FR2652694A1 - Device for input to a telephone line and system for remote control of an installation via a telephone line using this input device - Google Patents

Abstract

The invention relates to a device for input to a telephone line and a system for remote control of an installation via a telephone line using this input device, in particular of a central heating installation including a boiler the starting or stopping of which it is desired to control, remotely, by sending a command transmission via the switched telephone network. The device for input to a telephone line comprises an input interface (3) and a ringing detector (12). The system for remote control of an installation via a telephone line comprises a signal receiver (1) and a signal transmitter (2) which are connected respectively to an output (5) and to an input (4) of the input device (16) according to the invention, as well as to a control unit (31).

Description

 The invention relates to an input device on a telephone line and a remote control system for an installation by telephone line using this input device, in particular, of a central heating installation comprising a boiler which one wishes to control, remotely, starting or stopping by transmitting an order via the switched telephone network.

We know, in particular from documents FR-A-2 611 335 and
FR-A-2 520 907, remote control devices for electrical devices which use the switched telephone network as an information vehicle. In document FR-A-2 611 335, the device described comprises a remote control unit arranged near the microphone of the telephone handset of the calling station and designed to emit series of tones which are deciphered by a receiver coupled to the called and commanding line electrical appliances. The disadvantage of such a system is that it requires, for its use, a special housing without which no control is possible.

We also know, in particular from the document
FR-A-2 537 823, remote control systems for electrical devices, by telephone, without the need for special boxes. In this document, the orders sent to the receiver who controls the devices are given via the dial of a telephone set. The user of this system, once the communication with the receiver is established, can put into operation or stop the devices to be remote-controlled by dialing on its dial a two-digit number corresponding to the code of a preset remote control command . The receiving device will then signal to the user, with a short tone, that this remote control is being executed.

 In the documents mentioned above, the electronic circuits which carry out, on the one hand, the decoding of the signals received and, on the other hand, their interpretation in order to control the apparatuses to which they are connected, are connected to the telephone line by means of a transformer ensuring, on the one hand, the link for only the alternating signals and, on the other hand, current consumption on the telephone line and galvanic isolation between these circuits and the telephone line. This transformer forms an input interface allowing an adaptation of the impedances with the telephone line and a control of the consumption current on this line. To take into account all the requirements which this interface must meet in terms of impedances, current consumption on the line and galvanic isolation, transformers are generally used which are specially adapted to this type of interface, but which also have the drawback of being bulky, heavy and expensive.

 The cost of an input device on a telephone line being mainly due to the cost of the transformer, one of the aims of the invention is to provide such a device that does not require a transformer specially adapted for telephony.

 Another object of the invention consists in providing a remote control system for an installation by a telephone line which does not have the drawbacks mentioned above. To this end, the invention provides a system which does not require, for its use, special boxes and which is provided with an input interface allowing the use of a transformer having a low volume and a low weight and which is low cost.

 Furthermore, another object of the invention is to provide an input interface which complies with the standards in force in terms of telephony and, in particular, security standards.

 The invention therefore relates to an input device on a telephone line comprising an input interface and a ring detector, this detector receiving the signals from the telephone line and delivering a logic level on an output for controlling a socket relay. line.

 According to a characteristic of the invention, the detector controls the relay so that its contacts close the line loop when it receives at least one ringing signal, the input interface comprising a transformer and a circuit consuming a current when a voltage is applied to these terminals, this circuit being mounted in parallel on the telephone line just downstream of the contacts, the transformer having its primary winding connected in parallel to the circuit via a resistor and a capacitor and a secondary winding on which are mounted in parallel a capacitance and a resistance forming with the winding a circuit tuned for the transmission band of the telephone network.

 According to another characteristic of the invention, the circuit consuming a current is an electronic circuit of the current sink type having a high impedance for the frequencies included in the transmission band of the telephone network, and a low continuous impedance.

 The invention also relates to a system for remote control of an installation by a telephone line comprising a signal receiver and a signal transmitter connected respectively to an output and to an input of an input device as described above.

 According to one characteristic, it further comprises a control unit receiving from the input device a predetermined signal when the detector detects at least one ring signal on the telephone line, receiving from the receiver the signals of its output and sending to the transmitter of signals on its control input, also controlling a relay whose contacts effect the starting or stopping of the installation to be controlled and analyze the state of a contact mounted on said installation.

 According to another characteristic of the invention, the receiver delivers at its output a signal of a first level when it receives a first type of coded signal on its input and a signal of a second level when it receives a second type coded signal on its input.

 According to another characteristic of the invention, the receiver is a signal decoder with multi-frequency codes.

 According to another characteristic of the invention, the transmitter delivers at its output a first signal when a first signal is present on its input and a second signal when a second level is present on its input.

 According to another characteristic of the invention, the first signal emitted by the transmitter is a continuous tone signal, and the second signal, a clocked tone signal.

 According to another characteristic of the invention, the operation of the transmitter is inhibited by the sending, by the control unit, of a logic level on its input and the operation of the receiver is inhibited by the sending, by the control unit, a logic level on its input.

 The invention also relates to a system for remote control of an installation by a telephone line comprising a signal transmitter connected to an input of an input device on a telephone line, this input device being a device for entry according to the invention.

The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of a preferred embodiment of the invention, said description being made in relation to the accompanying drawings, among which:
Fig. 1 represents a simplified remote control system by a telephone line,
Fig. 2 is a diagram of an input interface provided in a remote control system according to the invention,
Fig. 3 represents a remote control system via a telephone line of an installation according to the invention,
Fig. 4 is a view showing a cycle of information exchange between the user and the remote control system according to the invention.

 The telephone system shown in FIG. 1 essentially comprises a signal receiver 1, a signal transmitter 2 and an input interface 3. The receiver 1 receives signals from output 4 of the input interface 3 and the transmitter 2 sends signals over the input 5 of the interface 3. The transmitter and the receiver can be, for example, respectively an amplifier delivering to the interface 3 a signal coming from a microphone and an amplifier delivering the signal coming from the interface 3 to a speaker. The signals transmitted have frequencies belonging to the frequency band of the signals transmitted by the telephone network, that is to say 300 Hz-3400 Hz. Contacts 6, 7 are mounted on the telephone line L in series with the input interface 3. These contacts can be the hook contacts of a telephone handset.

 The input interface 3 receives, on the one hand, by the wires 8, 9, the signals present on the loop of the telephone line L, when the latter is closed by the contacts 6, 7, and returns them to an input 10 of the receiver 1 and, on the other hand, receives the signals from the transmitter 2 and sends them back to the loop. Furthermore, it closes this loop, when the contacts 6, 7 are also closed, and then consumes sufficient direct current so that the exchange to which the line is connected can recognize the line seizure. The contacts 6, 7 are closed, either manually or by a relay 11 connected to a ring detector 12 itself connected to the telephone line L by the wires 13, 14. The ring signal is a frequency signal 50 Hz and of amplitude varying from 25 to 100 volts. The detector 12 delivers on its output 15 a signal of a first level when it detects this signal, and a signal of a second level when it receives a signal whose amplitude is less than 10 volts rms.

In addition, it meets security standards for telephony. In particular, it supports, for at least a quarter of an hour, a signal of 250 volts at 50 Hz, the line not being taken.

 The assembly 16 formed by the ring detector 12 and the input interface 3 constitutes the input device on a telephone line object of the present invention.

 Fig. 2 shows in detail the input interface 3 of this input device 16. It consists of a circuit 20 mounted on the wires 8, 9, just downstream of the contacts 6, 7, which consume a predetermined current when a voltage is present at these terminals. Circuit 20 is a circuit made up of active electronic elements, such as a current sink, known to a person skilled in the art in the field of telephony. It has a very high alternating impedance in the frequency range 300 Hz-3400 HZ. In addition, it allows the interface to comply with security standards for telephony. In particular, it comprises fusible elements which cut it off and which thus make it possible to open the loop of the telephone line when a voltage of at least 250 volts rms at the frequency of 50 Hz appears on the line.

 The input interface 3 further comprises a transformer 24, the primary winding 23 of which is connected in parallel to the wires 8, 9 via a resistor 21 and a capacitor 22. In parallel on the secondary winding 25, are connected a capacitor 26, a resistor 27 and a network 28 for adapting the impedances seen from the side of the secondary winding 25 to that of the input 5 receiving the signals transmitted by the transmitter 2 and that of the output 4 sending signals to the receiver 1. The capacitance 26, the resistor 27 and the winding 25 form a circuit tuned in the frequency range 300 Hz-3400 Hz.

 The impedance seen from the side of the primary winding 23 of the transformer 24 is, because the secondary winding 25 is tuned, substantially equal to the value of the resistor 27, in the frequency range 300 Hz-3400 Hz. L the impedance across the circuit 20, in this frequency range, can be considered infinite. The impedance of the assembly formed by the capacitor 22 and the resistor 21 has a value substantially equal, in the frequency range envisaged here, to the value of the resistor 21. The impedance of the input interface, seen on the line side, is therefore substantially equal to the value of the resistor 27 plus that of the resistor 21. It can be seen, in particular, that it is independent of the electrical characteristics of the transformer 24, which authorizes the use of a transformer not suitable for telephony. In addition, the direct current on the loop being entirely derived by the circuit 20, no direct current flows in the primary winding 23 of the transformer 24. Again, no requirement as to the electrical characteristics of the transformer is not requested by the input interface 3.

 In practice, the transformers which can be used with the input interface of the present invention are less bulky, less heavy and less expensive than those which would be necessary for a direct connection.

 There is shown in FIG. 3 a remote control system by telephone using an input device according to the invention. This system essentially comprises a logic control unit 31, a signal receiver 32, a signal transmitter 33 and the input device 16 shown in FIG. 1. The latter receives, by the wires 13, 14, the signals present on the telephone line L and its ring detector 12 supplies a line pickup relay 11 provided with contacts 6, 7 mounted in series on the loop of the line . It also receives, via wires 8, 9, the signals from the line, when the loop is closed by contacts 8, 9, for its input interface 3. The logic control unit 31 is connected to a relay control 34 and to a contact 35 both mounted on a user installation. This installation can be, for example, a central heating installation, the relay 34 then controlling the start-up of the boiler and the contact 35 indicating the on / off state of this boiler. Alternatively, contact 35 could indicate the status of an alarm and monitoring system.

 The receiver 32 receives on its input 36 the signals coming from the output 4 of the input device 16. For reasons which will be explained below, the signal receiver 32 is advantageously a decoder of signals with multifrequency codes. On reception, on its input 36, of signals having the frequencies which correspond to an "O", its output 37 delivers a first logic level, a "0" for example, and on the reception of signals having frequencies which correspond to a "1", its output 37 delivers a second logic level, a "1" for example. These logic levels are transmitted to the logic unit 31. The operation of the receiver 32 can be inhibited by the sending, by the logic unit 31, of a logic signal on its input 38.

 The transmitter 33, for its part, receives on its input 39 logic signals coming from the control unit 31. I1 delivers at its output 40, a first signal when a first level is present on its input 39, and a second signal when a second logic level is present on this input. The first signal is, for example, a continuous tone, while the second signal is a clocked tone. These output signals are transmitted to the input 5 of the input device 16. The sending by the logic unit 31 of a logic signal to an input 41 of the transmitter inhibits the operation of the latter.

The operation of the remote control system is now described with reference to Figs. 3 and 4. FIG. 4 schematically represents the signals present on the line during a remote control cycle. When the user calls the telephone number of the line on which the system is connected, a ring signal 50 appears on the wires 13, 14. The detector 12 of the input device 16 detects this signal and, after a predetermined time corresponding to several rings, it controls, via the wire 15, on the one hand, the line pickup relay 11 whose contacts 6, 7 close, and, on the other hand, the control unit 31. The contacts 6, 7 will remain closed for a predetermined time sufficient for the exchange of information between the user and the remote control system to be possible. The closing of the contacts 6, 7 closes the loop of the telephone line L. The input interface 3 of the input device 16 then consumes the current which is necessary so that the telephone exchange can recognize the line seizure and establish communication satisfactorily. A time after it has received the control signal from the input device 16, the logic unit 31 controls the transmitter 33 so that it provides, as acknowledgment of line seizure, a signal of tone 51 on the loop. The transmitter 33 is then inhibited by sending by the unit 31 of a logic signal on its input 41 and the receiver 32 is put on hold for a signal 52 of the type with multifrequency codes. It is the user, by hitting the keys of the keypad of his telephone set, which must be of the type with dialing with multifrequency codes, which will allow the sending of this signal. receiver 32 detects it and delivers on its output 37 a signal of level "0". This signal is transmitted to the logic unit 31 which controls the relay 34 so that these contacts remain, for example, at rest. If the signal 52 transmitted corresponds to a "1", the receiver 32 delivers on its output 37 a level "1" and the logic unit 31 controls the relay 34 so that these contacts are, for example, in the working position. After a certain predetermined time, sufficient to carry out the remote control of the relay 34, the receiver 32 is inhibited by sending by the unit 31 of a logic signal on its input 38:
Note that, if at the end of this time, the user has not pressed any key on his handset, and has therefore not sent any signal, the output 37 of the receiver 32 has neither the level "0", nor the level "1". The logic unit 31 is warned that no signal has been transmitted and therefore does not modify the state of the relay 34.

 After this control phase of the relay 34, the logic unit 31 analyzes the state of the contact 35. If the latter is closed, it controls the transmitter 33 so that it sends a continuous tone 53 on the line.

On the contrary, if it is open, a cadenced tone will be emitted. If the contact 35 is one of the contacts of the relay 34, it will be understood that it will serve as an acknowledgment of the order transmitted previously. However, it may be independent of this relay, and in this case give a representation of the state of the installation to which the present system is connected.

 Once the contact status report signal has been sent, the line can be released. It will be at the end of the pre-determined line seizure time. The detector 12 of the input device 16 cuts off the supply to the line take-up relay 11, the contacts 6, 7 of which open and then monitors the appearance of a ringing signal on the wires 13, 14.

 In the description which has just been made, only one cycle of information exchange has been considered. In order for the system of the present invention to be more convenient to use, several such cycles may follow. In the case of two cycles, we would then have the following phases: acknowledgment of line seizure, command or not of the relay by the user, verification of the state of the contact, command or no of the relay, then verification. In practice, five cycles can follow.

Claims (9)

 1) Input device on a telephone line comprising an input interface (3) and a ring detector (12), this detector receiving the signals of the telephone line L by wires (13, 14) and delivering a level logic on an output (15) for controlling a line take-up relay 11, characterized in that the detector (12) controls the relay (11) so that its contacts (6, 7) close the loop of the line when it receives at least one ringing signal, the input interface comprising a transformer (24) and a circuit (20) consuming a current when a voltage is applied to these terminals, this circuit (20) being mounted in parallel on the telephone line just downstream of the contacts (6, 7), the transformer (24) having its primary winding (23) connected in parallel to the circuit (20) via a resistor (21) and a capacitor (22) and a secondary winding (25) on which a capacity (2 6) and a resistor (27) forming with the winding (25) a circuit tuned for the transmission band of the telephone network.  2) Input device on a telephone line according to claim 1, characterized in that the circuit (20) is an electronic circuit of the current sink type having a high impedance for the frequencies included in the transmission band of the telephone network, and a low continuous impedance.  3) Remote control system of an installation by a telephone line comprising a signal receiver (1, 32) and a signal transmitter (2, 33) connected respectively to an output (5) and to an input (4) of an input device according to claim 1 or 2, characterized in that it further comprises a control unit (31> receiving from the input device (16) a predetermined signal when the detector (12) detects at least one ringing signal on the wires 13, 14 connected to the telephone line L, receiving from the receiver (32) the signals of its output (37) and sending to the transmitter (33) signals on its control input (39), also controlling a relay (34), the contacts of which initiate or stop the installation to be controlled and analyze the state of a contact (35) mounted on said installation.  4) System according to claim 3, characterized in that the receiver (32) delivers at its output (37) a signal of a first level when it receives a first type of coded signal on its input (36) and a signal of a second level when it receives a second type of coded signal on its input (36).  5) System according to claim 4, characterized in that the receiver (32) is a decoder of signals with multifrequency codes.  6) System according to claims 3, 4 or 5, characterized in that the transmitter (33) delivers at its output (40) a first signal when a first signal is present on its input (39) and a second signal when 'a second level is present on its entry (39).  7) System according to claim 6, characterized in that the first signal emitted by the transmitter is a continuous tone signal, and the second signal, a clocked tone signal.  8) System according to one of claims 3 to 7, characterized in that the operation of the transmitter (33) is inhibited by the sending, by the control unit (31), of a logic level on its input (41) and the operation of the receiver (32) is inhibited by the sending, by the control unit (31), of a logic level on its input (38).  9) Remote control system of an installation by a telephone line comprising a signal transmitter connected to an input of an input device on a telephone line, characterized in that this input device is a device for input according to claim 1 or 2.