RU2127492C1 - Device for connecting modem to one of set of telephone lines - Google Patents

Abstract

FIELD: telephone communications engineering. SUBSTANCE: device has first codec connected to modem, set of second codecs each connected to respective telephone line, and delay relay inserted between first and second codecs. First codec functions to convert output analog signal arriving from modem into digital signal to be transmitted to telephone line and also to convert output digital signal coming from telephone line to analog signal to be transmitted to modem. Each second codec is used to convert analog signal coming from telephone line to digital signal to be transmitted to first codec and also to convert output digital signal of first codec to analog signal to be transmitted to telephone line. Delay relay conveys output digital signal from first codec to one of second codecs and also transmits output digital signal from one of second codecs to first codec. EFFECT: provision for connecting modem to one of common telephone networks without interfering with data transmission. 2 dwg

Description

 The invention relates to a data transmission system, and more specifically, to an improved device for connecting a modem to a common telephone network.

 Typically, a modem is connected between data transmission systems to correctly transfer data between them. Such a modem is widely used for communication systems such as a computer, a radiotelephone / for example ST-2 (radiotelephone of the 2nd generation) / and so on.

 FIG. 1 illustrates communication between a modem and a common telephone network according to the prior art. As shown in the figure, the modem 10 has an input / output terminal, which can optionally be connected to several lines from the set of telephone lines through an analog switch 14. It should be noted that here the analog switch 14 is connected between the modem 10 and the general telephone network, since the analog output the signal from modem 10 cannot be directly transmitted to the telephone line.

 Therefore, if the telephone line assigned to the modem has a malfunction, then the known system cannot provide data services. Usually, since data transfer organizes the transfer of important information, such as system management information and billing information, failure of the data transfer can cause a serious blow to the communication system. Further, the modem input-output signal may undesirably be attenuated by the natural resistance of the analog switch itself.

 Therefore, an object of the present invention is to provide an improved device for connecting a modem to a public telephone network.

 Another objective of the invention is to provide a device for connecting a modem to a common telephone network, which prevents damage to data transmission.

 Another objective of the present invention is to provide a device to prevent attenuation of the input-output signal of the modem.

 In accordance with an aspect of the present invention, a device for connecting a modem to a telephone line includes a first codec connected to the modem and a second codec connected between the first codec and the telephone line. The first encoder-decoder converts the analog output signal of the modem to a digital signal for transmitting the converted digital signal to the second encoder-decoder and converts the digital output signal of the second encoder-decoder to an analog signal for transmitting the converted analog signal to the first encoder-decoder. The second encoder-decoder converts the digital output signal of the first encoder-decoder into an analog signal for transmitting the converted analog signal to a telephone line and converts the analog signal from the telephone line to a digital signal for transmitting the converted digital signal to the first encoder.

 In accordance with another aspect of the present invention, a device for connecting a modem to one of a plurality of telephone lines includes a first encoder-decoder connected to a modem, a plurality of second color coders-decoders, each of which is connected to a respective one of the telephone lines, and a time delay relay connected between the first encoder-decoder and the second encoder-decoder. The first encoder-decoder converts the analog output signal from the modem to a digital signal for transmission to the telephone line and converts the digital output signal from the telephone lines to an analog signal for transmitting the converted analog signal to the modem. Each of the second encoder-decoders converts the analog signal from the telephone line into a digital signal for transmitting the converted digital signal to the first encoder-decoder and converts the digital output signal from the first encoder-decoder into an analog signal for transmitting the converted analog signal to the telephone line. The time delay relay transmits a digital output signal from the first encoder-decoder to one of the second encoder-decoders and transmits a digital output signal from one of the second encoder-decoders to the first encoder-decoder.

 The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of an exemplary embodiment, given in conjunction with the drawings, in which FIG. 1 is a block diagram illustrating a connection between a modem and a common telephone network in accordance with the prior art, FIG. 2 is a block diagram illustrating a connection between a modem and a common telephone network in accordance with an embodiment of the present invention.

 A detailed description of a preferred embodiment of the present invention.

 A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings, in which like reference numerals represent like elements. Further, it should be clearly understood that many features, such as detailed circuit elements, are shown by way of example only in order to provide a better understanding of the present invention, and the present invention can be carried out without these features. Moreover, it should be noted that detailed descriptions of related prior art may be deliberately omitted, assuming that they are not needed when describing the concepts of the present invention. The terms used in the description are defined taking into account the functions of the invention and can be replaced in accordance with the usual practice or intention of the user or the designer of the chip. The terms should preferably be determined based on the content used throughout the description.

 FIG. 2 illustrates a connection between a modem and a common telephone network in accordance with the present invention, which can generally be found in a CT-2 base station connected to multiple telephone lines.

 Referring now to FIG. 2, note that in the reception mode, the modem is optionally connected to a plurality of telephone lines TEL1 to TEL3 through the first encoder-decoder 16, the time delay relay 18 and the second - the fourth encoder-decoder 20-24. If a speech signal is received on the first telephone line TEL1, then this speech signal will be converted to a digital pulse code modulation (PCM) signal by means of a second encoder-decoder 14. The digital PCM signal is loaded into a specific channel using a time delay relay 18. The digital PCM signal in a specific channel is converted into an analog signal RX (receiving device) by the first encoder-decoder 16. The analog signal RX generated by the first encoder-decoder 16 is fed to the modem 10.

 In contrast, in the transmission mode, the TX analog signal (of the transmitting device) produced by the modem 10 is converted by the encoder-decoder 16 into a PCM digital signal and supplied to the time delay relay 18. The time delay relay 18 transmits a PCM digital signal to the selected one of the second or fourth encoders-decoders 20, 22, 24. Then, the selected encoder-decoder converts the received digital PCM signal into an analog signal for transmitting the converted analog signal over the corresponding telephone line connected to it.

 The time delay relay 18 functions as a switch for connecting a speech signal to a desired one of the telephone lines TEL1 to TEL3. The analog output signal from the modem 10 cannot be directly supplied to the time delay relay 18. Thus, in accordance with the present invention, the first encoder 16 is located between the modem 10 and the time delay relay 18 to convert the analog output signal of the modem 10 to a digital signal and supply the converted the digital signal to the time delay relay 18. Further, the first encoder-decoder 16 converts the digital output signal from the time delay relay 18 to an analog signal to supply the converted analog signal to modem 10.

 As can be clearly seen from the above description, by applying to the CT-2 base station connected to a plurality of telephone lines, the apparatus of the present invention can successfully achieve data transmission even if a malfunction occurs in a particular telephone line. Further, the device does not require an analog switch in the signal channel of the modem, thereby solving the problem of attenuation of the signal, which had a known device. In addition, it is possible to freely control the gain of the signal transmitted to the modem from the first encoder-decoder, so that the performance of the communication system can be improved.

 Although the preferred embodiment of the present invention has been described in detail above, it should be clearly understood that a large number of variants and / or modifications of the basic concepts of the invention are contemplated herein, which, as those skilled in the art can understand, still fall within the essence and scope of the present invention as defined in the attached claims.

Claims (1)

 A device for connecting a modem to one of a plurality of telephone lines in a data transmission system including a modem for transmitting and receiving an analog signal for transmitting data over telephone lines, characterized in that it comprises a first codec connected to said modem for converting an analog output signal from said modem to a digital signal and converting the digital output signal from said telephone lines to an analog signal for transmitting the converted analog signal to Ignal on the aforementioned modem, a plurality of second encoder-decoders, each of which is connected to a respective one of the telephone lines, where each of the said second encoder-decoders converts the analog signal from the telephone line to a digital signal and converts the digital output signal from the first encoder-decoder into an analog signal for transmitting the converted analog signal to a telephone line, and a time delay relay connected between said first encoder-decoder and said second encoder-dec an oder for transmitting a digital output signal from said first encoder-decoder to one of said second encoder-decoders and transmitting a digital output signal from one of said second encoder-decoders to said first encoder-decoder.

Images