corresponds to a measurement frequency point. At each measurement frequency point, a predetermined time constant voltage is used, and this interval can be used as a level measurement time of a measurement signal. The control voltage is repeatedly generated at a predetermined sweep time.
Next, the control voltage output from the VCO control voltage generator 30 is input to the VCO 31 and converted into a frequency signal corresponding to the control voltage.

FIG. 6 shows an example of the output waveform of the VCO according to the present invention. Each value of f1, f2, f3, and f4 shown in FIG. 6 becomes a measurement frequency point, and a stepwise repetitive frequency signal is output at a predetermined sweep time in synchronization with the sweep timing signal.
Next, the measurement frequency signal output from the VCO 31 is input to the mixer 32 and mixed with the received measurement signal output from the amplifier 26 described above. The frequency signal for measurement and the received measurement signal are synchronized in sweep timing, and the predetermined sweep range is swept by a predetermined sweep time. Therefore, the output of the mixer 32 is f1, f2, f3, A component close to direct current can be obtained at each measurement frequency point of f4. Therefore, the output of the mixer 32 is input to the LPF 33 to remove unnecessary frequency components other than DC, and is input to the level measuring unit 34 to measure a predetermined time level at a predetermined timing under the control of the control unit 23. The measurement level is displayed on the display unit 28 to obtain the frequency characteristic of the power line.

As described above, in the first embodiment, since the measuring apparatus is separated into the oscillator and the measuring instrument, it is possible to provide a power line frequency characteristic measuring apparatus that is convenient to carry without restriction of the measuring range.
In the first embodiment, since the sweep timing signal of the oscillator 12 is synchronized with the sweep timing signal generated by the measuring instrument 13, a plurality of oscillators can be subordinated to one measuring instrument. A 1: N measurement system can be constructed.
FIG. 7 shows an example in which a 1: N measurement system is constructed in the frequency characteristic measurement apparatus for power lines according to the present invention. FIG. 7 shows a configuration in which three oscillators 12a, 12b, 12c are opposed to one measuring instrument 13, and when it is necessary to measure the frequency characteristics of power lines in a plurality of sections, the measurement time is shown. Is shortened.

  Next, the synchronization of the sweep timing between the oscillator 12 and the measuring instrument 13 will be described in more detail. As described above, in the first embodiment, the oscillator 12 inputs the sweep timing signal generated by the measuring instrument 13 to the PLL, holds the synchronization by inputting the synchronization command signal, and sweeps for the oscillator 12. A timing signal is obtained. Thereafter, since the reception of the sweep timing signal generated by the measuring instrument 13 is stopped, the oscillator 12 thereafter maintains the synchronization of the sweep timing signal by the PLL synchronization holding operation when measuring the frequency characteristics of the power line. Since the reference frequency oscillators of TCXO and VCXO built in each of the oscillators 12 have errors, the sweep timing signal generated in the measuring instrument 13 and the oscillator 12 are synchronized with each other after a long time has passed. A synchronization error occurs with the sweep timing signal. Therefore, the time position of the measurement frequency point of the frequency-swept measurement signal output from the oscillator 12 and the timing of the level measurement time at the measurement frequency point generated by the measurement device 13 are shifted, thereby the mixer 32 provided in the measurement device 13. , The received measurement signal and the frequency signal for measurement are mixed in phase, and when the phase exceeds a predetermined value, the desired DC component output from the mixer 32 is reduced. Therefore, the level measurement unit 34 performs level measurement. There is a danger of becoming impossible.

  FIG. 8 is a diagram for explaining the operation when the synchronization of the sweep timing signal between the oscillator and the measuring instrument is shifted. FIG. 8 shows a case where the time position of the measurement frequency point of the swept measurement signal output from the oscillator is shifted from the timing of the level measurement time at each measurement frequency point generated by the measurement device. The level measurement is performed at each measurement frequency point for a predetermined time, but the sweep timing of the measurement signal output from the oscillator shifts with time, and the signal at the measurement frequency point output by the oscillator is outside the predetermined measurement time of the measuring instrument. There is a possibility that the measurement becomes impossible after a certain amount of time has passed.

Therefore, in the frequency characteristic measuring device of the power line, the effective synchronization holding time of the oscillator 12 is finite, and when measurement is performed exceeding a predetermined synchronization holding time, the oscillator 12 and the measuring instrument 13 are again connected. The sweep timing signal output from the measuring instrument 13 is input to the oscillator 12 and the oscillator 12 is resynchronized based on the synchronization command signal, and the sweep timing signal between the oscillator 12 and the measuring instrument 13 is The synchronization deviation is eliminated, and thereafter, the oscillator 12 and the measuring device 13 are installed at a desired measurement place and measurement is started. Therefore, a timer is provided in the measuring instrument 13 so that the timer is started when the supply of the sweep timing signal to the oscillator 12 is stopped, and a warning signal indicating that there is a possibility of a synchronization error when a preset time has elapsed. Is desirable.
Note that the measurement time and the measurement interval time at each measurement frequency point can be arbitrarily set, and the influence of the synchronization deviation between the sweep timing signals of the oscillator and the measuring instrument varies depending on the set value. Therefore, when operating this frequency characteristic measuring apparatus, it is desirable to select an optimal setting value in consideration of measurement time, measurement costs, and the like.

Next, a second embodiment of the power line frequency characteristic measuring apparatus according to the present invention will be described. In the second embodiment, a circuit that synchronizes the phase with an externally input sweep timing signal is provided in the measuring instrument, and the measuring instrument inputs the sweep timing signal that is constantly generated by the oscillator and uses the synchronization command signal as a basis. This is different from the first embodiment in that the PLL built in is held in synchronization with the sweep timing signal output from the oscillator.
FIG. 9 is a block diagram showing a second embodiment of the power line frequency characteristic measuring apparatus according to the present invention. In this embodiment, the measuring device is divided into an oscillator 39 and a measuring instrument 40, a coupling unit 14 for injecting a signal output from the oscillator 39 into the power line is connected to the transmission end of the power line, and a signal input by the measuring instrument 40 Is coupled to the receiving end of the power line.

  The oscillator 39 receives a signal for setting a sweep time and a sweep frequency range of a measurement signal and a signal for switching an output interface condition of the oscillator 39 from the outside, and controls a predetermined functional block; A TCXO 42 that outputs a reference frequency signal, a frequency divider 43 that divides the reference frequency signal output by the TCXO 42 under the control of the control unit 41 and outputs a sweep timing signal and a measurement timing signal, and control of the control unit 41 A ramp voltage generator for inputting a sweep timing signal output from the frequency divider 43 and generating a triangular wave voltage in a predetermined voltage range repeatedly in a predetermined frequency in a predetermined sweep time in synchronization with the sweep timing signal. 19 and the voltage of the triangular wave are input to control the voltage controlled oscillation circuit and are synchronized with the sweep timing signal. A sweeper 20 that generates a measurement signal obtained by sweeping a frequency signal in a range of a predetermined frequency in a predetermined sweep time, an amplifier 21 that amplifies the measurement signal to a predetermined level, and an output interface condition of the oscillator 39 is 50Ω balanced or 50Ω unbalanced. And a switching unit 22 for switching to

  On the other hand, the measuring instrument 40 receives the synchronization command signal from the outside and synchronizes the PLL with the sweep timing signal input from the outside, and also sweeps the measurement time, the measurement interval time, the number of measurement frequency points, and the sweep frequency range from the outside. A control unit 44 that receives a signal for setting and a signal for switching an input interface condition of the measuring instrument 13 to control a predetermined functional block, a VCXO 45 that outputs a reference frequency signal of the phase synchronization circuit, and a measuring instrument 40 A switching unit 25 that switches the input interface condition to 50Ω balanced or 50Ω unbalanced, an amplifier 26 that amplifies the received measurement signal to a predetermined level, and a unique sweep timing signal that is phase-synchronized with the sweep timing signal received from the oscillator 39 Is generated and held, and the switch is synchronized with the sweep timing signal. At the measurement frequency point obtained by the loop, the received measurement signal is measured for a predetermined time level, and the frequency analysis unit 46 for obtaining the frequency characteristic of the power line and the display unit 28 for displaying the obtained frequency characteristic are configured.

  In addition, the frequency analysis unit 46 receives a PLL 47 that generates a unique sweep timing signal and measurement timing signal synchronized with a sweep timing signal input from the outside, and a sweep timing signal and measurement timing signal output from the PLL 47. The VCO control voltage generation that repeatedly generates a stepped triangular wave voltage in a predetermined voltage range synchronized with the sweep timing signal under the control of the sweep time, the measurement interval time, the number of measurement frequency points, and the sweep frequency range from the control unit 44 And a staircase having a measurement frequency point swept in a predetermined frequency range in a predetermined sweep time in synchronization with the sweep timing signal, and a stepwise triangular wave voltage output from the VCO control voltage generator 30 A VCO 31 that repeatedly outputs a shaped frequency signal; A mixer unit 32 that mixes the frequency signal output from the VCO 31 and the measurement signal output from the amplifier 26, an LPF 33 that extracts a DC component of the mixed signal output from the mixer unit 32, and a DC voltage output from the LPF 33 And a level measuring unit 34 for measuring the level at a predetermined timing.

  The operation of the second embodiment will be explained. As described above, the difference between the second embodiment and the first embodiment is that a circuit that is phase-synchronized with an externally input sweep timing signal is used as a measuring instrument. Provided that the oscillator 39 and the measuring device are provided only by inputting the sweep timing signal that is always generated by the oscillator and holding the PLL in synchronization with the sweep timing signal output from the oscillator based on the synchronization command signal. Only the method of phase synchronization of the sweep timing signal with 40 will be described, and the other operations are the same as in the first embodiment, and the description thereof will be omitted.

  Also in the second embodiment, the frequency characteristic measuring device is separated into the oscillator 39 and the measuring instrument 40, and the sweep timing of the measuring frequency signal is synchronized between the oscillator 39 and the measuring instrument 40 and is held there. There is a need to. Therefore, the oscillator 39 always generates a predetermined sweep timing signal by frequency-dividing the output signal of the TCXO 42 serving as a reference frequency oscillator into a predetermined value by the frequency dividing unit 43 controlled by the control unit 41. Next, before starting the measurement, the oscillator 39 and the measuring instrument 40 are collected in advance in one place, and the sweep timing signal output terminal of the oscillator 39 and the sweep timing signal input terminal of the measuring instrument 40 are connected using a coaxial cable or the like. . The measuring device 40 receives the sweep timing signal output from the oscillator 39, and holds the phase of the PLL 47 in synchronization with the phase of the received sweep timing signal in accordance with a synchronization command signal input to the measuring device 40 from outside. Thereafter, the signal is used as the sweep timing signal of the measuring instrument 40. As described above, after the synchronization of the sweep timing signal of the measurement frequency signal is established between the oscillator 39 and the measuring instrument 40, the oscillator 39 and the measuring instrument 40 are installed at a desired measurement point and measurement is started.

As described above, also in the second embodiment, since the measuring device is separated into the oscillator and the measuring device, it is possible to provide a frequency characteristic measuring device for a power line that is easy to carry without restrictions on the measuring range.
Further, in the second embodiment, since the oscillator 39 does not have a PLL, the oscillator can be miniaturized and the circuit configuration becomes simple. Therefore, when the oscillator is driven by a battery, the power consumption is reduced and the battery life is reduced. To prolong.
Also in the second embodiment, the effective synchronization holding time of the measuring instrument 40 is limited, and when the measurement is performed beyond the predetermined synchronization holding time, the oscillator 39 and the measuring instrument 40 are connected again. The sweep timing signal collected at one place and output from the oscillator 39 is input to the measuring device 40, and the measuring device 40 is resynchronized based on the synchronization command signal, and the sweep timing signal between the oscillator 39 and the measuring device 40 is The synchronization deviation is eliminated, and thereafter, the oscillator 39 and the measuring device 40 are installed at a desired measurement location and measurement is started.

It is a block diagram which shows the 1st Example of the frequency characteristic measuring apparatus of the power line which concerns on this invention. The example of the output voltage waveform of the lamp voltage generation part concerning this invention is shown. The example of the output waveform of the sweeper concerning this invention is shown. The structural example of the coupling unit concerning this invention is shown. 2 shows an example of an output waveform of a VCO control voltage generator according to the present invention. 2 shows an example of an output waveform of a VCO according to the present invention. In the power line frequency characteristic measuring apparatus according to the present invention, an example in which a 1: N measurement system is constructed will be described. It is a figure explaining operation | movement when the synchronization of the sweep timing signal of an oscillator and a measuring device shift | deviates. It is a block diagram which shows the 2nd Example of the frequency characteristic measuring apparatus of the power line which concerns on this invention. A configuration example in the case of measuring characteristics of a transmission line using a power line using a general-purpose network analyzer will be described. It is a figure which shows the mode of the installation of a network analyzer in the method of measuring the frequency characteristic of the conventional power line.

Explanation of symbols

1 ・ Network analyzer 2．Injector
3 .... extractor, 4 .... TCXO,
5 .... Ramp voltage generator, 6 .... Sweeper,
7. ・ Amplifier, 8. ・ Frequency analysis part,
9 ・ ・ Display unit, 10 ・ ・ Control unit,
11 .. Coaxial cable, 12, 12a, 12b, 12c .. Oscillator,
13 .. Measuring instrument,
14, 14a, 14b, 14c .. coupling unit,
15 .... Coupling unit, 16 .... Control part,
17 ·· PLL, 18 ·· VCXO,
19 ... Ramp voltage generator, 20 ... Sweeper,
21..Amplifier, 22..Switching unit,
23..Control part, 24..TCXO,
25..Switching unit, 26..Amplifier,
27. Frequency analysis part 28. Display part
29 .. Divider, 30 ... VCO control voltage generator,
31 ... VCO, 32 ... Mixer,
33 .. LPF, 34 .. Level measurement section,
35 ... Plug, 36 ... AC outlet,
37a, 37b, capacitors, 38, transformers,
39 ... Oscillator 40 ... Measuring instrument
41..Control part, 42..TCXO,
43 .. Divider, 44 ... Controller
45 ... VCXO, 46 ... Frequency analyzer,
47..PLL

Claims (3)

An oscillator that outputs a measurement signal for measuring the frequency characteristics of the power line; A first coupling unit that injects into the line, and a second that extracts the measurement signal from the power line. Measure the frequency characteristics of the power line by measuring the level of the coupling unit and the extracted measurement signal. Measuring instrument
The measuring instrument has a sweep timing signal generating means for generating a sweep timing signal. Measurement input from the second coupling unit based on the sweep timing signal Measuring the level of the signal,
The oscillator is synchronized with the sweep timing signal supplied from the measuring instrument. Synchronization holding means for generating a unique sweep timing signal, and the synchronization holding means A predetermined sweep frequency range based on a unique sweep timing signal. Output the signal obtained by sweeping with the sweep time to the first coupling unit as the measurement signal Power line frequency characteristic measurement method using a power line frequency characteristic measurement device. And
The oscillator and measuring instrument are connected by a coaxial cable, and one of the sweep timing signal generators is connected. The step of obtaining the synchronization by supplying the sweep timing signal output from the stage to the other synchronization holding means. And
Remove the coaxial cable and pair the oscillator and the first coupling unit. Pair the measuring instrument and the second coupling unit, and place each at a predetermined position on the power line. Steps,
The sweep timing signal output from the sweep timing signal generating means and the synchronization maintaining signal Performing a measurement based on the unique sweep timing signal output by the holding means; A frequency characteristic measurement method for a power line, comprising: An oscillator that outputs a measurement signal for measuring the frequency characteristics of the power line, and the measurement signal to the power line A first coupling unit to enter and a second cup to extract the measurement signal from the power line Measure the frequency characteristics of the power line by measuring the level of the ring unit and the extracted measurement signal It consists of a measuring instrument,
The oscillator has a sweep timing signal generating means for generating a sweep timing signal. And a predetermined sweep frequency range based on the sweep timing signal for a predetermined sweep time. That outputs the signal obtained by sweeping at the first coupling unit as the measurement signal And
The measuring device synchronizes with the sweep timing signal supplied from the oscillator. Synchronization holding means for generating a unique sweep timing signal, and the synchronization holding means Input from the second coupling unit based on the unique sweep timing signal Power line using a power line frequency characteristic measuring device that measures the level of the measured signal The frequency characteristic measuring method of
The oscillator and measuring instrument are connected by a coaxial cable, and one of the sweep timing signal generators is connected. The step of obtaining the synchronization by supplying the sweep timing signal output from the stage to the other synchronization holding means. And
Remove the coaxial cable and pair the oscillator and the first coupling unit. Pair the measuring instrument and the second coupling unit, and place each at a predetermined position on the power line. Steps,
The sweep timing signal output from the sweep timing signal generating means and the synchronization maintaining signal Performing a measurement based on the unique sweep timing signal output by the holding means; A frequency characteristic measurement method for a power line, comprising: The measuring device includes a timer means,
The timer means counts when the supply of the sweep timing signal to the synchronization holding means stops. Starts time and issues a warning signal when a preset time has elapsed The frequency characteristic measuring apparatus of the power line according to claim 1 or 2.

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