JPH022275A - Signal identification system in full duplex - Google Patents

Abstract

PURPOSE:To ensure the communication between different kinds of MODEMs and to attain the mutual connection by allowing a caller receiving a reply signal to seek a reference value in which a received reply signal is within a criterion based on the specific reference value to the reply device so as to identify the reply device. CONSTITUTION:A caller receiving a reply signal uses a means 11 demodulating an input signal to demodulate a reply signal and a means 13 normalizing the amplitude of signal normalizes the amplitude of the demodulated signal. Then a means 14 obtaining a single signal obtains the signal by one tap and a means 18 identifying the signal checks whether or not the reply signal is a signal within the criterion by using a means 16a or 16b identifying the signal by the reference specific to the reply device and the signal by one tap. When the identification signal is within the criterion, the device having the reference sends the reply signal. Then the reply device corresponding to the reply signal is connected.

Description

[Detailed Description of the Invention] [Summary] A two-wire full-duplex modem recognizes and connects a partner modem during a handshake using a signal identification method, and transmits each response signal during a handshake between arbitrary modems. means for demodulating the modulated input signal for the purpose of making the identification possible;
means for normalizing the amplitude of the demodulated input signal; means for obtaining a single signal of the normalized input signal; and means for identifying the signal using the real and imaginary components of the obtained single signal. The system is equipped with the following.

(Industrial Application Field) The present invention relates to a signal identification method in a two-wire full-duplex switched line, and particularly to a signal identification method for a two-wire full-duplex modem to recognize and connect to a partner modem during a handshake. .

[Conventional technology]

In a conventional 2400bps full-duplex modem for a two-wire full-duplex switched line, a modem compatible with CCITT (International Telegraph and Telephone Consultative Committee) recommendations, such as V22 bis or V22,
or a US Bell standard modem, such as the Be 212.
There are models such as "Be Bun Bun" 03.

Among these, the signal transmission method in modems compatible with CCITT recommendations is, for example, in the handshake sequence between V22bis of the same model, after the answering modem 2 connects in response to the call originating from the calling modem 1, as shown in Figure 3. , 210 seconds after a 2150 ms no signal period from the answering modem side.
A response signal of 0Hz is output for about 3300 milliseconds and sent back.

After the response modem 2 transmits the response signal, there is a no-signal period of approximately 75 milliseconds, and then the unscrambled signal "(binary) 1" of 12001)it/s is sent to (
The calling modem 1 outputs an unscrambled 00 or 11 repeated dibit pattern signal S1 at 1200 bits/s for about 711 milliseconds (until it detects the end of the repeated dibit pattern signal S1 sent out). Output for about 100 milliseconds, then 1200
bit/s scrambled signal “(binary) 1
" is output for about 600 milliseconds, and then 2400b is output.
it/s scrambled signal “(binary) 1”
is output for about 200 milliseconds, and then data is sent to the calling modem 1 side.

The calling modem 1 receives the response signal and connects with the response modem 2, and the response modem 2 transmits an unscrambled signal "1" of 1200 bit/s, and from the first time about 6
After 11 milliseconds have elapsed, a 1200 bit/s scrambled signal "(binary) 1" is output for about 700 milliseconds, and then a 2400 bit/s scrambled signal "(binary) 1" is output for about 700 milliseconds. After outputting for 200 milliseconds, the data is sent to the response modem 2 side.

Also, in the handshake sequence between different types of V22 bis calling modem and V22 answering modem, the fourth
As shown in the figure, after the V22 response modem 4 connects in response to the call originating from the V22bis calling modem 3, there is a no-signal period of about 2150 milliseconds from the V22 response modem 4 side, and then the V22 response modem 4 connects.
A response signal of 1.0 Hz is output for approximately 3300 milliseconds and sent back.

In the V22 response modem 4, there is a 75 millisecond no-signal period after sending the response signal, and then 1200 bits/
s unscrambled signal "1" for about 981 milliseconds, followed by outputting a 1200 bit/s scrambled signal "1" for about 765 milliseconds, and then
The data is sent to the V22 bis calling modem 3 side.

The V22bis calling modem 3 receives the response signal and
V22 response modem 4 is connected to V22 response modem 4, and V22 response modem 4 is connected to 12
00 bit/s unscrambled signal “1
” After approximately 611 milliseconds elapsed since the first message, 1200
The unscrambled OO or 11 repeating dibit pattern signal S1 in bit/s is about 10
It outputs for 0 milliseconds, and then outputs a 1200 bit/s scrambled signal "1" for about 1305 milliseconds, and then sends the data to the V22 response modem 4 side.

For example, in the handshake sequence between Be11212 models of the same model, the signal transmission method in the Bell standard modem is as shown in FIG. 6 transmits a 2225Hz response signal after a predetermined time elapses, and continues to transmit a 2225Hz response signal.
The calling modem 5 outputs a scrambled signal "1" of 00 bit/s, then sends data, and after receiving the response signal, the calling modem 5 outputs a scrambled signal "1" of 1200 bit/s. , then sends the data.

In the case of a handshake sequence between Be statements 1103 of the same model, as shown in FIG. After receiving the calling modem 7's calling signal, the calling modem 7 sends a response signal, then sends data (after receiving the calling modem 7's calling signal), and after the calling modem 7 receives the response signal,
After a predetermined period of time has elapsed, a 1270 Hz calling signal is transmitted, and then data is transmitted.

As described above, the signal transmission method in a modem differs depending on the standard or standard that the model complies with.

[Problem to be solved by the invention]

Transmission speed 240 connected to the above conventional full-duplex switched line
When transmitting signals between 0bps full-duplex modems, the modem of the other station connected via a switched line can be a CCITT recommendation compatible modem or a US Bell standard modem, and it is unclear which modem is connected. be. Therefore, as explained in the above-mentioned conventional technology, the frequency of the response signal during handshake is different between the CCITT Recommendation compliant modem and the Bell standard modem of the United States, and between different models of Bell standard modem. There was a problem in that it could not be identified and could not be received, making it impossible to perform a handshake.

The present invention has been made in view of the above problems, and the technical problem set for solving the problem is to make it possible to identify each response signal during handshake between arbitrary modems. The object of the present invention is to provide a signal identification method in a full-duplex switched line.

(Means for Solving the Problems) As a specific means for solving the above-mentioned problems, the present invention provides, as a specific means for solving the above problems, a signal identification method for a full-duplex switched line, in which modulation is performed as shown in FIG. means 11 for demodulating the input signal carried by the carrier, means 13 for normalizing the amplitude of the demodulated signal, means 14 for obtaining a single signal of the normalized signal, and means 14 for obtaining a single signal of the normalized signal; It is provided with means 16 for identifying signals using real number components and imaginary number components.

Specifically, the input signal ACO5ωt of the frequency f that has been modulated and carried is converted into the signal Aexp (j(ω−ω.)1
), ROF (roll-off filter) 12 for removing noise from the demodulated signal, and means (AGC) 13 for normalizing the amplitude of the demodulated and noise-removed signal.
, the normalized signal exp (j (ω-ω.)1) and the signal exp delayed by one symbol by the delay device 14a.
(j(ω-ω.)t-T) to produce a single signal (signal for one tap) exp(-j(ω-ω.)T
) and the single signal exp(-j
Low-pass filter 1 that removes high-frequency components of (ω-ω,)T)
5 and a single signal exp(-j(ω
−ω・)T), real component)c=cos (ω−
ω. )T and the imaginary component y=-sin(ω-ω.) The sum of the squares of the values obtained by subtracting the real component hX and imaginary component hy of the specified threshold specific to the response device from T, respectively (X-
ThX)2+(y-Thy)2 is smaller than the threshold Th of the amplitude of the judgment condition and
means 16a for identifying a signal as a device having X, Thy sending and responding to the input signal; and a value y/I x I obtained by dividing the imaginary component y by the absolute value of the real component X.
means 16b for identifying the signal as having been sent and responded to by a device having the specified value tanφ when is larger than a specified value tanφ specific to the responding device;
The present invention includes means 16 for identifying a signal using the real component and imaginary component of a single signal having .

[Effect]

According to the above configuration, the present invention provides a response device (response modem) that transmits a response signal in response to a call from a calling device (calling modem) when a plurality of connectable devices each transmits response signals of different frequencies. For identification, the calling device that has received the response signal demodulates the response signal using the means 11 for demodulating the input signal, normalizes the amplitude of the demodulated signal using the means 13 for normalizing the amplitude of the signal, and then The means 14 for obtaining a signal obtains a signal for one tap, and the means 16 for identifying the signal obtains a signal for one tap and a reference value specific to the response device (specified thresholds ThX, Thy, amplitude threshold Th , or specified value tanφ), the response signal is smaller than the judgment condition (amplitude threshold Th or specified value t
whether the signal falls within the range of (greater than anφ),
The signal identifying means 16a or 16b examines the signal, and the signal identifying means 16a identifies the signal (x-ThX'
)2+ (y-Thy)2-Th becomes negative or the means 16b for identifying the signal determines that the signal X17anφ-y
If becomes negative, it is assumed that the signal is within the range of the determination condition, and that a device having the reference value at that time has sent a response signal, and by performing a handshake corresponding to that device and connecting, To enable sales by hand with a response device compatible with response signals.

〔Example 〕

Below, as an example of the present invention, answer back tone or 1
The case of detecting a 270 Hz, 2100 Hz, or 2225 Hz tone or an unscrambled binary 1 at 1200 bps will be illustrated and explained.

As shown in FIG.
-ω. ) A demodulating means 21 is provided for demodulating 1). Means 2
On the output side of 1, there is an ROF (ROF) that removes noise from the demodulated signal.
A roll-off filter) 22 is provided. A normalization means (AGC) 2 for normalizing the amplitude of the signal is provided on the output side of the ROF 22.
3 will be provided. A multiplier 24a is provided on the output side of the normalization means 23.
At the same time, a delay device 24b is branched to the output side of the normalization means 23, and the output side of the delay device 24b is connected to the multiplier 2.
Connect it to - on the input side of 4a to output the normalized signal ex.
p (j (ω-ω.) 1) and the signal exp (j (ω-ω.) t-T) delayed by one symbol are multiplied by the complex conjugate to produce a single signal (signal for one tack) exp ( −j(ω−
forming means 24 for obtaining ωc)T). Multiplier 24a
The resulting single signal exp(-j(ω-ω
. ) A low-pass filter 25 is provided to remove high-frequency components of T).

At the output side of the low-pass filter 25, a single signal exp(-
j(ω-ω.)T) real number component X=cos(ω-ω.

)T and the imaginary component y=-sin(ω-ωc)T, 210
The negative of the real component hX=1 and the imaginary component hy=1 of a defined threshold specific to a device (not shown) responding with a 0Hz tone.
Adders 26 and 27 that each add 0 are connected, multipliers 28 and 29 that square each output value are connected to each of the output sides of the adders 26 and 27, and each output value is connected to the output side of the multipliers 28 and 29. An adder 30 for adding values is connected, and an adder 31 for adding a negative number -Th of the amplitude threshold Th as a determination condition is further connected to the output side of the adder 30 to form a signal identifying means 32.

On the output side of the low-pass filter 25, there is a 2225 filter with a similar configuration.
an adder that adds the negative number of the real component h 33. Signal identification means 35 comprising 34
and the real component hX=cos(7π/30
) and the imaginary component, = sin(-7π/30)
A signal identification means 38 is connected in parallel with the signal identification means 32, comprising adders 36, 37 for adding the negative numbers of .

Furthermore, an absolute value calculating means 39 for calculating the absolute value 1xl of the real number component X of the output is connected to the output side of the low-pass filter 25, and the absolute value IXI
A multiplier 40 is connected to the output side of the multiplier 40, which adds a negative number of the imaginary component y of the low-pass filter output to the output side of the multiplier 40. If the value y/lxl obtained by dividing the imaginary component y of the output of 25 by the absolute value of the real component The signal identifying means 42 is connected in parallel with the signal identifying means 32 so that y becomes a negative value, and in this case, the signal identifying means 42 identifies the signal as having sent an unscrambled binary 1 at 1200 bps as a response.

These signal identification means 32, 35, 38.degree. 42 are put together to form a signal identification means 43 that identifies a signal using the real component and imaginary component of a single signal.

When this embodiment configured as described above is used, the following will occur.

demodulation stage 2 to which the response signal Acosωt of frequency f is input;
1, the signal A e x p (J (ω-ωC)t)
The amplitude of the demodulated and noise-removed signal is normalized by a normalizing means 23. Normalized signal exp (j
(ω-ω.)1) The means 24 for obtaining a single signal from the normalized signal and its one-symbol delayed signal ex
p (j (ω-ω.)t-T) is multiplied by a conjugate complex number to produce a single signal (for one tack) exp<-j(ω-ωC
) obtain T). The resulting single signal exp(-j(ω-
ω. )T), high-frequency components are removed by a low-pass filter 15.

The signal identifying means 43 receives the single signal from which the high-frequency components have been removed, and receives the single signal exp(-j
(ω-ωc)T) real number component X=cos (ω-7,L
). )T and the imaginary component y=-sin(ω-ω.)T respectively by the signal identifying means 32°35.38. and 42 for identification.

The signal identification means 32, 35, and 38 respectively determine the real number components hX=−1, cos (7π/12), and c of the specified threshold values.
os (7π/30) and the imaginary component hy=O, s i
n (7π/12) and s in (-7π/30) are subtracted by adders 26, 33.36 and adders 27, 34, and 37, respectively, and the values are subtracted by multipliers 28. ...and multiplier 29. The squared real number component and the imaginary number component are added by the adder 30, and the adder 31
．． ..., the value of the sum of squares (x-Thx) 2+ (
'J Thy) Subtract the threshold Th from 2 and output the negative result as the specified threshold ThX.
, Thy, the input signal, i.e. 210
0Hz.

Assume that a response is sent by sending 2225 Hz and 1270 Hz tones.

In the signal identification means 42, the absolute value calculation means 39 calculates the absolute value IX+ of the real component X of the output of the low-pass filter 25, and the multiplier 40 multiplies the output by a specified value tanφ.
The adder 41 adds the negative number of the imaginary component y of the low-pass filter output to the output of the multiplier 40, and if the value is a negative value,
Assume that a response is sent by sending an unscrambled binary number 1 at 1200 bps.

For the response signal Acosωt of frequency f, the signal identifying means 43 identifies the signal identifying means 32, 35° 38, and 42
One of them outputs a signal with a negative value, so by sending that signal and connecting to the device that responded, 12
70Hz.

2100Hz, 2225Hz)-on, or 1200b
By detecting the unscrambled binary 1 of ps, they are identified and connected.

In this example, the frequency is 1270Hz.

2100Hz, 2225Hz tone, or 1200b
A BefLu103 calling modem, a V22 answering modem or a V22bis answering modem, a Be1u103 answering modem or a Be11212 answering modem, or V22bis
A handshake to the calling modem can be performed and the connection can be established.

(Effects of the Invention) As described above, in the present invention, the calling device that has received the response signal searches for a reference value within which the received response signal falls within the range of the determination condition based on the reference value specific to the response device. By making it possible to identify the device that has the found reference value as the response device that sent the response signal, it is now possible to have the identified response device perform a handshake corresponding to the connection sale, and arbitrarily A calling device that can be connected to any answering device, and a answering device that can be connected to any calling device.

As a result, compatibility can be ensured between the CCITT Recommendation compliant modem and the American Bell standard modem, and even between different types of Bell standard modems, allowing them to connect to each other.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a signal identification method according to the present invention, FIG. 2 is a block diagram showing a signal identification method according to an embodiment, and FIG. 3 shows a handshake sequence between V 22 b i s. The explanatory diagram, Figure 4, shows the handshake between V22bis and V22.
An explanatory diagram showing the sequence, FIG. 5 is a handshake between Be sentences 212. An explanatory diagram showing a sequence. FIG. 6 is an explanatory diagram showing a handshake sequence between Be11103. 11...Means for demodulating the input signal 13...Means for normalizing the amplitude 14...Means for obtaining a single signal 16...Means for identifying the signal

Claims (1)

[Claims] means (1) for demodulating the input signal that has been modulated and conveyed;
1) and means (13) for normalizing the amplitude of the demodulated signal.
and means (14) for obtaining a single normalized signal; and means (16) for identifying a signal using the real component and imaginary component of the obtained single signal. signal identification method for full-duplex switched lines.