JP2746288B2 - Communication device - Google Patents

Description

The present invention relates to a communication device connected to a digital line. <Prior Art> Transmission lines (lines) include a digital line for digital signals and an analog line for analog signals. The line used in the telephone is, of course, an analog line. In order to transmit a digital signal using this telephone line, a modem for transmitting the digital signal to an analog line, a so-called modem, is required. This modem has been developed as facsimile, personal computer communication and the like have been developed. On the other hand, with the development of ISDN and the like, digital circuits are gradually being improved, and digital communication equipment is also developing.
In the future, all digital lines will be replaced. There is one G4 fax of this digital communication equipment. <Problems to be Solved by the Invention> By the way, as a communication device capable of transmitting digital information by using both the digital line and the analog rotation, a digital line for performing digital processing for the digital line is used. A processing unit, an analog line digital processing unit that performs digital processing of digital data for the analog line, and an analog line processing unit that has a modulation unit that modulates the digital data after performing the digital processing into an analog signal. Since each of them had, the circuit scale was inevitably increased, which not only hindered the cost increase and miniaturization of the device, but also caused the above-described digital circuit processing unit and analog line processing unit to adversely affect each other. There has been a problem that this may occur. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to enable a modulated signal to be transmitted to a digital line with a simple configuration. <Means for Solving the Problems> In order to achieve the above object, the present invention is a communication device having a generating means for generating a modulated signal by digital processing, wherein the digital modulated signal is converted into an analog signal. And sending the digital data to the other party connected via the analog line by sending the digital data to the other party connected via the analog line. By digital processing according to the modulation method for transmitting to the other party, to generate the digital modulation signal, the communication device, further,
And transmitting means for transmitting the digital modulation signal generated by the generating means to a digital line without modulating the digital modulated signal into an analog signal. <Operation> In the above configuration, the transmission means can transmit the digital modulation signal to the digital line without converting it into an analog signal. <Embodiment> An outline of an embodiment of the present invention is to provide a device (digital modem) in which an input / output portion of a modem for analog equipment conventionally used for analog transmission is provided in digital form. In other words, by installing this digital modem in a digital line device, data transmission from a digital line device to an analog device through a digital line is enabled. FIG. 1 shows a schematic configuration diagram of a digital modem according to the present invention. The difference from conventional modems is that the cut on the communication path side is digital, that is,
There is no D / A or A / D converter. FIG. 1 shows a digital modem according to the present invention. 100 is a transmitting terminal for generating a transmission digital signal, and 118
Is a receiving terminal receiving the same signal. 101 serves to clarify the delimitation of the signal on the receiving side and whitens the transmission data (arranges randomly)
A scrambler 102 is an encoder for assigning a code to the tributary and the dibit of the scrambler output signal, and 103 is a pulse shaping filter (roll-off filter) for preventing intersymbol interference of signals. 104 is a signal FSK, PSK, Q previously determined in the transmission standard of G III
This is a modulator that performs modulation such as AM. The modulation method in this modulator is performed digitally, and digitally modulated data is converted into an analog signal by an external D / A converter. As this modulation method, for example, phase modulation (PSK): changing the phase of a carrier frequency modulation (FSK): changing the frequency of the carrier wave (AM): changing the amplitude of the carrier wave: quadrature amplitude modulation (QAM): carrier phase And change the amplitude. The above is the transmission system, and the transmission unit of the digital modem of the present embodiment is a portion 200 indicated by a dotted line surrounded by the output terminal 105 except for the terminal 100. This system is all digital signals, so the output signal is also digital,
Can be connected to a digital line (conventional modems have D /
A converter and low-pass filter were added). Next, on the receiving side, digital data from the digital line is directly input to the digital demodulator 113 and demodulated into a signal before modulation. Reference numeral 114 denotes an equalizer, which is originally for correcting line distortion, and thereby improves transmission quality. Although the digital line has less distortion than the analog line, the embodiment uses an equalizer in order to be compatible with a conventional analog line modem. This equalized output signal is determined as a code point by a determiner 115, decoded by a decoder 116, and
The (scrambled) signal whitened at 17 is returned to the original signal, and the original transmission signal is received at the receiving terminal 118. Except for the terminal 118, the receiving section of this digital modem has a portion 20 indicated by a dotted line surrounded by an input terminal 112 and an output terminal 119.
It becomes 1. Note that what is called a digital modem is the portion 203 including the transmission / reception section. As described above, in the present embodiment, digital data before D / A conversion can be transmitted to the communication path, so that the output of the analog line device can be transmitted through the digital line, and the analog line device which has been impossible in the past can be used. And digital line equipment are connected via digital lines, enabling mutual data transmission. An example of this mutual transmission of data will be described with reference to FIG. Reference numerals 300, 301, and 302 are conventional digital line devices (for example, G4FAX), and reference numeral 303 is a conventional analog line device (for example, G3FAX). If the digital modem 203 of this embodiment is installed at both ends between the digital line 305 and the digital line 305 as shown in the figure, mutual communication between the G3FAX and the G4FAX, which was impossible in the past, is enabled. It is needless to say that the present invention is not limited to mutual communication with G3FAX and G4FAX, but can be applied to other communication. In the embodiment described above, especially when a digital modem is provided in an analog line device, since this modem has common factors with a conventional analog modem, the common elements are shared as shown in FIG. If the switch 300 can switch between the two directions (analog line and digital line), a more efficient and compact device can be realized. The non-common elements when transmitting to the analog line are the D / A converter 401 and the low-pass filter 402 on the transmitting side, and the band-pass filters 403, AGC 404 and A / D on the receiving side.
Other parts of the converter 405 are considered common elements. As described above, if the digital modem according to the present embodiment is used, the signal output to the line-side output terminal of the analog line device can be converted into a digital signal, thereby enabling data transmission to the digital line of the device. Mutual data with digital line equipment was made possible. In addition, according to the embodiment shown in FIG. 3, the common part between the digital modem and the conventional analog modem can be shared, so that the modem section can be made more effective and compact, and the apparatus itself can be made compact and high in cost performance. There is an effect that can be. <Effects of the Invention> As described above, according to the present invention, it is possible to transmit digital data to a partner connected via the analog line when the signal is converted into an analog signal and transmitted to the analog line. The signal can be transmitted to the other party via a digital line with a simple configuration.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of a digital modem according to an embodiment of the present invention. FIG. 2 is a diagram showing an analog line device and a digital line device using a digital line when a digital modem is used. FIG. 3 is a diagram showing a state of mutual communication with a device, and FIG. 3 is a configuration diagram in a case where a common part of a digital modem of the present embodiment and a conventional analog modem is also used. 100 Terminal 101 Scrambler 200 Transmitter

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Yuko Ichikawa               3-30-2 Shimomaruko, Ota-ku, Tokyo               Inside Canon Inc.                (56) References JP-A-62-274866 (JP, A)                 JP-A-62-289027 (JP, A)                 JP-A-61-200763 (JP, A)                 JP-A-59-122078 (JP, A)                 JP-A-58-197952 (JP, A)                 JP-A-53-109451 (JP, A)

Claims (1)

(57) [Claims] A communication device having generating means for generating a digitally modulated signal by digital processing, wherein the digitally modulated signal is converted into an analog signal and transmitted to an analog line, so that the digitally modulated signal is transmitted to a partner connected via the analog line. A signal capable of transmitting data, wherein the generation means converts the digitally modulated signal by digital processing according to a modulation method for transmitting digital data to a partner connected via the analog line. The communication device, further comprising: a transmission unit that generates and transmits the digital modulation signal generated by the generation unit to a digital line without converting the digital modulation signal into an analog signal.