PROCESS AND RELATED DEVICE FOR REMOTE-CONTROLLED SWITCHING-ON OF TERMINAL EQUIPMENTS USED IN DATA TRANSMISSION AND TELE-PROCESSING

Abstract: The invention can be applied to terminals for data transmission and tele-processing. It provides that on arrival of a call signal to one or more unattended switched off terminals, a device (10') supplies power to the called terminals (7) and at the same time simulates at the calling terminal (1), during a time interval X greater than the time necessary to start-up the called terminals (7), the "ready to data transmission" condition causing a waiting phase. Following the subsequent recognition of the called terminals (7) from the calling one (1), feeding is maintained only to the called terminals interested in the dialogue with the calling terminal. Once the dialogue is over, power supply is cut to all the called terminals (7).

Description: "PROCESS AND RELATED, DEVICE FOR SE-HσiE-∞NTR- .T.FT) SWπαπHG-OM OF T-CRMINAL -B lPMENTS USED IN DATA TRANSMISSION AND TELE¬ PROCESSING" The subject of the invention is a process and device for the renote-co rolled switching-on of teππinal equipmer.-s for data transmission and tele-processing. At present anyone wishing to tele-transmit data __ust cαπply - with sσπe .basic regulations established by CCπT standards (Consultative Commitee on International Telephone and Tele¬ graph) and universally adopted by manufacturers of data tele-processing (or.IP) equipments. These standards basically provide that the data are exchanged 10. between DTE (Data Terrninal Equipment) user systaπs inter- connected by a data link (generally consisting of a public or private network), through which a correct transfer of data is carried out by means of suitable interface units (DCE - Data O-mπunication Equipment) located between the user system and 5- the data link (network). The user systems which can be connected for transmitting and tele-processing data may be of different types: basically they can be grouped into "Independent Processing Units", ccmparable to processors and generally indicated by the abbreviation CPU 10. (Central Processing Unit), and "more or less intelligent teππinals* * of the above-mentioned processors. With DTE, both types of user systems are hereafter intended. When the data link consists of a telephone channel, the DCE .interface unit is made up of a MODEM (Modulator-Demodulator). 15. This is a unit for converting data frcm the digital form, used by teππinals and * mainframe processors, into analogue form, suitable for transmission through a telephone channel and viceversa. Sometimes the said MODEMS are connected to PSTN (Public Switched Telephone Network). However, the MODEM and 20. PSTN interfaces on both the network side and the terrπinal equipment side must cαπply with the recc mendations in the CCΠT standards. Nowadays, in order to operate in an unattended environment, all the peripheral teirninal equipment must be left continually 25. switched on and supplied with power. This may not be advisable, especially if the data is to be transmitted at night - in any case, when no personnel is present - and the transmission - 3 - involves the peripheral terrriinal equipment (DTE/CPU) for a very short time ccmpared to that in which the power supply should be on. The object of this invention is therefore to eliminate manual 5. intervention for switching on and supplying power to the peripheral terminal equipments. This is done by a process and related device which supply power to each called terminal only when there is the need to exchange data with a main calling te_τninal, and cut off the said power supply when the data 1°. exchange has ended. A further object is to provide a process and a device which protect the called terrninal by cutting off the power supply in case of wrong calls (more or less accidental), and prevent erroneous data transfer. 15. Another object is to provide a device which interfaces perfectly with existing CCITT standards equipments, and which is not too expensive. The object is achieved with a switch-on device employed in a connection between at least one calling terrninal equipment and 20. at least one called teirπinal, each being linked to the related interface unit connected to the data link, wherein the called terminal equipment normally uses a start-up procedure. The said switch-on device is ncrmally connected to the mains supply and only supplies power to the called teirriinal when it receives an 25- ON signal frαπ the interface unit on the called side. According to the invention, the switch-on device cαrtprises a timer with - 4 - a pre-set timing interval which is greater than the time interval required by the start-up procedure of the called terminal. Said timer acts by allowing the feeding of a switch device which connects the mains supply with the called terminal and maintains the said connection for the whole time interval needed to complete the start-up procedure. When the peripheral unit has terminated the said procedure, the supply of power is maintained only if the called terrninal sends a consent signal to the interface (DCE). If this does not happen, the supply o£ 10. power to the called terrninal is cut off. The * invention will now be described with reference to some exemplary embodiments shown in the enclosed drawings, wherein: Fig. 1 is a schematic representation of a conventional connec¬ tion on PSTN between a calling teirninal and a called 1 • teraiinal; . ' Fig. 1a shows another conventional connection on PSTN equipped with Modems provided with automatic calling and answer¬ ing features; Fig. 2 shows the configuration of the device according to the 20. invention in a connection through PSTN, the said device being placed between the called interface unit (DCE) and the called terrninal (DTE). Fig. 3 shows the block diagram in a point to point connection between two terminals connected to a 4-wire dedicated 25- telephone line; Fig. 3a shows, for a full duplex type data transmission through a 4-wire dedicated telephone line, the . connection - 5 - diagram shown in Fig. 3 placed between the called DCE and the called DTE; Fig. 4 shows the block diagram in a multi-point connection between a calling terminal and several called terminals - - connected to the first one through a 2-wire or 4-wire dedicated telephone line. Fig. 4a shows, for a full duplex or a half duplex type data transmission through a 2-wire or 4-wire dedicated telephone line, the connection diagram of the device 10- shown in Fig. 4 placed between the called DCE and the called DTE. Fig. 1 shows a schematic representation of an exemplary .connection for data transmission through PSTN. 1 indicates the CPU user system which transmits and receives data in digital 1 - form (it may, however, be any terminal able to carry out the above-described function). 2 and β indicate the local connec¬ tion between the user system (DTE) and the MODEM (DCE), the said connection being a physical-local link, according to the CCITT standards, in which the data transit in digital form. 20. 3 and 5 indicate the DCE interface unit, in this case a MODEM with CCITT interfaces on the user side and line side, which transforms the data frσn digital (user side) into analcgue (line side) and viceversa. 4 identifies the PSTN link; 7 identifies the DTE equipnent 25. receiving and transmitting data in digital form. - 6 - In order to start the data transmission and receiving procedure, several preliminary conditions must exist, that is: the user systems must be supplied with power and be in the ready condition, that is, they must have positively completed 5. their own start-up stage, which is a preset procedure in the equipment itself. Moreover the DCE interface units must be in a switched-on condition and physically connected to the corre¬ sponding user system and to the. line. Finally, the telephone line must be connected, that is, there must be a physical 10. connection between the line and the DCE, the two latter communicating with one another and with the respective user, systems. To achieve these prelijninary conditions, manual intervention is required at some stage, even if seme devices can be programmed 15. for automatically carrying out some functions. By way of example, a connecting process through a PSTN (Public Switched Telephone Network) with the type of connection process involving maximum manual intervention, that is, foreseeing an operator at each end of the data link is as follows: the 20. operator at terminal 1 and corresponding interface 3 must connect the two equipments to the power supply and initiate the start-up procedure of the said terminal 1. At the same time, the operator at terminal 7 and relative interface unit 5 must connect the two equipments to the power supply and initiate the 25. start-up procedure of the said terminal 1. The next step is network connection including calling of the 7/02534 - 7 - desired equipnent (DCE) and manual execution of one convention¬ al known procedures for establishing the connection between the two interface units and related terminals, and for starting the data exchange. 5- However, the actual data transmission is controlled by suitable software procedures resident in the respective terminal and handled on the telephone line by the DCE interface units. If suitable devices are provided, such as an automatic calling device or autodialer at the calling terminal (indicated by 9 in 10 - fig. 1a) and automatic answering device at the called terminal (generally contained in the interface unit 5), seme of the manual operations needed , for establishing the said connection . can be avoided. This type of connection procedure, especially suitable for batch transfer of data in an unattended environ- 1 - ment, still requires a manual intervention phase for the feeding and switching on of the called user peripheral systems (DTE). The present invention provides an automatic feeding system which enables a completely automated data transmission both on 0. a switched telephone network and a dedicated line in unattended environments, where the called terminal equipnent is normally off. CASE I: Switched Telephone Network, full duplex (FDX) or half duplex (HDX)transmission. 25. it can be seen in fig. 2 that the device 10 according to the invention is connected, in case of a switched telephone line, to the local connecting link β between the interface unit 5 and the called terminal 7. The interface unit may be a DCE device, for example a MODEM, or also a switched network terrninal 5- usually supplied by the local telephone company. . * .. -_y— The device 10 according to the invention is connected to the . - --...power supply at " 11 " . The unit is provided with a transformer -. device TRAS, one part thereof is connected to a stabilizing circuit. The other part of the circuit is connected to a power 10. connecting device W, such as a relay switch, the latter being • connected to the contacts W1 between the mains supply and the feed circuit 12 of the terminal. The c__rcuit is completed by a switch device made up of a relay , controlled by a suitable . .,. feed control circuit 0 by means of the DSR signal (Data Set. 15. Ready) outputed from the interface unit 5 on the user side (C 107). Finally, the device 10 is provided with a timer T - essential element - which receives a signal from the signal detector circuit out putted from the interface unit 5 (C 125) and acts on the DTR circuit which inputs the interface unit on 20. the user side (C 108/2). The preset timing interval X is • greater than the time interval required for the start-up procedure of peripheral unit 7, including the " times for delayed switch-on and autotest of the terminal plus the loading and _ r___ning of the data transmission procedure already preset in 25. the terminal. The device of this invention works according to the following logical scheme. - 9 - When the call arrives from the calling terminal, the interface unit 5 puts the pin C 125 into the ON condition ( as established ' by CCITT standards). This activates the timer T for the whole time interval X. The pin C 108/2 of the interface unit 5 is 5. thereby placed in the ON condition. The interface unit 5, in turn, puts the pin C 107 in the ON condition, which activates by means of feed, control circuit 0 the relay K. The latter closes the contact K1 , thereby supplying power to the relay switch W, which closes the contacts WI supplying voltage to the 10. terminal 7. At this stage said terminal 7 initiates the start-up procedure which ends in a time interval T which is smaller than X. As provided in the CCITT standards, at the end of this procedure the called terminal 7 puts its own output pin 108/2 1 . in the ON condition. When time interval X ' elapses, the timer T switches off its connection with the pin C 108/2 of the interface unit 5; however this has no effect because the pin C 108/2 of the interface unit 5 is held in the ON condition by said terminal 7, which has positively ended its start-up 20. procedure. When the data exchange is at an end, either the calling terminal or the called one itself cuts off the connection. It does this by putting the pin C 108/2 of the interface unit on the called side at the OFF condition. As a.result, the pin C 25. 107 is placed at the OFF condition. Consequently, the feed control circuit 0 disactivates the relay K which opens the contact 1 by causing the contacts WI to open. The power supply is thereby cut off. - 10 - If the terminal 7 includes in its start-up phase a control software procedure of authorised calls, in case of a wrong or unauthorised call it switches on.and initiates start-up for a time interval X. When the interval X is over, if no valid call 5. condition occurs, said software procedure places the pin C 108/2 on OFF, consequently the pin C 107 is placed on OFF and- . the feed control circuit Q acting on the relay cuts of power . to the called teirninal 7. . ' The .circuits of device 10 can also comprise integrated 10. .components with semiconductors carrying out the same functions described above. According to the invention, the CCITT connecting procedure and the interfaces to the DCE and DTE equipment are in no way affected. Telephone charges are at the expenses of the calling 1 . user. .. . Both in this case as in the following ones, at the start of. each call, the calling processor must activate a software procedure which guarantees that the..data transmission does not start before the called peripheral unit is ready to receive it. 20. CASE II: Device for point to point connection on a 4-wire non-switched telephone link (figures 3 and 3a), (full duplex transmission). On receiving a tx__rιsmission request signal sent by the interface unit 3 (calling DCE) the interface unit 5 (called DCE) places pin C 109 (also called DCD) in the ON condition. This signal activates the timer T for the whole time " interval X. This immediately places the pin C 105 (also called RTS) of the interface unit 5 in the ON state and keeps it for the whole 5. time X. In its turn, the interface unit 5 places in the ON state the pin C 106 (also called CTS). This signal, by means of the feed control circuit 0, activates the relay which closes the contact K1 feeding the relay switch W which acts by closing the contacts WI , which supply 10. voltage to the terminal 7- At this stage the terminal 7 initiates its start-up procedure (inclusive of the time necessary to the DTE to carry out the recognition of its address) which ends in a time interval t1 shorter than X. As provided by CCITT standards, if the start-up procedure is ' 15. positive, the terminal 7 places its output pin C 105 in the ON condition. At the end of the time interval X, the timer X cuts off voltage rσn its connection to pin C 105, this has no effect however because the pin C 105 of the interface unit 5 is kept on ON by the terminal 7 itself which, having recognised 20. its address, has ended its start-up procedure positively. When the exchange of data is over, it is necessary for the software resident, on the called terminal 7 to place its pin C 105 in the OFF condition. As a result the pin C 106 of the interface unit 5 (called DCE) is placed at the OFF condition. 25. Consequently the feed control circuit Q disactivates the relay K which opens the contact 1 causing the opening of the contacts WI . - 12 - Power supply to the called terminal equipment 7 is thus disconnected and consequently it- switches off and is ready for a subsequent power up when the terminal equipment 1 will call again. In the case of a connection on a dedicated line - therefore also for the following CASE III - at the end of each trasmission the calling processor must place on OFF its pin C 105. This task can be left to one of the software program resident in the calling processor. This causes the voltage on 10. the pin C 109 at the called interface unit 5 to drop. . " . After that the timer T is able to start again a new count for time X (during which it keeps forced in the ON condition the pin 105 of the interface unit 5) when a subsequent ON condition of the pin C 109 of the interface unit " 5 takes place, as a 15- consequence of the launching of a new call by the calling processor. CASE III: Device for multi-point connection on a 2-wire or 4-wire non—switched telephone link (figures 4 and 4a), full duplex or half duplex transmission. 20. To carry out devices apt to function in both half duplex and full duplex transmissions through 2-wire or 4-wire dedicated telephone lines for point to point-and multi-point connections, it is necessary for the timer and the feed control circuit-of said devices to have the following characteristics: The timer T' ' must be controlled by the eed control circuit Q' by means of an inhibiting signal , i. according to the ollowing logic: ■ - in the absence of signal i_ (i = OFF) when the timer T' 5. receives in input the C 109 ON signal it must send, during the whole externally preset time X, , the a activation signal of the relay . .. - in the presence of signal i_ *(i_ = ON) the timer T cannot activate the signal a, even if it receives the C 109 ON signal 10. in input. .. The feed control circuit Q' receives in input the C 109 and C 105 signals and sends in output the timer control i_ and feed control £ signals, the i. signal being delayed as regards to the C 109 signal in input. 15- The-feed control circuit Q * is to carry out also an externally predeterminable reset function, so that in the case of simultaneous absence of the C 109 and C 105 signals for a time interval equal or greater than Y (externally predeterinable Reset condition), the £ and i_ signals are placed in the OFF 20. . condition. The functioning logic of the feed control circuit Q' must be the following: a) in the absence of signal i_ (i = OFF) - on receiving signal -C 109 in input, the circuit 0' 25. activates the signal i_ placing it in the ON state in a slightly delayed mαnent as regards to the activation mαnent of the a signal sent by the timer T * and keeps it constantly in that state until the reset condition occurs. •b) in the presence of signal i_ (i ^ = ON) - on receiving the C 105 ON signal in input - it activates 5• the signal c placing it in the ON state and keeping it ' constantly in that state until the reset condition occurs. c) when the reset condition occurs, the same consisting in the simultaneous absence of signals C 105 and C 109 or a time ' interval equal or greater than Y, the Q' circuit lowers the 10. signals £ and i placing then in the OFF state. A manual reset of the circuit 0' can eventually be foreseen by means " of a switch. The device's logical functioning diagram is the following: On receiving the transmission request signal sent by the 1 5- . interface unit 3 (calling DCE), the called interface units 5 (DCE) place the pin C 109 at the ON condition (DCD). This signal is sent to each feed control circuit Q* and to each timer T' , the latter - in the absence of the inhibiting signal i. - lif ing and r____mta__ning for the whole time interval X the 20. activation signal a of the relay K which closes the contact T and maintains feeding to relay switch W which in turn acts by closing the contact WI giving voltage to the power supply of the corresponding terminal 7. - 15 - At this stage each terminal 7 initiates its start-up procedure which ends' in a time interval t1 , t2, t3 shorter than X and must also include the time necessary for the recognition of its address. As provided by CCITT standards, at the end of the start-up procedure, only the terminals 7 which have recognized their address place their own output pin C 105 at the ON condition. This signal is sent in input to the feed control circuit 0' which, in the presence of signal i_.= ON lifts in ON the signal 10. £ which it sends to the relay K. The signal £ performs as "consent to feeding" and replaces signal a in the excitation of the relay allowing the contact K1 to remain close and also therefore to carry on feeding to the connected terminal, even after expiration of the time X. "• 5. Once " lifted, the signal £ is kept activated until the reset condition of the feed control circuit 0' occurs. At the expiration of the time interval X, the timer T cuts off voltage from its connection a. This action is without effect, as the relay K ranains activated by the presence of the signal 20. £. Therefore all the terminals 7 which have recognized their address remain fed. In all the devices connected to the other terminals 7 instead, after expiration of the time X, the timer T' disactivates the signal a, in the absence of signal £. This results in the drop 25- of excitation to relay K which opens the contact K1 causing the opening of contacts WI with consequent feed break to the supplies of the terminals 7 connected to them. Therefore at the expiration • of• time X all . the. teirninals 7 . which have not recognized their address are switched off. 5. In the meantime the ON condition of the ' signal C 109 which had detected, the call frσn. the calling terminal 1 had been sent ■ also to the feed control circuit Q' causing the switching on of the signal i (slightly delayed as regards to the moment when the signal a has been activated by timer T'). This signal i_ 10 ' . remains till the reset condition occurs. ■ This signal 1 is sent to timer T* which, because of the signal's presence, is unable to activate anew the signal a when subsequent variations in the ON state of the signal C 109 occur. 15. During the talking phase between calling terminal 1. and called terminals 7, the presence of the -_r_hibiting signal i_ in the devices 10' prevents the 'un-fed' terminals 7 to switch on again at the variation frαn OFF to ON state of the signal C 109 when the data transmission is carried out in half-duplex. 20. Similarly to what described in the previous case II, at the end of the talking phase, the calling processor 1 and the terminals 7 interested to the dialogue must place their pin C 105 in the OFF state keeping it continuously in said condition for the time interval Y equal or greater than the one set up for the 2 . reset condition of circuit Q' . - 17 - As at the pin C 105 OFF condition on calling interface unit 3 corresponds a signal drop on pin C 109 of all the called interface units 5, this causes a reset condition in each device 10' and the consequent disactivation of the i and £ signals of 5. the feed control circuit 0' • The fall of the signal £ causes an excitation drop in relay which opens the contact K1 causing withdrawal of feeding to terminal equipnent 1. The fall of the signal i. allows for a possible new activation of the timer T 1 , with the consequent 10. re-feeding of the terminal equipment.

Claims: - 1.8 - C L A I M S 1. A process for remote-controlled switching on of terminals for data transmission and tele-processing, according to which at least one DTE Calling Terminal (1 ) sends a calling • signal, by means of at least one DCE Interface Unit (3), ' ~ through at least one data link connected to an interface unit (5), in turn connected ' to at least one called DTE (7), the latter being able to carry out a start-up procedure whenever connected to the power supply, characterized in that it foresees that on receiving a calling signal to an unattended 10. terminal (7), a device (10, 10') provides I) to give voltage to the called terminal (7) which starts up; II) to simultaneously simulate or the calling unit (1 ), during a time interval (X) greater than the time necessary for the start-up procedure of the called terminal ' (7), the 'ready' 15. condition of the called terminal, causing on the calling one a waiting phase which maintains the call for all this time interval (X), then at expiration of the time interval (X) the waiting phase is interrupted and power supply to the called terminal (7) continues only if the terminal has teimnated 20. positively its start-up procedure. - 19 - 2. A process according to claim 1 characterized in that the start of the significant data transmission happens only when the called terminal (7) has con irmed by so tware the positive result of its start-up phase. 5- 3. A process according to claim 1 or 2 characterized in that a) the calling signal activates a timer (T), through connection to the signal detector pin (C 1 5, C 109) of the interface unit (5) on the called side, for a preset time interval (X) 10. greater than the time interval needed to carry out the start-up procedure; b) said timer sends immediately to the called interface unit (5) a signal which puts the 'terminal equipment ready' indicator pin (C 108/2, C 105) on the ON condition and 1 5. maintains this condition for all the time interval X; c) as a result thereof the pin (C 107, C 106) of the called interface unit (5) is put in the ON state causing feeding of the called terminal equipnent (7); d) the start-up procedure initiates and proceeds during its 20• distinctive time interval; if the end result of said procedure is favourable for the continuation of the connection, the called equipnent (DTE) 7 sends a signal which puts in ready the terminal equipnent pin (C 108/2, C 105) at the ON state; 25. e) at the end of the time interval (X) the output of the timer (T) is changed so that, subsequently, the connection between the mains supply (11) and the called terminal (7) only remains active if the called terminal (7) maintains the • terminal equipnent ready' pin (C 108/2, C 105) at the ON state. 4. A process according to claim 1 or 2 characterized in 5- ' that a) the calling signal, through a connection with the signal detector pin (C 109) of the interface unit (5) on the called side, activates a timer (T* ) for a preset time interval (X) greater than the time interval (t1 , t2, t3) needed to carry out 10. the start-up procedure; b) said timer causes immediate feeding of the called terminal (7) and keeps it on for the whole time interval (X); c) the start-up procedure initiates and proceeds during its distinctive time interval (t1, t2, t3); if .it ends with a 15. result favourable to continuation of the connection, the called unit (7) sends out a signal which activates the 'terminal ready' pin (C 105); d) the calling signal, through the connection with the signal detector pin (C 109) of the interface unit (5) on the called 20. side, is also sent to a feed control circuit (Q') which in turn sends a signal (i_) to the timer (T' ), the signal -jihibiting by its presence reactivation of the feeding of the called terminal (7); e) the feed control circuit (Q 1 ) is connected to the pin C 105 25. of the called terminal (7) so that, once the starting-up is positively completed and the pin (C 105) is placed in the ON state, the latter causes the sending out of a signal (£) which maintains power supply to the called terminal (7); ) at the end of the timing interval (X), the timer (T' ) cuts off the signal that had activated supply (feeding) from the mains (11 ) to the called terminal (7); feeding persists only if the called te_τninal (7) keeps, the 'terminal ready' pin (C 105) active; 5. g) the simultaneous absence of voltage to the pins (C- 109 and C 105) for a preset time interval (Y) causes a feed drop in the called terminal (7). 5. A device for remote-controlled switching-on of called terminals (7) for data transmission and tele-processing, 10. said device being part of a system which comprises at least one calling terminal (1 ) and at least one called terminal (7), .- ' connected to the corresponding interface units (3, 5), the latter connected to a data link (4, 4a); said called terminal (7) being able to carry out its own start-up procedure, 15. characterized in that a) said switch-on device is located between the called interface unit (5) and the called terminal (7) and b) it comprises at least one timer (T, T' ) with a preset time ' interval (X) greater than the time interval (t , t , 20. t..required by the called terminal (7) to carry out its own start-up procedure, the input of said timer (T, T 1 ) being connected to the pin (C 125, C 109) of the interface unit (5), the output of said timer controlling the feeding of the called terminal (7) by means of at least one switch device 25. (K, W). 6. A device according to claim 5, characterized in that the switch device comprises one relay switch (W) connected to a relay (K). . 7. A device according to claim 5 or 6, characterized in that it is fed by a suitable transformer (TRAS) connected to the external mains supply (11 ). 8. A device according to any of the claims from 5 to 7, 5. characterized in that it also provides a feed control circuit (0) . which, in the presence of the okay signal taken frαn the connection to the 'interface unit ready' indicator pin (C 107, C 106), sends an excitation voltage to the switch device (K, ,.. v) -. .. 10. 9. A device according to any of the claim 5 to 7, • characterized in that it foresees a feed control circuit'(Q r ) connected to the signal detector pin (C 109) and to the 'terminal ready' indicator pin (C 105), said circuit (Q' ) being such that: 15. - on receiving the (C 109) ON signal, it sends a signal (i_) to the timer (T' ) which remains till the reset condition occurs and prevents the timer (T' ) to send out a signal (a_) which causes the closing of the switch device (K, W) as long as (i.) ' is ON. 20. - on receiving the (C 105) ON signal, it sends a signal (£) which keeps the switch device (K, W) closed until the reset condition occurs. - on detection of the simultaneous absence of signals (C.105 and C 109), during the preset tine interval (Y), it cuts off 25. the signals (_i) and (£) thus cutting supply to the called terminal 7.

Inventors: BERNARDI GUIDO, BERNARDI, GUIDO
Applicants: BERNARDI GUIDO, BERNARDI, GUIDO
Application year: 1986
Main classification: H04L11
IPC codes: H04L12