CN1213924A - Method of transmitting data signal on analogue user's line - Google Patents

Abstract

The data transmission on both sides between the subscriber terminal equipment and the central office should also be possible during voice signal transmission and can be realized with little overhead. A signal, preferably a charge pulse signal, which is generated at least at the central office for other applications is used as carrier signal. Thereby it is possible to utilize the existing infrastructure.

Description

Method for transmitting data signal on analog subscriber line

The invention relates to a method of transmitting data signals on an analog subscriber line between a subscriber terminal equipment and a central office, in particular during the transmission of voice signals of an already existing telephone connection.

For the transmission of data on analog lines, above all for the transmission of voice signals between the telephone terminal and the central office, a number of different methods can be used. There are DC signaling methods, where data transmission is achieved through a series of loop breaks, which can provide a symmetric or asymmetric cyclic signaling with respect to ground. There is also an AC signaling method in which an asymmetrical 50Hz AC signal input to ground is coupled to the subscriber line loop. Another data transmission technique is the so-called DTMF signaling (multi-frequency coding signaling) method, in which signaling information is created from n audio signals by means of an m-of-n coding. Finally, so-called modem transmission is mentioned, which converts binary data signals into line signals which are advantageous in transmission technology, these signals comply with the electrical conditions of analog connections, mainly frequency modulation, phase difference modulation, and quadrature amplitude modulation .

The DC signaling method has no advantage because it interferes with voice transmission. The AC signaling method is very slow and therefore only suitable for certain types of data transmission. The latter two data exchange methods use the voice frequency region and are therefore not suitable for simultaneous transmission of data and voice. There is therefore a need for this, in particular for the functionality provided for modern comfortable user terminals.

It is therefore the object of the present invention to provide a method for transmitting data signals on an analog subscriber line, which can also be carried out during the transmission of voice signals, and which is to be realized with little effort.

This object is achieved by a method with the features of claim 1 .

According to the invention, the data signal is modulated on a periodically varying signal as a carrier signal in the subscriber connection circuit and subscriber terminal equipment of the central office, the frequency of which is outside the voice band and has been used at least in the central office other applications.

In the method according to the invention, an already existing infrastructure can be used.

Further developments of the invention are given by the dependent claims.

According to a first variant, the signal generated for other applications is used as the carrier signal for the data transmission according to the invention as the signal transmitted from the central telephone office to the subscriber terminal for charge instructions or charge write-offs to the subscriber.

That is, in order to be able to use the method of the invention, no special hardware expenditure needs to be added in the central office providing for the generation and transmission of such charge signals.

The method of the invention realizes the possibility of new functions. According to a solution of the invention, information can then be transmitted as data signals during the transmission of voice signals, which information is used to authenticate the terminal device and to provide a more secure method of preventing misuse of the user's personal device than only during the establishment of a telephone connection. method.

According to another solution of the present invention, the method of the present invention realizes the possibility of issuing an expense instruction or expense verification to the user, which will be briefly described later.

Further aspects of the invention relate to a circuit arrangement in its general form and in a specific form, the specific form being used in connection with user authentication, for the purpose of carrying out the method according to the invention.

The present invention will be described in detail below based on an embodiment with reference to the drawings.

The drawing shows the interesting parts of a subscriber terminal TEE relevant to the description of the method according to the invention, as well as the subscriber circuit TSCH belonging to this subscriber terminal, which is a component of a central telephone exchange not further shown.

The subscriber terminal equipment TEE is connected to the subscriber connection circuit TSCH via the subscriber line TL. The subscriber terminal equipment TEE comprises telephone terminal equipment FEA, which transmits and receives analog voice signals, so that the subscriber lines are referred to as so-called analog subscriber lines. The analog voice signal transmitted from the telephone terminal via the subscriber line to the subscriber connection circuit TSCH is here converted into a digital signal after the transmission amplifier Tx in a device AD for analog/digital conversion or digital/analog conversion, after which the channel The filter KFT limits the frequency band to 0 to 4 kHz and finally leads via a PCM line PCM to the connection field of the central telephone office (not shown here). Conversely, voice information from the central office, which exists as a digital signal, undergoes digital/analog conversion after passing through the voice filter of the above-mentioned A/D device and is transmitted via the subscriber line TL to the telephone terminal equipment FEA after passing through the receiving amplifier Rx.

The other parts of the subscriber terminal equipment TEE and the subscriber connection circuit TSCH indicated here in addition relate essentially to the data transmission corresponding to the method according to the invention.

In the subscriber connection circuit TSCH, the frequency generator FG is first described, which is for example a sinusoidal signal generator with a frequency of 12 or 16 kHz, which is originally used for transmission in the form of fee pulses to the subscriber terminal, in order to serve there as a fee indicator or For example, in the case where the user terminal is a coin terminal, the charge is written off.

The signal generated from the frequency generator FG is used according to the invention as a carrier signal for transmitting data between the central office and the subscriber terminal equipment. It first passes through the pulse-forming circuit PFT, which is an integrator or a band-pass filter etc., in order to prolong the set-up and damping times when the generator is switched on or off in such a way that the subscriber terminal or telephone terminal FEA at This switching does not generate click noise when receiving the same signal. The carrier signal then goes to a modulator M, to which it directs the data to be transmitted to the user terminal equipment TEE from a device denoted as overall data source DQ. In modulator M, these data are modulated on a carrier signal supplied from frequency generator FG. The modulated signal is then passed through a filter BPTR in the form of a bandpass, which is used to filter out modulation products whose frequency is in the voice band 0 to 3.4 kHz or thereabouts. At the summing element S, the modulated signal is superimposed with the speech information from the channel filter KTR.

The subscriber terminal equipment TEE comprises corresponding components for transmission in the direction of the subscriber circuit, namely a frequency generator, which is considered here as a component of the transmitter TR, the data source DQ, the modulator M, the pulse forming circuit PFT and a filter BPE in the form of a bandpass BPE.

In the user terminal equipment TEE as standard equipment for the reception direction of data transmission, the bandpass filter BPE is used again, whose function is to guide only the latter from the mixed voice signal and the data signal modulated on the carrier frequency to the data The application, in addition to the demodulator D accessible via the switching function U, the data collector DS and TR as part of the application circuit arrangement under consideration. In the subscriber circuit TSCH there are correspondingly on the receiving side a bandpass filter BPTT, a demodulator D and a data collector DS.

In the presented case it is assumed that the data transmitted between the subscriber circuit and the subscriber terminal equipment should involve relevant data existing for subscriber authentication, therefore, in the subscriber circuit the data source DQ and the data collector DS are connected with an authentication module AM connection. The authentication data is provided by the authentication module AM, and after receiving the authentication data, the user terminal equipment sends an answer information response in a certain way, and then analyzes these answers in the authentication module. In the event that such an answer function disappears or an answer function that does not correspond to the desired form is received, the remote indicator is interrupted by the authentication module AM, for which the data connection, not shown here, serves as a relay for the central office control.

Such an exchange of authentication information that can be realized by the method according to the invention during voice transmission is of particular interest to subscriber terminals in the form of coins or in the form of terminals installed for settling telephone charges by canceling a so-called prepaid card. That is to say, in this case, by listening to the subscriber line after the connection is established, a call can be made from the authorized telephone device without payment.

The data transmission of the inventive technique can also be carried out independently of the transmission of the voice signal, in the case of the above-mentioned prepaid card, for example after the prepayment has been effected, the loading of the prepaid content.

Another application of the transmission of data during the transmission of voice signals realized in the manner of the invention is the detailed billing of charge indications and charge write-offs, including data information on increased charges, which, in addition to ordinary telephone connections, when established This is particularly relevant when a telephone connection such as a satellite connection is particularly expensive and therefore the cost indication or write-off spectrum can no longer be readily revealed using the usual rate pulse transmission.

Claims (7)

1. the method for analog line (TL) the transmitting data signal between subscriber terminal equipment (TEE) and central office, particularly during the voice signal transmission that the phone that has existed connects, according to this method, in user's connecting circuit (TSCH) and subscriber terminal equipment (TEE) data signal modulation on the signal that changes as the one-period of carrier signal, its frequency and produces for other application in central office outside voice band at least.

2. according to the method for claim 1, it is characterized in that the signal that produces for other application cycle in central office is in order to check and write off the signal to subscriber terminal equipment (TEE) transmission from central office to customer charge indication or expense.

3. according to the method for claim 1 or 2, it is characterized in that, be used to differentiate that the information of subscriber terminal equipment (TEE) is as data.

4. according to the method for claim 1 or 2, it is characterized in that, be used for drawing up information that expense indication or expense check and write off as data to the user.

5. for be implemented in the circuit arrangement of analog line (TL) transmitting data signal according to claim 1, it is characterized in that, following as subscriber terminal equipment (TEE) each part and in the equipment of central office's equipment as each part of affiliated subscriber line circuit (TSCH): carrier signal generator (FG), data source (DQ), the modulator (M) of the data signal modulation that provides by data source on the carrier signal that provides by carrier signal generator, filtering falls into the transmitter side filtering stage (BPTR) of voice signal area modulation product, the stack level (S) of modulated carrier signal and voice signal stack, receiver side filtering stage (the BPTT of the carrier signal that filtering is modulated, BPE), at the latter linked demodulator of this filtering stage (D), the data application circuit (DS) that on demodulator, connects, and for blocking (FEA) the preceding filter apparatus that connects of the telephone terminal at subscriber terminal equipment (TEE) (BS) that frequency of carrier signal is used.

6. according to the circuit arrangement of claim 5, it is characterized in that, the pulse shaping circuit (PFT) that connects behind the carrier signal generator at user's connecting circuit (TSCH) (FG), it avoids the edge of a pulse noise made in coughing or vomiting loudspeaker noise that produces by prolonging starting of oscillation or weakening time when switching on or off the carrier frequency generator in telephone terminal (FEA).

7. according to the circuit arrangement of claim 5 or 6, it is characterized in that, one group of preferred identification module (AM) of user's connecting circuit (TSCH), its produces the data be used for User Recognition and send to the relevant reception of the data of subscriber terminal equipment or analysis user terminal equipment (TEE), and interrupts being defined as not confirmed phone if possible and connect.

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