Measuring device, measuring method, and recording medium

Abstract

A reproducing device (10) (measuring device) in a recording and reproducing system (1) comprising a record player (100) and a reproducing device (10) measures frequency characteristics of a plurality of input signals corresponding to the plurality of test signals recorded thereon, input from the record player (100) to the reproducing device (10), when the record player (100) reproduces a plurality of test signals for measuring characteristics of the recording and reproducing system (1) and the test signals are recorded thereon, calculates measurement errors between the measured frequency characteristics of the plurality of input signals and a predetermined frequency characteristic, selects a frequency characteristic having the smallest measurement error among the frequency characteristics of the plurality of input signals as a measurement result of the recording and reproducing system (1), and outputs the selected measurement result.

Description

Technical Field

[0001] The present disclosure relates to a measuring device, a measuring method, a recording medium, and a record for measuring various characteristics of a pickup cartridge (hereinafter, also referred to as a cartridge) or a transmission path between a turntable system and a phono equalizer in a recording and reproduction system. Background Art

[0002] Patent document 1 discloses a technique for measuring the characteristics of a recording and reproducing system that changes according to various characteristics of a cartridge, etc., using a record having a raised cosine pulse waveform having a short pulse width. Specifically, the characteristics of the recording and reproducing system are the frequency characteristics (frequency amplitude characteristics and frequency phase characteristics, etc.) of an input signal input from a record player to a reproducing device having a phono equalizer and an amplifier, etc.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Publication No. 58-33605 Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, in the technology disclosed in Patent Document 1, when measuring the characteristics of a recording and playback system using a raised cosine pulse waveform with a short pulse width, it is easily affected by interference factors such as scratch noise, making it difficult to measure the S / N ratio (signal-to-noise ratio) well. On the other hand, in order to measure the S / N ratio well, it is considered to use a SS (Swept Sine) signal such as a TSP (Time Stretched Pulse) signal in which the pulse signal is stretched in the time direction. However, when the SS signal is applied to a record, there is a case where the original characteristics cannot be measured due to the influence caused by the record player and the record.

[0008] The present disclosure provides a measuring device and the like that can efficiently measure the characteristics of a recording and playback system.

[0009] Means for solving problems

[0010] The measuring device disclosed in the present invention is a measuring device in a recording and reproducing system having a record player and a measuring device, and comprises: a processor; and a memory, wherein the processor executes a program stored in the memory, and when a plurality of test signals for measuring the characteristics of the recording and reproducing system are reproduced by the record player and recorded on a record, the processor measures the frequency characteristics of a plurality of input signals input from the record player to the measuring device and corresponding to the plurality of test signals recorded thereon, calculates the measurement errors between the frequency characteristics of the plurality of input signals being measured and the prescribed frequency characteristics, selects the frequency characteristic with the smallest measurement error among the frequency characteristics of the plurality of input signals as the measurement result of the recording and reproducing system, and outputs the selected measurement result.

[0011] The measuring method disclosed in the present invention measures the frequency characteristics of a plurality of input signals input from the record player and corresponding to the plurality of test signals recorded thereon, when the system is reproduced through a record player in the system for measuring the characteristics of the record player, calculates the measurement errors between the frequency characteristics of the plurality of input signals being measured and the prescribed frequency characteristics, selects the frequency characteristic with the smallest measurement error among the frequency characteristics of the plurality of input signals as the measurement result of the record player, and outputs the selected measurement result.

[0012] The recording medium of the present disclosure is a computer-readable recording medium recording a program for causing a computer to execute the above-mentioned measuring method.

[0013] The record disclosed in the present invention has a plurality of test signals recorded in the soundprint within one turn for measuring the characteristics of the recording and reproducing system.

[0014] Effects of the Invention

[0015] According to the measuring device and the like of the present disclosure, it is possible to efficiently measure the characteristics of a recording and reproducing system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a diagram showing an example of the configuration of a recording and playback system according to an embodiment.

[0017] Figure 2 This is a circuit diagram showing an example of an equivalent circuit of a load and a transmission path connecting the load and the load in a moving magnet type pickup.

[0018] Figure 3A It is a top view showing an example of a record according to the embodiment.

[0019] Figure 3B This is a cross-sectional view showing an example of a voiceprint of a recording test signal and a detection signal for detecting a reproduction speed.

[0020] Figure 4A It is a top view showing another example of a record according to the embodiment.

[0021] Figure 4B It is a cross-sectional view showing another example of a voiceprint of a recording test signal and a detection signal for detecting a reproduction speed.

[0022] Figure 5 This is a flowchart showing an example of the operation of the measuring device according to the embodiment.

[0023] Figure 6 This is a diagram for explaining a method of measuring frequency characteristics of a plurality of input signals.

[0024] Fig. 7A This is a diagram for explaining a method of calculating measurement errors between frequency characteristics of a plurality of input signals and predetermined frequency characteristics.

[0025] Figure 7B It is a diagram for explaining the method of selecting measurement results.

[0026] Figure 7C It is a diagram for explaining a specific example of the method of selecting measurement results.

[0027] Figure 8 It is a diagram for explaining conversion of the sampling rate. DETAILED DESCRIPTION

[0028] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings as appropriate. However, sometimes more detailed descriptions than necessary are omitted. For example, sometimes detailed descriptions of matters that are already widely known or repeated descriptions of substantially the same configurations are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art.

[0029] The inventor provides the drawings and the following description for those skilled in the art to fully understand the present disclosure, and does not intend to limit the subject matter described in the scope of the claims by them.

[0030] (Implementation Method)

[0031] Below, use Figures 1 to 8 An implementation method will be described.

[0032] Figure 1 It is a diagram showing an example of the configuration of the recording and reproducing system 1 according to the embodiment.

[0033] The recording and playback system 1 is a system for playing back analog recordings, and includes a record player 100 , a playback device 10 , and a speaker 80 .

[0034] The record player 100 is an acoustic device for reproducing a signal (for example, a sound signal) recorded on a record, and includes a turntable 101 and a pickup 102 .

[0035] The turntable 101 is a turntable on which a record is placed and which rotates (specifically, rotates) at a certain speed.

[0036] The pickup 102 is provided at the front end of the tone arm (not shown), and is a pickup having a stylus for tracking the sound pattern of the record placed on the turntable 101. The pickup has various structures such as a moving magnet type or a moving coil type according to its structure. Such a pickup obtains the signal of the sound pattern recorded on the record as vibration via the stylus, and the magnet or coil vibrates according to the obtained vibration to generate voltage, which is converted into an analog electrical signal and output. In this embodiment, the pickup 102 is described by taking a moving magnet type pickup as an example.

[0037] The speaker 80 converts the power of a signal output from the amplifier 70 described later into acoustic energy and outputs the sound to the space.

[0038] The playback device 10 is a device that adjusts or amplifies the frequency characteristics of an input signal input from a record player 100 that plays back a record, and includes a processor 20, a memory 30, a phono equalizer 40, an A / D converter 50, a D / A converter 60, and an amplifier 70. The playback device 10 is an example of a measuring device.

[0039] The phono equalizer 40 is an equalizer that corrects the frequency amplitude characteristic of the electric signal output from the cartridge 102 to a flat characteristic. Generally, a record effectively uses the dynamic range, and therefore, a frequency emphasis process is applied when cutting. If the frequency characteristic of the sound source is not corrected and the cutting is performed as it is, the amplitude becomes larger in the low frequency. Therefore, when cutting, the amplitude limit of the cutter head is exceeded, and tracking during reproduction becomes difficult. On the other hand, the amplitude becomes smaller in the high frequency, and therefore the S / N ratio decreases. Therefore, cutting is performed on the basis of correcting the soundprint of the record in a manner that the signal level of the low frequency is reduced in advance and the signal level of the high frequency is increased. This correction generally uses a characteristic curve determined by RIAA (Recording Industry Association of America). During reproduction, a curve that is an inverse characteristic of the above-mentioned characteristic curve is used for correction so that the frequency characteristic is restored to the original flat characteristic.

[0040] The A / D converter 50 is a converter that converts the electric signal (analog signal) output from the Phono equalizer 40 into a digital signal. The A / D converter 50 outputs a digital signal.

[0041] The D / A converter 60 is a converter that converts a signal (digital signal) whose frequency characteristics have been adjusted by a digital filter 13 described later into an analog signal. The D / A converter 60 outputs an analog signal.

[0042] The amplifier 70 is an amplifier that amplifies the analog signal output from the D / A converter 60. The amplifier 70 may be, for example, a class D amplifier or the like.

[0043] The characteristics of the recording and reproducing system 1, specifically, the frequency characteristics of the input signal input from the record player 100 to the reproducing device 10, vary depending on the characteristics of the cartridge 102 of the record player 100, the load connected to the cartridge 102 (for example, the reproducing device 10, specifically, the phono equalizer 40), and the transmission path connecting the cartridge 102 and the load (for example, impedance mismatch, etc.). In this regard, the frequency characteristics of the input signal from the record player 100 to the reproducing device 10 vary. Figure 2 Provide explanation.

[0044] Figure 2 1 is a circuit diagram showing an example of an equivalent circuit of a load in the moving magnet type pickup 102 and a transmission path connecting the pickup 102 and the load.

[0045] The input signal (input voltage Ei) to the reproduction device 10 becomes a value corresponding to the open-circuit output voltage Ec of the cartridge 102, the DC resistance r of the cartridge 102, the inductance L of the cartridge 102, the parasitic capacitance C of the transmission path, and the load resistance R, that is, the frequency characteristics of the input signal to the reproduction device 10 change according to these characteristics.

[0046] The playback device 10 is also a device for measuring the characteristics of the recording and playback system 1. Specifically, as described above, the frequency characteristics of the input signal to the playback device 10 are measured based on the changes in the characteristics of the cartridge 102, the load connected to the cartridge 102, and the transmission path connecting the cartridge 102 and the load. The playback device 10 may also have a function of correcting the frequency characteristics according to the changes. The function of measuring the characteristics of the recording and playback system 1 and the function of correcting the frequency characteristics of the playback device 10 are realized by the frequency characteristics measuring unit 11, the filter coefficient calculating unit 12, the digital filter 13, and the playback speed detecting unit 14. The frequency characteristics measuring unit 11, the filter coefficient calculating unit 12, the digital filter 13, and the playback speed detecting unit 14 will be described in detail later.

[0047] When the reproduction device 10 measures the characteristics of the recording and reproducing system 1, a record that is not for viewing but for measuring the characteristics of the recording and reproducing system 1 is placed on the turntable 101, and the test signal recorded on the record for measurement is reproduced. The test signal is an SS signal such as a TSP signal. The SS signal is a signal in which the energy is relatively increased by stretching the pulse signal along the time direction. In the SS signal, the frequency changes from a low frequency to a high frequency, or from a high frequency to a low frequency in time. By using the SS signal, it is possible to perform a measurement with a high S / N ratio.

[0048] However, when an SS signal is applied to the record for measurement, when measuring the characteristics of the recording and reproducing system 1, it is affected by the record player 100 and the record. For example, there is an influence of the warping of the record, in which the tone arm vibrates up and down due to the warping of the record, so that the appropriate needle pressure is not applied to the stylus, and the stylus is separated from the record and cannot accurately track, causing the open-circuit output voltage Ec of the voiceprint pickup 102 to change. For example, there is an influence of a change in radius due to a positional offset of the center hole of the record (positional offset of the center of the record) or a change in the radius of the record caused by the feeding of the track during the production of the record (when engraving), which changes the linear velocity and changes the reproduction speed of the sound source. For example, there is an influence of a rotational speed offset that causes the reproduction speed to change due to an offset in the rotation speed of the turntable 101. In this way, when an SS signal is applied to the record, there is a problem that it is difficult to accurately measure the input signal due to the influence unique to the record player 100 and the record. In order to solve this problem, in the present disclosure, a record 200 and a reproducing device 10 are used. Use FIG. 3A to FIG. 4B The record 200 will be described.

[0049] Figure 3A It is a top view showing an example of a record 200 according to the embodiment.

[0050] Figure 3B This is a cross-sectional view showing an example of a voiceprint of a recording test signal and a detection signal for detecting a reproduction speed.

[0051] Record 200 is a record used exclusively for measuring the characteristics of recording and reproducing system 1, and multiple (multiple) test signals for measuring the characteristics of recording and reproducing system 1 are recorded in the soundprint. The test signals recorded multiple times are the same signals, which are SS signals such as TSP signals. In record 200, the test signals for measuring the characteristics of recording and reproducing system 1 are recorded multiple times in soundprints within one circle. This is because when the test signal is recorded multiple times in soundprints of more than one circle, there is a risk that interference will occur between adjacent soundprints in the radial direction of record 200 if the track pitch is small during engraving, thereby deteriorating the S / N ratio. Figure 3AIn FIG. 1 , an example of a voiceprint in which a test signal is recorded multiple times in about 1 / 4 of a circle is output. In this way, by recording a test signal multiple times in a voiceprint within one circle, it is possible to suppress the deterioration of the S / N ratio.

[0052] In the record 200, the test signal is recorded multiple times in the soundprint of the outer peripheral area of ​​the record 200. This is because in the turntable system, the turntable 101 rotates at a certain rotation speed (for example, 331 / 3rpm), and therefore the linear velocity of the inner peripheral area of ​​the record 200 is slow. In the case where the test signal is recorded in the soundprint of the inner peripheral area of ​​the record 200, the S / N ratio becomes worse. The soundprint of the outer peripheral area of ​​the record 200 refers to the soundprint located at a position farther than half the radius of the record 200 from the center of the record 200 toward the outer periphery of the record 200. Figure 3A , the case where the distance R2 from the center of the record 200 to the soundprint where the test signal is recorded is larger than half the radius R1 of the record 200 is shown, and the test signal such as the SS signal is recorded multiple times in the soundprint at the position of R2.

[0053] In the record 200, a detection signal for detecting the reproduction speed of the record 200 is recorded at a position adjacent to the position of the soundprint where the test signal is recorded multiple times on the outer circumference side or the inner circumference side of the record 200. For example, the detection signal is a single-frequency sine wave signal, and is recorded in such a way that it becomes a known frequency (for example, 1 kHz) when the record 200 is reproduced at a known rotation speed such as 331 / 3 rpm, so the period of the sine wave signal can be calculated in advance. Therefore, by comparing the time interval of the zero-crossing point when the record 200 is reproduced at an unknown rotation speed (equivalent to a half period of the sine wave) with the period of the sine wave signal calculated in advance when the record 200 is reproduced at a known rotation speed, the reproduction speed can be obtained. For example, the sampling rate conversion rate is calculated using the number of samples between adjacent zero-crossing points of the sine wave signal when the record 200 is reproduced at an unknown rotation speed and the number of samples between adjacent zero-crossing points of the sine wave signal when the record 200 is reproduced at a known reproduction speed (for example, stored in advance in a memory, etc.), and the sampling rate conversion is performed. The test signal is recorded multiple times at positions adjacent to the position of the soundprint where the test signal is recorded. If the change in the radius of the record caused by the positional deviation of the center hole of the record or the change in the radius of the record caused by the track feeding during the groove of the record is adjacent to the soundprint, the change in the reproduction speed can be considered equal. Therefore, by detecting the reproduction speed (number of samples) in the soundprint of the test signal recorded on the record 200, the reproduction speed in the soundprint of the test signal recorded adjacent to the soundprint of the test signal can be measured.

[0054] exist Figure 3A as well as Figure 3B, an example is shown in which a detection signal is recorded in a soundprint adjacent to the outer circumference of the record 200 relative to a soundprint in which a test signal is recorded multiple times. In this case, the detection signal is recorded in a channel (right channel (recorded as Rch in the figure)) on the outer circumference of the soundprint. Generally speaking, the right channel of the soundprint is located on the outer circumference of the record, and the left channel of the soundprint (recorded as Lch in the figure) is located on the inner circumference of the record. In the case where the detection signal is recorded in a soundprint adjacent to the outer circumference of the record 200 relative to a soundprint in which a test signal is recorded multiple times, the right channel of the soundprint in which the detection signal is recorded is farther from the soundprint in which the test signal is recorded than the left channel. As a result, the influence of the detection signal on the test signal can be suppressed, and the deterioration of the S / N ratio can be suppressed.

[0055] In the record 200, a soundprint corresponding to a plurality of test signals may be recorded, and a detection signal for detecting the reproduction speed of the record 200 may be recorded in the adjacent soundprints on the inner circumference of the record 200. Figure 4A as well as Figure 4B Provide explanation.

[0056] Figure 4A It is a top view showing another example of the record 200 according to the embodiment.

[0057] Figure 4B It is a cross-sectional view showing another example of a voiceprint of a recording test signal and a detection signal for detecting a reproduction speed.

[0058] exist Figure 4A as well as Figure 4B , an example is shown in which a detection signal is recorded in a soundprint adjacent to the inner circumference of the record 200 relative to a soundprint in which a test signal is recorded multiple times. In this case, the detection signal is recorded in a channel (left channel) on the inner circumference of the soundprint. In the case in which the detection signal is recorded in a soundprint adjacent to the inner circumference of the record 200 relative to a soundprint in which a test signal is recorded multiple times, the left channel in the soundprint in which the detection signal is recorded is farther from the soundprint in which the test signal is recorded than the right channel. Thus, the influence of the detection signal on the test signal can be suppressed, and the deterioration of the S / N ratio can be suppressed.

[0059] In the case where the detection signal is recorded in a soundprint adjacent to the outer circumference of the record 200 relative to the soundprint in which the test signal is recorded multiple times, the detection signal can be reproduced earlier than the test signal, so the test signal can be reproduced after the sampling rate conversion rate is determined in advance, and the sampling rate conversion can be performed in real time. Therefore, compared with the case where the detection signal is recorded in a soundprint adjacent to the inner circumference of the record 200 relative to the soundprint in which the test signal is recorded multiple times, the case where the detection signal is recorded in the soundprint adjacent to the outer circumference is more preferred. In the case where the detection signal is recorded in a soundprint adjacent to the inner circumference of the record 200 relative to the soundprint in which the test signal is recorded multiple times, first, the test signal is reproduced and stored in a memory, etc., and then the detection signal is reproduced to determine the sampling rate conversion rate and perform the sampling rate conversion.

[0060] It is also possible to record the test signal and the detection signal in the right channel and the left channel of the same voiceprint in a manner opposite to each other. FIG. 3A to FIG. 4B As shown, from the viewpoint of measurement accuracy, it is preferable that the test signal and the detection signal are recorded in different voiceprints (tracks) that are one turn apart.

[0061] Next, the frequency characteristic measuring section 11 , the filter coefficient calculating section 12 , the digital filter 13 , and the reproduction speed detecting section 14 will be described in detail.

[0062] The playback device 10 is a computer having a processor 20 (e.g., a DSP (Digital Signal Processor)) and a memory 30, etc. The memory is a ROM (Read Only Memory) and a RAM (Random Access Memory), etc., and can store programs executed by the processor. The frequency characteristic measuring unit 11, the filter coefficient calculating unit 12, the digital filter 13, and the playback speed detecting unit 14 are implemented by the processor 20, etc. executing the program stored in the memory 30.

[0063] When a test signal that has been recorded multiple times on the record 200 and is used to measure the characteristics of the recording and reproducing system 1 is reproduced by the record player 100, the frequency characteristic measuring unit 11 performs sampling rate conversion on the test signal based on the reproduction speed of the test signal detected by the reproduction speed detecting unit 14, and converts the test signal into a test signal with no deviation in the reproduction speed. Thereafter, the frequency characteristic measuring unit 11 measures the frequency characteristics of multiple input signals corresponding to the test signal that has been recorded multiple times, which are input from the record player 100 to the reproducing device 10, calculates the measurement error between each of the measured frequency characteristics of the multiple input signals and a specified frequency characteristic, selects the frequency characteristic with the smallest measurement error among the frequency characteristics of the multiple input signals as the measurement result of the recording and reproducing system 1, and outputs the selected measurement result. Figures 5 to 7CThe frequency characteristic measuring section 11 will be described in detail later.

[0064] The filter coefficient calculation unit 12 calculates the filter coefficient of the digital filter 13 based on the measurement result output from the frequency characteristic measurement unit 11. For example, when the frequency characteristic shown in the measurement result is too high or too low in level at a specific frequency relative to the desired frequency characteristic, the filter coefficient is calculated so that the frequency characteristic shown in the measurement result is close to the desired frequency characteristic. The filter coefficient calculation unit 12 outputs the calculated filter coefficient to the digital filter 13.

[0065] The digital filter 13 is a filter that adjusts the frequency characteristics of the input signal input from the record player 100 to the playback device 10 based on the filter coefficient calculated by the filter coefficient calculation unit 12. For example, the digital filter 13 is a FIR (Finite Impulse Response) filter.

[0066] The playback speed detection unit 14 detects the playback speed of the position where the test signal is recorded multiple times on the record 200 based on the detection signal recorded on the record 200. For example, a 1kHz sine wave is used as the detection signal. The playback speed detection unit 14 calculates the time of a half cycle of the sine wave at each zero crossing point of the sine wave, and detects the deviation of the detection time by comparing it with the known cycle of the sine wave. Figure 8 The details of the reproduction speed detection unit 14 will be described later.

[0067] Figure 5 FIG. 1 is a flowchart showing an example of the operation of the playback device 10 (specifically, the frequency characteristic measuring unit 11) according to the embodiment. For example, after a user places a record 200 on the turntable 101 of the record player 100 and starts to play back a test signal recorded multiple times on the record 200, the playback device 10 performs Figure 5 Action shown.

[0068] When the test signal recorded multiple times on the record 200 is reproduced by the record player 100, the reproduction device 10 measures the frequency characteristics of multiple input signals corresponding to the test signal recorded multiple times and input from the record player 100 to the reproduction device 10 (step S11). Figure 6 Provide explanation.

[0069] Figure 6 This is a diagram for explaining a method of measuring frequency characteristics of a plurality of input signals.

[0070] like Figure 6 As shown, for example, it is assumed that five test signals (SS signals) are recorded in the left channel of the soundprint of the record 200, and five test signals are recorded in the right channel. Figure 6As shown, a trigger signal may also be recorded in the soundprint of the record 200. The trigger signal can identify the timing of the start and end of the test signal in the record 200. An example is shown in which the test signal recorded in the left channel is measured first, and then the test signal recorded in the right channel is measured, but it is also possible to measure the test signal recorded in the right channel first, and then the test signal recorded in the left channel. It is also possible to record test signals in the right channel and the left channel opposite to each other in the soundprint, and measure the test signal recorded in the right channel and the test signal recorded in the left channel at the same time.

[0071] The playback device 10 extracts test signals from a plurality of input signals, which are input signals corresponding to the test signals recorded multiple times and are input from the record player 100 that reproduces the test signals recorded multiple times on the record 200. At this time, the playback device 10 performs sampling rate conversion on the extracted test signals based on the reproduction speed of the test signals detected by the reproduction speed detection unit 14, and converts them into test signals with no deviation in the reproduction speed. The playback device 10 estimates the impulse response of the combination of the input impedance of the pickup 102, the transmission path, and the load by performing a convolution operation between the test signal engraved on the record 200 for measurement and a signal (for example, an inverse TSP signal) whose complex conjugate is taken for the test signal after the sampling rate conversion. The playback device 10 obtains the frequency characteristics (specifically, the frequency amplitude characteristics and the frequency phase characteristics) by performing FFT (Fast Fourier Transform) on the estimated impulse response. The playback device 10 performs the above processing similarly for each of the test signals recorded multiple times on the record 200, and obtains the respective frequency characteristics. At this time, there is a case where a measurement error occurs in a certain measurement result of the test signal recorded multiple times due to the influence caused by the record player 100 and the record 200 as described above. However, in the present disclosure, the test signal is recorded multiple times on the record 200, so by selecting and using the frequency characteristic with less measurement error, the influence of the measurement error can be reduced.

[0072] return Figure 5 Next, the playback device 10 calculates the measurement error between each of the measured frequency characteristics of the plurality of input signals and the predetermined frequency characteristics (step S12). Figure 2In the example of the moving magnet type pickup 102, it can be expected that in the equivalent circuit of the pickup 102, the load, and the transmission path connecting the pickup 102 and the load, the frequency amplitude characteristic produces a peak at the resonant frequency of the circuit determined by the inductance of the pickup 102, the parasitic capacitance of the transmission path, and the load resistance, but the frequency characteristic becomes a flat characteristic in other frequency bands. The resonant frequency of the circuit in the moving magnet type pickup 102 is generally generated between approximately 5kHz and 20kHz. Therefore, when the frequency characteristic is not flat in the frequency band other than the resonant frequency, it can be regarded as an error in the measurement. Based on such a feature, the reproduction device 10 calculates the measurement error of the frequency band other than the resonant frequency from the frequency characteristic results obtained from the test signal recorded multiple times, and selects the frequency characteristic with the smallest measurement error as the measurement result of the recording and reproduction system 1 (step S13). In this regard, using Fig. 7A as well as Figure 7B Provide explanation.

[0073] Fig. 7A This is a diagram for explaining a method for calculating a measurement error between each of the frequency characteristics of a plurality of input signals and a predetermined frequency characteristic. Fig. 7A The upper side of FIG. 1 shows a plurality of input signals corresponding to the test signals recorded multiple times, which are input from the record player 100 to the playback device 10. Fig. 7A The lower side of shows the frequency characteristics of a plurality of input signals (here, the frequency-amplitude characteristics are taken as an example).

[0074] Figure 7B It is a diagram for explaining the method of selecting measurement results.

[0075] For example, in Fig. 7A The five input signals are shown on the upper side. The five input signals correspond to the five test signals recorded on the record 200. The five test signals recorded on the record 200 are respectively the same signals, so it is ideal that the five input signals also have the same waveform. However, for example, it can be seen that due to the influence of the warping of the record 200, the waveform of the second input signal from the left is greatly different from that of the other input signals. Based on this, Fig. 7A As shown in the lower side of , it can be seen that the second frequency-amplitude characteristic from the left (measurement result 2) is significantly different from the other frequency-amplitude characteristics.

[0076] The prescribed frequency characteristics are the frequency characteristics (frequency amplitude characteristics and frequency phase characteristics) of the input signal input from the record player 100 that reproduces the test signal to the reproduction device 10, which are assumed to be free from the influence caused by the record player 100 and the record 200. That is, the prescribed frequency characteristics are the frequency characteristics of the ideal input signal input to the reproduction device 10 when the record player 100 reproduces the test signal. For example, in the case where there is a change in frequency characteristics that is different from the peaks / troughs of the frequency amplitude characteristics caused by the pickup 102, the transmission path, and the input impedance of the load, the measurement error between the frequency characteristics of the input signal input from the record player 100 that reproduces the test signal to the reproduction device 10 and the prescribed frequency characteristics becomes larger. The reproduction device 10, as Figure 7B The measurement errors between the five frequency-amplitude characteristics and the predetermined frequency-amplitude characteristics are calculated, and the frequency-amplitude characteristic with the smallest measurement error among the five frequency-amplitude characteristics (measurement result 4) is selected as the measurement result of the recording and playback system 1. Here, Figure 7C A specific example of the method of selecting the measurement results will be described.

[0077] Figure 7C It is a diagram for explaining a specific example of the method of selecting measurement results.

[0078] The reproduction device 10, for example, Figure 7C As shown, with respect to the measured frequency amplitude characteristic (solid line), the frequency band is divided for each frequency octave (for example, every octave), and the error with respect to the frequency characteristic (dashed line) of the ideal input signal is calculated. The reproduction device 10 calculates the sum of the errors for each octave, and selects the input signal with the smallest sum of errors from the measurement results of multiple input signals obtained from the test signal recorded multiple times as the measurement result. Figure 7C , an example is shown in which the measurement results are selected with attention paid to the amplitude characteristics, but the measurement results may be selected with attention paid to the phase characteristics in the same manner.

[0079] There are cases where the reproduction speed of the test signal changes due to the influence of the deviation of the rotation speed of the turntable 101, and the measurement error becomes larger, but in the present disclosure, these effects can be offset by using the sampling rate conversion of the detection signal. Figure 8 Provide explanation.

[0080] Figure 8 It is a diagram for explaining conversion of the sampling rate.

[0081] For example, when the reproduction speed is changed and when it is not changed, Figure 8 As shown in the upper and middle parts of FIG. , a time shift occurs until the reproduction of the five recorded test signals is completed. Figure 8As shown in the center of FIG, by using the sampling rate conversion of the detection signal adjacent to the test signal, as shown in FIG. Figure 8 As shown below, such a time shift can be offset and the playback speed can be returned to the original playback speed. Figure 4A As shown, the detection signal and the test signal are recorded in adjacent voiceprints with a difference of one turn in such a way that the recording start position (angle) of the detection signal is the same as the recording start position of the test signal, and in such a way that the recording end position (angle) of the detection signal is the same as the recording end position of the test signal. Therefore, the sampling rate conversion rate obtained from the detection signal can correspond to the test signal.

[0082] For example, a sine wave signal is used in the detection signal, and the number of samples (Ni (i natural number)) between each time interval (half cycle of the sine wave signal) of the zero crossing point of the detection signal is calculated according to the change in the amplitude of the detection signal. A correspondence is established between the position corresponding to the detection signal between the recording start position and the recording end position of the test signal and the number of samples per half cycle of the detection signal. For example, the detection signal and the test signal are each configured with a trigger signal at the beginning and the end, and the sampling numbers are corresponding with respect to the positions of the trigger signals of each other. It is also possible not to configure a trigger signal, for example, a correspondence can be established with respect to the timing from a silent state to the start of the detection signal.

[0083] Assume that the ideal number of samples M per half cycle of the detection signal when the reproduction speed does not change is known, for example, recorded in a memory, and the sampling rate conversion is performed at a conversion rate of M / Ni in the interval of the test signal corresponding to each half cycle of the detection signal. For example, when N1=110 and N2=100 relative to the ideal number of samples M of 100, the sampling rate conversion is performed at a conversion rate of M / N1=100 / 110 relative to the initial interval of the test signal (i.e., the interval of the test signal corresponding to the half cycle of the detection signal after the trigger signal). As a result, the interval has 100 samples and can be converted to the ideal number of samples. That is, the sampling rate conversion is performed for the interval in a manner that becomes the original reproduction speed. The next interval is N2=100, and the conversion rate becomes M / N2=100 / 100, and the sampling rate conversion is not performed. In the same way, the sampling rate conversion is applied to the interval corresponding to each half cycle of the detection signal. The time interval of the zero crossing point can be obtained per half cycle of the sine wave, so the reproduction speed (i.e., the number of samples) can also be obtained per half cycle of the sine wave. By converting the sampling rate according to the obtained reproduction speed, the original data number without the deviation of the reproduction speed can be accurately returned. In order to shorten the calculation time, the sampling rate conversion can also be performed using the average value of multiple cycles instead of the half cycle of the sine wave.

[0084] The sampling rate conversion can also be simplified. For example, the number of samples when reproducing the detection signal from the beginning to the end can be set to N, and the ideal number of samples at this time is M, and the sampling rate conversion of the entire test signal is performed at a conversion rate of M / N. In this case, the detection signal can be any signal as long as it can detect the amplitude, and it can also be white noise or a pulse signal. When the trigger signal is not configured, the detection signal can be silent (no signal) in addition to the selectable detection signal.

[0085] return Figure 5 Next, the playback device 10 outputs the selected measurement result (step S14). Thus, the filter coefficient calculation unit 12 can calculate the filter coefficient of the digital filter 13 based on the frequency characteristics that are less affected by the record player 100 and the record 200.

[0086] As described above, in the recording and reproducing system 1 including the record player 100 and the reproducing device 10, the processor 20 and the memory 30 are provided. The processor 20 executes a program stored in the memory 30. When a test signal for measuring the characteristics of the recording and reproducing system 1 and a plurality of test signals recorded in the record 200 are reproduced through the record player 100, the frequency characteristics of a plurality of input signals input from the record player 100 to the reproducing device 10 corresponding to the plurality of test signals recorded therein are measured, the measurement error between each of the measured frequency characteristics of the plurality of input signals and a prescribed frequency characteristic is calculated, the frequency characteristic having the smallest measurement error among the frequency characteristics of the plurality of input signals is selected as the measurement result of the recording and reproducing system 1, and the selected measurement result is output.

[0087] According to this, a plurality of test signals for measuring the recording and reproducing system 1 are recorded in the record 200, and the probability of all the test signals failing to be measured is reduced. Therefore, the frequency characteristic with a large measurement error, i.e., the frequency characteristic with a failed measurement, can be selected as the measurement result of the recording and reproducing system 1, instead of selecting the frequency characteristic with the smallest measurement error, i.e., the frequency characteristic accurately measured, as the measurement result of the recording and reproducing system 1. Thus, the characteristics of the recording and reproducing system can be measured efficiently.

[0088] For example, the test signal may also be a SS signal.

[0089] This enables good measurement of the S / N ratio.

[0090] For example, in the record 200, a detection signal for detecting the reproduction speed of the record 200 may be recorded at a position adjacent to the outer circumference or inner circumference of the record 200 relative to the position of the soundprint where the plurality of test signals are recorded, and the reproduction device 10 may detect the reproduction speed of the position on the record 200 where the plurality of test signals are recorded based on the detection signal, and convert the sampling rate of the recording and reproduction system 1 according to the detected reproduction speed.

[0091] This can offset the change in the radius of record 200 caused by the positional deviation of the center hole of record 200 or the change in the radius of record 200 caused by the track feeding of the groove head when grooving record 200, thereby reducing the measurement error.

[0092] In the record 200, a plurality of test signals for measuring the characteristics of the recording and reproducing system 1 are recorded in the soundprint within one turn.

[0093] Thus, a plurality of test signals for measuring the characteristics of the recording and reproducing system 1 are recorded in the record 200, and the probability of failure in all the test signal measurements is reduced. Therefore, the characteristics of the recording and reproducing system 1 can be measured efficiently by using the record 200 by the reproducing device 10 or the like. Since a plurality of test signals are recorded in a soundprint within one circle, interference between adjacent soundprints in the radial direction is unlikely to occur, and deterioration of the S / N ratio can be suppressed.

[0094] For example, the test signal may also be a SS signal.

[0095] This enables good measurement of the S / N ratio.

[0096] For example, a plurality of test signals may be recorded in the soundprint of the outer peripheral area of ​​the record 200 .

[0097] According to this, the reproduction speed of the outer peripheral area of ​​the record 200 is fast, so it is possible to suppress the deterioration of the S / N ratio.

[0098] For example, in the record 200 , a detection signal for detecting the reproduction speed of the record 200 may be recorded at a position adjacent to the outer circumference or inner circumference of the record 200 relative to the position of the soundprint where the plurality of test signals are recorded.

[0099] This makes it possible to detect changes in the playback speed caused by changes in the radius of the record 200 due to positional deviation of the center hole of the record 200 or changes in the radius of the record 200 due to the feed of the groove head when grooving the record 200.

[0100] For example, with respect to a soundprint in which a plurality of test signals are recorded, the detection signal may be recorded on the wall of the right channel in the soundprint adjacent to the outer circumference of the record 200 .

[0101] According to this, it is possible to suppress the deterioration of the S / N ratio.

[0102] For example, with respect to a soundprint in which a plurality of test signals are recorded, the detection signal may be recorded on the wall of the left channel in the soundprint adjacent to the inner circumference of the record 200 .

[0103] According to this, it is possible to suppress the deterioration of the S / N ratio.

[0104] (Other embodiments)

[0105] As described above, the embodiments are described as examples of the technology disclosed in this application. However, the technology disclosed in this application is not limited thereto, and can also be applied to embodiments that are appropriately changed, replaced, added, omitted, etc. It is also possible to combine the various components described in the above embodiments to form new embodiments.

[0106] For example, in the above embodiment, the test signal is described as an example of an SS signal, but it is not limited to this. For example, the test signal is not particularly limited as long as it is a known signal containing a frequency component to be measured (for example, ordinary music, white noise or pink noise, etc.).

[0107] For example, in the above-mentioned embodiment, the reproduction speed detection signal is recorded on the record 200 , but the reproduction speed detection signal may not be recorded on the record 200 .

[0108] For example, in the above-described embodiment, the playback device 10 is described as including the playback speed detection unit 14 , but the playback device 10 may not include the playback speed detection unit 14 .

[0109] The present disclosure can be implemented not only as the playback device 10 but also as a measurement method including steps (processing) performed by components constituting the playback device 10 .

[0110] Specifically, if Figure 5As shown, the measuring method includes the following processing: when a plurality of test signals recorded on a record for measuring the characteristics of the recording and reproducing system are reproduced by a record player in the recording and reproducing system, a processing of measuring the frequency characteristics of a plurality of input signals input from the record player and corresponding to the plurality of test signals recorded thereon (step S11); a processing of calculating the measurement errors between the measured frequency characteristics of the plurality of input signals and the prescribed frequency characteristics respectively (step S12); a processing of selecting the frequency characteristics with the smallest measurement error among the frequency characteristics of the plurality of input signals as the measurement result of the recording and reproducing system (step S13); and a processing of outputting the selected measurement result (step S14).

[0111] For example, the measuring method may be executed by a computer (computer system). Furthermore, the present disclosure may be implemented as a program that causes a computer to execute the steps included in the measuring method. Furthermore, the present disclosure may be implemented as a non-temporary computer-readable recording medium such as a CD-ROM having the program recorded thereon.

[0112] For example, when the present disclosure is implemented by a program (software), the program is executed using hardware resources such as a computer's CPU, memory, and input / output circuits, thereby executing each step. That is, the CPU obtains data from the memory or input / output circuits, performs calculations, and outputs the calculation results to the memory or input / output circuits, thereby executing each step.

[0113] The components included in the playback device 10 of the above-described embodiment may be implemented as an integrated circuit (IC: Integrated Circuit) LSI (Large Scale Integration).

[0114] The integrated circuit is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. A programmable FPGA or a reconfigurable processor in which the connection and setting of the circuit cells inside the LSI can be reconfigured may also be used.

[0115] Furthermore, if an integrated circuit technology that replaces LSI emerges due to advancement of semiconductor technology or other derived technologies, then of course, the components included in the playback device 10 can also be integrated into an integrated circuit using this technology.

[0116] As described above, the embodiments have been described as examples of the technology of the present disclosure. Therefore, the drawings and detailed description are provided.

[0117] Therefore, the components described in the drawings and detailed descriptions include not only components that are necessary to solve the problem, but also components that are not necessary to solve the problem. Therefore, it should not be immediately determined that these non-essential components are necessary just because they are described in the drawings or detailed descriptions.

[0118] The above-described embodiments are provided to illustrate the technology of the present disclosure, and therefore, various changes, substitutions, additions, omissions, etc. may be made within the scope of the claims or the scope of their equivalents.

[0119] Industrial Applicability

[0120] The present disclosure can be applied to a device for measuring characteristics of a recording and playback system, and the like.

[0121] Description of Reference Numerals

[0122] 1 Recording and playback system

[0123] 10 Reproduction Device

[0124] 11 Frequency characteristics measurement section

[0125] 12 Filter coefficient calculation unit

[0126] 13 Digital Filter

[0127] 14. Reproduction speed detection unit

[0128] 20 Processors

[0129] 30 Memory

[0130] 40 Phono Equalizer

[0131] 50 A / D converter

[0132] 60 D / A converter

[0133] 70 Amplifier

[0134] 80 Speakers

[0135] 100 Record Player

[0136] 101 Turntable

[0137] 102 Cartridge

[0138] 200 records

Claims

1. A measuring device, which is a measuring device in a recording and reproducing system including a record player and the measuring device, comprising: Processor; and Memory, The processor executes the program stored in the memory to perform: When a plurality of test signals recorded on a record for measuring the characteristics of the recording and reproducing system are reproduced by the record player, the frequency characteristics of a plurality of input signals corresponding to the plurality of test signals recorded thereon, which are input from the record player to the measuring device, are measured; calculating a measurement error between each of the measured frequency characteristics of the plurality of input signals and a predetermined frequency characteristic, selecting a frequency characteristic having the smallest measurement error among the frequency characteristics of the plurality of input signals as a measurement result of the recording and reproducing system, The selected measurement result is output.

2. The measuring device according to claim 1, The test signal is a Swept Sine signal, that is, a sine frequency sweep signal.

3. The measuring device according to claim 1 or 2, In the record, a detection signal for detecting the reproduction speed of the record is recorded at a position adjacent to the outer circumference or inner circumference of the record relative to the position of the soundprint where the plurality of test signals are recorded. The measuring device, detecting the reproduction speed of the positions on the record where the plurality of test signals are recorded based on the detection signal, The sampling rate of the recording and reproducing system is converted based on the detected reproduction speed.

4. A determination method, When a plurality of test signals recorded on a record for measuring characteristics of the record-recording and reproducing system are reproduced by a record player in the record-recording and reproducing system, frequency characteristics of a plurality of input signals input from the record player corresponding to the plurality of test signals recorded thereon are measured, calculating a measurement error between each of the measured frequency characteristics of the plurality of input signals and a predetermined frequency characteristic, selecting a frequency characteristic having the smallest measurement error among the frequency characteristics of the plurality of input signals as a measurement result of the recording and reproducing system, The selected measurement result is output.

5. A recording medium that can be read by a computer. A program for causing a computer to execute the measuring method according to claim 4 is recorded.

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