FR2635632A1 - Interface for fax machine - Google Patents

Abstract

The subject of the present invention is an electronic interface device for conversion between a radio telephone and a two-wire telephone input/output. It consists of the combination of an electronic assembly effecting the conversion of the transmission path 6 and reception path 4 of the transmitter/receiver into a two-wire telephone-type input/output 8, of a generator of hold-on tone 13, 22, 23 and of line current 25 simulating the presence of a telephone line during transmission, of a converter of the call signal from the transmitter/receiver into a ringing train 13, 14, 15, 16 recognisable by automatic answering telephone terminals, and of a means 21 of simulating the lifting of the handset of the transmitter/receiver. It makes it possible to link to a duplex radio transmitter/receiver a terminal designed to be connected directly to the switched telephone network, especially on board a vehicle.

Description

INTERFACE FOR FAX
The present invention relates to an electronic interface device for converting between a radio telephone and a two-wire telephone input.

 I1 allows a terminal designed to be connected directly to the switched telephone network, in particular on board a vehicle, to be connected to a duplex radio transceiver.

It is known, to obtain an equivalent result, to use acoustic coupling devices which have a high sensitivity to ambient noise and therefore cannot ensure the necessary transmission reliability. In addition, certain functions cannot be performed by this type of coupler. As a result, it is currently impossible to use professionally on board a vehicle, the terminals designed to be connected to the switched telephone network.

The device according to the present invention eliminates these drawbacks. In fact, it allows direct connection to a duplex transceiver of all terminals intended to operate with a telephone line, such as fax, telex, minitel or modem.

 I1 consists of the combination of an electronic assembly converting the transmission and reception channels of the transceiver into a two-wire telephone-type input-output, a tone generator on hold and simulating line current the presence of a telephone line during transmission, a call signal converter from the transceiver to a ringing train recognizable by the automatic response telephone terminals, and a hook simulation means of the transceiver handset.

In the appended drawing, given by way of nonlimiting example of one of the forms of the invention, a block diagram of the subject of the invention can be seen.

The device, Figure 1, consists of an electronic card comprising a DC power supply terminal block 1, a connection terminal block with the transceiver composed of a call detection input 2, a reception input handset 3, a transceiver reception output 4, a combined transmit output 5, a transceiver transmit input 6 and a line outlet 7, and finally a two-wire line output terminal block telephone type 8.

The two-wire / four-wire conversion is obtained by a duplexer 9 associated with a line transformer 10 of ratio 1, with adjustable rejection rate. A first operational amplifier
It allows the amplification of the received signals with level adjustment. A second operational amplifier 12 allows the amplification of the signals transmitted with level adjustment and adaptation to the input circuit of the transceiver.

The reception of the call signals from the transceiver 2 triggers a ring generator, using a multi-frequency oscillator 13 associated with a voltage booster formed by two transistors 14 and the transformer 15, and with a rectifier-filter assembly 16.

A comparator circuit 17 and an opto-coupler circuit 18 make it possible to detect the line seizure by the peripheral connected to the two-wire output 8, in order to establish communication and to cut off the ringing signal thanks to the relay 27 and 20, after action of the time delay 19, and of simulating the unhooking of the handset of the transceiver by putting the output 7 to ground by the transistor 21.

Each line seizure by the peripheral causes, thanks to the gate 23, and after the action of a time delay 22, the sending on the two-wire output 8, of a tone generated on the output 26 by the multi-frequency oscillator 13, simulating the presence of a telephone line.

A negative voltage generator 25, associated with an electronic choke 24 makes it possible to generate a line current on the two-wire output 8, simulating the presence of a telephone line during transmission.

 Thanks to its simplicity, its reduced volume and its low cost price, the device which has just been described lends itself particularly well to the production of mobile stations making it possible to use all the peripherals adapted to the telephone network, such as fax machine , telex, telematic terminal, particularly for equipping vehicles intended for those who need to remain in permanent contact with a fixed or mobile point.

The positioning of the various constituent elements gives this device a maximum of useful effects which had not been obtained to date by similar devices.

However, the shapes, dimensions and arrangements of the various elements, as well as the materials used for their manufacture may vary within the limit of equivalents, without changing the general design of the invention which has just been described.

Claims (1)

10 Electronic interface device for conversion between a radio telephone and a two-wire telephone input-output whose purpose is to allow connection to a duplex radio transceiver, terminals designed to be connected directly to the switched telephone network, such as a fax machine , telex, minitel or modem, in particular on board a vehicle, characterized by the combination of an electronic assembly supplied with direct current (1) connected on the one hand to the transceiver by a link comprising a detection signal (2), a combined input / output (3, 5), a transceiver input-output (L, 6) and a line socket output (7) and, on the other hand, to a terminal designed for be directly connected to the switched telephone network via a matching two-wire telephone type (8), the electronic assembly first consisting of a duplexer (9) associated with a line transformer (10) ratio (1) with adjustable rejection rate, and two amplifiers  operational ficers (11 12) allowing the amplification of the signals received and transmitted, as well as the level adjustments and the adaptation to the input circuit of the transceiver, then of an associated multi-frequency oscillator (13) a voltage booster formed by two transistors (14) and a transformer (15), as well as a rectifier-filter assembly (16) generating a ring signal on reception of the call signals from the transmitter -receiver (2), then a comparator circuit (17) and an opto-coupler circuit (18) detecting line seizure by the device connected to the two-wire output (8), and controlling on the one hand a relay (27) via a timer (19) establishing communication with the transceiver, and a transistor (21) simulating the lifting of the handset of the transceiver and on the other hand a relay (20 ) switching the two-wire output (8) of the ring signal to the duplexer (9) as well as timed electronic gate (22, 23) injecting on the two-wire output (8) a tone generated by the multi-frequency oscillator (13, 26) and simulating the presence of a telephone line, finally of a negative voltage generator (25 ) associated with an electronic choke (24) making it possible to generate a line current on the two-wire output (8) simulating the presence of a telephone line.