JPH0140419B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a measurement and inspection device for circuit boards, and particularly to a circuit that generates a frequency-modulated audio signal and supplies it to a recording head, and a circuit that generates a frequency-modulated audio signal and supplies it to a recording head, and a circuit that generates a frequency-modulated audio signal and supplies it to a recording head. This invention relates to a device that measures, inspects, and adjusts a circuit board equipped with a circuit that demodulates and outputs a frequency-modulated audio signal by FM.

BACKGROUND ART The present applicant previously disclosed in Japanese Patent Application No. 57-210211 that magnetically modulated frequency-modulated audio signals (FM audio signals) are generated using a dedicated rotary head provided separately from a rotary head for recording and reproducing video signals. We proposed a method in which a video track on a tape is recorded by forming an audio track at the same position, and this is then played back. According to this proposed method, since the FM audio signal is recorded using a dedicated rotating head, it can be distinguished from the FM audio signal.
Compared to the conventional method of multiplexing FM video signals and recording and reproducing them using the same rotating head, mutual interference due to beats between carrier frequencies can be greatly reduced, and moiré on the playback screen can be reduced significantly. It has excellent features such as being able to record and reproduce extremely high-quality audio signals even when the running speed of the magnetic tape is particularly slow, such as in a long-time mode.

A magnetic recording and reproducing device (VTR) to which this proposed method is applied will incorporate a circuit board equipped with the above-mentioned FM audio signal recording and reproducing circuit, which was not available in the past. This circuit board did not exist in conventional helical scan VTRs, and therefore there was no equipment for measuring and adjusting each circuit on this circuit board. For circuit measurement and adjustment, for example, the first
It is conceivable to use a measurement and inspection device having a schematic configuration as shown in the figure.

In Figure 1, circuit board 1 includes a frequency modulator (FM modulator) that converts an input audio signal into an FM signal.
It consists of an audio signal recording circuit consisting of a level compression circuit for noise reduction, an FM demodulator for FM demodulating the reproduced FM audio signal, a dropout compensation circuit, a de-emphasis circuit, and a level expansion circuit for noise reduction. It is equipped with an audio signal reproducing circuit, which is extracted from within the VTR2.
The measurement and inspection items for the audio signal recording circuit on the circuit board 1 include the carrier frequency of the FM audio signal, the FM
There are modulation factors, FM recording level, etc., and measurement and inspection items for audio signal reproduction circuits include audio signal output level, separation, S/N, etc.

First, to explain the measurement inspection of the audio signal recording circuit, the input of the recorded audio signal is stopped and the frequency at the output end of the FM modulator, that is, the FM carrier frequency when no modulation is performed, is measured using the frequency counter 3 shown in FIG. Measure and select a predetermined frequency (for example, 3.1MHz for the left channel, 3.1MHz for the right channel,
1.7MHz) and adjust to the specified frequency. Next, a sine wave of, for example, 1 kHz at the reference level and in the audio band is generated and outputted from the oscillator 4 shown in FIG. The signal is supplied to the recording circuit, where it is converted into an FM signal, and then supplied to the FM modulation degree measuring device 5. The FM modulation degree measuring device 5 demodulates the input FM signal to obtain a demodulated sine wave, and then converts the DC level into a frequency.
The frequency deviation of the FM signal is measured, and the FM modulation degree is measured using this and the modulation frequency. Also, the above
The FM signal is also supplied to an oscilloscope 6, where its level (that is, the FM recording level) is measured, and if it is not a predetermined value, the level is adjusted to a predetermined value using a variable resistor on the head input side.

Next, to explain the measurement inspection of the audio signal reproduction circuit, the first recording track has an FM signal frequency-modulated with a sine wave of a constant frequency at a predetermined reference level recorded for both the left and right channels. , a measuring magnetic tape 7 on which a second recording track in which only the FM signal of one channel is recorded and no signal in the other channel, and a non-recorded portion in which both channels have no signal are formed. Load it into VTR2 and play it. Thereby, the signals reproduced from the magnetic tape 7 are reproduced by the audio signal reproduction circuit on the circuit board 1 and then supplied to the measuring instrument.

In this case, the output level can be measured by measuring the demodulated signal level of the FM signal reproduced from the first recording track, and when the second recording track is reproduced, the output level of the other channel, which has no signal, can be measured. Separation can be measured by measuring the level of the demodulation output end (leakage signal level from one channel). Furthermore, an S/N check can be performed by measuring the noise level when a portion where there is no signal in both channels is reproduced.

Problems to be Solved by the Invention However, the above measurement and inspection device
For measurement and inspection, it is necessary to prepare separate equipment such as the frequency counter 3, oscillator 4, FM modulation degree measuring device 5, and oscilloscope 6, which is expensive. The work is complicated because it has to be used depending on the audio channel, and especially when there are two audio channels, the work is even more complicated, and space efficiency is also poor. Furthermore,
The measuring magnetic tape 7 must be used for various measurement tests of the audio signal reproduction circuit.
Since the magnetic tape 7 comes into sliding contact with the head each time it is reproduced, problems arise in terms of durability and reliability.

Therefore, the present invention provides a signal generation circuit, an FM demodulator,
This circuit board solves the above problems by incorporating a detection circuit, frequency counter, frequency modulator, display, etc. into one housing, and is configured to generate and output a signal equivalent to the reproduced FM signal. The purpose is to provide measurement and inspection equipment.

Means for Solving the Problems The present invention is a measurement and inspection device for a circuit board, which is equipped with a recording circuit that outputs a frequency-modulated wave signal as a recording signal, and a reproducing circuit having an FM demodulation circuit. an FM demodulator for FM demodulating a first frequency modulated wave signal obtained through the recording circuit with a reference level signal corresponding to the input signal; and a first for instructing the degree of FM modulation from the output signal level of the FM demodulator. a detection circuit for detecting the first frequency modulated wave signal, a second display for displaying a recording level based on the output signal level of the detection circuit, and the recording circuit for the signal at the reference level. a frequency counter that measures the frequency of the first frequency-modulated wave signal when transmission is stopped; a signal generation circuit that generates a signal whose level can be varied; and an output signal of the signal generation circuit that measures the frequency of the first frequency-modulated wave signal. a frequency modulator that outputs a second frequency-modulated wave signal obtained by frequency modulating the same carrier frequency to the reproducing circuit, and the circuit board is It is configured to perform measurement inspection, and one embodiment thereof will be described below with reference to FIGS. 2 to 5.

Embodiment Before explaining one embodiment of the device of the present invention,
First, to explain the circuits mounted on the circuit board to be measured and inspected by the apparatus of the present invention, FIG. 2 is a circuit system diagram of an example of the recording circuit on the circuit board, and FIG. 3 is the reproduction circuit on the circuit board. An example circuit diagram is shown. In both figures, each circuit on the left channel audio signal transmission line is numbered with a suffix L, and each circuit on the right channel audio signal transmission line is numbered with a suffix _R. In Fig. 2, left and right channel audio signals received and demodulated by the tuner enter input terminals 9 _L and 9 _R , and input terminal 1
0 _L and 11 _L , 10 _R and 11 _R receive left and right channel audio signals from microphones and other audio equipment, and input terminals 12 _L and 12 _R receive left and right channel audio signals from a television camera. A signal comes in. The left and right channel audio signals are supplied to AGC circuits 15 _L and 15 _R through switching circuits 13 L and 13 _R and variable resistors 14 _L and 14 _{R ,} respectively.

The AGC circuits 15 _L and 15 _R are configured to be turned off and on by a switch 16, and when turned on, limit the peak level of the input audio signal to a constant value. The output audio signals of these AGC circuits 15 _L and 15 _R are subjected to level compression and encoder 1 for noise reduction.
7 _L , 17 _R , amplifiers 18 _L , 18 _R , low-pass filters 19 _L , 19 _R , limiters 20 _L , for limiting the amplitude of excessive levels when the AGC circuits 15 _L , 15 _R are off.
20 _R , variable resistors 21 _L , 21 _R , and frequency modulators (FM modulators) 22 _L , 22 _R are supplied through a pre-emphasis circuit (not shown), respectively.

The carrier frequency of the FM modulator _22L is set to, for example, 1.3MHz by the variable resistor _23L ,
Frequency modulates 1.3MHz with the left channel audio signal and outputs a frequency modulated audio signal (FM audio signal). This left channel FM audio signal is supplied to the preamplifier 26 through a low-pass filter 24 _L and a recording level adjusting variable resistor 25 _L , respectively. On the other hand,
The carrier frequency of the FM modulator _22R is set to, for example, 1.7MHz by the variable resistor _23R ,
Outputs the right channel FM audio signal. This right channel FM audio signal is supplied to the preamplifier 26 through the low-pass filter 24 _R and recording level adjustment variable resistor 25 _R , where it is frequency division multiplexed with the left channel FM audio signal, and then output to the output terminal. Two audio signal recording rotary heads (not shown) are supplied through 27-1 and 27-2, respectively.

Next, to explain the reproducing circuit shown in FIG. 3, as in the signal recording and reproducing system proposed by the applicant, for example, two audio signal rotary heads are provided separately from the video signal rotary head. Respective playback signals (left channel) from rotating heads (not shown)
A frequency division multiplexed signal of the FM audio signal and the right channel audio signal) enters the input terminals 28-1 and 28-2 alternately every field period, and is further supplied to the amplifier 30 through the preamplifier 29. The reproduced signals extracted from the amplifier 30 are supplied to band filters 31 _L and 31 _R , respectively, where the left channel FM audio signal and the right channel FM audio signal are frequency-selected and extracted. The reproduced left channel FM audio signal is supplied to a limiter _33L and a dropout detection circuit _34L through an amplifier _32L , respectively. Limiter 33 _L output playback FM
The audio signal is FM demodulated by a well-known phase-locked loop (PLL) FM demodulator consisting of a phase comparator 35 _L , a voltage controlled oscillator (VCO) 36 _L , and a buffer amplifier 37 _L , and then converted to a signal with a cutoff frequency of about 60 kHz. The signal is supplied to a sample and hold circuit _41L through a low-pass filter _39L and an amplifier _40L . Similarly, the reproduced right channel FM audio signal taken out from the band filter _31R is supplied to the dropout detection circuit _34R through the amplifier _32R , and is sampled and held after being FM demodulated by an FM demodulator using a PLL. It is supplied to the circuit _41R . Sample hold circuit 4
1 _L and 41 _R are dropout detection circuits 34 _L ,
Based on the detection signal from 34 _R , during the period when dropout occurs, the circuit holds the previous playback signal level (terminal voltage of hold capacitors 42 _L and 42 _R ), and during the period when dropout does not occur, the input signal level is maintained. This is a circuit that allows the signal to pass through as is.

The output reproduction audio signals of the sample and hold circuits 41 _L and 41 _R are transmitted through amplifiers 44 _L and 44 _R , de-emphasis circuits 45 _L and 45 _R , and variable resistors 46 _L and 46.
output terminals 49 _L , 4 through level expansion and decoders 47 _L , 47 _R , and amplifiers 48 _L , 48 _R , respectively _.
9 Output to _R. In this way, output terminal 4
The reproduced left channel audio signal which has been FM demodulated and subjected to dropout compensation and noise reduction processing is taken out to 9 _L , and the reproduced right channel audio signal which has been subjected to similar signal processing is taken out to the output terminal 49 _R. It will be done. Note that the circuit portions surrounded by broken lines 50 _L and 50 _R can be implemented as an IC (integrated circuit).

Next, an embodiment of the present invention apparatus for measuring and inspecting each part of the recording circuit and reproduction circuit on the circuit board will be described. 4A and 4B are block system diagrams of an embodiment of the apparatus of the present invention, and FIG. 5 is an external front view of an embodiment of the apparatus of the present invention. In both figures, the same components are designated by the same reference numerals. This embodiment is a device that performs measurement inspection of a recording circuit and supplies a measurement inspection signal to a reproduction circuit, and all the circuits shown in FIGS. 4A and 4B are housed in a casing 70 shown in FIG. 5. has been done. Note that the measurement test of the reproducing circuit is performed in the same manner as explained in FIG. First, to explain the measurement and inspection operation of the recording circuit, see Figure 5.
Press the record button indicated by REC to enter recording adjustment mode. When measuring and inspecting the FM carrier frequency, press button 71 _L or 71 _R in Figure 5. When the button 71 _L is pressed, the switch 58 in Fig. 4A is connected to the contact L side, and when the button 71 _R is pressed, the switch 58 is connected to the contact L side.
is connected to the contact R side. Furthermore, no signals are supplied to the input terminals 9 _L to 12 _L and 9 _R to 12 _R of the recording circuit shown in FIG. Therefore, the FM signal that enters the input terminal 54 of FIG. 4A via the output terminal 27-1 or 27-2 is the left channel FM signal when no modulation
This is a frequency division multiplexed signal of the signal and the right channel FM signal, and this multiplexed signal is sent to the buffer amplifier 55.
are supplied to bandpass filters 56 _L and 56 _R , respectively.

Band filter 56 _L has a passage band on the left channel.
The band filter 56 R is selected to have a pass band necessary to pass the FM audio signal (for example, 1.3 MHz ± 150 kHz), and the band filter 56 _R has a pass band that is necessary to pass the right channel FM audio signal (for example, 1.7 MHz ± 150 kHz). The band has been selected. Therefore, from the band filter 56 _L , the left channel FM when no modulation is
The signal is taken out, and the right channel FM signal without modulation is taken out from the band filter _56R .
FM extracted from band filters 56 _L and 56 _R
The signal is split into three by splitters _57L and _57R.
FM demodulators 61 _L , 61 _R , average value detection circuit 62 _L ,
62 _R and contacts L and R of the switch 58. Here, assuming that the button _71L is pressed, the output FM signal of the distributor _57L is
8 to a frequency counter 59, where the frequency is counted and the value is digitally displayed by a frequency display 60. This frequency value is the unmodulated carrier frequency of the left channel FM signal, so it is 1.3MHz. This frequency value is
For example, if it is more than 10kHz away from 1.3MHz,
Figure 2 Adjust variable resistor 23 _L to 1.3MHz±10k
Adjust the frequency to within Hz.

Similarly, by pressing the button _71R , the unmodulated carrier frequency of the right channel FM signal taken out from the distributor _57R can be measured and displayed on the frequency display 60. This frequency value is 1.7MHz
If the frequency is outside ±10kHz, change the resistance value of variable resistor _23R in Figure 2 to 1.7MHz±10kHz.
Adjust the frequency to within Hz. In this way, by simply pressing the buttons _71L and _71R , the unmodulated carrier frequencies of the FM audio signals of the left and right channels to be recorded can be measured and inspected, and furthermore, their adjustment becomes easy.

Next, when measuring and inspecting the FM modulation degree and FM signal recording level, supply a 1kHz sine wave of -20dB as a modulation signal to the recording circuit on the board, and
The FM output is input to the input terminal 54. As a result, the FM demodulator 6 using the PLL detection method shown in FIG.
FM demodulated 1kHz sine waves are taken out from 1 _L and 61 _R and supplied to the modulation index display 63, respectively. As shown in FIG. 5, the modulation degree indicator 63 has two pointers 72 _L and 72 _R of different colors, and indicates the DC peak-to-peak level of the demodulated signal of the left channel from the FM demodulator 61 _L. is converted into a deviation frequency (unit: kHz) and displayed on the pointer 72 _L , and the DC peak-to-peak level of the demodulated signal of the right channel from the FM demodulator 61 _R is similarly converted into a deviation frequency and displayed on the pointer 72 L. Display in _R.
The above reference level is selected to a value that allows the operational deviation (for example, ±50 kHz) of the FM signal to be obtained, so while monitoring the display 63, the second The resistance values of the variable resistors 21 _L and 21 _R shown in the figure are varied. In this way, measurement inspection and adjustment of the FM modulation degree can be performed.

On the other hand, the detected signals of the FM signals of the left and right channels taken out from the average value detection circuits 62 _L and 62 _R are supplied to the recording level indicator 64. As shown in FIG. 5, the recording level display 64 has two pointers 73 _L and 73 _R of different colors, and the pointer 73 _L can display a level of up to 50 mV _pp , and the pointer 73 _R It is configured to be able to display up to a level of 200mV _pp .
The output detection voltage of the average value detection circuit 62 _L is set as the pointer 73 _L.
The output detection voltage of the average value detection circuit _62R is displayed by the pointer _73R . Therefore, the recording level of the left channel FM signal is measured and displayed by the pointer 73 _L of the display 64.
The recording level of the right channel FM signal is measured and displayed by the pointer _73R . While watching the pointers _73L and _73R , set the second pointer so that the predetermined recording level is displayed.
The resistance values of the variable resistors 25 _L and 25 _R shown in the figure are varied. As is well known, the level characteristics of tape recording and playback decrease at high frequencies, so in order to compensate for this, the recording level is set higher for the higher frequency right channel FM signal than for the left channel FM signal. recorded.

Next, to explain the operation of supplying the measurement signal to the reproducing circuit, first press the button indicated by PB in FIG. 5 to set the measurement signal output mode. This measurement signal is generated based on the output signal of the signal generation circuit 65 shown in FIG. 4B. The signal generation circuit 65
For example, 20Hz, 100Hz, 400Hz can be set using the knob 74 in the figure.
8 of Hz, 1kHz, 5kHz, 10kHz, 15kHz and 20kHz
Generates and outputs one of the types of frequencies. The single frequency signal from this signal generation circuit 65 is supplied to a variable attenuator 66, where the signal is sent from 0 to
The amount of attenuation can be varied in 1 dB steps or 10 dB steps within the range up to -60 dB. This attenuation amount is 1dB
To decrease the attenuation in steps, press button 75 in Figure 5. To increase it in 1 dB steps (to obtain a larger amount of attenuation), press button 76 to decrease or increase the attenuation in 10 dB steps. press buttons 77 and 78. The number of times buttons 75 to 78 are pressed becomes the step number.

The signal generation circuit 65 and the variable attenuator 66 constitute a signal generation circuit, and the output signal frequency and attenuation amount are indicated by the indicators 81 and 8 in FIG. 5, respectively.
2 is digitally displayed. The single frequency signal in the audio band taken out from the variable attenuator 66 is sent to a frequency modulator (voltage-to-frequency converter) 67.
_L and 67 _R, respectively, and converted into FM signals. As an example, the deviation of the FM signal is ±50kHz when the attenuation amount is -20dB. The frequency modulator 67 _L frequency-modulates the carrier frequency of 1.3 MHz using an input signal, and supplies the obtained FM signal as a left channel FM signal to the mixing circuit 69 through a normally closed switch 68 _L. Also, like the frequency modulator 67 _L , the frequency modulator 67 _R has an internally adjusted distortion rate of 1 kHz.
Less than 0.05% of the carrier frequency in the input signal
The FM signal obtained by frequency modulating 1.7MHz is supplied as a right channel FM signal to the mixing circuit 69 through a normally closed switch _68R . As a result, from the mixing circuit 69, a signal obtained by frequency division multiplexing the left channel FM signal and the right channel FM signal, respectively, is transmitted as a reproduction FM signal to the band filter of the reproduction circuit shown in FIG. 3 on the circuit board. 31 _L and 31 _R input side.

Thereby, various measurements of the reproducing circuit can be performed without using the reproduction signal of the magnetic tape. In addition, when checking the separation,
Press the button 79 or 80 shown in Fig. 5 to turn off the switch 68 _L or 68 _R shown in Fig. 4B, and select one of the two channels of FM signal.
The signal is output from the mixing circuit 69 with no signal, and the buttons 79 and 80 are pressed when checking the S/N.
Press both to make the output FM signal of the mixing circuit 69 no signal. Note that when the switch 83 shown in FIG. 5 is set to the "MIX" side, the output signal of the mixing circuit 69 shown in FIG. 4B is outputted to the outside,
When switched to the "SEPARATE" side, switch 68
Both _{the L} and _68R output signals are separately output to the left and right channel FM signal output terminals, respectively.

Effects As described above, according to the present invention, the signal generation circuit,
Since the FM demodulator, detection circuit, frequency counter, frequency converter, display, etc. are built into one housing, space efficiency can be improved compared to when separate measurement equipment is provided. It can be constructed at low cost, and the desired measurement and inspection items can be measured simply by operating switches and buttons provided on the casing without changing the connection to the circuit board, greatly improving measurement work efficiency. In addition, since the signal generation circuit generates and outputs a signal equivalent to the reproduced FM signal, it is possible to improve the adjustment work efficiency. It is possible to solve problems such as deterioration of the magnetic tape, greatly improve adjustment accuracy, and eliminate the hassle of storing magnetic tapes. Also, since the detection circuit is an average value detection circuit, the circuit configuration is simple. Further, since only one frequency counter is required regardless of the number of input signal channels, the circuit configuration can be further simplified.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a configuration that can be used as a circuit board measurement and inspection device, FIG. 2 is a circuit system diagram showing an example of a recording circuit on a circuit board that can be measured by the device of the present invention, and FIG. A circuit system diagram showing an example of a reproducing circuit on a circuit board that can be measured by the inventive device, FIGS. 4A and 4B are block system diagrams each showing an embodiment of the inventive device, and FIG. FIG. 2 is a front view showing the appearance of the example. DESCRIPTION OF SYMBOLS 1... Circuit board, 3... Frequency counter, 7... Magnetic tape for measurement, 9 _L to 12 _L ... Left channel audio signal input terminal, 9 _R to 12 _R ... Right channel audio signal input terminal, 17 _L , 17 _R ... Level Compression and encoder, 22 _L , 22 _R ... Frequency modulator (FM modulator), 25 _L , 25 _R ... Variable resistor for recording level adjustment, 28-1, 28-2... Reproduction FM audio signal input terminal, 34 _L , 34 _R ...Dropout detection circuit,
47 _L , 47 _R ...Level expansion and decoder, 50 _L ,
50 _R ...IC, 54...FM signal input terminal, 56 _L , 5
6 _R ...Band filter, 58...Switch, 59...Frequency counter, 60...Frequency display, 61 _L , 6
1 _R ...FM demodulator, 62 _L , 62 _R ...average value detection circuit, 63...modulation degree indicator, 64...recording level indicator, 65...signal generation circuit, 66...variable attenuator, 67 _L , 67 _R ...frequency Modulator, 69...Mixing circuit, 72 _L , 72 _R , 73 _L , 73 _R ... Pointer.

Claims (1)

[Claims] 1. A recording circuit that generates and outputs a frequency modulated wave signal obtained by frequency modulating a predetermined carrier frequency with an input signal as a recording signal, and a recording circuit that generates and outputs a frequency modulated wave signal input as a reproduction signal. A measurement and inspection device for a circuit board is equipped with a circuit for demodulating and outputting the signal, and FM demodulates a first frequency modulated wave signal obtained through the recording circuit with a reference level signal corresponding to the input signal. an FM demodulator, a first indicator that indicates the degree of FM modulation from the output signal level of the FM demodulator, a detection circuit that detects the first frequency-modulated wave signal, and an output signal level of the detection circuit. a second indicator that displays a recording level; a frequency counter that measures the frequency of the first frequency-modulated wave signal when the sending of the reference level signal to the recording circuit is stopped; and a frequency counter that is capable of varying the level. a signal generating circuit that generates a signal; and a frequency modulation circuit that outputs a second frequency-modulated wave signal obtained by frequency modulating a carrier frequency that is the same as the predetermined frequency using the output signal of the signal generating circuit to the reproducing circuit. 1. A measurement and inspection device for a circuit board, characterized in that the circuit board is measured and inspected using each of the circuits described above housed in one housing. 2. The signal generation circuit attenuates a signal of one frequency arbitrarily selected from a plurality of signals having different frequencies by an attenuation amount arbitrarily selected from among a plurality of preset attenuation amounts and outputs the attenuated signal. A measurement and inspection device for a circuit board according to claim 1, which is a circuit. 3. The circuit board outputs frequency modulated wave signals of multiple channels having different carrier frequencies as recording signals, and also outputs FM signals of the multiple channels.
A circuit for obtaining a demodulated signal is installed, and a plurality of the FM demodulators, detection circuits, and frequency modulators are provided in parallel according to the number of channels, and the pointer of the first and second display 2. The circuit board measurement and inspection apparatus according to claim 1, wherein a plurality of said channels are provided according to the number of said channels. 4 The detection circuit is an average value detection circuit, and the FM
2. The circuit board measurement and inspection apparatus according to claim 1, wherein the demodulator is a peak detection type circuit using a phase locked loop. 5 The circuit board outputs frequency modulated wave signals of multiple channels having different carrier frequencies as recording signals, and also outputs FM signals of the multiple channels.
The frequency counter is equipped with a circuit for obtaining a demodulated signal, and the frequency counter has a switch at the input stage that selects and outputs only the frequency modulated wave signal of an arbitrary channel among the frequency modulated wave signals of the plurality of channels. A measurement and inspection device for a circuit board according to claim 1 or 3, characterized in that: