WO2001003352A1

WO2001003352A1 - Jammer

Info

Publication number: WO2001003352A1
Application number: PCT/KR2000/000108
Authority: WO
Inventors: Hi Chul Gim
Original assignee: Jamming Electronic Co., Ltd.
Priority date: 1999-07-05
Filing date: 2000-02-12
Publication date: 2001-01-11
Also published as: KR19990083728A; KR100357375B1; AU2578200A

Abstract

The subject invention discloses a jammer for jamming at low power radio transmission/reception by wireless communication units such as cellular phones so that communications over said wireless communication units are interfered. A jammer in accordance with the subject invention comprises an oscillator for generating oscillating signal having a fixed frequency; an up converter for multiplying the frequency of said oscillating signal from said oscillator to up-convert it to one or more desired frequencies; power-on resetting means for resetting said up converter when said jammer is porwered on; one or more band extending means for extending the frequency band of output signal from said up converter; one or more power amplifier for amplifying output signal from said band extending means to a jammable level; and one or more antenna connected with each of said amplifiers.

Description

JAMMER

Technical Field of the Invention

The subject invention relates to a jammer, in particular, to a jammer for jamming at low power radio transmission/ reception by wireless communication devices such as mobile telephones so that communications over said wireless communication devices are interfered.

Background Art

Recently, after the number of mobile telephone users has increased explosively some of them are using their mobile phones carelessly even at public places such as theaters, concert halls, etc.. thus, such indiscreet use of mobile telephones has become a social problem. Nameh . although mobile telephone users are expected to turn off their mobile telephones or. at least change the receiving mode to vibration mode at such public places in consideration of others, many of them tend to neglect such social etiquette, because they momentarih forget to turn off their mobile telephones or consider it bothersome to change the receiving mode to vibration mode. As a result, some mobile telephones release bell sounds even during public performances so that the artists and other audience are disturbed.

In order to solve the above problem, some mobile telephones recently on the market are equipped with an etiquette function. The etiquette function, performed in one-touch manner, not only changes the receiving mode from bell sound to vibration mode, but also turns off message receiving sound, button sound, call connection sound, call disconnection sound, etc.

However, since such mobile telephones with etiquette function need to be changed to etiquette mode by users in the same manner as the conventional mobile telephones terminals, the expected improved effect of such mobile phones is not much greater than that of the conventional mobile telephones.

Another method has been proposed to resolve the above problem according to which radio transmitter is installed at public place to automatically change call sounds of mobile telephones to vibration mode when the users of the mobile phones enter the public place. This method uses a channel, which is not currently used by the existing mobile phones. This method is an improved one in that it compulsively changes bell mode to vibration mode regardless of the intentions of the users.

However, the above method is disadvantageous in that the existing mobile telephone terminals needs to be upgraded because they are not equipped with the function of automatically changing bell sound to vibration mode. Furthermore, even if the receiving mode of mobile telephones may be automatically changed from bell sound to vibration mode, it is not excluded that the users speak audibly over the mobile telephones at place without quitting the place when they receive phone calls. In such case, their disturbance would remain the same.

As an alternative approach, conventional jammers capable of radiating strong radio waves over all frequency bands of wireless communication units such as mobile telephones are in use to disturb communications over wireless communication units. However, since a Code Division Multiple Access (hereinafter. "CDMA^") system, now adopted as a communication system for digital mobile telephones in Korea, has a wide bandwidth, and the conventional jammer should radiate very strong radio waves to cover such a wide bandwidth Although such strong radio waves can disturb communications over radio communication units the\ may irritate operation of other electronic equipments or injure health of the people in the vicinit)

Furthermore, since a side spurious component \ is generated in conventional jammers as shown in (a) of Fig 8. a power difference x required for jamming effect is obtained

setting power at a center frequency of z higher than the side spurious component y by x The resultant power is so high that it greatly affects other radio equipment and human body Thus, there has been need for a jammer which has a low side spurious component and requires low power at the center frequency while generating the desired power difference

Detailed Description of the Invention

The subject invention, conceived to resolve the above problems, aims to provide a jammer which is capable of automatically blocking communications via digital mobile telephones at certain public places

Another objective of the subject invention is to provide a jammer which is capable of blocking communications over mobile telephones while radiating radio waves of low power Brief Description of the Drawings

The subject invention w ill be more clearly understood from the drawings attached herein, in which: Fig. 1 is a block diagram showing the overall construction of a jammer in accordance with the subject invention:

Fig. 2 is a circuit diagram showing an embodiment of an oscillator of a jammer in accordance with the subject invention:

Fig. 3 is a block diagram of a band extending circuit of a jammer in accordance with the subject invention;

Fig. 4 is a circuit diagram showing an embodiment of the band extending circuit in accordance with the subject invention;

Figs. 5a to 5c are spectrum diagrams showing spectral variations of a signal from the band extending circuit of a jammer in accordance with the subject invention;

Fig. 6 is a circuit diagram showing an embodiment of a power amplifier of a jammer in accordance with the subject invention:

Fig. 7 is a spectrum diagram showing a power spectrum from said

er amplifier; and Fig. 8 is for illustrating a comparison of output spectrum of a conventional jammer with that of a jammer in accordance with the subject, wherein:

(a) is an output spectrum diagram from a conventional jammer; and

(b) is an output diagram from a jammer in accordance with the subject invention. Best Mode or Modes for Carrying Out the Subject Invention

Fig. 1 is a block diagram showing the overall construction of a jammer in accordance with the subject invention.

In Fig. 1 . oscillator 10 oscillates at a fixed frequency of. for example.

22MHz or 28MHz. An embodiment of oscillator 1 0 is shown in Fig. 2. In Fig.

2. crystal resonator(Xtal) is selected with an appropriate frequency which is desired to be oscillated by oscillator 10. Appropriate resistor Rl and capacitors C l . C2 are selected similarly according to said desired oscillating frequency.

Oscillating signal is transmitted from oscillator 10 to up converter 40 via buffer 30. Up converter 40 is adapted to multiply the oscillating signal frequency so that said frequency is up converted to the frequency bands of wireless communication units to be interfered with. Power-on resetting circuit 20 functions to prevent up converter 40 from free running when the jammer is powered on. To this end. power-on resetting circuit 20 resets up converter 40 when a predetermined period of time has elapsed after the jammer is powered on.

Up converter 40 is adapted to perform individual frequency multiplication operations according to the types of wireless communication units to be interfered with. In the present example of embodiment, wireless communication units to be interfered with are PCS phones of a 1 .8GHz band and cellular phones of an 800MHz band.

After the frequency signals are multiplied by said up converter to the respective frequency bands of the wireless communication units to be interfered with, band extending circuits 50a 50b are adapted to extend frequency bands ot the trequenc\ signals as will be explained later in detail

Said signals, hav ing been extended their respectiv e frequency bands, are amplified to predetermined power levels by power amplifiers 60a. 60b. and are transmitted through antennas ANTl . ANT2 which are designed to fit into their respecm e frequenc\ bands As a result, the surrounding communication units are jammed b> signals

Next, a detailed description of an embodiment of the band extending circuits is giv en w ith reference to Figs 3 to 5 below Fig 3 is a block diagram of the band extending circuit of a jammer in accordance w ith the subject invention. Fig 4 is a circuit diagram showing an embodiment of the band extending circuit of a jammer in accordance with the subject invention, and Figs 5a to 5c are spectrum diagrams showing spectral variations of an output signal from the band extending circuit of a jammer in accordance with the subject invention

Band extending circuits 50a. 50b extend the bandw idth ol the signals from up conv erter 40 because said signals have narrow bandw idth

Fig 3. schematicalh shows the construction of the band extending circuit in accordance w ith the subject invention Signals from up converter 40 contains an image frequencx component produced during the multiplication operation Low Pass Filter 5 1 removes the frequenc\ components exceeding upper limit

of the frequency band of desired wireless communication units from said image frequency component Band Pass Filter 52 determines the frequenc\ bandwidth of a signal to be produced which is then transferred to pow er amplifiers 60a. 60b through buffer 53 Fig. 4 is a detailed circuit diagram showing an embodiment of the band extending circuit in accordance with the subject invention.

In Fig. 4. resistors Rl l . R12. variable resistor VR and capacitor C l l constitute Low Pass Filter 51 . Variable resistor VR adjusts center frequency fo. A signal at point Va has a spectrum as shown in Fig. 5a. A curve indicated by "B" in Fig. 5a represents filtering characteristic of Low Pass Filter 5 1 .

Varicap VAR has a capacitance characteristic, varying with direct current(hereinafter. "DC^") voltage component applied thereto. That is. the capacitance of varicap VAR becomes lower as the applied voltage becomes higher. The pass band is controlled in accordance with the capacitance variation of varicap VAR. The spectrum of a signal at point Vb is as shown in Fig. 5b. The curve indicated with 'C^" in Fig. 5b represents the spectrum of a signal passed through point Vb. and the curve in dotted line in Fig. 5b represents the spectral variation of the passed signal based on the capacitance variation of varicap VAR.

Said signal, after passing Band Pass Filter 52. composed of variable capacitor VC. inductor L l l and capacitor C 12. and thus, removed of signal components beyond the pass band from that signal, passes further through

Buffer 53. composed of transistor Tr. l . to become a signal having a spectrum as shown in Fig. 5c and to be discharged from emitter of said transitor.

In Fig. 4. capacitors C 13. C 14 have been added to prevent transistor

Tr. l from oscillating. Resistor R14. together with resistor R13 not only determines bias, but also enhance thermal stability. Capacitors C 1 5. C 1 6 have been adopted to remove effects from the distribution capacity between collector and emitter of transistor Tr. l . and to reduce the power noise. Fig. 6 is a circuit diagram showing an embodiment of the power amplifiers in accordance with the subject invention.

Generally, the bandwidth of a single-stage power amplifier is not so wide as to cover a wide bandwidth of. for example. CDMA cellular phones. For this reason, it is preferred that a plurality of power amplifiers for amplification of different frequencies are used to cover a wide band as shown in Fig. 7.

In other words, a plurality of power amplifiers each of which is so designed to amplify certain predetermined parts in a given wide band, that the sum of the parts (a. b and c in Fig. 7) amplified covers the whole of desired wide band ('D^' in Fig. 7).

There is of course no need for using such a method to jam communications over wireless communication units of which the bandwidth are not wide. Capacitor C25 and inductor L21 in Fig.6 determine the center frequency of each of the power amplifiers in Fig.7. Namely, by adjusting the value of capacitor C25 and inductor L21 any one of a. b or c in Fig. 7 can be selected. For jamming communications over wireless communication units having a narrow bandwidth, only a coil can be used instead of capacitor C25 and inductor L21 .

Capacitors C26. C27 in Fig. 6 correspond to the capacitors C 1 5. C 16 in Fig. 4 respectively and aim to remove effects from the distribution capacity between collector and emitter of transistor Tr.2 and to reduce the power noise.

The part indicated with "A^' in Fig. 6 offsets the effects from distribution capacity and lead inductance of the parts. Although the detailed description of the subject invention as above has been made in the light of examples of embodiment of the subject invention, the scope of the rights of the subject invention is not limited thereto, but rather shall be determined by the claims as attached below , so that the scope comprises a wide range of variations insofar as they do not go beyond the essence of the subj ect invention, as persons skilled in this art would recognize

Industrial Applicability

As apparent from the above description, the subject invention discloses a jammer w hich is capable of automatical cutting off communications over mobile telephones at certain public places to prevent harms resulting from indiscreet use of the mobile telephones

Further, a _jammer according to the subject invention is capable of effectiveh cutting off communications over mobile telephones while radiating radio wav es of low spurious component requiring relativ elv low power at center frequenc Therefore said jammer can be operated bv low power consumption and. thus, can reduce negative effects of a jammer on other radio equipments and human bodv In addition, the subject invention allows to easilv adjust the desired frequency band using variable resistor and variable capacitor

Furthermore, since a jammer in accordance with the subject invention is capable of jamming communications over wireless communication units by suppressing frequencv bands of the radio communication units, said jammer can interfere with communications regardless of communication sv stems of the radio communication units, such as an analog communication system, digital communication svstem. etc.

Claims

What Is Claimed Is:

1 . A jammer comprising: an oscillator for generating oscillating signal having a fixed frequency: an up converter for multiplying the frequency of said oscillating signal from said oscillator to up-convert it into one or more desired frequencies; power-on resetting means for resetting said up converter when said jammer is powered on; one or more band extending means for extending the frequency band of output signal from said up converter; one or more power amplifier for amplifying output signal from said band extending means to a jammable power level: and one or more antenna connected with each of said power amplifiers: whereby said jammer jams communications over wireless communication units by suppressing all available frequency bands of said wireless communication units.

2. A jammer as set forth in Claim 1. wherein said band extending means comprises: a low pass filter: a band pass filter for band pass filtering output signal from said low pass filter; and a buffer for buffering output signal from said band pass filter.

3. A jammer as set forth in Claim 2. wherein said low pass filter comprises: a voltage divider consisted of resistors; and a capacitor connected in parallel to a connection point of said voltage divider: and wherein said band pass filter comprises: a varicap connected to ground at the input stage of the band pass filter: an inductor; and capacitors.

4. A jammer as set forth in Claim 3. wherein at least one of said resistors which constitutes said voltage divider in said low pass filter is a variable resistor; and at least one of said capacitors in said band pass filter is a variable capicitor.