JPH04102083U - Loran C interference check device - Google Patents

Abstract

(57) [Summary] [Purpose] To detect the presence or absence of interference waves in a Loran C band signal and to confirm the effectiveness of a notch filter against interference waves. [Configuration] An amplifier 12 for amplifying the received Loran C band signal, a notch filter 13 for removing a specific frequency from the output signal of the amplifier, and a notch filter 13 for selecting either the output signal of the amplifier or the output signal of the notch filter. A switch 14, a peak level detector 15 that performs peak level detection of the signal selected by the switch, a signal level meter 16 that visually displays the output level of the peak level detector, and average level detection of the signal selected by the switch. The noise level meter 18 has an average level detector 17 that performs the following, and a noise level meter 18 that visually displays the output level of the average level detector.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention simultaneously measures the reception level of the Loran C band signal and the noise within the Loran C band. This invention relates to a Loran C interference wave checking device for measuring.

0002

[Conventional technology]

When performing position measurement using the Loran C system, the measurement results of the position measurement Reliability is proportional to signal strength and inversely proportional to noise and interference (continuous waves of constant frequency) strength. Proportional. Therefore, the location where the receiver is installed should be as free from interference as possible. First, you need to choose a location with strong signal strength. Regarding interference waves, Can be removed by installing a notch filter that matches the frequency of the interference wave. However, it is difficult to distinguish whether the noise is atmospheric noise or interference waves. Not only is it difficult to distinguish just by operating the device, but it is also difficult to know the frequency of the interference wave. It is also difficult. Traditionally, when installing a Loran C system, the frequency characteristics considered appropriate for the receiver were set. A notch filter with a characteristic of We are installing the transmitter.

0003

[Problem that the idea aims to solve]

As mentioned above, conventionally, when installing a Loran C system, the receiver is A notch filter with frequency characteristics that is considered to have the strongest signal strength is installed. Since the receiver is installed in a position where the notch filter can effectively block interference waves, The problem is that it is difficult to know whether the This invention determines the most optimal installation position of the Loran C system and the most optimal notch. To aid in determining the frequency characteristics of the filter, the signal strength and noise strength are separated. It can be measured and displayed, and it can also be recognized whether the noise is a single frequency (interference wave) or not. The purpose is to provide a Loran C interference wave checking device.

0004

[Means to solve the problem]

The present invention receives a Loran C band signal and amplifies the Loran C band signal. an amplifying means for outputting the Loran C band signal as a first signal; a notch filter that removes a specific frequency from the signal and outputs it as a second signal; Select one of the first signal and the second signal and output the selected signal. and a peak level detector for detecting the peak level of the selected signal. wave means, and first display means for visually displaying the output level of the peak level detection means. and average level detection means for detecting the average level of the selected signal; a second display means for visually displaying the output level of the level detection means; The Loran C signal level is displayed on the display means, and the noise signal level is displayed on the second display means. A Loran C interference wave checking device is obtained, which is characterized in that it is shown as follows.

[0005]

【Example】

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram of an embodiment of the present invention. Loran C interference wave check of this embodiment The lock device includes an amplifier 12 having an input terminal 11, a notch filter 13, and a switch. 14, peak level detector 15, signal level meter 16, average detector 17, and noise It has a level meter 18.

[0006] A Loran C band signal received by an antenna (not shown) is input to input terminal 11. Ru. The Loran C band signal input to the input terminal 11 is amplified by the amplifier 12. It will be done. The amplified Loran C band signal is branched into two, one of which is passed through notch filter 1. 3 and the other is input to switch 14. Notch filter 13 is Loran A specific frequency is removed from a C band signal, and the Loran C band signal is obtained by removing the specific frequency. is output to switch 14. Switch 14 connects the signal from amplifier 12 or the Switching is performed to selectively output one of the signals from the filter 13. I can. The signal selected by switch 14 is passed through peak level detector 15 and The signals are input to the average detector 17, and peak level detection and average level detection are performed respectively. It will be done. The results of the detection performed by the peak level detector 15 and the average detector 17 are as follows. The signals are input to a signal level meter 16 and a noise level meter 17, respectively.

[0007] Here, the Loran C band signal is composed of the Loran signal 21 and the noise 22 as shown in FIG. Contains. The Loran signal 21 and noise 22 have the following characteristics. That is, the Loran signal 21 is pulse-like, has a high peak level, and has a low average level. The noise 22 has a low peak level and a high average level. Therefore, when peak level detection is performed on the Loran C band signal, the signal strength of the Loran C signal is degree can be detected. In addition, when performing average level detection of the Loran C band signal, the noise signal Strength can be detected. That is, the signal level meter 16 and the noise level meter 17 each measure the Loran signal level. display the signal and noise level. Note that the time constant of the average detector 17 is determined by Loran C to remove the influence of the Loran signal. It is necessary to set it sufficiently longer than the signal repetition time.

[0008] As mentioned above, the Loran C interference wave checking device of this embodiment detects the Loran C signal and noise. Each level can be displayed separately. Therefore, the switch 14 When selecting the signal from the notch filter 13, the band rejection of the notch filter 13 By changing the interference frequency, it is possible to know whether there is an interference wave and its frequency. Also, by switching the switch 14, the effectiveness of the notch filter can be confirmed. recognition, and whether there is any effect on the Loran signal (attenuating the Loran C signal). I can do that.

[0009]

[Effect of the idea]

According to the present invention, the Loran C band signal is received and the Loran C band signal is amplified and increased. amplifying means for outputting the widened Loran C band signal as a first signal; a notch filter that removes a specific frequency from a signal and outputs it as a second signal; Select one of the first signal and the second signal and output the selected signal. a selection means for detecting the peak level of the selected signal; and a peak level detection means for detecting the peak level of the selected signal. a detection means and a first display means for visually displaying the output level of the peak level detection means; an average level detection means for detecting the average level of the selected signal; and a second display means for visually displaying the output level of the average level detection means. , presence or absence of interference waves in Loran C band signal, and notch filter for interference waves It is possible to easily and accurately confirm the effects of

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a waveform diagram of a Loran C band signal.

[Explanation of symbols]

11 Input terminal 12 Amplifier 13 Notch filter 14 Switch 15 Peak level detector 16 Signal level meter 17 Average level detector 18 Noise level meter 21 Loran signal 22 Noise

Claims (1)

[Scope of utility model registration request] Claim 1: Receiving a Loran C band signal and transmitting the Loran C band signal.
an amplifying means for amplifying a band signal and outputting the amplified Loran C band signal as a first signal; a notch filter for removing a specific frequency from the first signal and outputting it as a second signal; a selection means for selecting one of the signal and the second signal and outputting the selected signal; a peak level detection means for detecting the peak level of the selected signal; and an output of the peak level detection means. It has a first display means for visually displaying the level, an average level detection means for detecting the average level of the selected signal, and a second display means for visually displaying the output level of the average level detection means. A Loran C interference wave checking device, characterized in that the first display means displays the Loran C signal level, and the second display means displays the noise signal level.