Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
  • H04M11/08—Telephonic communication systems specially adapted for combination with other electrical systems specially adapted for optional reception of entertainment or informative matter
  • H04M11/085—Telephonic communication systems specially adapted for combination with other electrical systems specially adapted for optional reception of entertainment or informative matter using a television receiver, e.g. viewdata system
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/14—Two-way operation using the same type of signal, i.e. duplex

Definitions

• the subject of the present invention is a process for automatic communication in duplex or i-duplex (called alternating duplex) of a single-mode or multimode equipment and of a single-mode or multimode equipment for the modulations such as for example V23, V27 ter and V29 through the general switched telephone network and on peer-to-peer telephone circuits, such as two-wire leased circuits.
• alternating duplex duplex or i-duplex
• the "Minitel” uses, in France, a transmission speed of 1200 bits per second to receive information from the services consulted and a speed of 75 bits per second to transmit user input.
• This transmission mode, in full duplex (“full duplex") is based on V23 modulation, namely a speed of 1200/75 bits / s between the "Minitel” and Videotex Access Point (“PAVI") equipment.
• the link between the Minitel and the PAVI relies on the Switched Telephone Network (R.T.C.).
• the link between "PAVI” and “Teletel” servers is based on the "TRANSPAC" network with transmission speeds of 19.2Kbps or 48Kbps.
• This new “Teletel” access service called “Fast Speed Teletel” (or TVR) access service thus authorizes a useful rate of communication multiplied by four in V27ter and by eight in V29 compared to the useful speed of V23 accesses. . It thus allows rapid transfer of pages requiring a large volume of information; it is the preferred channel for the functioning of the future photographic "Minitel” and for applications such as file transfers, fax, audiovideotex, etc.
• the consumer terminal (or "MINITEL”) is not currently able to connect, indifferently and without specific user intervention, to the "Telecommunicationtel” V23 access points, to the "Telecommunicationtel” V27ter access points and to the next V27ter / V29 access with connection times similar to the current V23.
• PSTN switched telephone network
• the request to establish the connection is made up of the actions of taking the telephone line (or taking the line) and dialing. This request can be initiated by: - the user (manual request)
• Minitel peripheral such as the memory card reader or LECAM. Detection of this request for connection establishment by the remote equipment (ringing call on "PSTN" or positioning of an indicator on line leased) authorizes it to establish the connection.
• the communication or physical connection is made by the exchange and recognition of signals between the modems of the two devices.
• the communication validation enables the two devices to transmit data and thus establish the logical connection such as the establishment of frame and packet levels of the communication protocol used for example in V27ter and in V29.
• the communication request (or "Communication order” or “connection order”) can be initiated: - by the user by pressing a key such as the "Connection-End” key of the Minitel,
• Minitel via the telephone and telematics directory.
• a Minitel device via a command sequence.
• V27ter or V29 V23 / V27ter / V29
• Connection-End keys, one for each of the modes. This manual solution is not ergonomic for a general public user.
• Another solution would be to rely on a prior and systematic communication in V23 then, on reception of a particular sequence, switch to V27ter or V29 transmission. This solution would be penalizing in connection time, and would not allow communication with existing equipment only V27ter, which does not have V23 mode.
• the present invention relates to a method which does not have the aforementioned drawbacks and the basic idea of which is to allow reciprocal adaptation of the modes of transmission of the calling equipment (in general "MINITEL” or a “PAVI” or a terminal “PC” or “MACINTOSH” brand) and the equipment called ("PAVI", "MINITEL”, "PC” or “MACINTOSH” terminal).
• the terminal must one and / or the other be capable of managing preferably more than one modulation, and preferably , as regards the calling equipment to manage either the two V23 / V27ter or V27ter / V29 modulations or the three V23 / V27ter / V29 modulations in order to allow: the physical connection in a transmission mode common to the two equipments according to the modulation preferably the fastest as presented in the summary table of the types of physical connection (case of initial connection), and / or the physical restoration of communication in at least one mode, for example at least one of the three modes V23, V27ter and V29 (case of the voice-data or audiovideotex application).
• the invention relates to a method of automatic duplex communication between two pieces of equipment A and B through a telephone line, characterized in that the two pieces of equipment are arranged to communicate, after establishment of the telephone link. , according to at least one half-duplex transmission mode and in that the method implements at least one exchange of tuning signal trains, (for example long learning sequence) for communication in a half-duplex transmission mode, each train of tuning signals starting with an unmodulated carrier signal (in particular an echo cancellation segment) of given nominal duration having a carrier frequency characteristic of said requested transmission mode, and also comprising at least one conditioning segment (for example segments 3, 4 and 5 of the long learning sequences V27ter or V29) and in that each of the two pieces of equipment is arranged so as to detect the frequency of said unmodulated carrier signal characteristic of said transmission mode used, and method in which the two devices A and B are capable of exchanging two trains of matching signals according to the following steps: a) transmission by one of the devices called
• first equipment for tuning of a first train of tuning signals according to a given mode of duplex transmission to the half-duplex.
• second equipment for tuning analysis by the other equipment, called “second equipment for tuning” of the frequency of the unmodulated carrier signal of said first train of tuning signals.
• Said validation of the communication by the first equipment may include the transmission by the latter of a train of synchronization signals (for example short learning sequence called "short train” in V27ter or V29 mode) not starting by an unmodulated carrier signal.
• a train of synchronization signals for example short learning sequence called "short train” in V27ter or V29 mode
• the technique based on the exchange of tuning signal train according to the method according to the invention can be used in a more general context such as that of a method of maintaining duplex communication at 1. alternating based on mechanisms for physical resumption of communication and / or speed fallback with change in the type of modulation such as V29 to
• the method according to the invention can allow
• the invention relates to a method in which the second device is device B and is arranged to communicate according to said first mode of transmission (for example V27ter) as well as a third mode of transmission (for example V29) in 1 • half duplex faster than the first transmission mode and, in that the first equipment, which is equipment A, is arranged to communicate only according to said third transmission mode.
• said first mode of transmission for example V27ter
• a third mode of transmission for example V29
• each ⁇ equipment A and B is operable either as original equipment or as a second equipment.
• the first equipment is either the calling equipment, that is to say the line seizure, (the most favorable case) or the equipment called (for example connection called “delayed").
• the unmodulated carrier signal is an echo cancellation segment used as a discriminator from the duplex transmission mode to the half-duplex.
• a validation according to the transmission mode adapted to the two pieces of equipment is advantageously obtained by the fact that said validation of the connection by the piece of equipment validating the reception of the second train of matching signals, comprises the emission of a train synchronization signals not starting with an unmodulated carrier signal.
• a connection request immediately following a line seizure order i.e. a request to set up the telephone link (DLT)
• DLT telephone link
• the method is characterized in that that a connection request is immediately consecutive to a request for connection establishment by the equipment A and in that the equipment A and B are arranged to perform the following preliminary steps:
• the method can be characterized in that the equipment A and B are arranged to carry out the communication using a duplex transmission mode not in the half-mast if, after step 4-0), the equipment A measures a silence duration below a given duration threshold.
• This method according to the invention thus also allows so-called “top-down” compatibility towards a mode of operation in duplex mode not in the half-cycle (or
• a first variant (case n ° 4 and n ° 8) of the method is for this purpose characterized in that an order to put in communication is not immediately consecutive to an establishment of the connection by the equipment B, which is consecutive to a request for establishment of the connection by the equipment A, in that the communication order occurs during a transmission sequence by the equipment B of trains of tuning signals according to the mode given of transmission, and in that said transmission sequence constitutes said step a), the first equipment therefore being equipment B and the second equipment, equipment A.
• a second variant (case n ° 4bis and 9) of this process is for this purpose characterized in that an order to put in communication is not immediately consecutive to an establishment of the connection by the equipment B, which is consecutive to a request for establishment of the link by the equipment A, and in that the communication order occurs during a sequence of transmission by the equipment B of trains of tuning signals according to said second slower mode of transmission than said first mode of transmission and in that it involves the implementation of steps a) to i) according to the first mode of transmission, during which the first equipment is equipment B and the second equipment is equipment A.
• a preferred variant (case 5bis) of the method is for this purpose characterized in that an order to put into communication is not immediately following an establishment of the connection by the equipment B, which is consecutive to a request for establishment of the link by the equipment A, in that the connection order occurs during a transmission sequence by the equipment B of tuning signal trains according to said first mode of transmission more faster than said second mode of transmission, and in that the equipment A is arranged to communicate in said second mode but not in the first mode, and in that the equipment B is arranged to communicate both in the first and the second mode, and in that the equipment A is arranged to analyze the carrier frequency according to the first mode, and in that it comprises the following steps: - analysis by equipment A of the carrier frequency of a said train of tuning signals,
• the invention also relates to a method for establishing communication in a fallback mode, for example the V27ter, slower than the V29 mode, but more robust than the latter.
• the method is characterized in that, for example in the case where the order to connect is immediately consecutive ( case n ° 6) to an establishment of the connection by the equipment B which is consecutive to a request for establishment of the connection the equipment A, or not immediately consecutive (case n ° 4bis) the equipment A and B are arranged to perform before step a) the following preliminary steps:
• equipment is equipment A.
• the invention also relates to a method enabling voice-data switching ensuring a protocol for returning to full-time duplex mode after a given delay time.
• said communication is consecutive to a transition to voice mode (cases 16 to 18) and in that it comprises the following preliminary steps:
• the method can be characterized in that the two devices A and B are arranged so as to detect the frequency of said carrier signal unmodulated characteristic of each transmission mode as well as in voice mode and in that the equipment A and B are arranged to perform after steps 13-1 and 13-2, the following steps:
• the invention also relates to equipment for implementing the method according to one of the preceding claims and comprising a unit for processing, a modem, a line interface and a control bus between the processing unit and the modem, the control unit having a sequencer for sequentially programming said modem, characterized in that said sequencer is arranged for:
• the equipment can also be characterized in that the sequencer is arranged so that, when the modem is in reception mode, said detection of at least one unmodulated carrier frequency is carried out permanently.
• the equipment is characterized in that said sequencer is arranged to validate said transmission by the modem of a train of tuning signals according to 15-1 when one of the following conditions is met:
• the present invention also relates to a method which makes it possible to maintain duplex communication in the half-school in the presence of disturbances of the telephone line.
• This new “Teletel” access service called “Fast Speed Teletel” access service (TVR) thus authorizes a useful rate of communication multiplied by four (in the case of V27ter) and by eight (in the case of V29) compared to useful throughput of V23 accesses.
• PSTN switched telephone network
• the network structure is relatively complex and implements a wide variety of equipment. Disturbances, in particular in the form of impulsive noise, come for example from crosstalk, pulses from charging systems or from episodic desynchronizations between the switches.
• certain digital high-speed links (2 Mbits / s) between switches can, in the event of link overload, increase the number of simultaneous communications by a ratio of 2 (MIC.DA process) by compressing the transmission. This method, well suited to telephony, disrupts the continuity of communications in V29 modulation.
• the disturbance caused by an impulsive noise introduces effects varying according to the principle of data modulation used. According to the V23 standard, we generally obtain 1 false bit online; this type of error is recovered by the implementation of a known error correction procedure.
• the purpose of 1 • invention allows to implement in the case of duplex communicatons in the half-board, for example V27ter and V29, a protocol for maintaining and resuming communication at the physical level, without disconnecting the so-called “higher levels” "(packets and frame).
• the basic idea of the invention consists in implementing this protocol in the form of a recovery-adaptation process.
• V27ter modulation of the DPSK (Differential Phase Shift Keing) type is more "robust” than the V29 modulation of the QAM (Quadrature Amplitude Modulation) type with respect to disturbances due to the telephone network.
• the Teletel network is structured so that the Minitel and Pavi equipment are linked by short distance telephone links. Measurement campaigns carried out by the Applicant have shown that the majority of the so-called short local links of the switched telephone network have stationary transmission characteristics (such as attenuation, group time distortion) and are only subject to occasional disturbances, mainly impulsive noise type. In fact, although the V29 modulation which is optimal for most communications is preferred, it appears essential to set up communication maintenance mechanisms when this modulation is weakened to the point of breaking the communication.
• the mechanism ensuring the freezing of the coefficients during the exchange of tuning signal trains allows better control of the transmission efficiency by the reliable and faster detection of erroneous synchronization signal trains.
• a second mechanism called recovery is implemented to cause a new exchange of signal trains. of agreement.
• This method can be used in duplex transmission modes such as V27ter, V29, V17. It relies on the presence of segments 1 & 2 of the tuning signal trains, thus enabling their identification during communication.
• the originality of this process allows reliable resynchronizations at the physical level without altering the upper logical levels of the communication protocol, which allows transmission to continue without interruption at the application level, although the physical medium is altered.
• speed fallback (such as V29 to V27ter).
• the modem speed fallback modes such as those provided for example by the CCITT standards V27 ter, V29 and V17 consist in effecting a reduction in the speed of modulation by reducing the number of states without changing the type of modulation.
• This fallback mode does not provide a satisfactory result in particular in the case where the communication medium is affected by impulsive noise and it is used in practice only for certain lower speed equipment.
• the objective of the recovery-adaptation process is to overcome these drawbacks of the state of the art, by allowing a decline in a slower, but more robust modulation compared to the disturbances originating in particular from the evolving and / or unstable characteristics of the telephone line, or which originate from a compression of the transmission speed (see the MIC.DA process mentioned above).
• the invention thus relates to a resumption-adaptation method for at least one half-duplex modulation between two pieces of equipment A and B through a telephone line, characterized in that it implements, during exchanges of train of synchronization signals possibly followed by application information, an exchange of train of signals of agreement on the initiative of one of the pieces of equipment called first piece of equipment for resumption-adaptation, preferably following the detection by this one at least two successive trains of erroneous synchronization signals, each train of tuning signals starting with an unmodulated carrier signal of given nominal duration having a carrier frequency characteristic of the transmission mode, the other equipment being called second equipment for resumption-adaptation, in that each of the two equipment A and B is arranged so as to detect the frequency of said signal d e carrier not modulated and in that the first and second equipment are arranged to effect the exchange of two trains of matching signals according to the following steps: a) initialization by the first equipment of a resumption-adaptation, preferably following detection by the first equipment of
• Said initialization can be carried out on the initiative of the higher levels of the protocol (frame- packet) to attempt synchronization in V29 mode of a transmission folded back into V27ter (on detection of a low or zero number of defective CRC codes). This case can occur in particular in the event of the end of overloading of a MIC-DA transmission. Said initialization can also take place on the initiative of the application itself. Initialization allows the modem to go into long train transmission mode.
• the method according to the invention is characterized in that the first and second equipment are arranged so as to manage at least a second half-duplex transmission mode (for example V27ter) slower than the initial transmission mode (for example V29) but more robust against online disturbances and in that the first and second equipment are arranged to perform after steps a) to g) the following steps: k) in the event of the first equipment not recognizing the train of tuning signals transmitted by the second equipment, and possibly after a period of given time delay, transmission by the first equipment of a train of tuning signals in the second transmission mode.
• a second half-duplex transmission mode for example V27ter
• V29 initial transmission mode
• the first and second equipment are arranged to perform after steps a) to g) the following steps: k) in the event of the first equipment not recognizing the train of tuning signals transmitted by the second equipment, and possibly after a period of given time delay, transmission by the first equipment of a train of tuning signals in the second transmission mode.
• step 1) analysis by the second equipment of the frequency of the unmodulated carrier signal of said train of tuning signals emitted by the first equipment m) in the event of recognition of said frequency during step 1), which then characterizes a request for resumption of adaptation in the second transmission mode, positioning of the second equipment on reception of a train of tuning signals according to the second transmission mode.
• adaptation of the second equipment to the second transmission mode preferably by freezing the coefficients of the reception filter adapted to the new characteristics of the transmission medium and adapted to the second transmission mode.
• the method according to the invention can also make it possible to manage the case where the recovery-adaptation protocol does not meet with success during a first attempt, that is to say from an initial modulation of high speed (V29 cf. case n ° ll, or V27ter cf. case n ° 10) (but without possibility of fallback modulation), either from an initial fallback modulation after a previous successful recovery-adaptation procedure (case 10).
• the method is characterized in that the first and second equipment are arranged to carry out after steps a) to g) the following steps: t) in the event of non-recognition of the train of matching signals by the first equipment, possibly at the end of a given delay time, renewal by the first equipment of the transmission of the train of tuning signals according to said transmission mode. u) steps c) to j).
• stage n ° 12bis and 13 it can also be characterized in that it comprises the following stage (case n ° 12bis and 13): v) in the event of non-recognition by the first equipment, during stage g of said sequence u) of the train tuning signals emitted by the second device, and possibly after a given time delay, last attempt made by the first device according to t) and u) before the link between the two devices is broken.
• the method is characterized in that the equipment is arranged, after reception of the tuning signal trains, to freeze the coefficients of their reception filter after convergence of the coefficients of said reception filter and in that the equipment is arranged to inhibit any possible modification of the coefficients of the reception filter during the exchange of the synchronization signal trains during communication so as to preserve, independently of the characteristics of the physical transmission medium, the values of the coefficients of the filter reception values calculated upon reception of the last train of tuning signals.
• This can be implemented during a recovery-adaptation procedure in the same transmission mode or in a fallback modulation.
• the carrier signal is characterized in that the unmodulated carrier signal is an echo protection segment used on the satellite links.
• the unmodulated carrier signal is an echo protection segment used on the satellite links.
• said validation of the communication by the equipment includes the emission of a train of synchronization signals not starting with an unmodulated carrier signal so as not to degrade the useful bit rate during communication . This makes it possible to validate the reception of the second train of tuning signals exchanged according to the transmission mode adapted to the two devices.
• the invention also relates to equipment for implementing the above method and comprising a processing unit, a modem, a line interface and a control bus between the processing unit and the modem, the control unit having a sequencer for sequentially programming said modem, characterized in that said sequencer is arranged for:
• 10-2) program the transmission by the modem of a tuning signal train preceded by an unmodulated carrier signal, preferably according to the same modulation as said erroneous signaling signal train, said tuning signal train in agreement constituting a request for resumption-adaptation.
• 10-3) program the detection by the modem of at least one unmodulated carrier frequency located at the start of a received tuning train, and to position the modem in a duplex mode of transmission corresponding to the corresponding half-cycle at said carrier frequency, so as to allow the modem to detect a resumption-adaptation request to receive the other signals from said received tuning train and to freeze the coefficients of the reception filter after reception of the tuning train.
• the sequencer can be arranged so that, when the modem is in reception mode, said detection of at least one unmodulated carrier frequency is carried out permanently and in the event of such detection carried out while the equipment is in a configuration duplex communication course, as well as a train reception
• It can also be arranged to validate said transmission of a tuning signal train according to 10-2 when the modem has detected at least one synchronization train in a main transmission mode, to carry out at least one setting attempt. tuning according to the main transmission mode and in the event of failure to validate a so-called transmission of a tuning signal train according to 10-2 in a fallback transmission mode according to a more robust half-duplex modulation than modulation of the main transmission mode.
• it can be arranged to validate said transmission of a train of tuning signals in a main transmission mode, to carry out at least one attempt to harmonize according to the main transmission mode, to carry out at minus an attempt to tune according to the main transmission mode and in the event of failure to validate said transmission of a train of tune signals according to step 10-2) in a fallback transmission mode according to a more robust half-duplex modulation than the modulation of the initial transmission mode.
• the sequencer is preferably arranged to manage the higher logic levels of the communication protocol with a disconnection timeout of duration greater than that of the execution of the resumption-adaptation process.
• the standard provides for a level 2 repeat delay (frame) which is reset when a frame is transmitted.
• ⁇ time delay increments a re-transmission counter in the event of an erroneous train detection or absence of detection.
• the maximum value of this storyteller can be modified, its nominal value being 10. With this value and in the most unfavorable case of resumption-adaptation, the maximum limit is never reached, and the transfer is only slowed down momentarily without interaction with level 3 (packet).
• FIGS. 2 to 20 cases 1 to 9 and 14, corresponding to different connection configurations, cases 10 to 13 corresponding to resumption-adaptation configurations and cases 15 to 20, to given voice switching configurations, the calling equipment being in the left column, and the calling equipment in the right column,
• FIGS. 22a to 22d a transmission sequence respectively of a long train V29, of a long train V27ter, of a short train V29, and of a short train V27ter, SI designating a unitary interval according to the standard
• FIGS. 23a to 23d a sequence for receiving respectively a long train V29, a long train V27ter, a short train V29, and a short train V27ter,
• FIG. 26a an automatic communication device of an equipment (calling mode and called mode) it being understood that a particular equipment can implement the two modes, or even only one of the modes, and Figure 26b the beginning of the connection automaton (socket minus two modes.
• the method according to the invention while having the same behavior as in V23 connection "MINITEL" "full duplex” authorizes and optimizes the connection of "Minitel” (upward compatibility) on T.V.R. (V27ter and / or V29 Fast Speed Terminal) and on V23 accesses, without any specific action by the user (Connection-End key), by automatic distinction of the transmission speed.
• the distinction between two modulations or three modulations is based on one or the other of two discriminants, one to differentiate fast speed from normal speed (V23), the other to separate the two modulations retained in fast speed (V27ter / V29).
• the echo cancellers are neutralized by the 2100 Hz response tone (see CCITT recommendation V25).
• the presence of this tone is justified for transmissions of the full duplex ("full-duplex”) or partial (“se i-full-duplex”) type, as for example in V23.
• the echo protection devices are reactivated by a signal stop (silence) equal to or greater than 100 ms .
• the neutralization of these devices is maintained by the reappearance of the signal before the expiration of a delay of 75 ms + or - 20 ms.
• FIGS. 27a to 27g the connection automaton in calling mode and implementing elementary sequences of FIGS. 22a to 25f, - FIGS. 28a to 28e, the connection automaton in called mode of FIG. 26 and implementing elementary sequences of FIGS. 23 to 25, FIGS. 29a to 29c, an automatic voice switching automaton and implementing elementary sequences of FIGS. 22a to 25f, FIGS. 30a to 30d, a communication and resumption-adaptation automaton in V29 modulation (30a and 30b) and V27ter modulation (30c and 30d) and using the elementary sequences of FIGS. 22a to 25f.
• videotex 14, audiotex (voice) 15, videotex and photographic 16 servers connected to the TRANSPAC network are accessible to users 1 to 6 by the telephone network switched through videotex access points (PAVI), V23 (asynchronous 7 bits plus parity bit for example numbering 3614 or 3615 in France) or in V27ter and / or V29 mode (synchronous 8 bits).
• a terminal (V23), for example microcomputer V23 1 or Minitel V23, 2 can only access a PAVI V23.
• a multimode terminal for example Minitel 3 (V23 / V27ter) or 4 (V23 / V27ter / V29), microcomputer 5 (V23 / V27ter / V29) or Microcomputer Access Service 6 V23 / V27ter / V29, can have access to all PAVI.
• a single-mode terminal V27ter or V29, for example a microcomputer 5, can have access to a corresponding PAVI V27ter or V29.
• Terminal 6 allows in particular a file transfer (STUTEL) and secure application (LECAM: 1200 or 4800/9600 bps Memory Card Reader).
• STUTEL file transfer
• LECAM 1200 or 4800/9600 bps Memory Card Reader
• the invention therefore provides a method for automating connection procedures for single-mode or multimode operation depending on the - silence of 75 ms + or - 20 ms for the mode
• This first discriminant only needs to be implemented for equipment capable of accessing networks according to the different types of duplex link. It should be noted in particular that the equipment according to the invention may not be provided for example to operate only in V27ter and / or in V29.
• the first discriminant can be implemented alone for equipment intended to operate in V23 mode and in V27ter mode, or else in V23 mode and in V29 mode, in the case of normal connection known as anticipated.
• the second discriminant which makes it possible to identify two modes of duplex operation in alternation at two different bit rates for example, between the V27ter and the V29, is, according to the invention, the frequency of the signal of the carrier which is 1800 Hz in V27ter and 1700 Hz in V29.
• a signal at the frequency of the unmodulated carrier is sent at the start of the long learning sequence (long train).
• the equipment receiving this signal detects its frequency and can automatically position its modem in the required mode (tuning) or else find that it cannot operate in the modulation with this carrier frequency.
• a long learning sequence therefore fulfills, according to the invention, the function of matching the two devices on the same modulation.
• segments used for the echo cancellation in satellite links are used as discriminant.
• these segments implement a transmission of the unmodulated carrier for a period of 185 to 200 ms followed by a silence of 20 ms at the start of the long learning sequence (long train); this emission corresponds to segments 1 and 2 described in recommendation V27ter and V29 of the CCITT.
• the presence of these segments before learning sequences corresponds to the "speaking" mechanism on the satellite links; indeed, the echo suppressing devices use threshold detection systems which have a non-negligible response time; it is to guard against this response time that the "speaking" mechanism, based on segments 1 and 2, is used in satellite connection.
• the invention takes advantage of the recognition that the duration of segment 1 (185 to 200 ms) is compatible with the programming time of a modem, and in particular of its reception filter, which allows the envisaged application. .
• the speech mechanism available by the presence of segments 1 and 2 is thus, according to the invention, deviated from its primary function to be used as a discriminator V27ter / V29.
• the V27ter and V29 modulations use different carriers: the carrier frequency in V27ter is 1800 Hz and that in V29 is 1700 Hz. Due to its possibilities of reliable detection of tones by digital filtering, the DCE component (or modem) allows, during the initial connection, as will be described later, to distinguish these two frequencies when the long learning sequences are transmitted with segments 1 and 2. This therefore makes it possible to program the modem in the selected mode (setting agree), to correctly receive the corresponding long learning sequence. According to a preferred mode, a long learning sequence can only be validly received if its carrier frequency
• segment 1 has been recognized by the receiving modem. If the carrier frequency is not recognized, the learning sequence is detected as non-compliant.
• the modem of an equipment is programmed to recognize the carrier frequency of the modulations that it can receive and transmit (for example equipment which cannot operate in V29 does not necessarily recognize the frequency 1700 Hz, which allows effective discrimination of the various cases as will be described later ).
• segments 1 and 2 are, however, not used in the short learning sequences (synchronization) transmitted on each modem reversal so as not to slow down the useful speed of the communication.
• the use of the same process with emission of long learning sequences makes it possible to reliably manage recovery communication physics in the appropriate V27ter or V29 modulation with test in the fastest modulation.
• the application software must in this case manage a context for the mode of reestablishing telematic communication V23 or V27ter / V29 in the absence the discriminant normal speed / fast speed (duration of silence).
• the communication software in fast speed mode, unlike the recovery and fallback processes, the communication software must completely restore the different upper levels (connection frame and call packet).
• the "reconnection" is of the simplified type by detection of 600 ms at least 1300 Hz without searching for the 2100 Hz frequency; the error correction procedure is activated by the user.
• the automatic processes of physical establishment of the communication and of reestablishing during communication allow, according to a preferred embodiment, to automatically establish the connection in the three modulations and the returns in connected mode for the voice application. given.
• the voice-data application known per se in V23 is renewed at high speed by the introduction of the automatic connection process V27ter / V29 authorizing programmable alternations from speech mode to given mode for example for an audiotex or audiovideotex service at 9600 bps.
• the physical recovery process is implemented in particular during variations in the line gauge or during disturbances generating erroneous short sequences. It allows you to reconcile the equipment according to the same modulation allowing resynchronization of the modems at both ends according to the new characteristics of the line.
• This transmission resumption mechanism is possible by the presence of segments l and 2 of the long learning sequence indicating the start of the resumption process.
• the "speaking” mechanism is also used here as an indication signal of a physical resumption, during communication, for example on the initiative of the remote equipment.
• the recovery mechanism can be based on the possibility for the receiving equipment, in the event of reception of one or more erroneous short synchronization sequences (alternation), to effect a new physical matching.
• the desynchronism of the two modems can be caused by variations in the size of the line or during disturbances on the telephone network.
• this connection phase takes place only at the physical level without loss of connection of the higher levels, namely the frame level and the packet level, and without modifying the parameters of these levels. superiors.
• the speed fallback mechanism is based on the possibility presented by the receiving equipment, in the event of reception of a false long learning sequence, during the resumption process in V29 modulation, of performing a resynchronization at the physical level of the modems. in V27ter modulation. If the particularly difficult reception conditions do not in fact allow a successful resumption of communication in V29, it is then possible to perform a resynchronization of the modems in V27ter, taking into account the better robustness of this modulation vis-à-vis the line disturbances. As in the case of physical recovery, the communication recovery and speed fallback mechanisms do not disturb the higher levels (frame and packet), although there is a change in modulation.
• Modems V27ter (4800 Bits / s), V29 (9600 Bits / s) of group 3 facsimile type are known (ROCKWELL R96 VFX).
• the transmission speed is 9600 or 4800 Bits per second on the two channels, the modem operating in alternation.
• the actual speed of the "PAVI" - “Minitel” link is optimized by the use of short learning sequences each time the modems are turned over, the “short and stationary line” characteristics of this link allowing the use of this mode.
• the V27ter standard has two types of learning sequence (long and short) but the V29 standard originally only has the long learning sequence.
• the Rockwell company has developed, in collaboration with the Applicant, the short learning sequence in V29, which is integrated in the appendix F of the CCITT recommendation T104.
• the physical connection process of the equipment according to the invention allows the automatic adaptation of the transmission speed to that of the called equipment, while presenting the same process as in V23 connection. and respecting the recommendations CCITT V25 and VI00.
• the main objective is to specify the physical connection processes for "Minitel” V23 / V27ter, "Minitel” V23 / V27ter / V29 and “PAVI” V27ter and V29 / V27ter, taking into account the following constraints:
• V27ter / V29 modems currently on the market (for example the R96EFX / VFX) which, thanks to their internal signal processor, also provide reliable selective digital filtering functions.
• the originality of the connection principle therefore rests on one prior analysis of the pure frequencies or tones present on the telephone link. Indeed, before any connection attempt, a detection of tones makes it possible to discriminate the carrier frequencies of the V27ter, V29 modulations and the frequency of rest of V23 modulation (respectively 1800 Hz, 1700 Hz and 1300 Hz), or even telephone signaling (440 Hz clocked).
• the frequencies not modulated in V27ter and V29, with a duration of 187.5 ms for the R96VFX correspond to the first segment of the long learning sequence, (see recommendation V27ter and V29 for the meaning of the segments of the short learning sequences and long).
• the originality of the resumption-adaptation principle is based on the analysis during communication of the carrier frequencies of the V27ter, V29 modulations allowing resumption of the physical level (synchronization of the clocks of the modems) without disturbing the higher levels, ie during variations in the size of the line or during disturbances, and more generally any cause giving rise to erroneous short learning sequences, either on the order of one of the devices.
• V29 -> V27ter maintains the parameters of the higher levels (for example the packet level anticipation window), leading to a slight decrease in interactivity.
• this operation notably allows the "Minitel" V23 / V27ter / V29 to quickly and reliably adapt their transmission speed with respect to a remote device (V23, V27ter, V29) and with respect to the line used (gauge, disturbances, etc.).
• the characteristic tones detected in the communication phase for possible resumptions at the physical level are: - 1700 Hz to detect the unmodulated carrier
• the first device sends a long tuning train; if the second device receives it correctly, it in turn issues a long tuning train; if the first equipment receives it correctly, the communication is established at the physical level, which results in the emission by the first equipment of a short synchronization train, followed by data, or signals to establish the communication at the frame level , then back to the package level, in a manner known per se.
• the hardware architecture of modem access
• V27ter of "PAVI” Fast Speed (in general called equipment) is based on the case R96EFX from Rockwell. That of the V29 / V27ter accesses of "PAVI” VR of second generation is based on possibilities at least equal to the R96VFX unit (digital filtering capacity, short train V29 ). As the "PAVI" VR (fast speed) accesses are only called at 9600/4800 bits / s, only the detections of the carrier frequencies of the V27ter (1800 Hz) and V29 (1700 Hz) modulations are necessary at this level.
• Fast V23 / V27ter / V29 is given in Figure 1B. It includes a MC INTEL 80C154-1 microcontroller connected by a BUS bus link to a SRAM "NEC” 43256 memory of 32 k.bytes associated with a backup battery P, to a programmable EPROM read-only memory from the company "INTEL” 27C512 of 64 k.bytes and an MDM1 modem from the company "ROCKWELL” R96VFX (V27ter / V29).
• the MC microcontroller is connected to an MDM2 "HERMES" V23 modem (ALCATEL) via a LS serial link of TTL type.
• the outputs of the MDM1 and MDM2 modems are applied to the inputs of a DX duplexer for connection to an LT telephone line.
• a MINITEL card can operate in V27ter / V29 only by removing the MDM2 modem.
• a Minitel card operating only in V27ter can be realized by using as modem MDM1, a modem R96EFX. Detection during connection phase: - In the reception mode of the long learning sequence V29 or V27ter is associated a detection filter of 1700 Hz and 1800 Hz. The reception mode is activated after the transmission of 3.3 seconds of
• the" PAVI programs the modem in V29 reception mode for the reception of the complete long learning sequence (conditioning segment). The "PAVI” then goes into transmission for sending the corresponding long learning sequence (segments 1 to 5). The physical connection is established in V29 modulation.
• the "PAVI” programs the modem in V27ter reception mode for the reception of the learning sequence long complete.
• the "PAVI” then goes into transmission for sending the corresponding long learning sequence.
• the physical connection is established in V27ter modulation.
• the "PAVI" V29 / V27ter performs by default the following processing:
• connection attempt in V27ter mode by sending a long V27ter learning sequence
• Photographic Fast Speed (M2 VRP) and "Minitel” 2 fast speed VR (generally calling equipment) is based on the R96 VFX modem box from Rockwell and on the Hermès box or its equivalent the ST7514 box from SGS-Thomson. In fact, these "Minitel” can connect indifferently to V23 and V27ter “Teletel” doors. Only 2100Hz tones, 1300Hz, and 1800 Hz are then detected during the connection phase. In addition, the 1800 Hz tone is detected during the communication phase in order to ensure an incorrect short-train recovery-adaptation process. It is possible to discriminate between modes
• V23 and V27ter only with the first discriminant (nominal duration of silence of 75 or 150 ms), and therefore not to detect the frequency 1800 Hz.
• the reception of a long learning sequence V27ter takes place on segments 3 to 5 only, the modem having been positioned in this mode after detection of a 150 ms silence.
• the Minitel Speed Rapid V23 / V27ter / V29 must be able to connect indifferently to doors "Teletel" V23, V27ter and V29 / V27ter.
• the 2100 Hz, 1300 Hz, 1700 Hz and 1800 Hz tones are detected during the connection phase.
• the 1700 Hz and 1800 Hz tones are detected during the communication phase to ensure the physical recovery-adaptation process.
• the 440 Hz tone can be searched continuously to monitor telephone signaling.
• the "Minitel" When pressing the connection / end key, the "Minitel" is in the connection phase with line socket and is able to detect the frequencies 2100 Hz, 1800 Hz, 1700 Hz and 1300 Hz, the frequency 440 Hz is sought if there is energy on the line, without the presence of the previous frequencies. These frequencies are validated if the signal duration is at least equal to 300 ms for the 2100 HZ, 80 ms for the 1300 Hz, 100 ms for the 1700 Hz and 100 ms for the 1800 Hz.
• the "Minitel" 2 Fast Photographic Speed switches to V23 modulation if: - 300 s of 2100 Hz are detected followed by 75 ms (+ or - 20 s) of silence then by 80 ms of 1300 Hz,
• the frequency of 2100 Hz is not detected, but the frequency of 1300 Hz is detected for 1.7 s (or 1.8 s from M2).
• the following silence is 150 ms (+/- 20 ms) knowing that the fastest modulation of the "Minitel" is the V27ter,
• the "Minitel” programs the modem in V27ter reception mode for the reception of the complete long learning.
• the following silence is 150 ms (+/- 20 ms) knowing that the fastest modulation of the "Minitel” is V29.
• the "Minitel” then transmits the long learning sequence V29.
• the "Minitel” programs the modem in V27ter reception mode in order to detect the presence of an incomplete V27ter training sequence (absence of segments 1 and 2, as is the case for EBS). To do this, it suffices to delete in the sequencing, the logical condition for detecting segments 1 and 2.
• the validation of the reception of a compliant long train is then carried out in a conventional manner, on segments 3 to 5.
• the "Minitel" transmits in response the complete V27ter long learning sequence (there is no problem in transmitting segments 1 and 2) and the communication is established in V27ter modulation, in the short learning sequence mode,
• the Minitel transmits the long learning sequence V29 . If the "Minitel” detects the presence of the unmodulated frequency (or segment 1) of the V27ter (187.5 ms of 1700 Hz validated for 100 ms), it then programs the modem for the reception of the long learning sequence V27ter . In response to the complete long learning sequence V27ter, the "Minitel” transmits the complete long learning sequence V27ter. Communication is established in V27ter modulation, in the short learning sequence mode. - consecutive detection of, for example, three erroneous V27ter short sequences or, for example, of three erroneous V29 short sequences followed by one or two long V29 sequences wrong (recovery process).
• a long learning sequence (segments 3 to 5) is preceded by the emission of, for example, 180 to 200 ms of unmodulated carrier (segment 1) followed by 20 ms of silence (segment 2).
• the transmission of the long learning sequence is conditioned for the equipment calling:
• the transmission of a long learning sequence is also always preceded by the transmission of 180 to 200 ms of unmodulated carrier (segment 1) followed by 20 ms of silence ( segment 2).
• the transmission of the long learning sequence is conditioned: For the V29 modulation: - either by the recognition of 100 ms of carrier 1700 Hz followed by the detection of the long learning sequence V29,
• the modems of the two devices are synchronized and the exchanges are then carried out in the short learning sequence mode.
• connection recovery process provides for a return to long learning sequences either in the same modulation or in V27ter in the event of desynchronization and failure to resume in V29 modulation (process fallback).
• connection order for example pressing the Connection-end key or sending a sequence according to the" Minitel "protocol
• the connection order arrives before the last 300 milliseconds of the 2100 tone Hz to line management software.
• connection order reaches the line management software in the last 300 milliseconds of tone 2100 Hz or after.
• Equipment V23 / V27ter or equipment V23 / V27ter / V29 is called any equipment called, ie a "PAVI" V.R. either a "Minitel” used in so-called “frontal” mode (micro-pavi), or any device likely to be called and able to meet the specifications of this document.
• PAVI Picture Engineering Task Force
• Segments 1 to 5 of a V27ter or V29 training sequence are as follows (according to CCITT recommendations):
• Segment 1 unmodulated carrier Segment 2: no energy transmitted Segment 3: continuous phase reversals of
• Segment 4 equalizer conditioning sequence: 2 phases 0 ° and 180 °
• Segment 5 continuous emission of scrambled "1".
• SI unit interval of the dibit; the durations of segments 3 to 5 are expressed in unit intervals.
• TC short learning sequence or short train (synchronization)
• TLV27 long learning sequence V27ter or long train V27ter
• TLV29 long learning sequence V29 or long train V29
• TCV27 short learning sequence V27ter or short train V27ter
• TCV29 short learning sequence V29 or short train V29
• TLV27 segment 1: 185 to 200 ms of unmodulated carrier; segment 2: 20 to 25 ms without transmitted energy; segment 3: 50 SI (unit intervals); segment 4: 1074 SI; segment 5: 8SI TC V27: no segments 1 and 2; segment 3:
• segment 1 185 to 200 ms; segment 2: 20 ms; segment 3: 128 SI; segment 4: 384 SI; segment 5: 48 IF TC V29: no segments 1 and 2; segment 3:
• the physical connection is established after
• connection in V23 modulation including the transmission of the sequence of connection 13, 53
• V29 modulation connection :
• the detection according to the invention of 75 ms of silence after transmission at 2100 Hz makes it possible to validate the procedure known per se for connection according to the V23 mode (detection by the calling equipment of at least 80 ms of a signal to 1300 Hz transmitted for 40 seconds by the "PAVI - V23", and transmission by the calling equipment with a frequency of 390 Hz, and establishment of the connection in full duplex ("full-duplex").
• Case n c 2 corresponds to a delayed connection.
• the connection order occurs after the end of the 2100 Hz transmission (or too late for the calling equipment to detect 300 ms of the 2100 Hz frequency).
• the calling equipment identifies a called V23 equipment, by a detection (known per se) of 1.8 seconds of the 1300 Hz signals.
• Case n ° 3 corresponds to the early connection of a "MINITEL" V23 / V27ter to an equipment responding in V27ter mode.
• the calling equipment After detection of 300 ms at the frequency 2100 Hz, the calling equipment detects a silence of 150 ms, which indicates that the communication will not be in V23 mode.
• the calling equipment sends a long train TL V27 (including segments l and 2) and the called equipment detects the carrier frequency (1800 Hz) which characterizes the V27ter mode (detection of 100 ms of 1800 Hz from segment 1 ).
• the called equipment sets (if necessary) its modem in V27ter mode and then transmits a long train TL V27 (including segments 1 and 2) which is received by the calling equipment. If this reception is valid, the connection is established (each device has sent and received a long train TL V27) and communication is established by exchanging short trains TC V27 in V27ter mode (without segments 1 and 2).
• the connection is established first at the frame level (LAPX), then at the packet level (X25) in a manner known per se.
• Case n ° 4 corresponds to a delayed connection to a V27ter device.
• the equipment called transmits, after a time interval of 200 ms after the end of the transmission of 2100 Hz (3.3 s), an alternation long trains TL V27 and short trains TC V27 at a rate of 2 seconds (until the expiration of a delay time of 40 seconds after which, in the absence of successful connection, the called equipment automatically releases the link).
• the equipment calling in reception mode detects 100 ms of the 1800 Hz frequency of the first long train TL V27 it receives and following this reception, it in turn sends a long train TL 27 which is received by the called equipment.
• the connection is. established at the physical level, each of the equipment having emitted and received a long train V27.
• Case n ° 4bs differs from the previous one in that the calling Minitel operates at least according to the V27ter / V29 modes while the called equipment does not operate according to the V29 mode.
• the calling equipment detects the 1800 Hz frequency characteristic of the V27ter mode, but in response, this time it sends a long train V29 to make a connection attempt at V29.
• the called equipment does not recognize the long train V29, again transmits a long train V27ter, to which the calling equipment responds with a long train V27ter, which allows the establishment of the connection. This procedure makes it possible to check whether the called equipment is likely to connect in V29 mode (see case n ° 9 below).
• Case n ° 5 corresponds to a delayed connection to a V29 / V27ter device.
• the called equipment After the silence of 200 ms that follows the transmission at 2100 Hz, the called equipment tries to establish communication in V29 mode.
• the equipment calling V27ter / V23 remains "mute" because its modem, in reception mode after the connection order, does not recognize the carrier frequency V29 (1700 Hz) in segment 1 of the TLV29 trains.
• the called equipment After three unsuccessful attempts in V29 mode (6 seconds in total), the called equipment transmits a long train TL V27 whose unmodulated carrier at 1800 Hz of segment 1 is detected by the modem of the calling equipment which in turn transmits a long train TL V27 whose carrier not modulated at 1800 Hz is detected by the modem of the called equipment.
• the connection is then established at the physical level, and continues by exchanging short TC V27 trains and establishing higher levels (frame and packet).
• the calling equipment is able to recognize the frequency of 1700 Hz, although it does not work in V29 mode, (it is enough for that to add an additional filter to the modem) , and it directly transmits a long V27ter train, hence a much faster connection than in case 5, by exchange - of two long V27ter trains.
• Case 6 ( Figure 7) concerns the early connection of equipment calling V29 / V27ter or
• V29 / V27ter / V23 to equipment called V27ter.
• the calling equipment After detection of 150 ms of silence after detection of 300 ms of 2100 Hz, the calling equipment positions its modem in V29 transmission mode and transmits a TL V29 long train. The equipment called does not recognize a long train
• TL29 it transmits in turn, after a time delay of 2 seconds, a long train TL V27.
• the calling equipment detects 100 ms of the frequency 1800 Hz of segment 1 of the long train TL V27 and positions its modem in V27ter mode. The duration of segments 1 and 2 allows this operation to be carried out before the arrival of segment 3.
• the calling equipment therefore recognizes the long train TL V27 and in turn responds to a long train TL V27. Communication is established at the physical level, and continues as before (exchange of short trains, etc.).
• Case n ° 7 (figure 8) is similar to case n ° 3, except that the communication is established in V29 mode in which the two devices can operate.
• Case n ° 8 (figure 9a) is similar to case n ° 4 except that communication is established in V29 mode.
• Case no. 9 (FIG. 9b) is close to cases no. 4bis and no. 8, but the delayed connection order occurs while the equipment called transmits long trains in V27ter fallback mode, after three attempts to emission of long trains V29. In this case, the calling equipment sends a long train V29 which allows the establishment of communication in V29 mode.
• Case 10 ( Figure 10) concerns a process
• Case n ° ll (figure 11) is similar to case n ° 10, except that the recovery takes place in V29 mode (without mode change) with detection of the 1700 Hz frequency not modulated (segments 1 and 2 of TL V29 ) by the equipment called.
• Case n ° 12 (figure 12a) describes a recovery process with mode change, after reception of three non-compliant TC V29 short trains (for example line disturbance), equipment (here the calling equipment) resumes the process learning in V29 modulation by transmission of a long train TL V29.
• This attempt being unsuccessful (here only one attempt), the calling equipment transmits a long train TL V27 whose carrier frequency of segment 1 is detected by the called equipment.
• Communication continues by exchanging short TC V27 trains without disturbing the upper levels (frame and package) due to compatibility within a few parameters.
• Case no. 12bis corresponds to the previous case, but the learning process is repeated twice in V29 mode (two attempts) and twice in V27ter mode (two attempts).
• Case n ° 13 (figure 13) concerns an aborted recovery from a communication in V29 mode.
• Equipment eg calling equipment
• the number of two attempts is given as an example, but it can be envisaged to make a single attempt.
• Case n ° 14 (figure 14) concerns the connection to a synchronized unmarked input (EBS) of the current TRANSPAC network, in V27ter mode.
• the process starts as in case 7.
• the long train TL V29 (or possibly TL V27) is not recognized by the EBS receiver, which transmits a long train (TL 27 fallback) corresponding to a fallback mode at 2400 bps then short trains (TC V27 fallback) fallback mode.
• the calling equipment does not receive any known mode for a time delay of 10 seconds (unmodulated carrier detection failure), it automatically programs its modem to receive long trains TL V27 without segments 1 and 2, this is that is, it removes the logical condition for detecting the frequency of the unmodulated carrier.
• the duration of 10 seconds is sufficient to discriminate this case compared to the others (in particular case n ° 5).
• Case 15 concerns the known procedure for switching to voice-data mode with V23 modulation.
• the called equipment transmits a changeover sequence in voice mode for N seconds.
• a disconnection is carried out by dropping the carrier without breaking the telephone link and an audible message is emitted during a selected delay time.
• the complete connection is again carried out in a conventional manner (MINITEL V23 equipment).
• Case n ° 16 (figure 16) concerns a voice-data process according to the invention in V29 modulation.
• the voice switching sequence produces a logical disconnection with release of the higher levels (packet and frame) and physical disconnection by falling of the carrier.
• An audible message is emitted during a given time interval (voice mode).
• the connection is resumed in V29 mode on the initiative of the equipment called (transmission of TL V29) and the physical connection is established after an exchange of TL V29 long trains, then at packet and frame level in the TC V29 short trains which follow to restore the previous state given in V29 modulation.
• Case n ° 17 (figure 17) is analogous to the procedure except that the given mode is the V27ter mode folded back from the V29 mode.
• the called equipment On reconnection in given mode, the called equipment attempts a recovery in V29 mode. After this attempt has failed, recovery is carried out in V27ter fallback mode, which is much less sensitive to line disturbances.
• Case n ° 18 (figure 18) is similar to case n ° 17, but the resumption in V29 mode is successful and the connection is made at the physical level in the long trains TL V29, then at the frame level and at the packet level in the following short trains TC V29.
• Case n ° 19 also relates to a voice-data process, in which the calling equipment makes an anticipated request to return to communication in data exchange mode, before the end of the delay time of N seconds of the mode speech.
• This anticipated request manifests itself in the form of the transmission of a segment 1 of unmodulated carrier V29, to which the called equipment responds with an attempt to connect in V29 mode (transmission of long trains V29). In this case, the connection cannot be established in V29 mode.
• the called equipment then transmits V27ter long trains (fallback mode) leading to synchronization in V27ter mode.
• the anticipated request for return to data exchange mode by equipment only V27ter is effected by the emission of a segment 1 of unmodulated carrier V27ter.
• FIGS. 21a to 21s give the writing instructions for the elementary operations implemented in the sequencer, from the instruction set of the ROCKWELL R96-VFX modem, for operation in V27ter or in V29. These instructions are implemented in the immediately higher level sequences of FIGS. 22a to 22d, for the transmission of long and short trains in V27ter and V29, and for the reception of these trains in FIGS.
• Figures 24 to 24d further characterize the end phases of transmission of such trains and Figures 25a to 25f, the end of reception of such trains, Figure 25c to f concerning the case of long or short trains presenting application data (pennant or "flags" and data).
• the automaton of FIG. 26a comprises a sequence of operation in local mode, making it possible to switch following a connection order OC sent or received, either to a connection automaton in mode calling AC1, or to a connection automaton in mode called AC2, which are also connected to a communication automaton ACV23 in mode V23.
• Each of the AC1 and AC2 PLCs is connected to an ACV27ter PLC in V27ter mode and / or to a PLC in V29 ACV29 mode.
• the ACV29 PLC is connected to a recovery automaton in V29 ARV29 mode, to allow one or more recovery-adaptation attempts in V29 mode which can also be connected to an AREP fallback automaton allowing a fallback to the ACV27 automaton.
• the ACV27 automaton can also be joined by an ARV27 automaton for resumption in V27 mode to allow one or more resumption-adaptation attempts in V27ter mode.
• the ACV27 and ACV29 PLCs are also connected to an APH PLC allowing a transition to speech mode, which is in turn connected to an APHD speech-data switching PLC for a return to positioning either in V29 mode (ACV29 PLC), or in V27ter mode (ACV27 PLC).
• the line can be released (return to "local" mode) from the ACV29, ACV27, ARV27 and APHD PLCs.
• the automaton in calling mode (left column) after the connection order that it sends following a telephone line seizure on its initiative, with a time delay (90 s) and programs the simultaneous detection by the modem of several frequencies (1300 Hz, 1700 Hz. 1800 Hz, 2100 Hz) (figure 27b).
• the PLC in called mode allows, after a received connection order, with a connection timeout (40 s) and emits a response tone (2100 Hz) (see point 1; figure 28a).
• FIG. 27a With regard to the connection mode automaton in calling mode (FIGS. 27a to 27g), a general diagram is given in FIG. 27a.
• the left branch represents a connection in V27ter mode (1800 Hz detection) and the right branch in V29 mode (detection 1700 Hz).
• FIG. 27b represents the branch performing the detection of the frequencies characteristic of each modulation.
• 1700 Hz detection go to point D (figure 27f) to establish communication in V29 mode.
• Figure 27c represents the sequencing starting from point B of figure 27b (detection of 300 ms of 2100 Hz) and leading either to an attempt of connection in V23 (20 ms of 1300 Hz), or to point F (fig 27d) . From point F (fig 27d), and after detection of 150 ms of silence, connection attempt in V29 and connection in V29 mode (point D and fig 27f) or in V27ter mode (point G and fig 27e).
• connection mode automatic controller comprises the sequences making it possible to discriminate between the modes V23, V27ter and V29, a sequence of setting in communication in V29 mode being represented in FIG. 28c , in V27ter mode in Figure 28d, and in V23 mode in Figure 28e.
• operation in two modes or in a single mode can be obtained by deleting the superfluous elementary sequences from the sequencer.
• the NB PASSAGE parameter makes it possible to make several connection attempts (3) in V29 mode and / or in V27ter mode by sending a long train without valid reception of a long train in return (point 6 of the fig 28b, 28c and 28d).
• the voice-data switching sequencer is represented in FIGS. 29a to 29c, and allows a new communication connection in V29 mode by means of sequences of FIG. 28c and in V27ter mode by means of the sequences of FIG. 28d, without, however, that this implies that the equipment comprises the entire connection automaton in called mode.
• the same goes for the procedure for releasing the link in Figure 29b (point 6 in Figure 29a).
• the communication and resumption-adaptation automaton in V29 modulation (fig 30a to 30b) makes it possible to ensure resumption-adaptation in the same mode, or else in the fallback mode V27ter.
• the resumption-adaptation automaton also ensures short train emissions after communication (signals COM V27-1, COM V27-
• the NB PASSAGE parameter allows several attempts (here 2) to be resumed-adaptation in V29 (fig 30b) and / or V27ter (FIG 30d).
• the two automata vertical branches of the figures

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• 1993
  • 1993-11-23 WO PCT/FR1993/001152 patent/WO1994013094A1/fr not_active Application Discontinuation
  • 1993-11-23 US US08/424,510 patent/US5867487A/en not_active Expired - Fee Related
  • 1993-11-23 EP EP94900868A patent/EP0700618A1/de not_active Withdrawn

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