JPH0743422B2 - Interference removal device for Loran C receiver - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interfering radio wave removing device in a Loran C receiver, and more specifically, to a continuous transmission signal intermittently at the same time as a measurement pulse signal in the Loran C receiver. The present invention relates to an improvement in an interfering radio wave removing device when a decker signal provided with a rest period is received as an interfering radio wave.

[Conventional technology]

In the Loran receiver, if there is an interfering radio wave within the reception band, the S / N ratio deteriorates, so it is necessary to remove these interfering radio waves as much as possible.

Conventionally, as the interference radio wave removing means, the received signal is swept by the tuning frequency variable circuit, and the presence or absence of the interference radio wave is confirmed by judging from the signal level observed at this time, and thereafter,
The notch filter was tuned to the interfering radio waves to remove the interfering radio waves.

However, since the above-mentioned means performs sweeping manually, there are large individual differences and it is difficult to remove uniformly.Furthermore, even if the frequency is set once, the set frequency changes depending on the ambient temperature condition of the notch filter. In some cases, the above settings may become invalid due to changes in the frequency of the jammed radio waves, and the setting operation must be repeated as appropriate, which is a complicated task.

In order to solve such a problem, the applicant of the present application has previously proposed a jamming radio wave removing device that can be fully automatically performed without manipulating the jamming radio wave (Japanese Patent Application No. 60-99150).
issue).

The jammer removing device automatically sweeps a frequency of a certain band width, detects the maximum spectrum of the jamming radio wave from the obtained information, matches the spectrum with a narrow band filter narrower than the certain band width. Is automatically tuned to the jamming radio wave to remove the jamming radio wave, and the device eliminates the complexity of manual operation.

[Problems of conventional technology]

However, since the above-mentioned device performs the spectrum detection and removal cycle of the jamming radio wave for each sweep, there is a problem in that the spectrum of the jamming radio wave which is changing every moment cannot be quickly dealt with.

For example, suppose that the detection output is in the state shown in FIG. 2A when there is no noise in the Loran band and the Loran C signal is well received, and in this state, the maximum is as shown in FIG. When an interfering radio wave of the frequency component of the value P _O occurs, the interfering radio wave of the maximum value P _O during the first sweep is removed by the operation of the notch filter and is arranged as shown in FIG. When the jamming radio wave is stopped, the setting of the notch filter remains as it is, so as shown in (c) of Fig.
Detection output P _O position is lowered, the result and the minimum value P _L by jamming disappears, the maximum value P _N is generated to occur with the minimum value P _L, the maximum value P _N position is determined as an interfering frequency There are times.

The jamming wave characteristic that shifts from (b) to (c) in FIG. 2 is likely to occur when a jamming wave due to a Decker signal in which a continuous transmission signal is provided with intermittent rest periods is received. If this pause phenomenon occurs during the frequency sweep, the minimum value P _L due to the decrease in the detection output occurs when the jamming radio wave is paused.

When the discrimination operation is performed for the interference wave having such characteristics, the notch filter acts on the frequency where the interference wave does not originally exist, and the notch filter does not act on the existing interference wave. There was a problem that caused a malfunction.

[Problems to be Solved by the Invention]

In view of the above problems, the present invention provides a jamming radio wave removing device for a Loran C receiver, which can detect a spectrum of jamming radio waves due to an ever-changing decker signal and the like, including a change state thereof, and can perform swift and appropriate jamming radio wave removal processing. It was made for the purpose of providing.

[Means for Solving the Problems]

That is, the jamming device in the Loran C receiver of the present invention is a jamming device in the Loran C receiver in the case where a Decker signal in which continuous transmission signals are provided with intermittent rest periods serves as jamming waves. , A variable frequency tuning circuit for sweeping a signal input through a plurality of variable frequency notch filters within a constant bandwidth, and a command for repeating the sweep in the variable frequency tuning circuit two or more times. An arithmetic storage circuit that stores the spectrum of the bandwidth more than once, that is, a signal level and a frequency, calculates an average value of the signal level at the same frequency, and stores the result, and an interference of the stored signal information. The one having the maximum influence is discriminated, and the corresponding one of the plurality of variable frequency notch filters is tuned to the signal information having the maximum disturbance influence. And it is characterized in that comprising a command circuit.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples.

FIG. 1 is a circuit block diagram of the present invention, FIG. 2 (a),
(B), (C), and (D) are explanatory views showing the changing state of the spectrum of the jamming radio wave.

The interference radio wave removing device R of the present invention includes a plurality of variable frequency notch filters 1, 2, 3, 4, 5 and 6, and an amplifier circuit 7 for a signal input through the variable frequency notch filters 1 to 6 and the circuit 7. Variable frequency tuning circuit 8 for sweeping the input signal from within a constant bandwidth, and a command for repeating the sweep in the circuit 2 twice or more, and storing the obtained spectrum two or more times, at the same frequency An arithmetic storage circuit 10 including a microprocessor T _O , a D / A converter 11A, a multiplexer M, a DC voltage holder 10A, a detection circuit 10B and an A / D converter 10C, which calculates an average value of signal levels and stores the result. Of the stored information, the one having the largest interference influence is discriminated, and one of the plurality of variable frequency knock filters is tuned to the interference signal.
A command circuit including a microprocessor T _O , a D / A converter 11A, a multiplexer M, and DC voltage holders 1A to 6A
It is composed of 11 and.

[Action]

In FIG. 1, the input signal from the antenna Aut is a plurality of narrow band variable frequency notch filters 1, 2, 3, 4,
The frequency is amplified by the amplifier 7 through 5 and 6 and the frequency in the constant bandwidth is swept by the variable frequency tuning circuit 8.

The sweep operation of the variable frequency tuning circuit 8 is controlled by the microprocessor T _O.

That is, the microprocessor T _O is
For example, 8-bit data is given to the D / A converter 11A stepwise by using 3 bits of A, B and C as a control code (7) to change the tuning frequency of the tuning circuit 8 from f _L to f _H.

At this time, the microprocessor T _O simultaneously converts the output of the detection circuit 10B by the A / D converter 10C for each minimum change width of the D / A converter, and reads and stores it as digital data.

As described above, the microprocessor T _O measures the detection output within the band by one sweep in, for example, 25 steps, and stores the measured value as a digital value.

At this time, in the microprocessor T _O , the digital value of each step obtained by the first sweep and the second sweep is summed and averaged, and the average value is compared with a fixed setting reference value to measure the interference wave. Existence is judged.

For example, assume that the detection output is as shown in FIG. 2 (a) when the Loran C signal is well received without noise in the Loran band as described above.
As shown in Fig.2, the interference wave of the frequency component of the maximum value P _O is generated, and the interference wave disappears immediately after the corresponding notch filter is activated. As a result, as shown in Fig. 2 (C), the minimum value P _L And, even if the maximum value P _N is generated along with the minimum value P _L , the spectrum of the average value becomes the state shown in Fig. 2 (D), and the jamming radio wave P that is not detected in the second sweep _O'can be detected and the maximum value temporarily occurs
Malfunction due to P _N is prevented.

When the spectrum S of the interfering radio waves averaged as shown in FIG. 2 (d) exceeds a certain standard, the band is narrowed through the D / A converter 11A and the multiplexer M according to the frequency of the spectrum S. The frequency notch filters 1 to 6 are selected and activated to remove and reduce interference waves.

In addition, the above-mentioned operation of removing the interfering radio wave is programmed so as to be repeatedly operated at all times, and if another interfering radio wave spectrum is further detected after operating either of the frequency variable notch filters 1 and 2. The notch filters 3, 4 ... After that are sequentially assigned.

The notch filter 1 ... Divides the bandwidth of the amplifier into two so that two adjacent resonance frequencies do not approach each other. Of the six notch filters, the odd number is the lower half frequency band and the even number is the even number. Are allocated to the upper half frequency band to prevent mutual interference.

〔effect〕

According to the present invention, when detecting the spectrum of an interfering radio wave in which a continuous transmission signal is provided with intermittent rest periods, it is decided to sweep within a certain frequency band twice or more, and to judge by the average value thereof. Even in the case of an interference wave whose spectrum changes moment by moment, the change state can be comprehensively detected, and it becomes possible to quickly and appropriately remove the interference wave.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of an embodiment of the present invention, and FIGS. 2A, 2B, 2C and 2D are graphs showing the spectrum of a detection signal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 59-132246 (JP, A) JP 58-17734 (JP, A) JP 51-20688 (JP, A)

Claims (1)

[Claims] 1. A jamming radio wave removing device in a Loran C receiver when a decker signal in which a continuous transmission signal is provided with intermittent dwell periods becomes a jamming radio wave, which is input through a plurality of variable frequency notch filters. A variable frequency tuning circuit for sweeping a signal to be swept within a constant bandwidth, and a command to repeat sweeping in the variable frequency tuning circuit twice or more, and the obtained spectrum of the bandwidth of two or more times, that is, a signal The level and frequency are stored, the average value of the signal level at the same frequency is calculated, and the result is stored, and the stored signal information is determined to have the maximum interference influence, and the interference influence is determined. A Loran C receiver comprising a command circuit for tuning and operating a corresponding one of the plurality of variable frequency notch filters for maximum signal information. Jamming removal device according machine.