JP3489405B2 - Modem and data transmission method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modem and a data transmission method, and more particularly to a modem and a data transmission method which are characterized by a portion that enables high-speed data transmission.

[0002]

2. Description of the Related Art In recent years, there has been a great demand for transmitting a large amount of data via a public line, such as transmitting a large amount of data in the field of computers, and how to improve the data transmission speed has become a problem.

However, the maximum frequency of signals in the telephone network guaranteed by the telephone company (NTT) is 3.4 kHz.
Since it is z and a signal having a frequency of 3.4 kHz or higher is not passed, there is a restriction from this point.

According to the international standard for data transmission, it is a multiple of 300 bit / sec, that is, 600,
Standards such as 1200 and 2400 bit / sec are provided. Therefore, due to such circumstances and restrictions on the line, the current frequency of 2400 Hz (2.4 kHz) is used as the highest frequency in data transmission. Therefore, as a modem (modulation / demodulation device) that realizes data transmission between computers via a telephone line, high-speed data transmission is often required today, and mainly 2.4 kH.
A transmission frequency of z is used. Therefore, a transmission frequency of 2.4 kHz is also used as a modem.

However, 2400 bits / sec is not sufficient as the data transmission rate, and conventionally, the data transmission rate has been improved under the restriction of the transmission frequency of 2.4 kHz.

FIG. 11 is a diagram illustrating a conventional method for improving the data transmission rate. In the figure (a), 2.4k
It shows a basic example in the case of transmitting 2400 bit / sec data at a frequency of Hz.

In FIG. 1B, which is the first example of the prior art, 2.4 kHz is obtained by superimposing signals of two kinds of wave heights.
It shows a case where data of 4800 bit / sec is transmitted at the frequency of.

FIG. 1C is a second example of the prior art, and it is possible to transmit a plurality of signals (4 in the example in the same figure) within one cycle by shifting the phase from the reference waveform. age,
It shows a case of transmitting data exceeding 2400 bits / sec at a frequency of 2.4 kHz. In the method of FIG. 11 (c), the phase shift currently causes 1
It is possible to transmit about two signals.

[0009]

However, in the method of improving the data transmission rate by the phase shift, there is a limit to the minimum angle of the shiftable phase angle. That is, the data transmission signal is transmitted from the modem to the telephone or exchange to the exchange of the telephone company, and from there to a similar line to reach the other modem. There will be a delay. Therefore, if the phase shift angle becomes smaller than the delay, normal data transmission becomes impossible. Therefore, there is a predetermined limit on the number of signals that can be transmitted within one cycle due to signal delay.

Under these circumstances, when the phase shift technique is used, the data transmission rate of the modem is 2 above.
It is believed that 8.8 kbps will be the limit. However, for future data transmission by modem, further improvement of data transmission speed is required, and reliable signal transmission is possible without deteriorating the signal quality, and data transmission is realized by an inexpensive method. Required to do so.

The present invention has been made in consideration of such circumstances, and enables a reliable signal transmission without degrading the signal quality and a data transmission method capable of improving the data transmission rate. The purpose is to provide.

[0012]

In order to solve the above problems, the invention according to claim 1 uses a plurality of patterns of waveforms having the same frequency and different distances from the rising edge of the waveform to the peak position . Positive / negative and multi-bit data
The most significant bit of the data
Different distances to the peak position and the above multi-bit data
Associate the bit combinations below the most significant bit
By, as well as representing multiple bits of data in one cycle, the input data of a combination of the plurality of patterns
The modem is provided with a pattern selecting means for converting into one of the waveforms and a data transmitting means for transmitting the waveform signal converted by the pattern selecting means to a data transmission line.

Since the present invention is provided with such means, it is possible to transmit a plurality of bits of data for a signal to be sent to a telephone line or the like in one cycle, and it is possible to determine a pattern by the distance from the rising edge of the waveform to the peak position. As a result, reliable signal transmission that is not affected by signal attenuation or the like is possible.

Next, in the invention according to claim 2, in the invention according to claim 1, the pattern selecting means prepares a data sequence forming the waveform of each pattern in advance for each pattern, and uses the data sequence. The data transmitting means is a modem which generates a digital waveform signal having a pattern corresponding to the input data and which performs D / A conversion of the digital waveform signal and transmits it.

Since the present invention is provided with such means,
In addition to the same operational effect as the invention corresponding to claim 1, it is possible to easily and reliably generate a pattern waveform. Further, the invention according to claim 3 uses a receiving means for receiving a waveform signal and a plurality of patterns of waveforms in which the waveform signal has the same frequency and the distance from the rising edge of the waveform to the peak position is different . Different and multi-bit
Correlate the most significant bit of data to determine if the waveform is rising.
From the distance from the peak position to the peak position and the above multi-bit data
The bit combinations below the most significant bit of are associated
Accordingly , when a plurality of bits of data are expressed in one cycle of the waveform signal, it is determined which pattern of the waveform signal the waveform signal has, by the distance from the rising edge of the waveform to the peak position. A modem having a data extracting means for extracting a plurality of bits of data.

Since the present invention is provided with such means, it is possible to reliably and stably take out data from the signal waveform transmitted from the modem of the invention according to claim 1 or 2.

Further, in the invention according to claim 4, in the invention according to claim 3, the data extracting means performs A / D conversion of the waveform signal, and from the rising edge to the peak position by the digitized waveform signal. It is a modem that detects the distance of, and uses the detected distance, and determines the pattern based on the peak position of each preset pattern.

Since the present invention is provided with such means,
The same effect as that of the invention according to claim 3 can be obtained .

[0019]

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. (First Embodiment of the Invention) FIG. 1 is an overall configuration diagram showing an example of a network system to which a modem according to a first embodiment of the present invention is applied.

In this network system, a modem 2 is connected to a computer 1 such as a personal computer or a workstation which is a source of data transmission, and these modems 2 are connected via a telephone line 3. It should be noted that in the network system shown in FIG.
Although shown as an example of a set, a large number of sets are actually connected to each other.

The computer 1 outputs the transmission data to be transmitted to the modem 2 and receives the reception data from the modem 2 when receiving the data. Each modem 2 includes a signal modulation / transmission unit 6 for converting the digital transmission data 4 into an analog signal that can be sent to the telephone line 3, and a signal reception / demodulation unit 7 for converting the received analog signal into digital reception data 5. Is provided. The modem 2 is characterized by the configurations of the signal modulation / transmission unit 6 and the signal reception / demodulation unit 7, and although not shown in particular, it has all the configurations required for data transmission as a modem. It should be noted that this modem 2 may be of a type incorporated in the main body of the computer 1.

FIG. 2 is a block diagram showing the detailed arrangement of the signal modulation / transmission unit and the signal reception / demodulation unit in the modem of this embodiment. As shown in the figure, the signal modulation transmission unit 6 is composed of a pattern selection unit 11, a pattern table 12, a modulation unit 13, a transmission unit 14, and other peripheral elements not shown. In addition, the signal modulation transmission unit 6
A 2.4 kHz signal is used as the transmission frequency.

Although not particularly shown, the signal modulation / transmission unit 6 is applied with the transmission speed improving method by phase shift explained in FIG. 11 (c) in the prior art.
Eight signals are transmitted within one cycle by the phase shift.

The signal modulation / transmission unit 6 uses the positive / negative of the waveform to set the most significant bit, and further creates the signal of the lower 2 bits by using the signals of the special shapes of four types of patterns. In other words, a combination of these patterns makes it possible to transmit a 3-bit signal with a signal wave of 2.4 kHz. Therefore, in the modem of this embodiment, the method of mounting the 3-bit logic on the 2.4 kHz special waveform and the method of the phase shift are combined to obtain 8.0.
A data transmission rate of kbps is realized.

The setting method for these 3 bits will be described below. FIG. 3 is a diagram for explaining the setting of the most significant bit in the modem of this embodiment.

As shown in the figure, when the transmission signal is a wave similar to a sine wave including a rectangular wave or the like, it is distinguished whether the waveform is the positive waveform # 1 or the negative waveform # 2. can do. This is used as one bit for data transmission, and the most significant bit is set.

As shown in the figure, in this embodiment, when the signal waveform is the positive waveform # 1, the most significant bit is set to "1", and when it is the negative waveform # 2, the most significant bit is set. The upper bit is set to "0".

FIG. 4 is a diagram for explaining the setting of bits below the most significant bit in the modem of this embodiment. Patterns A, B, C and D shown in the figure show one cycle of the special shape signal used in the modem of this embodiment.

As described above, four kinds of signals having the same half cycle time but different peak positions are prepared so as to weight two bits. As a result, two bits below the most significant bit are set.

First, in the example shown in the figure, since the waveform is positive, the most significant bit is "1". For the two bits below the most significant bit, as shown in FIG.
"00", pattern B "01", pattern C "1"
0 "and the pattern D is" 11 ". With this, 3-bit data can be transmitted in one cycle, and the receiving side distinguishes the positive / negative of the wave of one cycle and the time from the rise to the peak, that is, 3-bit data is detected by determining the rising position.

FIG. 5 is a diagram showing an example of a waveform having data of 3 bits by the modem of this embodiment. In the figure, an example of two cycles of the waveform generated by the method of FIGS. 3 and 4 is shown. In this way, 6 bits of data can be transmitted in two cycles.

Hereinafter, each concrete configuration for carrying 3-bit data on the 2.4 kHz signal of 1 for one period in the signal modulation transmission unit 6 will be described. The pattern selection unit 11 receives transmission data from the computer 1 and generates a digital waveform signal. That is, the waveform signal of the 3-bit data is generated, and using the pattern table 12,
The transmission data is converted into the above waveform signal sequence.

The pattern table 12 stores the shapes of the patterns A, B, C and D. By holding each data value with respect to time for each pattern, it is possible to provide the shape of a digital waveform signal.

The modulator 13 is composed of a D / A converter 15 and a filter 16. D / A converter 15
Converts a waveform signal of digital 3-bit data received from the pattern selection unit 11 into an analog signal, and the filter 16 removes noise from the analog signal.

The transmitter 14 sends the analog waveform signal output from the modulator 13 to the telephone line 3. Next, the configuration of the signal reception / demodulation unit 7 that receives a signal and determines the logical value will be described.

As shown in FIG. 2, the signal reception demodulator 7
The demodulator 21 and the pattern table 22 are included. Although not particularly shown, the signal receiving / demodulating section 7 is also provided with a means for reproducing the phase shift signal described in FIG. 11 (c) in the prior art, and the means corresponds to the signal modulation / transmitting section 6. There is.

The demodulation section 21 comprises a reception section 23 and an A / D conversion peak point determination section 24. The receiving unit 23 receives an analog waveform signal from the telephone line 3,
It is delivered to the A / D conversion peak point determination unit 24.

The A / D conversion peak point judging section 24 converts the received analog waveform signal into a digital waveform signal, detects the time position from the rising edge to the peak, and refers to the pattern table 22. , It is determined which of the patterns A to D the received waveform signal is. Further, it is also determined whether the waveform signal is a positive waveform or a negative waveform, the received waveform signal sequence is converted into data, and the data is delivered to the computer 1 as received data.

The pattern table 22 stores changes in the values of the patterns A, B, C and D with respect to the time axis. As a result, the A / D conversion peak point determination unit 24 is provided with information about which peak is from the rising edge of the waveform signal.

Next, the operation of the modem according to the embodiment of the present invention configured as above will be described. First,
When the transmission data is sent from the computer 1 to the modem 2, the transmission data is transmitted to the modem 2 by the signal modulation transmission unit 6 in the modem 2.
The waveform is converted into a 2.4 kHz waveform signal including 8 bits in one cycle by phase shift with one cycle of 3 bits.
This signal is further D / A converted and sent to the telephone line 3. Here, the telephone line 3 is an analog line.

On the other hand, on the receiving side, the signal receiving / demodulating section 7 of the modem 2 performs A / D conversion on each waveform signal and also performs wave positive / negative determination and peak point determination, is extracted as received data, and is received side. Sent to computer 1.

The generation operation of the patterns A, B, C or D and the peak point determination operation will be described in more detail with reference to FIGS. 6 and 7. FIG. 6 is an explanatory diagram showing how a waveform of pattern A, B, C or D is generated from transmission data.

In the figure, the case where the pattern B is generated is shown. First, when the pattern selection unit 11 receives the transmission data, the pattern selection unit 11 determines whether the data for which the waveform signal is to be generated has a positive or negative waveform and which of the patterns A to D corresponds. For example, the lower 2 bits are "0"
If it is 1 ", the pattern B is selected.

Here, the data string x1 = b of the pattern B is read from the pattern table 12 by the pattern selection unit 11.
1, x2 = b2, x3 = b3, x4 = b4 ,. ． ． Is taken out, and a digital waveform signal as shown in FIG. In this case, it is assumed that the waveform is positive. In the case of a negative waveform, for example, a digital waveform signal is generated by reversing the positive / negative of the data sequence of pattern B.

Next, this digital waveform signal is applied to the modulator 1.
6 is D / A converted and filtered in FIG.
It becomes an analog waveform signal as shown in (b), and this waveform is sent to the analog telephone line 3 as it is.

FIG. 7 is an explanatory diagram showing how to judge which of the patterns A, B, C or D the received analog waveform signal is. As shown in FIG. 7A, the waveform signal transmitted via the analog line is received by the receiving unit 23, A / D converted by the A / D conversion peak point determining unit 24, and the waveform is positive or negative. The determination and the peak point determination are performed (FIG. 7 (b)).

The peak point determination is performed by the data sequence x1, x2, x3, x4 ,. ． ．
Of the pattern A, B, C or D corresponds to the position from the rising edge of the waveform.

That is, since the position of the peak point from the rising edge of the waveform of each pattern is stored in the pattern table 22, the peak points detected by the A / D conversion peak point determination section 24 are the patterns A, B and C. Alternatively, the pattern determination is performed depending on which one of the D peak points is the closest.

In this way, if the pattern determination of the waveform signal is performed based on the peak point position from the rising edge of the waveform,
Even if the signal is attenuated or slightly distorted during transmission, accurate determination can be performed as long as the approximate waveform shape is maintained. In addition, even if the signal is totally delayed, accurate pattern determination is possible. Therefore, extremely reliable data transmission is performed.

As described above, in the modem and the data transmission method according to the embodiment of the present invention, the most significant bit is set by the positive and negative of the wave, and the four patterns having the same half cycle time and different peak positions are used. The signal of 2 bits is used to perform weighting for 2 bits to perform data transmission and reception data determination and extraction. Therefore, reliable signal transmission can be performed without degrading signal quality in data transmission, and data can be transmitted. The transmission speed can be improved. Specifically, it is possible to realize a transmission rate of 3.33 times per one transmission cycle as compared with the conventional one.

Further, the modem according to the present embodiment digitally generates the above-mentioned four patterns of waveforms by using a predetermined data string stored in the pattern table 12, and D
Since the A / A conversion is performed and the data is transmitted, simple and reliable pattern generation can be performed.

Further, since the modem of this embodiment is configured to judge each pattern by the distance between the rising edge of the waveform and the peak position, the receiving side can reliably detect the logical value from the transmission signal. The transmitted data can be reproduced. Therefore, even if the signal is attenuated or slightly distorted during data transmission, accurate pattern determination can be performed as long as the approximate waveform shape can be maintained. In addition, even if the signal is totally delayed, accurate pattern determination is possible. In the method of this embodiment, for example, the determination can be made more reliably than when the strength of the waveform signal is determined by the threshold value.

Since data transmission by phase shift is also combined in data transmission, it is 8.0 kbp.
A modem with a transmission rate of s can be realized. In addition,
In the present embodiment, two bits are weighted using waveforms of four patterns having different peak positions in a half cycle time, but the present invention is not limited to the case of these four patterns. That is, according to the same idea as shown in the embodiment, more information can be transmitted by increasing the number of patterns of waveforms having different peak positions in a half cycle time. Here, when the number of patterns is 8, the weighting is for 3 bits, and when there are 2 ⁿ patterns, ^{n is} assigned.
It becomes the weighting for bits. (Second Embodiment of the Invention) In the first embodiment,
The case where the modem according to the present invention is used for the analog telephone line 3 has been described. This is more specifically the case where the situation is as shown in FIG.

FIG. 8 is a diagram showing a case where the modem according to the present invention is applied to an analog telephone line. For example, if the telephone line is an analog dedicated line, as shown in the same figure, from the transmitting side to the receiving side,
As described in the first embodiment, a 3-bit signal waveform can be transmitted in one cycle. That is, since the waveform signal capable of transmitting 3-bit data for one period as shown in FIG. 5 is an analog signal, it is possible to transmit 3-bit data with one waveform.

However, in recent years, telephone companies have introduced a mechanism in which telephone lines of homes or offices to exchanges are analog lines, and data transmission between exchanges is performed using digital lines. The present invention cannot be applied to a portion related to a digital line in such data transmission. Further, in such a case, high-speed data transmission is performed in the digital transmission portion and low-speed data transmission is performed in the analog transmission portion, and the analog transmission portion is a bottleneck for speeding up. .

In the present embodiment, application of the modem according to the present invention in such a case will be described. FIG. 9 is a diagram for explaining the second embodiment of the present invention. The same parts as those in FIGS. 1 and 2 are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the modem 2 described in the first embodiment performs D / A conversion of transmission data from the transmission side to the A / D conversion of the exchange 31 and the exchange 33. It applies to the part from the part to the receiving side.

That is, the transmission side exchange 31 and the reception side exchange 33 are each composed of the exchange main body 32 and the modem 2 of the first embodiment. The modem 2 in each of the exchanges 31 and 33 performs A / D conversion and D / A conversion, and exchanges signals with the exchange main body 32 as digital data.

Modem 2 on the transmitting side and modem 2 on the exchange 31
Are connected by an analog line 34, and data transmission similar to that described in the first embodiment is performed. Also, similarly,
The modem 2 of the exchange 33 and the modem 2 on the receiving side are connected by an analog line 35, and the same data transmission as in the first embodiment is performed. Therefore, these analog lines 3
High-speed data transmission is performed in each of the sections via the lines 4 and 35.

Further, since the data transmission between the exchanges 31 and 33 via the digital line 36 is high speed, the high speed data transmission is performed as a whole from the transmitting side to the receiving side.

As described above, in the modem and the data transmission method according to the embodiment of the present invention, the exchange 31 and the exchange 3 are used.
Even when digital data is transmitted between 3
It can be applied between the exchanges 31 and between the exchanges 33 and the receiving side, and high-speed data transmission can be performed as a whole from the transmitting side to the receiving side. (Third Embodiment of the Invention) This embodiment describes application of the modem according to the present invention in a situation similar to that of the second embodiment.

In recent years, A / D and D / A converters have been provided on telephone poles to digitize the transmission from here to the exchanges. In the present embodiment, such A / D and D / A
The modem 2 of this embodiment is provided in the converter.

FIG. 10 is a diagram for explaining the third embodiment of the present invention. The same parts as those in FIG. 9 are designated by the same reference numerals and the description thereof will be omitted. In the case shown in the figure, telephone poles 37, 3
The modem 2 described in the first embodiment is used as the A / D and D / A converter provided in the No. 8.

Therefore, first, the analog data sent from the transmitting modem 2 is transmitted at high speed through the analog line 34, and is converted into digital data by the modem 2 of the telephone pole 37. Then, up to the digital line 39, the transmitting side exchange 40, the digital line 36, the receiving side exchange 41, the digital line 42, and the telephone pole 38, high-speed digital data transmission is performed.

In the telephone pole 38, the D
/ A conversion and modulation are performed, and data is transmitted to the modem 2 on the receiving side via the analog line 35. Data transmission during this time is also performed at the high speed because it is performed by the method of the first embodiment.

Therefore, high-speed data transmission is performed as a whole from the transmitting side to the receiving side. As described above, in the modem and the data transmission method according to the embodiment of the present invention, even when digital data is transmitted between the telephone pole 37 and the telephone pole 38, between the transmission side and the telephone pole 37, the telephone pole 38 is used. It can be applied between the receiving side and the receiving side, and high-speed data transmission can be performed as a whole from the transmitting side to the receiving side.

The present invention is not limited to the above-described embodiments, but can be variously modified without departing from the scope of the invention. For example, in the first embodiment, the case where the modem according to the present invention is connected to a computer and used has been described, but the present invention is not limited to such a usage method, and the second and third embodiments are not limited thereto. As described above, it is also possible to use it as an A / D, D / A conversion function of a switch or the like, and use a computer and a modem as the transmission partner. That is, it is possible to appropriately insert the set of the modems of the present invention at a portion during the analog data transmission to improve the overall data transmission speed of the data transmission system.

Furthermore, in the above-described embodiment, the case of data transmission between computers by a modem has been described, but the application target of the data transmission method of the present invention is not limited to data transmission between computers, and a predetermined transmission frequency is used. The data transmission by signals can be applied to various data transmissions.

In addition, the method described in the embodiments is applied to a storage medium such as a magnetic disk (floppy disk, hard disk, etc.), optical disk (CD-ROM, DVD, etc.), semiconductor memory, etc. as a program that can be executed by a computer. It can also be stored and distributed.

[0071]

As described in detail above, according to the present invention, signal transmission is performed using a plurality of waveform patterns, so that reliable signal transmission can be performed without degrading signal quality and data can be transmitted. A modem and a data transmission method capable of improving the transmission speed can be provided.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an example of a network system to which a modem according to a first embodiment of the present invention is applied.

FIG. 2 is a block diagram showing a detailed configuration of a signal modulation / transmission unit and a signal reception / demodulation unit in the modem of the same embodiment.

FIG. 3 is a diagram explaining setting of the most significant bit in the modem of the same embodiment.

FIG. 4 is an exemplary view for explaining setting of bits below the most significant bit in the modem of the same embodiment.

FIG. 5 is a diagram showing an example of a waveform having data of 3 bits by the modem of the same embodiment.

FIG. 6 is an explanatory diagram showing how a waveform of pattern A, B, C or D is generated from transmission data.

FIG. 7 shows received analog waveform signals of patterns A, B,
Explanatory drawing which shows a mode that it determines whether it is C or D.

FIG. 8 is a diagram showing a case where the modem according to the present invention is applied to an analog telephone line.

FIG. 9 is a diagram illustrating a second embodiment of the present invention.

FIG. 10 is a diagram for explaining the third embodiment of the present invention.

FIG. 11 is a diagram exemplifying a conventional method for improving the data transmission rate.

[Explanation of symbols]

1 ... Calculator 2 ... Modem 3 ... Telephone line 4 ... Transmission data 5 ... Received data 6 ... Signal modulation transmitter 7 ... Signal reception / demodulation unit 11 ... Pattern selection section 12 ... Pattern table 13 ... Modulator 14 ... Transmitter 15 ... D / A converter 16 ... Filter 21 ... Demodulation unit 22 ... Pattern table 23 ... Receiver 24 ... A / D conversion peak point determination unit 31 ... Sending side exchange 33 ... Receiving side exchange 34, 35 ... Analog line 36, 39, 42 ... Digital circuit 37, 38 ... Telephone pole

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04L 27/32

Claims (4)

(57) [Claims] 1. A plurality of patterns of waveforms having the same frequency and different distances from the rising edge of the waveform to the peak position are used.
, The positive / negative of the waveform and the most significant bit of the multi-bit data.
From the rising edge of the waveform to the peak position.
From the distance and from the most significant bit of the above multi-bit data
By associating lower bit combinations with each other, data of a plurality of bits is expressed in one cycle, and pattern selecting means for converting input data into one waveform in the combination of the plurality of patterns, and the pattern selecting means. And a data sending means for sending the waveform signal converted by the above to a data transmission path. 2. The pattern selecting means prepares a data sequence for forming a waveform of each pattern in advance for each pattern, generates a digital waveform signal of a pattern corresponding to the input data using the data sequence, and outputs the data. 2. The modem according to claim 1, wherein the sending means D / A converts the digital waveform signal and sends it. 3. A receiving means for receiving a waveform signal, and a plurality of patterns of waveforms, wherein the waveform signal has the same frequency and the distance from the rising edge of the waveform to the peak position is different .
, The positive / negative of the waveform and the most significant bit of the multi-bit data.
From the rising edge of the waveform to the peak position.
From the distance and from the most significant bit of the above multi-bit data
By associating the bit combinations below,
When a plurality of bits of data are expressed in one cycle of the waveform signal, it is determined which pattern of the waveform the waveform signal has by the distance from the rising edge of the waveform to the peak position. A modem having a data extracting means for extracting. 4. The data extracting means A / D-converts the waveform signal, detects a distance from the rising edge to a peak position by the digitized waveform signal, and uses the detected distance, 4. The modem according to claim 3, wherein the pattern determination is performed based on a preset peak position of each pattern.