WO2002056630A1

WO2002056630A1 - Process for detecting the presence of active cell phones in an area protected from their use, and correponding equipment

Info

Publication number: WO2002056630A1
Application number: PCT/IT2002/000020
Authority: WO
Inventors: Fabrizio Faggioni
Original assignee: Mesar S.R.L.
Priority date: 2001-01-16
Filing date: 2002-01-15
Publication date: 2002-07-18
Also published as: ITRM20010018A1; ITRM20010018A0

Abstract

A process for detecting the presence of active cell phones in an area protected from their use, comprising the following steps: acquiring the identification signals and codes of the cell base stations or BTS active in the protected area; transmitting radio interference into the protected area in the bands and on the frequencies used internationally for cellular telephony; stopping the emission of the aforesaid radio interference; creating a signal of a virtual BTS, or a local mobile telephone station not connected to the network, having an idenfication code different from those of the real BTS active in the protected area; receiving radio frequency registration signals from cell phones; determining the presence of these cell phones; and signalling their presence to responsible personnel.

Description

Process for detecting the presence of active cell phones in an area protected from their use, and corresponding equipment

The present invention relates to a process for detecting the presence of active cell phones in an area protected from their use. It also relates to electronic equipment for applying this process.

The following terms and abbreviations used in the rest of the text will first be defined. The term "cell phone" denotes a portable telephone for mobile telephony, also known as a "mobile phone", provided with its own identification number. "BTS" denotes a real local mobile telephone station or cell base station, controlling a cell connected to the operator's network and from this to the national and international fixed and mobile telephone network. A virtual BTS, on the other hand, is a local mobile telephone station which controls an area but is not connected to the operator's telephone network and/or to the normal or international network.

As is known, there are some areas in which the use of cell phones is strongly discouraged or even prohibited, because it can create situations of serious disturbance or danger. For example, the presence of a large number of people with cell phones in restricted environments, such as means of transport or other enclosed spaces, can create very strong electromagnetic fields which are hazardous to the health. In other places, the radio frequency emission of cell phones can disturb the operation of complex electronic equipment, which can be damaged or operate in an unsatisfactory way, and this may even endanger life. In theatres or meeting halls, in addition to the strong electromagnetic fields which are created, the radio frequency emissions can interact with audio and video reproduction systems, as well as causing annoying disturbances with ring tones and answers. Similar problems occur at sporting events and other public activities.

At the present time, attempts have been made to resolve these problems by simply asking cell phone owners to switch their phones off beforehand, relying on their sense of responsibility. However, this trust is not always justified, and the risk of failure to comply with the requests is such that serious measures must be taken to tackle the problem of checking the presence of cell phones in specified areas protected from their use, on board aircraft for example.

It will be useful to fist briefly the usual operating states of a cell phone. There are essentially four of these operating states:

1. The cell phone can be switched off, and in this state it obviously does not cause any problems until the user decides to switch it on.

2. The cell phone can be in the waiting or "standby" state: in this state, the telephone can wait for long periods, even several hours, without emitting signals. However, the cell phone is active, in that it is ready to receive calls and confirm its presence to the cell base station or BTS. This state is the most hazardous, since the problem is latent. A message can be received or confirmation sent at any time, entailing radio frequency emission, independently of any action by the cell phone owner. This is the state that has to be avoided.

3. The cell phone can be connected, in other words active; in this case, although the danger remains, the telephone can easily be identified because it is transmitting.

4. The cell phone can be network searching, and therefore active; in this case also, even though the danger remains, it can easily be identified because it is emitting signals at radio frequency.

The above list shows that the most difficult operating state to identify, apart from the first which is of no concern at all, is the second, in other words the waiting or "standby" state, since the cell phone emits practically no signals. It is easier to detect the presence of cell phones in the third and fourth states listed above. One object of the invention is to detect the presence in a protected area of active cell phones, particularly those in the standby state, and to notify their presence to responsible personnel by means of a warning.

Another object of the invention is to detect the presence in a protected area of active cell phones, particularly those in the standby state, and to permit the identification of the cell phones in this state, the recording of their identification numbers and, if necessary, the making of an automatic call to them.

In a first aspect, therefore, the invention provides a process for detecting the presence of active cell phones, particularly those in standby mode, in an area protected from their use, comprising the following steps: acquiring the identification signals and codes of the local mobile telephone stations or BTS active in the protected area; transmitting radio interference into the protected area in the bands and on the frequencies used internationally for cellular telephony; stopping the emission of the aforesaid radio interference; creating a signal of a virtual BTS, or a local mobile telephone station not connected to the network, having an identification code different from those of the real BTS active in the protected area; receiving radio frequency registration signals from cell phones; determining the presence of these cell phones; and signalling their presence to responsible personnel.

Advantageously, the process according to the invention additionally comprises the steps of identifying the active cell phones, particularly those in standby mode, recording their identification numbers, making an automatic call and sending a message to the said cell phones, checking that all the cell phones are switched off, and continuously checking that no cell phone has been switched on again.

In a second aspect, the invention provides equipment for the practical application of the aforementioned process. The present invention will now be described with reference to its preferred embodiments, although it is to be understood that it can be varied without departure from the scope of protection of the invention, and with reference to the figures of the attached drawing, in which:

Figure 1 is a flow chart which represents an embodiment of a process according to the present invention;

Figure 2 is a block diagram which shows in summary form equipment for the application of the embodiment of the process shown in the flow chart of Figure 1; and

Figure 3 is a block diagram which shows in an even more schematic way the equipment of Figure 2.

The process according to the present invention is related to the principles of operation of cellular telephony, according to which the territory is divided into cells, in each of which the cell phone or mobile terminal is connected to a cell base station, or BTS, which operates on different frequencies from those of the surrounding cells. The process can be applied in an area, generally a restricted area, which is to be protected from the use of cell phones, for example the interior of an aircraft or a railway carriage, this area being located at any given instant within one or more cells as defined above.

The following text describes the process for detecting the presence of active cell phones in an area protected from their use, according to the present invention, with reference to Figure 1, which shows the schematic flow chart of one embodiment of the process. This process is implemented with equipment which will be described subsequently with reference to Figures 2 and 3.

In this embodiment (Figure 1), immediately after the equipment has been switched on and started up (step 1), there is a step of preliminary checking of the operation of the equipment by which the process is implemented (step 2). From decision step 3 relating to this check, in case of a negative response, a fault signal is sent to an authorized operator of the equipment (step 4), followed by automatic switch-off (step 5). If the response at decision step 3 is positive, the operator can select or enter via a keyboard and monitor the names of the country or countries in which the system is to operate (step 6). The equipment is set to receive and identifies the characteristic codes of the real BTS active in the area (step 7) as if it were a cell phone in "roaming" mode.

When these codes have been acquired and processed, with the use of a database which contains information relating to various regulations of the different countries, a radio frequency interference signal is generated by means of the equipment in the band used by the cell phones for a certain time Tl (step 8). The transmission may be carried out by means of a directional antenna or an omnidirectional antenna, for example by making use of the natural Faraday cage effect of an aircraft fuselage.

Transmission is carried out with a strong neutral and/or white noise and/or RF.CW signal at radio frequency, whose frequency band lies in the cellular telephony band, which can be selected from the database at step 8 if required. A typical radio frequency signal can consist of an intentional continuous wave interference or a radio frequency emission modulated by a noise generator.

Any cell phones in the standby or operational state which are present in the protected area detect the aforesaid interference and, by means of their automatic gain control, reduce the sensitivity of their receivers and, in some cases, the power of their transmitters. The result is that that connection to the network is lost, because of the loss of the radio frequency signal information which is concealed by the interference. Consequently, if a cell phone is making a call there is an interruption and a network search operation has to be started. However, even if the cell phone is in the waiting or standby state, it still has to restart the operation of network searching and reconnecting to the network.

At step 9, typical signals of the cell base station of the cellular system are created and emitted for each operator of the telephone service which has its own signal in this cell in its own frequency band. The equipment acts as a virtual BTS. Each cell phone which is in the network search state following the creation and emission of the interference receives the emitted base station signal and, when the change of BTS is recognized, starts a new registration procedure.

At this stage, the cell phone normally registers itself by declaring its identification number and a set of codes sent from the BTS, which "handles" it as an "active user". In the case of the present process, the equipment which acts as a virtual BTS receives the registration signals of any active cell phones together with their identification (step 10).

The data for the active cell phones are stored in a data bank or archive (step 11) and their total number is notified to the responsible personnel (step 12). When the presence of active cell phones has been detected, an audio alarm signal is sent to the control personnel, who then request the owners to switch off all active cell phones (step 13).

The equipment remains inactive for a time T2 while waiting for all active telephones to be switched off (step 13'). To check that the telephones have actually been switched off, the state of the connection is verified, and, if it is still active, messages are sent to the cell phones registered previously as active (step 10). The messages, in the language of each of these telephones, can be of the SMS or voice type, and are logically preceded by the usual ring tones (step 14).

At this point, in order to improve security, a further check is made for telephones which are still active (step 15), followed by notification of the personnel (step 16). At decision step 17, the question asked is whether all the cell phones have been switched off. If the answer is negative, any number which is still active is notified to the personnel (step 18). The personnel can proceed to make a call to expressly request the owner to switch off (step 19).

At this point, a check is made as to whether all the telephones are switched off (step 20). If the cell phones are found to be switched off, the system proceeds to step 22; otherwise, it proceeds with more decisive action (step 21), for example suspending the activity after requests made by telephone calls and also by microphone and loudspeaker have met with no response. If all the telephones are switched off, the equipment automatically switches off the virtual BTS (step 22) and notifies this to the personnel (step 23). In the aeronautics field, this could indicate permission for taxiing. The equipment also activates (step 24) a receiver of the international telephony frequencies. At decision step 25, a check is made as to whether any new switch-on has taken place. The purpose of this action is to check constantly, during a flight for example, that no-one has switched a cell phone on again. If telephones are switched on again and attempts made to connect to the network, this immediately triggers the squelch circuit of the receiver and therefore triggers an alarm for the personnel (step 26) and then starts a whole new identification process. If necessary, or in case of doubt, the personnel can always use a key for activating a new search and identification cycle (step 26'). The monitoring of the situation, in other words the checking to ensure that no telephones are switched on, continues until the end of the whole operation (step 27) which can be a flight, a performance, a surgical operation, etc. At the end of this period, the personnel can dump the acquired data, in other words the identification numbers of the telephones that caused problems (step 28) and the process can be ended by pressing the stop key (step 29) which switches the equipment off. However, the equipment can also be switched off at any stage of the operation. This means that, in all operating states, the system must update and store the data in the database before it is finally switched off.

With reference to Fig. 2, this shows in a summary way a block diagram of the equipment which can be used to apply the process according to the invention. It shows the following units: receiving and transmitting antenna (50), narrow band receiver (51), wide band (sweep) receiver (52), demodulators (53, 54), acquisition (55), audio amplifier (56), loudspeaker (57), microphone (58), amplifier/microphone synthesizer (59), random noise generator (60), SMS message generator (61), synthesized message generator (62), multi-channel multiplexer (63), multi-channel exciter (64), wide band RF amplifier (65), solid state switch or fast electronic switch (66), start key (67), stop key (68), new cycle start key (69), "All OK" indicator (70), optical/audible indication of "at least one active telephone" (71), CPU (central processing unit) (72), alphanumeric display (73), keyboard (74), removable flash card store (75), database archive store (76), pre-recorded message archive store (77), program store (78), stores for geographical data, BTS frequencies, etc. (79), timer unit (80), ON indicator (81), power supply (82), and power switch (83).

The technical operation of the equipment shown in detail in Fig. 2, for applying the process, is organized around eight base units which facilitate the summary description of the equipment. With reference to Fig. 3, these units are as follows: the antenna 50, the transmitter 63-65, the receiver 51-54, the CPU 72, the timer unit 80, the noise source 60, the message unit 77 and the alarm device 70-71.

With reference to Fig. 3, the operation of the equipment can be simplified as follows. The transmitter 63-65, when commanded by the CPU 72, emits a radio frequency interference signal to disconnect the telephones from the real BTS.

When this has been achieved, the CPU 72 uses the transmitter 63- 65 and the receiver 51-54 to simulate a virtual BTS which "acquires" a cell phone by deception, establishes the presence of an active telephone, and generates an optical and audible alarm. At this point, the CPU 72 sends audio messages, by means of the message unit 77, to the telephone which has not been switched off, requesting the user to switch off the telephone. With reference to Fig. 2, the antenna 50, which has to be used both for the transmitter 63-65 and for the receiver 51-54, is connected to these by the fast electronic switch 66.

The transmitter 63-64-65, which consists of various RF stages, is connected to a set of signal generators represented as units: a voice unit 59, comprising an analogue/digital converter for conventional telephone calls, a noise source unit 60 for generating interference signals, an SMS unit for generating SMS messages, a voice processing unit including an adapter for sending pre-recorded messages stored in the store, and a "signal" input for sending numeric control codes.

The various signals relating to the units indicated above are time division multiplexed at the inputs of the various RF exciters 64 which create the RF signal to be sent to the final amplifier 65. The whole of this sequence is controlled in both frequency and time so that it can also operate on a time division basis.

There are at least two radio receivers, one of the wide band (sweep) type 52 and the other of the narrow band type 51. The number of narrow band receivers (51) can be more than one, preferably four, to permit simultaneous operations on a plurality of frequencies, as in the case of the transmitters.

The receivers 51, 52 are combined with the demodulation circuits 53, 54 and the data acquisition system 55 for data sent to the CPU 72. The acquisition system 55 is combined with the audio amplifier 56 which drives the loudspeaker 57 in such a way that audio messages can be received in combination with the voice channel described above.

The CPU 72 uses the timer unit 80 to control the whole operation of the system. It is connected to the operating controls, such as the start key 66, the stop key 67, the new cycle key 68, the OK lamp 69 and the alarm lamp 70 and acoustic warning device 71. The CPU 72 is also connected to the alphanumeric display 73 and the keyboard 74 which the operator uses to read and enter the data relating to operation.

The CPU 72 is connected to various stores shown schematically as the archive store unit 76, which contains the database, the message store 77, which contains the pre-recorded messages, the program store 78, which contains the system firmware and software, and the geographical data and BTS store 79, which contains data relating to the active operators, BTS, frequencies, etc.

The data in the database can be extracted from the equipment by means of a flash card 75 or other storage medium. These data can be used for statistical analysis by the safety services.

The equipment includes the power supply 82, with the power switch 83 and the ON lamp 81.

Claims

1. Process for detecting the presence of active cell phones in an area protected from their use, comprising the following steps: acquiring the identification signals and codes of the cell base stations or BTS active in the protected area; transmitting radio interference into the protected area in the bands and on the frequencies used internationally for cellular telephony; stopping the emission of the aforesaid radio interference; creating a signal of a virtual BTS, or a local mobile telephone station not connected to the network, having an identification code different from those of the real BTS active in the protected area; receiving radio frequency registration signals from cell phones; determining the presence of these cell phones; and signalling their presence to responsible personnel.

2. Process according to Claim 1, characterized in that it additionally comprises the step of identifying the cell phones active in the protected area.

3. Process according to Claim 2, characterized in that it additionally comprises the step of registering each cell phone which is identified as active in the protected area, and which has received its own network signal among those sent by the cell base station, and has declared itself.

4. Process according to Claim 3, characterized in that it additionally comprises the step of making an automatic call and sending a message to the registered cell phones which are present in the protected area.

5. Process according to Claim 1, characterized in that it additionally comprises the step of checking that all the cell phones present in the protected area are switched off.

6. Process according to Claim 1, characterized in that it additionally comprises the step of continuously checking that no cell phone has been switched on again in the protected area.

7. Equipment for detecting the presence of active cell phones in an area protected from their use, characterized in that it comprises an antenna, a transmitter, a receiver, a CPU, a timer unit, a noise source, a message unit and alarm devices.

8. Equipment according to Claim 7, characterized in that the receiving and transmitting antenna is directional.

9. Equipment according to Claim 7, characterized in that the receiving and transmitting antenna is omnidirectional.