WO2001069806A1 - Short distance radiocommunication system using electronic portable objects - Google Patents
Short distance radiocommunication system using electronic portable objects Download PDFInfo
- Publication number
- WO2001069806A1 WO2001069806A1 PCT/FR2000/000605 FR0000605W WO0169806A1 WO 2001069806 A1 WO2001069806 A1 WO 2001069806A1 FR 0000605 W FR0000605 W FR 0000605W WO 0169806 A1 WO0169806 A1 WO 0169806A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- channel
- private
- public
- portable object
- portable
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
- H04B1/40—Circuits
- H04B1/403—Circuits using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency
- H04B1/406—Circuits using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency with more than one transmission mode, e.g. analog and digital modes
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/72—Mobile telephones; Cordless telephones, i.e. devices for establishing wireless links to base stations without route selection
- H04M1/724—User interfaces specially adapted for cordless or mobile telephones
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/72—Mobile telephones; Cordless telephones, i.e. devices for establishing wireless links to base stations without route selection
- H04M1/725—Cordless telephones
Definitions
- Short-range radiocommunication system using portable electronic objects.
- the present invention generally relates to short-range radiocommunication systems between persons of the same group, and in particular a system allowing two persons among a group of persons to communicate by means of portable objects transceivers of radio waves. identical.
- Known radiocommunication systems which use portable or portable radio transceivers are currently very heterogeneous and their interoperability is very limited so that they cannot meet the basic communication needs of everyday life. Thus, in fact, they do not allow spontaneous and confidential communication with unknown people whom we come across from a distance, such as a police officer seen opposite a crossroads for ask him for information, call a taxi on the corner of a street, exchange words with someone you come across in a car, take part in a game in a shopping center, ask for help, search for a lost child or collect and / or hear informative messages. For example, a police radiotelephone cannot spontaneously communicate with a mobile terminal of a cellular communication network of the GSM type of an individual.
- the object of the invention is to overcome the aforementioned drawbacks by providing a short distance radiocommunication system between two people from the same set of people without having to use a confidential code to enter into communication.
- Another object of the invention is to provide a short-range radiocommunication system of the above type in which any two people from the set of people can communicate using a public analog channel and establish a communication between them on a private digital channel.
- the subject of the invention is a short-range radiocommunication system allowing a group of people to communicate with each other by means of portable objects emitting-receiving identical electromagnetic waves in which each portable object comprises analog means.
- public communication to allow several people to communicate with each other on the same public frequency channel, each person being able to listen to the conversations of other people and intervene, characterized in that it includes digital means of private communication to allow communications exclusively by couples of people, people of a couple communicating with each other on a private channel outside listening to other people and control means to switch automatically and at will from a public communication mode to a private communication mode and vice versa.
- each portable object comprises means for automatically searching for a free private channel actuated by control means programmed to perform a scan of the private channels and stop said scan on a channel on which another user is waiting for the establishment of private communication, or, in the absence of such another user, stop scanning on the first free private channel.
- control means programmed to perform a scan of the private channels and stop said scan on a channel on which another user is waiting for the establishment of private communication, or, in the absence of such another user, stop scanning on the first free private channel.
- any other user who activates the means of automatic search for a private channel will be in private communication.
- the main advantage of the invention is that it ensures spontaneous connection and perfect confidentiality of communications between two people without them having to use a confidential code. Because each portable object is connected by default on a permanent analog channel, each person can listen to and intervene at any time to question another person by asking him to communicate on a free public channel of his choice or in a strictly confidential manner on a private channel which is automatically assigned by the system.
- the invention also has the advantage that it makes it possible, thanks to the use of digital radioelectric technology with very low transmission power, less than 50 W for example, and with time multiplexing, to obtain an almost phonic quality. -perfect by operating on several bidirectional frequency channels.
- the use of a very low transmission power has the advantage for users of avoiding any administrative constraint on the use of these channels, the regulations following the DECT standard for example imposing constraints only for transmission powers greater than 50 mW.
- FIG. 1 an example of a frequency plan used for ensuring communications between portable objects according to the invention .
- FIG. 2 a diagram of the architecture of the electronics composing a portable object according to the invention.
- FIG. 3 an example of multiplexing of data frames according to the invention.
- Figure 4 the format of a data frame.
- FIG. 5 an algorithm for searching for a free channel implemented by the invention in the form of a flowchart.
- Figures 6a and 6b an embodiment of a housing containing the electronics of a portable object according to the invention.
- the system according to the invention consists of a plurality of identical portable radio-transmitter objects allowing two or more people using the system to communicate by speech in a very user-friendly manner over short distances. around 300 meters for example, people wishing to communicate can be in line of sight or not or in movement with respect to each other. It operates in two main modes, a first mode in which each person can listen to all the other people and transmit to them, having chosen the same public channel, and a second mode according to which only two people can communicate with each other without listening to other people.
- the dialogue between the people takes place on so-called public analog frequency channels in the sense that they can be used without restriction by all the user people whose portable objects are in transmission and in reception having chosen a same public channel.
- the establishment of communications is not governed by any protocol, except that it is provided in a similar way to what is practiced in the “city band” system, a common public channel allowing people to make a first contact and then go, if they wish, on an available private channel.
- a protocol is provided to allow the establishment of a communication between two people.
- This protocol provides for automatic allocation of a free "private” channel to two people who have indicated on a public channel their intention to communicate on a "private” channel.
- a “private” channel is assigned to the first person who requests it.
- n + 1 public frequency channels referenced from C0 to Cn and m + 1 private frequency channels referenced from PO to Pm the channels possibly being able to be images of each other with respect to a central frequency, is shown in the figure 1.
- a guard frequency band is provided.
- the bandwidth of each channel can be only a few KHz.
- the public channels are frequency modulated and the private channels are modulated by displacement of frequency according to the known modulation method according to the English abbreviation FSK for "Frequency shift keying".
- each portable object is composed, as shown in FIG. 2, of a transmit-receive antenna 1, of a transmit module 2, of a receive module 3, the latter two being represented respectively at inside closed dotted lines.
- a signal processing processor 4 connected respectively to the inputs and outputs of the transmission 2 and reception 3 modules is programmed to ensure, in known manner, speech coding, data shaping, channel coding as well as the digital modulation of the signal to be transmitted and the decoding of the data received by the reception module 3.
- a set of keys or keyboard 4a is connected to the processor 4 to ensure control in the public and private operating modes and the selection of the channels of corresponding frequency.
- the microprocessor 4 can optionally be connected to a memory external to the microprocessor 4, not shown, in order to allow the memorization of messages and their diffusion progressively, in real time or in deferred time.
- the transmission channel 2 comprises a radio frequency sub-assembly comprising an FM / FSK modulator 5 of signals modulated in frequency and / or in frequency displacement, an amplifier 6 whose output is coupled to the antenna 1 via a transmission-reception switch 7 and a transmission filter 8.
- the reception channel 3 comprises a radio frequency sub-assembly comprising, a reception filter 9, a low noise amplifier 10, a frequency transposition device 11, and an FM / FSK signal demodulator 12, these elements being coupled to each other in this order in series between the antenna 1 and the signal processing processor 4 via the switch 7.
- the signal demodulator 12 provides an RSSI test signal to the processor 4 representative of the energy of the demodulated signal. This signal is used in the search process for free channel as will be explained later in the following description.
- the modulator 5 includes a frequency synthesizer, not shown, voltage controlled by the signal processing microprocessor. When the circuit is in “emission” mode, the modulator 5 delivers a modulation signal on the input of the amplifier 6 via a switch 13. On reception, the signal supplied by the frequency synthesizer of the modulator 5 is applied to a first input of the frequency transposition device 11, the second input of which receives the reception signal supplied by the low noise amplifier 10.
- a microphone 14 applies the speech signal on the one hand, to a port d input of the processor 4 to ensure its digital transmission according to the FSK modulation and on the other hand, on the analog input of the modulator 5 to ensure its transmission in frequency modulation according to the operating mode chosen.
- a loudspeaker 15 receives on the one hand, the speech signal reconstructed by the processor 4 from the data it receives from the demodulator 12 when the speech is received from a private channel and on the other hand, the speech signal speech demodulated by the demodulator 12 when this signal is received from a public channel.
- this device can be by using the component marketed under the reference TRF 6900 by the law company of the United States of America TEXAS INSTRUMENTS which brings together on the same support all the elements of figure 2 except for the processor 4 which can also be constituted by a commercial component. It should be noted that since the same antenna 1 is used for both transmission and reception and that the transmission and reception modules use the same modulator 5, the circuit prohibits any simultaneous transmission / reception. To allow only two users to communicate in "Full Duplex", this problem is resolved by implementing a time division multiplexing of TDMA type frames, as shown in the diagram in FIG. 3. According to this diagram each frame is divided in two time intervals of equal duration T.
- the first time interval of duration T is allocated to the first user arriving on the free channel and the second is reserved for the second user arriving on this same channel. Reception takes place over the second time interval for the first user and over the first time interval for the second user.
- the synchronization of the frames is carried out by a “top frame” signal which is transmitted by the portable object of the first user which arrives on the free channel, this “top frame” is transmitted to the portable object of the second user so that it can synchronize.
- Each frame includes, as shown in FIG. 4, several information fields referenced Zl to Z.
- the Zl field contains the information necessary for acquiring and calibrating the data
- the Z2 field contains the frame synchronization bits
- the Z3 field contains the data
- the Z4 field constitutes a guard interval with the following frame.
- the allocation of resources for private communications is performed at the request of the user automatically. Of course, if all the resources are already used by other users, none can be reserved. This procedure essentially consists of a scan of the frequency band reserved for private communications with a test on the power received in time and in frequency.
- the link between two users in communication with each other on a private channel is maintained by the emission by each portable object in their respective time intervals of signals corresponding to the zones Z1 and Z2.
- the presence of its signals indicates to other portable objects located within reception range that this channel is already occupied.
- a timer having a time constant of approximately 20 ms which can be achieved by suitable programming of the processor 4, can be provided to release the link after a fixed duration of transmission without speech transmission.
- the selection of the digital channel is ensured automatically, that is to say completely transparent to the user according to a frequency exploration principle. According to this principle, a channel is considered to be usable if the portable object detects the presence of a user at most. If the tested channel is occupied the same search principle is applied to the next channel.
- the presence of a user on a channel is determined by an estimate of power for a duration equal to twice the duration Tf of a frame.
- the RSSI indicator is placed in the logical state "1" when the level of the detected signal is higher than a determined threshold value and is worth “0" otherwise.
- users A and B will each trigger in their respective portable object a scan of the private channels, according to the process represented in FIG. 5 and already described, from for example the first channel private to appropriate the first available channel following it in the order of scanning.
- the portable object of user A begins to transmit a signal comprising the frame acquisition and synchronization data of FIG. 4 without the speech data for a duration T COnnect i o n while listening to the signal in the second time interval T as soon as it has detected a free channel in performing an RSSI signal level test.
- the portable object of user B has also started scanning channels to find, similar to the scanning performed by the portable object of user A, the first available channel.
- the portable object of user B synchronizes and analyzes this signal from the instant that follows from a duration T the synchronization signal it receives. If a signal is present, portable object B considers that the frame is fully occupied. It then does not make the connection and proceeds to the analysis of the next channel. Otherwise, the portable object of user B considers that the channel is free and begins to transmit its signaling signals.
- the probability that there is actually a connection between the portable objects of users A and B is important if the two users started their search almost at the same time.
- the means for searching for a free private channel would consist in the electronics of each portable unit permanently identifying an available private channel, the identifier of the available channel being transmitted by the portable object of the first user. which presses the automatic "public / private" key (31).
- a portable object according to the invention is in the form of a box shown in Figures 6a and 6b containing an electronic card with the features described above, the microphone 14 and the speaker 15.
- the box has on its front face shown in FIG. 6a, a set of keys referenced from 24 to 30 intended for choosing a public channel as well as a public / private key 31 for the passage from a public analog channel to a private channel. digital.
- a channel selection button 24 to 30 switching to a private channel can be carried out as described above.
- the electronics of their portable object could not connect to the private channel used by the two previous interlocutors and would find themselves in private communication with a possible fourth interlocutor.
- Light emitting diodes 24 ⁇ to 30 ⁇ are respectively associated with the buttons or push buttons 24 to 30 for channel selection to indicate to the user the channel in use.
- a light emitting diode 311 is associated with the public / private key or button 30 so allow the user to recognize whether the portable object is in private mode or not.
- An on / off button or push button 32 and an audio headphone jack 33 are arranged on one side of the box shown in FIG. 6b.
- the headphone jack is mainly dedicated to the connection of a microphone and / or headphones, integrated or not, to the headsets of cyclists or motorcyclists connected respectively in parallel or in place of the microphone 14 and the speaker 15. The advantage of this provision is that it allows users to converse while always having their hands free. It also allows headset wearers to listen to broadcasts received by the reception tuner incorporated into the portable object.
- connection cable connecting microphone and headphones it is possible to use as receiving antenna all or part of the connection cable connecting microphone and headphones to the headphone jack, either again the microphone support rod or even if there is the metal strand connecting the two headphones between them.
- the headphone jack can also be used to connect the same portable object to two microphone / earpiece assemblies to allow the driver and his passenger to communicate by simple wired link between them outside the reception of the frequency channels by a simple press on a key provided for this effect not shown of the housing.
- a key 34 can be provided in order to validate the channel selection.
- the invention is assigned to the keys 24 to 30 for access to the public channels, different colors ranging for example from indigo to red following for example the seven traditional colors of the rainbow. sky which allows by appropriate programming of processor 4 to have access to seven public channels by a single key press and on the other hand, by the pressure of two keys simultaneously, for example red and blue, green and yellow, etc. .. to extend the selection to 28 manual channels.
- the adoption of the colors of the rainbow has the advantage that it allows, by its universal character, to integrate the invention into a multitude of portable objects for different uses, the simple view of the colors of the rainbow. - light on a set of keys of any object portable or not, allowing to instantly grasp its function and usage.
- the invention can thus be integrated into a cordless telephone, a cellular or other portable telephone, a traditional telephone handset, a remote control, portable computing objects, organizers, calculators or any other objects used in everyday life.
- certain manual channels corresponding to one or two colors can be dedicated to a well-defined application.
- the "yellow channel” will be the collective channel like channel 27 of the BC
- the "red channel” could be dedicated to traffic
- the "green channel” could be dedicated to tourist information
- Certain channels can also be preferentially dedicated to designated activities, for example: the blue channel for tourism, the red channel for crafts, the indigo channel for religious information, etc.
- Portable objects with a selection of two-color channels offer more possibilities because they have a larger number of channels. They can allow one or more people to come into contact fairly selectively with one or more people according to search criteria or predefined affinities by the choice of channels identified by their associated color code, for example the red and blue channel. will be awarded to collectors, orange and green to enthusiasts of philosophy etc.
- the contacting can be carried out automatically, it suffices to program the microprocessor 4 so that it emits a recurrent signal, with a high duty cycle to save energy, for example every two seconds on the preset channel. If two people who have chosen the channel are nearby, an acoustic and / or light signal is emitted and communication can be established.
- An even more sophisticated version makes it possible to program the microprocessor 4 to store the profile of a person in its memory and allow its search by transmitting the profile for a determined period of time on a digital channel dedicated to this application.
- the comparisons made by the microprocessor of each portable object between the prerecorded profile and the profile received from the transmission channel specially dedicated to this application allow this match to be detected.
- the portable object must verify before each transmission that the dedicated channel is available by a test on the level of the RSSI signal.
- a portable object finds a concordance with the profile it receives, it sends an acknowledgment possibly containing a copy of the received profile, then it switches to a private reference channel and if the latter is not available , on the first available private channel in numerical order following the reference channel by implementing the private channel scanning process described above.
- the receipt of the acknowledgment of receipt by the portable object which first emitted the profile of the wanted person also causes the switching of this last on the private channel of reference or if the latter is not available on the first channel available which follows it in the scanning order of the private channels, which allows the two people who have just met to communicate on the private channel which is thus automatically assigned to them.
- a sound or light signal is emitted by the loudspeaker 15 or an indicator provided for this purpose in order to warn the people that they can communicate.
- the emission a profile can be performed randomly during determined transmission times within contiguous time windows of equal duration, the ratio between the transmission time and that of the window being relatively small, for example less than 1/100 so that the probability of collision between two emissions is low.
- the programming of the microprocessor 4 can be carried out from a download by means of a scrolling menu appearing on a display screen and controlled from a keyboard or via a personal computer which can be coupled. at will by any appropriate means, optical, wired or radio, on its input / output ports.
- this provision will encourage the meeting of people who have been in the same school, employed in the same company or even people who have already been in contact and whose names have been previously programmed.
- This provision can also make it possible to put in contact people carrying out a matching offer and research respectively.
- the offer and research can relate to both services and products.
- a person offering a carpool place can communicate with a person looking for such a place; a person wishing to sell his vehicle may find himself in communication with a buyer.
- an "emergency" button, 33 to the portable object which can remain activated only after a pressure, for example of several seconds.
- all of the channels are activated and transmits an audible signal of particular tone recognizable by all of the users, who can then enter into communication with the person in distress by pressing a specific colored button, 24,. ... 30, for this use, or on the distress button, 33.
- This can be useful in cases of distress, in the mountains for example, to allow the rapid location of a person in danger, or, in the case of an elderly person who is immobilized following a fall.
- the device can make it possible to "make objects speak" such as works of art, monuments, or any other object whose information is to be disseminated locally by integrating a device according to the invention in objects, thus allowing any user of a portable device located nearby to listen to a voice message sent by the integrated device.
- the public channel on which the message is sent must be clearly visible, preferably by means of a color code in the image of the traditional colors of the rainbow so as to allow a user to a portable device seeing a color code at the foot of a church for example, to be able to listen to information concerning the church.
- the voice message emitted can either be continuously repeated or triggered by detection of the user's voice on the ad hoc channel. For example, the user, once connected to the channel corresponding to the correct color code, just has to say any word for the transmission of the message to start.
- a more advanced version uses voice recognition to broadcast a message based on requests.
- each portable object can be provided with a switch with two or three positions not shown, allowing to modify the power of the emission, for example 2m for a range of the order of 100 meters. or 10 mW for a range of the order of three hundred meters.
- a variant will consist in dividing the private channels into groups associated respectively with groups of public channels, the search for the channel then being carried out from the first channel. of the private channel group associated with the public channel group in which the public channel used by the two people is located and not by the first private channel in numerical order.
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Human Computer Interaction (AREA)
- Mobile Radio Communication Systems (AREA)
- Transceivers (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2001567148A JP2003528496A (en) | 2000-03-14 | 2000-03-14 | Short-range wireless communication system using electronic portable device |
EP00910930A EP1266457A1 (en) | 2000-03-14 | 2000-03-14 | Short distance radiocommunication system using electronic portable objects |
PCT/FR2000/000605 WO2001069806A1 (en) | 2000-03-14 | 2000-03-14 | Short distance radiocommunication system using electronic portable objects |
AU32967/00A AU3296700A (en) | 2000-03-14 | 2000-03-14 | Short distance radiocommunication system using electronic portable objects |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/FR2000/000605 WO2001069806A1 (en) | 2000-03-14 | 2000-03-14 | Short distance radiocommunication system using electronic portable objects |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2001069806A1 true WO2001069806A1 (en) | 2001-09-20 |
Family
ID=8846028
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/FR2000/000605 WO2001069806A1 (en) | 2000-03-14 | 2000-03-14 | Short distance radiocommunication system using electronic portable objects |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1266457A1 (en) |
JP (1) | JP2003528496A (en) |
AU (1) | AU3296700A (en) |
WO (1) | WO2001069806A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2839235A1 (en) * | 2002-04-26 | 2003-10-31 | Novatec | METHOD AND DEVICE FOR SWITCHING A DIGITAL RADIOTELEPHONE FROM A DIGITAL OPERATING MODE TO AN ANALOGUE MODE |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11968230B2 (en) | 2021-03-18 | 2024-04-23 | International Business Machines Corporation | Managing communication privacy in encroaching environments |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
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US4066964A (en) * | 1967-01-06 | 1978-01-03 | Rockwell International Corporation | Communication system |
EP0617528A2 (en) * | 1993-03-25 | 1994-09-28 | Kabushiki Kaisha Toshiba | Radio telecommunication apparatus with privacy or non-privacy communication mode |
GB2287612A (en) * | 1994-02-25 | 1995-09-20 | Motorola Ltd | Communications system |
WO1995026613A2 (en) * | 1994-03-22 | 1995-10-05 | Nokia Telecommunications Oy | Assigning of transmission turns to radio units |
US5553117A (en) * | 1994-01-03 | 1996-09-03 | Danny R. Peterson | Vehicular communications system |
WO1997007604A1 (en) * | 1995-08-14 | 1997-02-27 | Nokia Telecommunications Oy | Synchronizing a telecommunications connection in a mobile communications system |
WO2000004659A2 (en) * | 1998-07-15 | 2000-01-27 | Telefonaktiebolaget Lm Ericsson | Radio communications unit |
EP1026908A2 (en) * | 1999-02-01 | 2000-08-09 | Lucent Technologies Inc. | Dual mode mobile phone operating as a two-way radio |
-
2000
- 2000-03-14 AU AU32967/00A patent/AU3296700A/en not_active Abandoned
- 2000-03-14 WO PCT/FR2000/000605 patent/WO2001069806A1/en not_active Application Discontinuation
- 2000-03-14 EP EP00910930A patent/EP1266457A1/en not_active Withdrawn
- 2000-03-14 JP JP2001567148A patent/JP2003528496A/en active Pending
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4066964A (en) * | 1967-01-06 | 1978-01-03 | Rockwell International Corporation | Communication system |
EP0617528A2 (en) * | 1993-03-25 | 1994-09-28 | Kabushiki Kaisha Toshiba | Radio telecommunication apparatus with privacy or non-privacy communication mode |
US5553117A (en) * | 1994-01-03 | 1996-09-03 | Danny R. Peterson | Vehicular communications system |
GB2287612A (en) * | 1994-02-25 | 1995-09-20 | Motorola Ltd | Communications system |
WO1995026613A2 (en) * | 1994-03-22 | 1995-10-05 | Nokia Telecommunications Oy | Assigning of transmission turns to radio units |
WO1997007604A1 (en) * | 1995-08-14 | 1997-02-27 | Nokia Telecommunications Oy | Synchronizing a telecommunications connection in a mobile communications system |
WO2000004659A2 (en) * | 1998-07-15 | 2000-01-27 | Telefonaktiebolaget Lm Ericsson | Radio communications unit |
EP1026908A2 (en) * | 1999-02-01 | 2000-08-09 | Lucent Technologies Inc. | Dual mode mobile phone operating as a two-way radio |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2839235A1 (en) * | 2002-04-26 | 2003-10-31 | Novatec | METHOD AND DEVICE FOR SWITCHING A DIGITAL RADIOTELEPHONE FROM A DIGITAL OPERATING MODE TO AN ANALOGUE MODE |
WO2003092246A2 (en) * | 2002-04-26 | 2003-11-06 | Novatec S.A. | Method and device for transforming an analogue radiotelephone from analogue operating mode into digital mode and vice versa |
WO2003092246A3 (en) * | 2002-04-26 | 2004-07-15 | Novatec Sa | Method and device for transforming an analogue radiotelephone from analogue operating mode into digital mode and vice versa |
Also Published As
Publication number | Publication date |
---|---|
JP2003528496A (en) | 2003-09-24 |
AU3296700A (en) | 2001-09-24 |
EP1266457A1 (en) | 2002-12-18 |
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