JPS63193743A - Data modulator/demodulator - Google Patents

Abstract

PURPOSE:To automatically follow opposite communication speed, by setting a queue state at first communication speed at the time of issuing a call and the queue state at second communication speed at the time of receiving a call, and switching the speed to the second communication speed with a switching time T1 if no handshake pattern is detected at a call issuing side and the speed to the first communication speed with a switching time T2 (T1>T2) if no carrier is detected at a call incoming side. CONSTITUTION:When the call incoming side sends a modulated wave of 300bps, the data modem 6 of the call issuing side is impossible to detect the handshake pattern of 1200bps, therefore, the side switches the speed to 300bps with the switching time T1, and outputs the modulated wave of 300bps. In such a way, it is possible to communicate with each other with a rate of 300bps. Also, the data modem 6 of the call incoming side sends the modulated wave of 300bps, however, when detecting no carrier from an opposite side, it switches the rate to 1200bps with the switching time T2(T2<T1), then, sends a UB1. And since the data modem 6 of the call issuing side detects no UB1 within the switching time T1, it is possible to communicate with each other by sending an SB1 at the rate of 1200bps.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data modulation/demodulation device that can automatically follow the communication speed of a partner station.

[Conventional technology]

Recently, data modem equipment is CCITT Recommendation V2 Recommendation AA
Many of them have both the functions of CCITT Recommendation V2 and Recommendation A21 of CCITT Recommendation V2. This CCITT Recommendation V2 Recommendation AA22
The modem has a communication speed of 1200 bps and has a predetermined handshake pattern before entering the data communication state. On the other hand, a modem device compliant with CCITTV21 has a communication speed of 300 bps, has no handshake pattern, and immediately enters a data communication state. Therefore, conventionally,
Set the communication speed manually if the other station is 1200bps, and set the own station to 1200bps and the other station is 300bps.
If so, I manually set my own station to 300 bp.

Therefore, recently the communication speed of the other station is 1200bps or 30bps.
If you don't know 0 bps, K cannot set the communication speed, so there is a method to automatically follow the communication speed of the other station and communicate data. In other words, there is a Ka handshake pattern when the communication speed is 1200 bps, but if the communication speed is 30 bps,
Since there are many handshake patterns at 0 bps, it is not possible to simultaneously monitor 1200 bps and 300 bps, so cA) 1200 bps in standby mode) 8, and if no 1200 bph handshake pattern from the other station is detected, switch to 300 bps, (B) Standby. Set the status to 300 bps and send CD 300 from the other station.
bps 1200 if OFZ pattern cannot be detected
Possible methods include switching to bps.

[Problem that the invention seeks to solve]

Especially in the former case (4), when the other party is the calling party, the conventional data modulator/demodulator described above
1200bpa until switching from bps to 300bps
The handshake pattern (unscrambled binary 1) K has the drawback of outputting incorrect received data to the terminal of the other station.In the case of the latter ω), 3
00 bps, be sure to press F before entering the data communication state.
A restriction that a Z pattern must be sent is required (CCITTV21 does not have this restriction). In addition, if both stations are equipped with modem devices that use this automatic identification method, data communication will only be possible at a communication speed of 300 bps (procedurally, 1200 bps δ
The disadvantage is that the communication speed will never reach

[Rounding method to solve problems]

The data modulation/demodulation device of the present invention is in a standby state at a first communication speed when a call is made, is in a standby state at a second communication state when a call is received, and if a handshake pattern of the first communication speed cannot be detected on the calling side, the data modem is in a standby state at a first communication speed. The communication speed is switched at a switching time T, and if the called side cannot detect a carrier, it is set to switch to the first communication speed at a switching time Tt (T, >'r, ).

[Effect]

This invention can automatically follow the communication speed of the other station.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of a data modulation/demodulation device according to the present invention. In the figure, 1 is an input/output terminal connected to a telephone line (not shown), and 2 is this input/output terminal 1.
a carrier detection circuit that detects the power of a signal input to the 3
is the first communication speed, for example, CCITT recommendation V 22 O12
a first modulation/demodulation section that performs modulation/demodulation of 00 bps %-mode;
is the second communication speed, e.g. CCITT Recommendation V 21 O30
a second modulation/demodulation section that performs O modulation/demodulation (0 bps);
5 monitors the input signal from the carrier detection circuit 2, the input signal from the first modulation/demodulation section 3, and the input signal from the second modulation/demodulation section 4, automatically identifies the communication speed, This is a control section that controls the 2 modem/demodulator 4.

In addition, in FIG. 2, 6 is a data modulation/demodulation device with the above configuration, UB1 indicates an unscrambled binary 1 with a handshake pattern of 1200 bps, and 8B
1 represents a scrambled binary 1 with a 1200 bpa handshake pattern.

Next, the operation of the data modulation/demodulation apparatus having the above configuration will be explained with reference to FIGS. 2(A) to 2(E).

First, when the data modem 6 makes a call, the output is 1200 bpl.
! goes into standby mode. Therefore, when a UBI of 1200 bpfi is received from the called side as shown in FIG. Further, as shown in FIG. 2(b), when the called side sends a modulated wave of 300 bps, the data modulation/demodulation device 6 of the calling side cannot detect the 1200 bps handshake pattern, so the switching time T is shortened.

Then, it switches to 300 bps and outputs a modulated wave of 300 bps. This allows mutual communication at 300 bps. In addition, as shown in FIG. 2, when the data modulation/demodulation device 6 on the called side sends a modulated wave of 300 bpa but cannot detect a carrier from the other party, the data modulation/demodulation device 6 on the called side sends a modulated wave of 300 bpa.
00 bps and sends UBI. Then, since the data modulation/demodulation device 6 on the calling side cannot detect tJBl within the switching time of 1, it sends SB1') 120
They can communicate with each other at 0 bps.

Next, when the data modulation/demodulation device 6 receives a call, it enters a standby state at aoo bps. Therefore, as shown in FIG.
TI), switch to 1200 bps and send UBI. Then, receive the SBI from the calling party.1)
They can communicate with each other at 1200 bpa.

Also, as shown in Figure 2 (E), the calling side uses 300bp
By receiving a modulated wave of s and sending a modulated wave of 300 bps, it is possible to communicate with each other at fi 1200 bp8.

Note that in the case of switching time T, < switching time T, both stations can only communicate data at a communication speed of 300 bpa, so as mentioned above, switching time T, > switching time T
, of course. In addition, in the above-mentioned embodiment, the first multiplication speed is 1200 bps,
Although 300 bps is used as the second multiplication speed, it goes without saying that the present invention is not limited to this.

〔Effect of the invention〕

As described above in detail, the data modulation/demodulation device according to the present invention has the advantage of being able to identify the communication speed of the other station and automatically follow that communication speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a data modulation/demodulation device according to the present invention, and FIGS. 2(A) to 2(E) are diagrams showing the operation of FIG. 1. 1... Input/output terminal, 2... Carrier detection circuit, 3... First modulation section, 4...
...Second modulation section, 5...Control section.

Claims (1)

[Claims] a carrier detection circuit that detects the power of a signal input to an input/output terminal connected to a telephone line; a first modem section that performs modulation and demodulation at a first communication speed; and a second modulation and demodulation section that performs modulation and demodulation at a second communication speed. section, the output of this first modulation/demodulation section, and the second
The output of the modulation/demodulation section and the output of the carrier detection circuit are input, and when making a call, it waits at the first communication speed, and if the other party is not at the first communication speed, it switches to the second communication speed after time T_1, and the call is received. When making a call, standby at the second communication speed, and if the other party is not at the second communication speed, the time is T_2 (however, T_2<T_1)
A data modulation/demodulation device comprising: a control unit that controls a first modulation/demodulation unit and a second modulation/demodulation unit so as to switch to a first communication speed later.