JPH1155225A - Dead zone generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a dead zone for a receiver in a certain area by a simple device, and to prevent the influence of a portable telephone set on medical equipment or the like. SOLUTION: Only components in a frequency band for interference are extracted by a filter 2 from a wide band noise such as a white noise outputted by a wide band noise generator 1, and radiated from an antenna 3. This interference radio wave has a weak level to be received by a receiver so that the device itself can be made compact and inexpensive, and a generated noise can be prevented from affecting medical equipment or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention impairs the receivable signal, thereby deteriorating the S / N of a receiver input, making reception difficult, and making communication and control impossible. The present invention relates to a dead zone generator for creating an area.

[0002]

2. Description of the Related Art In a hospital or the like, there is a problem that radio waves emitted from a mobile phone cause electronic devices such as medical devices to malfunction. For this reason, hospitals have taken measures such as banning the use of mobile phones, but mobile phones automatically respond to the wireless base station and emit radio waves when a call is received if the power is on. . Therefore, it is necessary for the user to turn off the power in such a place where use is prohibited or where self-control is required. Further, as a related technique, a method of radiating a strong interference wave having a reception frequency for interrupting short-wave broadcasting or a close frequency is known. Also,
ECM (Electronic Co.)
unter Measure).

[0003]

If the user only relies on turning off the power in places where use is prohibited, forgetting to turn off the power cannot be completely prevented. In addition, the ECM of the short-wave broadcasting interference method and the military technology has a problem that the configuration is complicated, expensive, and large because it is necessary to support various frequencies and radio wave formats. Furthermore, military technology is often not disclosed technically and is difficult to apply to civilian applications. In addition, when a strong radio wave is emitted, it itself interferes with medical equipment.

An object of the present invention is to form a dead zone of a receiver in a certain area by emitting jamming radio waves with a device having a simple structure, and to prevent interference other than the communication to be jammed. To provide a dead zone generator.

[0005]

In order to achieve the above object, the present invention provides a broadband noise generator, a filter for extracting only a frequency component to be disturbed from an output of the broadband noise generator, An antenna for radiating an output of the filter is provided.

The present invention also provides a plurality of broadband noise generators, a plurality of filters provided for each of the plurality of broadband noise generators, and each of the filters for extracting a frequency component determined as a target of interference. Provided is a dead band generating device, comprising: a combiner for combining outputs of a plurality of filters; and an antenna for radiating the outputs of the combiners.

Further, the present invention provides one broadband noise generator, a distributor for distributing the output of the wideband noise generator, and a plurality of outputs provided by the distributor. A plurality of filters for extracting frequency components determined as interference targets, a combiner for combining the outputs of the plurality of filters, and an antenna for radiating the outputs of the combiner, A characteristic dead zone generator is provided.

Further, the present invention provides a dead zone generating apparatus, wherein the broadband noise generator is a white noise generator or an impulse train generator.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of the configuration of a dead zone generating apparatus according to the present invention, in which a broadband noise generator 1 for generating jamming radio waves and an output frequency band are limited so as not to interfere with other communications. Filter 2 for
It comprises an antenna 3 for radiating jamming radio waves.

FIG. 2 shows an example of the spectrum of the broadband noise output from the broadband noise generator 1. FIG. 2A shows the spectrum of white noise, and FIG. 2B shows the spectrum of an impulse train that repeats periodically. is there. The white noise in FIG. 1A can be obtained by amplifying thermal noise or the like. FIG. 2
In (b), the interval Δ of the line spectrum is T, where T is the period of the impulse train.

(Equation 1) Thus, as the period T of the impulse train is increased as much as possible to achieve a small Δ, the noise becomes closer to white noise and the effect as an interference wave becomes better. However, as the period T of the impulse train is larger, it is necessary to increase the power of one impulse in order to obtain a predetermined noise power. Therefore, an actual design is performed with this trade-off.

FIG. 3 shows an example of the amplitude characteristic of the filter 2, and its pass band is a band covering the downstream frequency of the PDC system. It is assumed that the spectrum shown in FIG. 2 covers at least this pass band. Then, the shape of the frequency spectrum on the output side of the filter 2 in FIG. 1 becomes the same as that in FIG. At the same time, since the interfering radio waves outside this band are cut, it is prevented from becoming a noise source to other systems.

FIG. 4 is an explanatory diagram of the interference effect. It is assumed that the reception bands f1 and f2 of the receiver are within the pass band of the filter 2, and the reception power of the signal in the reception band is Pi. Further, assuming that the noise power density determined by the NF (noise figure) of the receiver and the like is Nn and the power density of the disturbing noise generated from the dead zone generator of the present invention is N0, the reception S / N of the receiver is

(Equation 2) Given by Generally, the contribution of noise from the receiver NF or the like is sufficiently small. Therefore, if the contribution from the power density N0 of the jamming radio wave is set to be substantially equal to the reception signal power Pi, the S / S
N is in a very bad state and cannot be received. Therefore, in the case of the mobile phone, even if the power is forgotten to be turned off, the mobile phone cannot respond to the call from the base station, and it is possible to prevent a strong radio wave from being transmitted from the mobile phone to interfere with medical equipment and the like. Further, the received signal power Pi is generally an extremely weak radio wave, and therefore does not directly interfere with medical equipment or the like. Therefore, if the contribution of the interfering wave is substantially equal to the received signal power Pi, there is no fear that the interfering wave directly acts on medical equipment or the like to cause interference. Further, since the interference wave is not a single-frequency interference wave, there is no concern that interference other than the receiver as the interference target, such as a television or radio receiver, may cause reception due to intermodulation. Further, since a radio wave from a plurality of base stations can be received in a place with good visibility such as the top floor of a building, for example, the interference method using a single frequency switches to another base station, so that there is no effect. However, since the present invention utilizes broadband noise, it is possible to reliably prevent reception in such a case.

Further, since the present device requires only a low power output as described above and has a simple circuit, it can be made small and inexpensive. Therefore, for example, it is easy to put together as an outlet-mounted type or ceiling-mounted type device, and a radius of about several tens of meters is set as a dead zone of a mobile phone in a place where important medical equipment is installed, a conference room, a movie theater, or the like. Is also easier.

Next, another configuration example of the present invention is shown in FIGS. FIG. 5 shows two broadband noise generators 51 and 52 and a filter 5 for limiting the frequency band of each output.
3 and 54 are provided, and their outputs are combined by a combiner 55 to radiate from an antenna 56. FIG. 6 shows a configuration in which the output of one broadband noise generator 61 is divided into two by a distributor 62, each of which is band-limited by filters 63 and 64, combined by a combiner 65 and radiated from an antenna 66. doing. In any case, by appropriately setting the pass bands of the two filters, it is possible to realize a dead band in which reception is impossible in the two frequency bands. In FIGS. 5 and 6, two filters are provided. However, the number of filters can be three or more, and the same effect as in FIG. 1 can be obtained.

[0015]

According to the present invention, even when the power of the portable telephone is forgotten to be turned off, a dead zone in which a call from a base station cannot be answered can be easily realized, and the dead zone can be set within a small range. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of a dead zone generating device according to the present invention.

FIG. 2 is a diagram illustrating an example of an output spectrum of a broadband noise generator.

FIG. 3 is a diagram illustrating a characteristic example of a filter.

FIG. 4 is an explanatory diagram of an interference effect.

FIG. 5 is a block diagram showing another configuration example of the dead zone generating device according to the present invention.

FIG. 6 is a block diagram showing another configuration example of the dead zone generating device according to the present invention.

[Explanation of symbols]

 1, 51, 52, 61 Broadband noise generator 2, 53, 54, 63, 64 Filter 3, 56, 66 Antenna 55, 65 Combiner 62 Distributor

Claims (4)

[Claims] 1. A broadband noise generator, a filter for extracting only a frequency component to be disturbed from an output of the broadband noise generator, and an antenna for radiating an output of the filter. Characteristic dead zone generator. 2. A plurality of broadband noise generators, a plurality of filters provided for each of the plurality of broadband noise generators, each of which extracts a frequency component determined as an object of interference, A dead zone generator comprising: a combiner for combining outputs; and an antenna for radiating an output of the combiner. 3. A broadband noise generator, a distributor for distributing an output of the broadband noise generator, and a plurality of outputs provided for each output distributed by the distributor. A plurality of filters for extracting the obtained frequency components; a combiner for combining the outputs of the plurality of filters; and an antenna for radiating the outputs of the combiner. Generator. 4. The dead band generator according to claim 1, wherein the broadband noise generator is a white noise generator or an impulse train generator.