GB2437357A

GB2437357A - Method and appliance for detection of mobile telephones

Info

Publication number: GB2437357A
Application number: GB0606265A
Authority: GB
Inventors: Holger Megow; Peter Maurer
Original assignee: Rohde and Schwarz GmbH and Co KG
Current assignee: Rohde and Schwarz GmbH and Co KG
Priority date: 2005-04-06
Filing date: 2006-03-23
Publication date: 2007-10-24
Anticipated expiration: 2026-03-23
Also published as: GB0606265D0; GB2437357A8; GB2437357B

Abstract

In order to detect satellite mobile telephones (M1, M2, M3) which are active in the vicinity of an observer, the uplink signals (Up) of the satellite mobile telephones (M1, M2, M3) which are active in the vicinity of the observer are received by means of a broadband receiver (E) at the location (T) of the observer, and then the locations of the satellite mobile telephones (M1, M2, M3) which are active in the vicinity of the observer are determined from the location information transmitted via these uplink signals (Up), and are displayed on an electronic map (K).

Description

Method and appliance for detection of satellite mobile telephones The

invention relates to a method for detection of satellite mobile telephones which are active in the vicinity of an observer, and to a simple appliance for carrying out this method.

The direct provision of information in situ is a critical factor for the protection of important objects or spaces. In this context, satellite mobile telephones are evermore frequently playing a role in global use, and these satellite mobile telephones also transmit location information at the same time. One frequently used system is the so-called Thuraya mobile telephone, in which information about the location of the mobile telephone based on the GPS system (global positioning system) is transmitted in the so-called uplink channel (return connection from the mobile telephone to the satellite). This Thuraya mobile radio system uses geo-stationary satellites and supplies, for example, North Africa, Europe, the Middle East and parts of Asia independently of terrestrial mobile radio infra-structures.

It is known for the location of mobile telephones which are active in a monitoring zone to be determined centrally by evaluation of the so-called downlink signals which are transmitted from the satellite and of the so-called C bands which lead to base stations, and for this information to be transmitted, possibly together with the number of the called telephone and even together with the information content of the telephone call, to an observer who is stationed in the observation zone (Thuraya detection system GSAGOO Athos-l and Athos-2/3 from the company Rohda & Schwarz) . These known systems, which are based on a central detection device, have the disadvantage that the information path is too long and too complicated for assessment of the information during tactical use for the observer. Information which relates to the location in the handling area will generally arrive too late from the control centre to be taken into account in the decision-making by the remote observer.

One object of the present invention is thus to specify a method by means of which an observer can detect even satellite mobile telephones which are active immediately in the vicinity of his location, and can find out their location. A further object of the invention is to provide a simple portable appliance for carrying out this method.

This object is achieved by a method according to Claim 1, and by an appliance according to Claim 7.

Advantageous developments can be found in the dependent claims.

In the method according to the invention, an observer who is stationed well away from a control centre can directly, very quickly and in real time locate satellite mobile telephones which are active in his vicinity, and can thus include this information very quickly in his decisions to be made, for example for protection of important objects or areas. Highly effective object protection is thus possible because a local operation commander can himself very quickly determine whether a relevant satellite mobile telephone is active in the area to be protected by him, and in particular where this mobile telephone is currently located. This is also advantageous, for example, in the

military field, since a tactical troop commander

obtains information very quickly about adjacent activities in the case of so-called out-of-area operations, and can then react quickly to it.

The invention will be explained in more detail in the following text using one exemplary embodiment and with reference to a schematic drawing, in which: Figure 1 shows the principle of a satellite mobile telephone system.

Figure 1 shows the principle of the so-called Thuraya satellite mobile telephone system, in which telephone links to other subscribers can be set up worldwide from a mobile telephone M using a so-called L band, via geo-stationary satellites S which are themselves connected via so-called C bands to various base stations B which are distributed throughout the world, possibly with the interposition of terrestrial GSM telephone networks or landline networks. The communication with the mobile telephones M of the subscribers is in this case organized in relatively small so-called spot beams, which operate in a similar manner to the cells in the GSM system and each operate at different carrier frequencies in the L bands.

Data is transmitted continuously in signalling channels via the spot beams that are intended for the respective location, via the so-called downlink channels D of the L bands between the satellite S and the mobile telephone M. Furthermore, the frequencies are transmitted for the uplink channels Up which are associated with the respective mobile telephones M for the link between the mobile telephone and the satellite, as well as the respectively used modulation type and other time structures. When a mobile telephone M is active and on the one hand receives information from the satellite via the respective L band via the downlink channel D, and transmits information back via the uplink channel U from the mobile telephone M to the satellite, location information about the mobile telephone M and based on the GSP system is at the same time transmitted via the uplink channel Up.

This method of operation of the Thuraya mobile telephone is known per Se. In addition, there are also other corresponding satellite mobile telephone systems, which operate on a similar principle and likewise transmit corresponding information about the location in the uplink channels, possibly based on a different position-finding system than the GPS, for example based on the future European Galileo position-finding system.

This capability which is available in conventional satellite mobile telephone systems is used according to the invention to indicate by means of a convenient receiver G, directly at the location of an observer, for example a troop commander in an out-of-area operational zone or a local operation commander for an object-protection operation, where relevant mobile telephones M are active in his immediate vicinity. The receiver E receives the downlink signals D from the satellite S via a small planar antenna F which is roughly aimed at the satellite S, and receives the uplink signals Up which are transmitted to the satellite from the adjacent mobile telephones M in that local area via a small broadband antenna H with an omni-directional characteristic. The reception of the uplink signals is admittedly restricted to mobile telephones in the immediate vicinity of the receiver E because of the low transmitter power of the mobile telephones M, in practice up to a maximum radius of a few kilometres.

However, this is adequate for operations such as these in practice.

First of all, the spot beam which is relevant for the location of the receiver, as well as the spot beams in its vicinity, are determined in a short search run by the receiver E. The information which is associated with the satellite mobile telephones M in the vicinity and is transmitted via the usable uplink channels is then determined via the so-called broadcast channel BCCI-I of the downlink signal D which is transmitted from the satellite S (frequency, modulation type, time structures and the like) . A broadband receiving section provided in the receiver is then configured such that all of the respectively relevant uplink signals of the mobile telephones M which are active in the vicinity are received.

The location information which is transmitted in the so-called random access channel (RACH) and is based on the GPS system is determined from this random access channel RACH of the uplink signals which are thus received over a broad bandwidth, and is evaluated. The result of the process for determining the locations of mobile telephones M which are active in the vicinity is displayed on an electronic map K on the receiver E, as is illustrated in the example by the three mobile telephones Ml, M2 and M3. The location T of the observer is likewise shown, for example in the centre of the small map K which surrounds the immediate vicinity of the operation zone.

In addition to the location of the mobile telephone, the respective time of the activity of the mobile telephone can if required also be determined, and can likewise also be displayed for the observer on the screen. In the case of an outgoing call from an active mobile telephone it would also be possible, if required, to determine and display the called telephone number via the RJCH signal.

If the Thuraya operator is using a plurality of spot beams (sub-bands) at the location of the observer, then these are likewise detected. The receiver is in this case configured such that a plurality of so-called sub-bands can be evaluated at the same time.

The receiver E is preferably in the form of a digital receiver. The carriers which contain the signalling channels are demodulated and decoded in the digital receiving sections. Information obtained from the bursts of the signalling channels is temporarily stored in a data memory.

The receiver E is preferably designed to be very compact and robust, to be precise such that it can be installed as inconspicuously as possible in a vehicle.

The appliance is very simple to operate, and the results are displayed on a flat screen.

The display, with the equipment's own location preferably in the centre T of the map, always remains centred even during movement of the receiver E. The monitoring zone can be matched to the respective requirements. In addition, alarm functions can also be installed in the receiver. By way of example, it is possible to make an input to the receiver E but the aim in particular is to automatically monitor mobile telephone activities in a selected alarm zone A. If, for example, an activity of a mobile telephone is found in this alarm zone A, or a preponderance of activities in this zone, and/or in the case of calls from a mobile telephone from this alarm zone A to a specific telephone number or in specific zones, then an alarm is automatically triggered in the receiver E, thus alarming the observer. In the case of moving active mobile telephones, the direction of movement can also be displayed, if required.

The invention is not restricted to the illustrated and described exemplary embodiment. All the described and illustrated features can be combined with one another as required.

Claims

Patent Claims 1. Method for detection of satellite mobile telephones

which are active in the vicinity of an observer, with the uplink signals (Un) from the satellite mobile telephones (Ml, M2, M3) which are active in the vicinity of the observer being received by means of a broadband receiver (E) at the location (T) of the observer, and with the locations of the satellite mobile telephones (Ml, M2, M3) which are active in the vicinity of the observer being determined from the location information transmitted via these uplink signals (Up), and being displayed on a map (K).

2. Method according to Claim 1, characterized in that the downlink signals (Dc) of the satellite mobile telephones (Ml, M2, M3) which are active in the vicinity of the observer are received by means of a surveillance receiver (E) which is operated in the frequency range of the spot beams which are intended for the location (T) of the observer, and the uplink channel information of the mobile telephones (Ml, M2, M3) is determined from these downlink signals (Dc), and its location information is then evaluated.

3. Method according to Claim 1 or 2, characterized in that, in addition to the location, the time of activation of the satellite mobile telephone (Ml, M2, M3) is determined and displayed at the same time.

4. Method according to Claims 1 to 3, characterized in that, in addition to the location, the telephone number called by a mobile telephone (Ml, M2, M3) is determined and displayed at the same time.

5. Method according to one of the preceding claims, characterized in that a predetermined geographical alarm zone (A) is defined in the vicinity of the observer and an alarm for the observer is automatically triggered in the event of one or more activities of a mobile telephone in the alarm zone or in the event of a call of a mobile telephone from the alarm region to specific telephone numbers.

6. Method according to one of the preceding claims, characterized in that the frequencies of the current uplink signals (Un) for the respective mobile telephones (Ml, M2, M3) are determined from the broadcast channel (BCCH) of the downlink signals (Do) from the satellite (S) to the mobile telephone, and the additional GPS location information transmitted on the random access channel (RACH) is determined from this random access channel (RCH) of these uplink signals (Un), and is displayed on amap (K).

7. Appliance (G) for carrying out a method according to one of the preceding claims, having a portable broadband radio-frequency receiver (E) with an omnidirectional receiving antenna (H) for reception of the uplink signals (Un) from all of the satellite mobile telephones (M) which are active in the vicinity of the installation location, a device for evaluation of the location information (GPS) that is transmitted via these uplink signals (Up), as well as an electronic -10 -screen display device, for displaying a map (K) of the area surrounding the installation location (T) of the appliance (G) and f or overlaying the respectively determined locations of active satellite mobile telephones (Ml, M2, M3) on this map (K).

8. Appliance according to Claim 7, characterized in that the portable broadband radio-frequency receiver (E) can be operated as a narrowband surveillance receiver, and, in a previous surveillance run, can receive the downlink signals (Do) from the satellite mobile telephones (Ml, M2, M3) which are active in the vicinity of the installation location (T) by means of an antenna (F) which can be aligned with the satellite (S) and has a directional characteristic, and these downlink signals (D) can be evaluated in terms of the current spot beam and its surrounding area, and the frequencies of the associated uplink signals (Up)