JP5489215B2 - Filter device, signal processing device - Google Patents

Description

  The present invention relates to a filter device, a signal processing device, and an on-vehicle device for a railway vehicle.

  In the ATC system, an ATC signal flowing on a rail is received by an on-board device and used for train control, while power is supplied to a vehicle from a substation via an overhead line and a rail. Therefore, a return current flows through the rail together with the ATC signal current. This return current includes the harmonics along with the fundamental wave of 50 Hz or 60 Hz.

  Usually, the carrier frequency of the ATC signal is selected to be a value separated from the power frequency of the power for power. For example, while the fundamental frequency of the power for power is 50 Hz or 60 Hz, the carrier frequency of the ATC signal is selected as 3150 Hz as an example. Therefore, as far as the fundamental wave is concerned, the ATC signal can be separated and extracted from the retrace current using a band pass filter or the like. However, the retrace current includes its harmonics in addition to the fundamental wave. For this reason, this harmonic component becomes noise with respect to the ATC signal, which becomes a hindrance to the deterioration of the bit error rate and the increase of the transmission rate in data transmission by the ATC signal.

  As a means for solving a problem caused by harmonic noise, Patent Document 1 discloses that the output of an ATC signal detector arranged close to one rail is passed through a comb filter to thereby reduce the harmonic component of the train current. A technique for extracting an ATC signal for each band by removing the signal and passing the signal through a band filter is disclosed.

  However, when the frequency of the fundamental wave of the power supply for power changes, the harmonics cause frequency fluctuations that are orders of magnitude higher than the fundamental wave frequency fluctuations. The frequency may shift to a close frequency and the filtering effect may not be expected.

  To deal with such problems, it is conceivable to use an adaptive filter, but in general adaptive filters, the filter coefficient is updated so as to minimize the output signal, so the carrier frequency component with the largest power is removed. Resulting in.

  The above-described problem is that the basic of the second signal wave in the signal processing system that extracts the first signal wave by removing the component of the second signal wave from the input signal including the first signal wave and the second signal wave. It occurs evenly when the frequency fluctuates, and does not exist only in the ATC system.

Japanese Patent Laid-Open No. 2003-72549

  An object of the present invention is to change a fundamental frequency of a second signal wave when extracting a first signal wave by removing a component of the second signal wave from a signal including the first signal wave and the second signal wave. Even in such a case, a filter device that reliably extracts the target first signal wave and does not cause deterioration in bit error rate or increase in transmission rate in data transmission, and signal processing using the same An apparatus and an on-vehicle apparatus for a rail vehicle are provided.

  In order to solve the above-described problem, the filter device according to the present invention includes a first signal wave and a second signal wave component having a fundamental frequency different from that of the first signal wave. The first signal wave is extracted by removing the signal wave component, and includes a reference wave estimation unit, a band pass filter unit, a harmonic calculation unit, and a harmonic removal unit . The reference wave estimation unit estimates a reference wave having a specific frequency included in the second signal wave from the input signal. The band pass filter unit has a pass band for extracting the first signal wave. The harmonic calculation unit calculates the harmonic from the reference wave estimated by the reference wave estimation unit. The harmonic removal unit removes harmonics that have not been removed by the band pass filter unit from the harmonics calculated by the harmonic calculation unit.

  As described above, the filter device according to the present invention includes the band-pass filter unit, and the fundamental wave of the second signal wave having the highest power is converted from the first signal wave by the band-pass filter unit. Can be removed.

  The filter device according to the present invention includes a reference wave estimation unit. The reference wave estimation unit estimates a reference wave having a specific frequency included in the second signal wave from the input signal wave. By providing the reference wave estimation unit, even when the frequency of the fundamental wave of the second signal wave fluctuates, the frequency of the fundamental wave or the harmonic can be estimated by, for example, frequency spectrum analysis. The reference wave may be a fundamental wave or a harmonic. In this way, the harmonic calculation unit calculates the fundamental wave and the harmonics from the reference wave estimated by the reference wave estimation unit.

  The filter device according to the present invention further includes a harmonic removal unit. The harmonic removal unit removes harmonics that have not been removed by the band pass filter unit from the harmonics calculated by the harmonic calculation unit. As a result, even when the frequency of the fundamental wave of the second signal wave varies, harmonics that affect the first signal wave can be removed from the harmonics. The harmonic removal unit may remove not only harmonics adjacent to the pass frequency band of the first signal wave but also higher-order or lower-order harmonics.

  Therefore, according to the present invention, even when the fundamental frequency of the second signal wave fluctuates, the influence of the harmonics is avoided, the target first signal wave is reliably extracted, and in the data transmission, It is possible to realize a filter device that does not cause a failure of an error rate or an increase in transmission rate.

  The filter device according to the present invention is used to configure a signal processing device that separates and extracts a first signal wave from a second signal wave in a signal transmission system in which the first signal wave and the second signal wave are mixed. Can do. The signal processing apparatus includes a first signal source 2, a second signal source, a signal transmission path, and a receiving unit. The first signal source 2 supplies a first signal wave to the signal transmission path. The second signal source supplies a second signal wave to the signal transmission path.

  The receiving unit includes a filter unit and a signal processing unit. The filter unit includes a filter device according to the present invention. The filter device is supplied with the input signal from the signal transmission path. The signal processing unit processes a signal supplied from the filter device.

  Since the above-described signal processing device includes the above-described filter device according to the present invention in the receiving unit, the effect of the filter device is achieved.

  A typical application example of the signal processing device using the filter device according to the present invention is an on-board device for a railway vehicle. The filter device according to the present invention is combined with a signal processing unit to constitute an on-vehicle device for a railway vehicle. The signal processing unit decodes the signal output from the filter device.

  The on-vehicle device for a rail vehicle is specifically an on-vehicle device that constitutes an ATC system. In the application of the present invention, the ATC signal corresponds to the first signal wave, and the retrace current corresponds to the second signal wave. Therefore, the fundamental wave of the return current and the harmonics of the return current that become noise with respect to the ATC signal are removed regardless of the frequency fluctuation of the power source for power that supplies the return current. In data transmission, it is possible to realize an ATC on-board device capable of avoiding a failure in bit error rate and an increase in transmission rate.

  As described above, according to the present invention, when extracting the first signal wave by removing the component of the second signal wave, even if the fundamental frequency of the second signal wave fluctuates, the disturbance due to the harmonics is prevented. A filter device, a signal processing device, and a railway vehicle vehicle that avoids the problem and reliably extracts the first signal wave of interest and eliminates the obstacles to bit error rate degradation and transmission rate acceleration in data transmission. An upper device can be provided.

It is a block diagram which shows the structure of the filter apparatus which concerns on this invention. It is a block diagram which shows another embodiment of the filter apparatus which concerns on this invention. It is a block diagram which shows the structure of the signal processing apparatus using the filter apparatus based on this invention. It is a block diagram which shows the structure of the on-board apparatus for electric railway vehicles using the filter apparatus which concerns on this invention.

  First, referring to FIG. 1, a signal S3 including a first signal wave S1 having a frequency fs and a second signal wave S2 having a fundamental frequency f1 (f1 ≠ fs) is supplied to an input terminal Tin. The first signal wave S1 may be either an analog signal or a digital signal. Here, the first signal wave S1 is handled as a digital signal obtained by adding frequency shift keying (FSK) to a carrier wave having a frequency fs. Frequency shift modulation is a method of changing the carrier wave to a low frequency when the data is 0 and to a high frequency when the data is 1, for example. In the description of the frequency shift key modulation method, the MSK (Minimum Shift Keying) modulation method is used. The MSK modulation method is a phase continuous FSK modulation method with a modulation index of 0.5, and can use synchronous detection or delay detection, and is easy to demodulate. The second signal wave S2 may be either an analog signal or a digital signal. The second signal wave S2 includes a fundamental wave of frequency f1 and its harmonics (f2 to f7).

  A signal S3 including the first signal wave S1 and the second signal wave S2 described above is supplied to the input terminal Tin. The graph indicated by reference symbol (a) in FIG. 1 shows the frequency spectrum analysis of the signal S3, with the frequency F on the horizontal axis and the power P on the vertical axis.

  The filter device according to the present invention extracts the first signal wave S1 by removing the frequency components (f1 to f7) included in the second signal wave S2 from the signal S3 supplied to the input terminal Tin. A wave estimation unit 11, a band pass filter unit 12, a harmonic calculation unit 13, and a harmonic removal unit 14 are included.

  A demodulator 15 is provided at the subsequent stage of the harmonic wave remover 14, and the demodulated output signal S0 is supplied from the demodulator 15 to the output terminal Tout. When the first signal wave S1 to be demodulated is an MSK modulated wave, the demodulator 15 performs MSK demodulation.

  The reference wave estimation unit 11 estimates a reference wave having a specific frequency that is a reference for calculating a harmonic in the second signal wave S2 from the input signal S3. The reference wave may be the fundamental wave (f1) of the second signal wave S2, or may be a harmonic of a specific order. In this specification, in order to avoid a consistent explanation and confusion in understanding, a case where the reference wave is the fundamental wave (f1) will be described as an example.

  The estimation of the fundamental wave (f1) serving as the reference wave can be executed using, for example, an adaptive notch filter. Of the frequency components (f1 to f7) of the second signal wave S2, the frequency component f1 is a fundamental wave, and the frequency components f2 to f7 are a second harmonic to a seventh harmonic. However, in the present invention, the harmonics are not limited to the second harmonic to the seventh harmonic, and may be targeted for lower harmonics than the seventh harmonic, and may be targeted for higher harmonics. Also good.

  Even if the fundamental frequency f1 of the second signal wave S2 is known in advance, it is unavoidable that the frequency f1 fluctuates unless a special frequency stabilizing means is added. When the frequency f1 fluctuates by the frequency Δf1, the harmonics cause a frequency fluctuation that is an order multiple of the frequency fluctuation Δf1 of the fundamental wave. May approach or enter the interior. In such a case, the influence of the frequency fluctuation of the second signal wave S2 on the first signal wave S1 becomes extremely large. The present invention seeks to solve such problems.

  The band pass filter unit 12 has a pass band BP from which the first signal wave S1 is extracted. The graph indicated by reference symbol (b) in FIG. 1 schematically shows a signal that has passed through the band pass filter unit 12, and the second signal wave S2 has a fundamental frequency f1 outside the passband BP. It is in. In the example of FIG. 1, since the harmonics f2 and f7 are also outside the passband BP, the harmonics f2 and f7 are also removed (cut off) by the band pass filter unit 12 together with the fundamental wave (f1). The frequency components passing through the band pass filter unit 12 are the first signals S1 having the harmonics f3 to f6 and the frequency fs. The band pass filter unit 12 may be either analog processing or digital processing.

  The harmonic calculation unit 13 calculates the harmonics (f2 to f7) from the fundamental wave (f1) of the second signal wave S2 estimated by the reference wave estimation unit 11. When the fundamental frequency f1 varies, the frequency of the harmonics (f2 to f7) also varies, but there is a correlation in the overall frequency variation characteristics. Therefore, the frequency of the harmonics (f2 to f7) can be calculated from the estimated fundamental wave (f1). The graph indicated by reference sign (e) in FIG. 1 shows the harmonics (f2 to f7) calculated from the fundamental wave (f1) by the harmonic calculation unit 13 as a frequency spectrum.

  The harmonic removal unit 14 removes the harmonics f3 to f6 that have not been removed by the band pass filter unit 12 from the harmonics (f2 to f7) calculated by the harmonic calculation unit 13. Such a harmonic removal unit 14 can be realized by a variable digital notch filter. In FIG. 1, the graph with the reference sign (c) shows the harmonic removal using the digital notch filter, and the third harmonic f3 to the sixth harmonic f6 are removed by the notch filter characteristic NF. Has been.

  As described above, the harmonic removal unit 14 includes the harmonics (f3 to f6) that are not removed by the band-pass filter unit 12 among the harmonics (f2 to f7) calculated by the harmonic calculation unit 13. Therefore, even if the fundamental frequency f1 of the second signal wave S2 fluctuates, of the harmonics (f2 to f7), the harmonic adjacent to the pass frequency band that most affects the first signal wave S1. Waves f3 and f6 can be removed. However, not only the harmonics f3 and f6 adjacent to the passband BP but also higher harmonics f5 and f7 or lower harmonics f2 may be removed.

  Therefore, according to the present invention, even when the fundamental frequency f1 of the second signal wave S2 varies, the influence of the harmonics (f2 to f7) is avoided and the target first signal wave S1 is reliably extracted. In the data transmission, it is possible to realize a filter device that does not cause a failure in bit error rate or an increase in transmission rate.

  Reference numeral (d) in FIG. 1 indicates a signal after being extracted by the harmonic removal unit 14, and is a signal including the carrier frequency fs. The signal is supplied to the demodulator 15 and the demodulated signal S0 is output from the output terminal Tout.

  Next, another embodiment of the filter device according to the present invention will be described with reference to FIG. In FIG. 2, the same reference numerals are given to the components equivalent to those shown in FIG. 1, and the description of these components may be omitted. This embodiment corresponds to a case where the power level of the second signal wave S2 is not high, that is, equivalent or low with respect to the power level of the first signal wave S1. First, an input signal S3 including the first signal wave S1 and the second signal wave S2 is supplied to the band pass filter unit 12 and supplied to the signal band suppression unit 16. The signal band suppression unit 16 suppresses the band of the first signal wave S1 and attenuates the power level of the first signal wave S1.

  The graph indicated by reference symbol (e) in FIG. 2 is a diagram showing the frequency spectrum after suppression, and the power level P is significantly attenuated in the band including the carrier wave of the frequency fs. The signal band suppression unit 16 can be realized by using, for example, a low-pass filter LP. Then, the suppressed signal is supplied to the reference wave estimation unit 11 to estimate the fundamental wave (f1) of the second signal wave S2 as indicated by the reference symbol (f) in FIG. Thereafter, the output signal S0 is obtained by extracting the first signal wave S1 using the harmonic calculation unit 13, the harmonic removal unit 14, and the demodulation unit 15 as in the case of FIG. Further, the filter action by the band pass filter unit 12 is the same as in the case of FIG.

  According to the embodiment shown in FIG. 2, even when the fundamental frequency of the second signal wave S2 varies when the power level of the second signal wave S2 is not higher than the power level of the first signal wave S1. Thus, it is possible to reliably extract the target first signal wave S1 and to realize a filter device that does not cause a failure in bit error rate or an increase in transmission rate in data transmission.

  FIG. 3 is a diagram showing a configuration of a signal processing device using the filter device according to the present invention. Referring to FIG. 3, the signal processing apparatus includes a first signal source 2, a receiving unit 3, a second signal source 4, and a signal transmission path 5. The first signal source 2 supplies the first signal wave S 1 to the signal transmission path 5. The second signal source 4 supplies a second signal wave S2 having a fundamental frequency f1 different from that of the first signal wave S1 to the signal transmission line 5.

  The receiving unit 3 includes a filter unit 31 and a signal processing unit 32. The filter unit 31 includes a filter device according to the present invention. An input signal S3 including the first signal wave S1 and the second signal wave S2 is supplied to the filter unit 31 from the signal transmission path 5. The signal processing unit 32 processes the signal supplied from the filter unit 31.

  Since the signal processing device described above includes the filter device according to the present invention described above in the filter unit 31 of the receiving unit 3, the effect of the filter device is achieved.

  A specific application example of the signal processing device using the filter device according to the present invention is an on-vehicle device for a railway vehicle. FIG. 4 shows an example of the on-board device 3 constituting the ATC system. 4 will be described in comparison with FIG. 3. First, the ATC signal corresponds to the first signal wave S1. The ATC signal S1 is supplied from the ATC transmitter 2 serving as the first signal source to the rail 5 serving as the signal transmission path. The ATC signal S1 supplied to the rail 5 is received by the on-board antenna 33 and guided from the on-board antenna 33 to the on-board device 3. The ATC signal is, for example, an MSK modulated wave, and the carrier frequency fs is selected as 3150 Hz, for example.

  In the on-board device 3, the ATC signal is extracted by the filter device according to the present invention constituting the filter unit 31. The ATC signal is supplied to the signal processing unit 32 and used for vehicle control.

  The railway vehicle includes a power system such as a substation 41, an overhead line 42, a pantograph 43 provided in the vehicle TR, and a vehicle motor 44. These serve as the second signal source 4, and a return current flowing through the rail 5 is generated. This corresponds to the second signal wave S2. The return current S2 is received by the on-board antenna 33 and guided from the on-board antenna 33 to the on-board device 3. The electric power transmitted from the substation 41 via the overhead line 42 is an alternating current of 50 Hz or 60 Hz.

  As described above, the carrier frequency of the ATC signal S1 is selected to be a value separated from the power frequency of the power for power. As far as the fundamental wave of the power wave is concerned, the ATC signal S1 can be separated and extracted from the retrace current S2 using a band pass filter or the like. However, the return current S2 includes its harmonics in addition to the fundamental wave. For this reason, this harmonic component becomes noise with respect to the ATC signal S1, and in the data transmission using the ATC signal S1, the bit error rate is deteriorated and the transmission rate is increased.

  Therefore, in the present invention, the on-board device 3 includes the filter device 31 shown in FIGS. 1 and 2. As a result, the ATC signal S1 is extracted separately from the fundamental wave (f1) of the return current S2 in spite of fluctuations in the frequency of the power source at the substation 41 that supplies the return current. To realize an ATC on-board device that eliminates the harmonics of the return current S2 that causes noise and avoids the deterioration of the bit error rate and the increase in the transmission rate in data transmission using the ATC signal S1. Can do.

  Although the contents of the present invention have been specifically described above with reference to the preferred embodiments, it is obvious that those skilled in the art can take various modifications based on the basic technical idea and teachings of the present invention. It is.

DESCRIPTION OF SYMBOLS 11 Reference wave estimation part 12 Band pass filter part 13 Harmonic calculation part 14 Harmonic removal part 15 Demodulation part 16 Signal band suppression part

Claims (4)

An input signal in which a first signal wave and a second signal wave different from the first signal wave are mixed is supplied to a band-pass filter unit, and harmonic components of the second signal wave are removed to remove the second signal wave. A filter device for extracting one signal wave,
The first signal wave is in a pass band of the band pass filter unit, and the second signal wave has a fundamental wave on a low frequency side outside the pass band,
When the frequency of the second signal wave fluctuates, a harmonic is calculated from a reference wave that is a fundamental wave after the fluctuation or a harmonic of a specific order ,
Of the calculated harmonics, remove harmonics that have not been removed by the band pass filter unit ;
Filter device. The filter device according to claim 1,
The first signal wave is a signal obtained by modulating a carrier wave,
The second signal wave is a power power wave.
Filter device. A signal processing device including a filter device and a signal processing unit,
The filter device is described in claim 1 or 2,
The signal processing unit outputs a signal corresponding to the signal supplied from the filter device,
The signal processing apparatus, wherein the first signal wave and the second signal wave are transmitted through the same transmission path. The signal processing device according to claim 3,
The first signal wave is an ATC signal;
The second signal wave is a retrace current;
Railway vehicle signal processing device.

Images