JPS58168335A - Eliminating device of interference wave - Google Patents

Abstract

PURPOSE:To eliminate the influence due to a temporary break of an interference wave, by holding the stop center frequency of a narrow band stop filter, which stops the interference wave, in the state just before the break of the interference wave. CONSTITUTION:A controlling circuit 17 outputs the result of the phase locking between the input and the output of a narrow band stop filter 13 taken out through band pass filters 23 and 24. Center frequencies of the narrow band stop filter 13 and band pass filters 23 and 24 are controlled by the output of a holding circuit 19. When the center frequency of the narrow band stop filter 13 coincides with the frequency of the interference wave, the output of a level detector 26 is larger than the output of a level detector 27, and a switch 18 is turned on by the output of a comparator 28, and the output of the controlling circuit 17 is supplied to the holding circuit 19. When the interference wave is broken, outputs of level detectors 26 and 27 become the same level, and the switch 18 is turned off, and the output of the controlling circuit 17 is not supplied to the holding circuit 19.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an interference wave removal device for eliminating single-frequency interference waves existing in or near the reception frequency band in a receiver having a relatively wide reception frequency band, and particularly to The aim is to ensure that even in a state of temporary interruption, this will not affect the situation.

For example, in a Loran C receiver, radio waves from a Detsuka navigation device, so-called Detsuka radio waves, may be present in the vicinity of its reception frequency band. While a mobile object equipped with a Loran-C receiver is moving, it passes through an area where the frequencies of Detsuka radio waves differ. It is necessary to readjust the narrow band blocking P-wave device for removing deep radio waves. Since the stopband of the narrowband blocking P-wave device is very narrow, it takes time and skill to operate the blocking center network wave number to match the center frequency of the interfering wave correctly, and as mentioned above, there are different It was extremely troublesome to adjust the narrow band blocking device each time the interference frequency range was entered.

In this respect, it has been proposed to automatically match the center frequency of a narrowband F-wave filter that blocks interference waves with the frequency of the interference waves. However, when the interfering wave is an intermittent signal, for example, and the interfering wave is temporarily cut off, the control output of the control circuit that detects the difference between the center frequency of the narrowband rejector and the interfering wave frequency becomes The normal state is greatly confused, and if the blocking center frequency of the narrowband P-wave generator is controlled by an incorrect detection output, the interference wave will temporarily disappear when the interference wave is cut off. If blocking is no longer possible, it is necessary to perform the ninth control again to match the center frequency of the narrow band blocking P-wave device with the frequency of the interfering wave. If everything is done automatically, it requires time, and the blocking frequency is the same as the frequency of the interference wave.
In the case where the y-dispersion is manually controlled and then automatically matched accurately, the operator must perform the operations one by one.

The object of this invention is to prevent the interference wave from cutting off at the center frequency of a narrow band blocking P-wave device which blocks the interference wave without being affected by the interference wave even if the target interference wave Wa is temporarily cut off. An object of the present invention is to provide an interference wave removal device that can maintain the state immediately before the interference wave removal device.

According to this invention, a narrowband blocking P-wave device is inserted in the receiving signal path, and each signal on the input side and output side of the narrowband blocking P-wave device is branched and taken out, and from these two signals, a control circuit sends a narrow band blocking P-wave device. A deviation between the center frequency of the band-elimination p-wave device and the frequency of the intended interference wave is detected. The output of the control circuit is held by a holding circuit, and the center frequency of the narrowband assembled V wave generator is set by the output of the holding circuit. In this way, the center frequency of the narrowband rejection P-wave device is automatically made to match the frequency of the target interfering wave.

Further, signals #i 1 . These levels are detected by being amplified and rectified by a second level detector. Narrowband rejection F-wave l1iIF
When the center frequency correctly matches the target interference frequency, the level at the input side of the narrowband rejection P-wave device is high when the interference wave is input, but the level at the output side is extremely small. Become. However, even if the frequency of the interfering wave matches the rejection center frequency of the narrowband blocking V-wave powder, if the interfering wave is interrupted temporarily, the difference in signal level between the input side and the output side of the narrowband blocking R-wave filter will increase. It becomes very small. Therefore, the first.
By detecting it with the second level detector and comparing the nine levels with the comparator, it is possible to detect the intermittent state of the interference wave.
The detection signal of the control circuit is prevented from being supplied to the holding circuit when the interference wave is cut off. That is, a switch is inserted in the path of the detection signal that reaches the holding circuit from the control circuit, and when noise etc. is applied to the narrowband blocking P-wave device, or when the P-wave interference is cut off, the switch is activated by the output of the comparator. is turned off so that the output detected by the control circuit is not given to the holding circuit. Furthermore, when the inputs of the first and second level detectors both become low levels, the signal of the ml level detector, which detects the level on the input side, detects the level on the output side. These level detectors are constructed so that the output of the second level detector is also smaller than that of the second level detector. Make it output from .

Next, an embodiment of the interference wave removal device according to the present invention will be described with reference to the drawings.

In FIG. 1, the received signal is amplified from the input terminal 11 through the preamplifier 12, the interference wave is removed by the narrowband blocking P-wave device 13, and the output from which the interference wave has been removed is amplified by the postamplifier 14, and the output terminal 15 to a processing device fl16, such as a Loran C signal processor.

The signals on the input side and the output side of the narrowband blocking F-wave filter 13 are branched and supplied to the control circuit 17 . In the control circuit 17, a deviation between the blocking center frequency of the narrow band blocking filter 13 and the frequency of the target interference wave is detected. This detected deviation is supplied to a holding circuit 19 through a switch 18, which will be described later, and is held there. The holding signal is a narrowband stop-band filter 1
3 as its blocking center frequency control signal. The narrow band rejection PI device 13 is configured as a notch filter, for example, and includes variable capacitance diodes 21 and 22 as part of its configuration.
．． 22 is controlled by a control signal from the holding circuit 19 to control the blocking center frequency.

In the control circuit 37, for example, the narrowband blocking P-wave device 13
0 input side signal and output side signal are each bandpass P
These bandpass F
The outputs of the waveform generators 23 and 24 are phase-compared by the phase comparator 25, and the phase comparison output is used as the output of the control circuit 17. The band pass P wave device 28, 24 has its passing center frequency coincident with the blocking center frequency of the narrow band blocking single wave 1113,
These band-pass F-wave filters 23 and 24 have single-wave characteristics that are #1 equal to each other. The blocking center frequency of this narrow band blocking P wave device 13 is controlled by the output of the holding circuit 19, and a variable capacitance diode is installed in a part of the center circumference 23, 24 of the one band passing P* powder 23, 24, for example. is used, whose variable capacitance diode is controlled by the output of the holding circuit 19, and whose 11! The change characteristics of the center frequency with respect to the control signal are similar to the characteristics of the narrow band rejection P-wave device 13.

The phase frequency tl characteristic of the narrowband rejection Ptl1 device 130 is shown as a curve 66 in FIG.
On the frequency side, the phase is approximately 90°.
As a result, when the center frequency f/yoshi is low, the phase suddenly shifts by 90 degrees.っましfo−△f−fa+
The phase changes rapidly within the range of Δf. On the other hand, the band-pass wave transmitters 23 and 24 are configured as a peak-peak tuning type composed of, for example, a tuning circuit of a coil and a capacitor, and their phase frequency characteristics are as shown by the curve 67 in FIG. At low @, the phase gradually advances,
The phase gradually lags on the high side. Therefore, between frequencies Δf·−Δf and fo−Δf, the phase of the output of the F-wave generator 23, 24 is determined by the characteristic of the curve 66 #1. Therefore, when the phases of the outputs of these F wave generators 23 and 24 are detected by the phase comparator 1i25, it is possible to detect the deviation between the center frequency f· of the narrow band blocking F wave generator 13 and the frequency of the interference wave. If the frequency of the interference wave is higher than the blocking center frequency f, the output of the P-wave device 24 will be out of phase; if the frequency of the interference wave is lower, the output of the P-wave device 23 will be out of phase. The output has a smaller phase.

In this invention, input of narrowband rejection FM#xa! The output side signals are branched and their respective levels are detected by a level detector. In this example, the outputs of the bandpass F-wave devices 23 and 24 are each supplied to level detectors 26 and 27 to detect their respective levels, and the outputs of the level detectors 26 and 27 are compared in magnitude by a comparator 28. , the switch 18 is controlled by the comparison output of the comparator 28.

By the way, when the center frequency f of the narrowband rejection-wave device 13 matches the frequency of the interference wave, the output of the narrowband rejection-wavelength filter 13 becomes sufficiently smaller than the input. Therefore, level detector 2
The output of level detector 27 is large, and the output Fi of level detector 27 is considerably small. In this state, the output of the comparator 28 becomes high level, the switch 18 is turned on, and the control circuit 17
The output of is supplied to the holding circuit 19. However, when the interference wave is blown out, the narrowband blocking P-wave device 13 becomes in the same state as if noise had been input, and the input side and the output side are connected to each other.
'! ': Not the same level, so the level detector 26
．． 27 is the same as #1, and in this state, the detection level of the input side detector 26 is made to be smaller than the detection level of the output side detector 27. As a result, the switch 18 is turned off and the control circuit 17
The output of is not supplied to the holding circuit 19. Therefore, the detection signal of the control circuit 17 is not reliable in a good state when the interference wave is cut off, but such an erroneous control signal is not supplied to the holding circuit 19, and the holding circuit 19 If the control state is maintained and a disturbance wave is input again, it is possible to reliably block the disturbance wave by the narrow band blocking F-wave device 13.

The level detectors 26 and 27 are, for example, as shown in FIG.
#s is done. These level detectors 26 and 27 perform amplification and rectification, and for example, in the level detector 26, an operational amplifier 31 and a diode (32, 33), one end of which is connected to the output side of the operational amplifier 31, are used. A resistor 34 is connected between the other end and the other end of the diode 33, and the connection point between the diode 33 and the resistor 34 is connected to the operational amplifier 3.
10 on the inverted input side! #! The input resistor 35 and the smoothing circuit 36 that smooth the output of the diode 32 are further configured. These operational amplifiers 31° diodes 32, 33, feedback resistor 34, input resistor 3
5. An amplification and rectification circuit 37 is configured by the smoothing circuit 36. An amplification and rectification circuit 38 is connected to the amplification rectification circuit 37 . That is, the amplification and rectification circuit 38 includes a diode 39,
A series (low) circuit of a resistor 1141 is connected across the feedback resistor 34 (1111).

For example, when the input of the level detector 26 is positive, the output side of the operational amplifier 31 becomes negative and the diode 32 is not cut off, and a rectified output cannot be obtained. However, when the input becomes negative, the output of the operational amplifier 31 becomes negative. When the voltage becomes positive, the diode 32 operates and the voltage is supplied to the smoothing circuit 36, where it is half-wave rectified and output.

When the human power at that time becomes even more negative, the output level of the amplifier 31 becomes higher, the level at the input side of the rectifier circuit 36 also becomes higher, and the diode 39 of the amplification suppression circuit 38 becomes conductive. Until then, the gain was determined by the human resistor 35 and the NI feedback resistor 34, but the input resistor 35 and the resistor 34.
The gain is determined by the parallel circuit of 1, and the υ amplifier is lowered. In this way, the degree of amplification is suppressed for large human forces.

The level detector 27 also includes an amplification and rectification circuit 47 consisting of an operational amplifier 42, diodes 43 and 44, a feedback resistor 45, a smoothing circuit 46, an input resistor 50, and a diode 4.
8. It is composed of a resistor □□□ 49 and an amplification suppression circuit 51 made up of an amplification factor.

The input resistor 35.5 determines the boundary point of the inversion of the switch 18 of FIG. 1 in such a level detector 26.27.
Select and set a resistance value of 0.

In this example, the resistance value of the input resistor 35 is made significantly larger than the resistance value of the input resistor 50. In that case, resistor 34.45
The resistance values of resistors 41 and 49 are increased. For example, when the resistance value of the resistor 35 is made twice the resistance value of the resistor 50, the gain of the level detector 26 becomes 172 of the gain of the level detector 27, and therefore The degree of attenuation is, for example, 6 dB
, which is 1/92, then the narrowband blocking f-wave filter 1
When the level on the output side of the narrowband rejection F-wave detector 13 is half of the level on the input side of the level detector 26.
If the outputs of 27 are at the same level, the narrowband blocking P-wave device 13
The switch 18 is turned on only when the level on the 0 input side is twice as high as the level on the output side of the narrowband rejection F-wave device 13, and is turned off when it is twice as low.

For example, as shown in Figure 4, if one interference wave is an intermittent signal, and there is a signal during the Son period and no signal during the Sof period, when such a signal is input, the level detector 26 The output is at a high level during the period when the signal Son is present, as shown by the dotted line 26a in FIG. 4B, and is at a low level during the signal-off period SOf. However, the output of the level detector 27 remains at a small level even during the period of existence of the signal Son because the signal is interrupted by the narrow band blocking P-wave device 13, and is always at a small level as shown by the curve 27a in FIG. 4B. It becomes. Therefore, for example, the switch 18 is controlled so that when the signal level detection output 26a is more than twice the level detection output 27a, the switch 18 is turned on, and when it is less than that, the switch 18 is turned off. The output of the comparator 28 is as shown in FIG. 4C, and the switch 18 is turned on while the output of the comparator 28 is at a high level, that is, the switch 18 is turned on during the signal ON period Son.

Also, for example, as shown in the fourth diagram, the ON period of the signal Son
When a large noise Nl is mixed in, the level difference between the input side and the output side of the narrowband blocking p-wave filter 13 becomes small during the period in which this noise N1 exists, and the output of the comparator 28 becomes smaller during the noise period. As shown in FIG. 4 C°, the level becomes low and the switch 18 is turned off. Therefore, the output 11 of the control circuit 17 is supplied to the holding circuit 19 only when the control circuit 17 correctly detects the difference between the frequency of the interference wave and the blocking center frequency.

Voltages for setting the lowest output levels of the operational amplifiers 31 and 42 are applied to the terminals 52 and 52 through resistors 53 and 54, respectively, while for the operational amplifier 31 of the level detector 26, a resistor 55 is connected in series with the resistor 53. is inserted. When the input to the level detector 4126.27 is zero or extremely small, the lowest output level of the operational amplifiers 31 and 32 is set so that the detection level of the level comparison l1F26 is always smaller than the detection level of the level detector 27. K
do. By doing so, in a state where the output of the comparator 28 is at a low level and the control circuit 17 cannot operate properly, the switch 18Fi is turned off.

The narrowband blocking P-wave fence 13 does not have a phase characteristic as shown in -66 of Fig. 2. For example, as shown in Fig. 5, it has a phase characteristic of -1800 at the center frequency f, and a frequency slightly higher than that. -360, a phase frequency characteristic of 00 at a slightly lower frequency may be used. Furthermore, the present invention can also be applied to a case where a plurality of narrow band blocking F-wave devices are connected in series and their blocking center frequencies match the frequencies of different interference waves, and in that case, the control circuit 17 and the level detector 26, 27, and the comparator 28 can be used in common, and the holding circuit 19 may be provided for each narrowband blocking F-wave device to switch and supply the shift detection signal to each of them.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of an interference wave removal device according to the present invention, Fig. 2 is a phase characteristic curve diagram of a narrowband rejection filter, and Fig. 3 is a connection showing a specific example of the ore level detectors 26 and 27. 4 is a ninth waveform diagram for explaining the present invention in detail, and FIG. 5 is a diagram showing another phase frequency characteristic of the narrow band #R blocking P-wave device. 11: Input terminal, 12, 14: Amplifier, 13: Narrowband blocking F-wave device, 15: Output terminal, 17: Control (b) path, 18
: switch, 19: holding circuit, 26.27 = level detector, 28 two-level comparator. Patent applicant Koden Seisakusho Co., Ltd. Agent Taku Kusano Procedural amendment (voluntary) March 4, 1980 Commissioner of the Japan Patent Office Mr. Small case indication Patent application 57-506502 Title of invention Interference wave removal device 3, amendment Relationship with the patent applicant case: Kohden Seisakusho Co., Ltd. 4, Agent: 4-2-21 Shinjuku, Shinjuku-ku, Tokyo
Sokyoku Building 5, subject of amendment Detailed description of the invention in Specification 1 and drawings (2) As shown in red ink in the attached copy, the numbers "6" and "7" in Figure 2 have been changed to "66" respectively. ”
and corrected to "67".

Claims (1)

[Claims] (1) A narrow-band rejection V-wave generator that is inserted in series in the reception signal path and whose rejection frequency is changed by a control signal, and the signals on the input and output sides of the narrow-band rejection V-wave generator; A control circuit that detects the difference between the center frequency of the narrowband rejection waveform generator and the frequency of the target interference signal, and a control circuit that amplifies and rectifies the input side signal and output side signal of the narrowband rejection waveform generator, respectively. Detect the level 1! IJ1. A second level detector, a comparator to which the detection levels from these 1I second level detectors are supplied, and a signal corresponding to the frequency deviation of the control circuit are inputted to the narrow band Ffi&. a holding circuit for supplying a control signal; a switch inserted between the holding circuit and the control circuit and controlled by the output of the comparator; and means for making the output of the second level detector smaller than the output of the second level detector when the input of the second level detector is zero.