JPS58207743A - Simulator for rts and dcd - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention is in the field of modem devices used for digital data transmission, in particular for transmitting data on one or more selected channels, The present invention relates to an improvement in a multiplexing modem device in which data transmission occurs on one or more other channels while the channel is periodically inactive.

The data terminal equipment (hereinafter abbreviated as DTE) is interfaced with a modem having a plurality of output terminals, for example four, respectively connected at one terminal of the transmission channel of the remote modem and the other terminal of the transmission channel. is known in this technical field. In order to increase the time efficiency of data transmission, it is known to multiplex output channels on a time division basis. It can communicate with multiple modulators located at various locations, e.g., at remote locations and communicated with telephone lines, or at a central location of the DTE and communicated with fixed wire connections. Reduces the number of parts required for multiple DTEs. Prior to multiport modems, a DTE had to have multiple modems connected to the DTE, each corresponding to each port of the multiport modem.

However, if the multiplex modem connected to the DTE is
One of the features of replacing a multiport modem connected to a TE is that when a port becomes inactive, there is no longer a communication channel connected to that port;
It is known that the indication to the TE is that the channel is out of service, that is, the channel is neither in request-to-send mode (hereinafter abbreviated as RTS) nor in data carrier detection (hereinafter abbreviated as DCD) mode. In contrast to the aforementioned techniques, which use multiple modems between DTE and each transmit channel,
In the technique described above, the communication link between the modem δ and the modem with which it is communicated is not broken, but the communication link between the modem δ and the modem with which it communicates is not interrupted; There are pauses in the data transmission to further remote modems connected to the remote modem. In this case, during multiple pauses during data transmission, the carrier remains between each modulator and demodulator, so that the appropriate RTS and DCD signals also remain in place, while no data is transmitted.

There are several advantages to leaving the appropriate RTS and DCD signals on the DTE while no data is being transmitted. For example, as mentioned in U.S. Pat. There is time spent ensuring its equalization, after which time is wasted due to each apparent loss of conveyor.

Furthermore, if the receiving modem is a multiport modem connected to multiple DTEs or even other remote modems, similar problems will occur with the modem. When each port connected to one of these DTEs becomes inactive during multiplexing, these
The TE or one further remote modem, as appropriate,
It will indicate loss of TS or DCD signal.

In the DCD/RTS simulator, the multiport modem can be operated even during the flow of continuous carrier waves. Generally, in continuous carrier propagation mode, a local DTE sends a request-to-send (RTS) signal to a local modem connected to the local DTE when it wishes to communicate with a remote modem. For this purpose, the data set device (modulator/demodulator) requires that the DTE transmit the RT to the modulator/demodulator.
It must operate to send a Data Set Complete (hereinafter abbreviated as DSR) signal to the DTE to enable it to send an S signal. For example, in a telephone line, a four-wire semi-duplex transmission link, or a two-wire fully duplex transmission link, if the local modem detects the presence of a carrier going to the remote modem. , the modem generates a transmit stop (CTS) signal and is prevented from transmitting the CTS signal to the DTE.

This is because data is being received from a remote modem on that channel.

The carrier wave signal detection may take the form of delayed carrier wave signal detection (hereinafter abbreviated as DCD) in which the carrier wave signal detection is a signal output of a modulation/demodulation device that is delayed by a predetermined time before the DCD signal is generated.

In a multi-port system, it is important that the CD/RTS signal be stopped as appropriate even if a certain port becomes temporarily inoperable. It is also important to protect the means used to accomplish this function from interference and confusion with the stored data being transmitted on the data channel.

To this end, multiple encoding means have been used in the past to adjust multiport modems to appropriately disguise DCI or RTS signals. Additionally, these methods suffer from the drawbacks of being confused and distorted by the existing conventional data that is being transmitted. A typical key for decoding the code is, for example, 00
00...00#, ゝ1111...11''or'
It contained a repeating multi-bit symbol string such as 1oio...10''.

The present invention provides for dropping the DCD signal or data carrier detection signal so that a practical stop rather than an immediate stop of data transmission occurs in order for the transmit modem to perform multi-vote operation. We describe a new method for converting the signal into a signal and transmitting this signal to a remote modem. A feature of the invention is that the modem drops the DCD signal when received by the remote modem and provides a code signal that is always received before the DCD signal drops. It is virtually certain that the code signal will not be repeated again by an erroneous DCD or normal data being sent to prevent the DCD signal from dropping, and the single code signal will be
It is also ensured that it will not be accidentally mixed into the normal data received by the remote modem or DTE.

The problems mentioned above are less important, but rather the problems that tend to impair the effectiveness of the operation of the multi-boat modem device described above. Although there may be other notable problems, the aforementioned problems should be sufficient to explain why conventional multi-boat modems do not have fully satisfactory functionality. .

The foregoing has summarized examples illustrating the most important features of the invention so that the detailed description that follows may be better understood and its contributions to the art may be better appreciated. Of course, the invention has several additional features, which are described in detail below in support of the claims. These features of the invention will become apparent from the following detailed description of preferred embodiments of the invention in conjunction with the accompanying drawings.

Embodiment FIG. 1 shows a block diagram of a transmission network 10 of a multi-boat modem apparatus used in the present invention.

The transmission network IO has four data sources e.g. DT
E, A12, B14, C16, and D18, respectively. Each DTE12 I14.16 and 18
is connected to a modulation/demodulation device 20 whose output can be multiplexed via a transmission line 22, which is, for example, a telephone line. Through multiplexing, the modem 20 selects the data source DTE 12.14.1 to maximize the drive rate of the transmit link 22.
6 and 18, data transmission via link 22 can be time-shared.

A remote modem 24 is connected to the other end of the transmission link 22 and further includes a data storage A26. The remote modem 24 can also multiplex and transmit its received data to an appropriate data storage 26, 28, 30 or 32. Data storage section 26.28.30 and 32
It will be appreciated that the DTEs may be, for example, multiple DTEs or remote modems for transmitting data to additional locations. For the purpose of explaining the invention and for simplifying the description, data repositories 26.28.
30 and 32 are a plurality of DTEs that receive transmitted data for use therein, and multi-boat modems 2o and 24 are DTEAs, B, C and DTE.
Proceed with the post-DTE description. However, it will be appreciated that it may be possible to transmit simultaneously to, for example, DTETE. Furthermore, each DTEA, B, C, or the like may be transmitted. In this way, for example DTEA
11! :B is transmitting data while DTEC and D
is inactive and this data can for example be sent only to the DTED. Furthermore, for example, DTEA for DTEA may be followed by data destined for DTE B. The multiport modem 20.24 is D
The data sent from the TEAs, B, C and D as described above is multiplexed via the transmission link 22 and the received data is sent to the appropriate data repository 26.28.30.3.
Send to 2.

FIG. 2 shows that DTEAs B, C, and D can have data transmitted at various times and at various time intervals, and that this data transmission is caused by the presence of an RTS (Request to Send) signal 34. indicated to be directed. The RTS signal is routed via modems 20 and 24 to the appropriate remote data repository. In this example, DTEA 9B, C or D is each transmit DTEA, B
.

A modulation/demodulation device 111 transmits the DCD signal to C or D, respectively.
□ It is assumed that the data is specified to be returned via 24 and 20 in correspondence with the data source. Thereby, the transmitting DTEA, B, C: or D, can be used for multiplexing via the transmitting link 22 for sharing the receiving and multiplexing to the appropriate data store A, B, C or D. Each data 36, 38, 40, and 42 can be output to the multiport modem 20, respectively.

The operation of the multiport modulators 20 and 24 allows each D
Each data stream output from a TEA, B, C or D is not sent as a continuous stream, but rather is segmented and the data streams from other DTEs, B, C or D are split into two or more phases on a real-time basis. Data 36 in different data streams is received from the DTEA and the data streams 36 are aggregated. When the DTEA is not actually receiving a data stream from the remote modem 24, its DCD must still be maintained for the reasons discussed above.

The multiport modulation/demodulation device 20 includes each DTEA.

Detecting when B, C or D, respectively, drops its RTS signal to indicate that data is no longer being sent, the appropriate data repository A, B.

D
The data that is multiplexed to one of the storage parts is DC.
The D signal is transmitted, and the DCD signal is dropped from the modulator/demodulator 24.

The code signal that has been selected according to the invention may be, for example, at least
128'', ``64'', ``32'', or a relatively long sequence of binary digits ``1'' of 24'' bits.

The remote modem 24 includes logic circuitry for detecting data that is a stream of "1's"KJ' smaller than this transmitted one, e.g. 120.60.24 or 18, within the appropriate TEA, B block. We are prepared.

This is to account for possible transmission errors. The code signal in the incoming data is detected by detecting consecutive 6 bits, eg, a binary number, from a data group within, for example, three 6-bit data groups.
01,1001'', or the hexadecimal number ``'19'', operates additional logic circuitry within the modem 24 that maintains and samples the code signal. is provided to highlight possible transmission errors in one or two of the following.

If this code signal is detected, remote modem 24. G'! TEA, B, C shine or D as appropriate
Send a signal to drop the navel DCD signal. If no code signal is detected, the stored data being examined for code signal detection is normal data and not a code signal, and the appropriate TEA is performed as usual.
, B, C or D.

This code arrangement is a long repeating sequence of multiple bits of data which appears many times in the normal data and which, if confused with the output DCD code signal, will result in the corresponding D being aborted, for the above-mentioned code signal. A string of symbols, for example the binary number "0''.

'This method has an advantage in simulating DCD in multiplexing operation using a sequence of "1" or "01" as described above. Attempting to simultaneously effectively detect two code signals, i.e., a data stream of a certain minimum length of bits and a subsequent code signal of, say, 8 bits, is difficult due to the current nature of the code signals. significantly reduce the possibility of appearing in the data. The longer the repeating data symbols in the initial part of the code signal, the less likely it is that normal data will contain the code signal.

Detection of the code signal in the remote modem 24 can be performed using a single microprocessor. It will be appreciated that other large scale integrated circuits precisely formed with the required logic functions may also be used.

The remote modem 24 has a built-in microprocessor of, for example, 1 (×8 bits).

Demodulated by remote modem 24, e.g.
The data sent to the port connected to A is D T E
When supplied to A, the data is stored by the microprocessor in multiple (×8 bits) bytes in selected storage locations in the microprocessor's RAM (Random Access Memory). At any given point in time, the above storage location is, for example, the last 128 bits (16 bytes) of the data stream allocated to the DTEA.
It represents wo. Lower selected number of bytes, e.g. 15
The byte or 120 bit code signal is stored in a plurality of other memory locations within the microprocessor, for example in a ROM. The microphone (77" Cl processor compares the preceding 16 bytes or 12° bits of data so that each data group constituting 1.5 bytes of the data is selected repeatedly) and outputs a signal, e.g. It is programmed to detect whether the base number ゛OII +l I II contains a sequence of 01''. If a transmission error occurs in one byte of the preceding 16 bytes of data, attempting to detect only the repeating code signal in the 15 bytes of data reveals the possibility of a transmission error. If the microprocessor detects a repeating code signal in a desired byte from the data of the previous incoming byte, the microprocessor detects the next consecutively received preselected number of bits, e.g. 3 (× 8 bits). (7) 7'-data in its RAM and is programmed to compare the respective data with other code signals stored in the desired memory, either ROM or RAM. The other code signal is, for example, 011001'. If each of the preselected number of bytes of data includes the selected other code signal, the microprocessor outputs a signal that causes the DCD signal to be dropped into an appropriate data repository, such as a DTEA. It is programmed as follows.

The foregoing description of the invention has been presented as a particularly preferred embodiment for purposes of explanation and illustration.

However, it will be apparent to those skilled in the art that numerous embodiments and modifications of the apparatus and method of the invention may be made without departing from the spirit or scope of the invention. For example, a particular independent code signal, ie 011001', is selected because it is highly unlikely to occur in normal data. However, other 8-bit code signals consisting of a plurality of randomly selected binary 1's and 0's may be more suitable.

Furthermore, the independent code signals may be 1 or 2 (
x 8 bits) byte of data. As will be understood by those skilled in the art, the specific means described above for revealing possible transmission errors in repetitive data streams or independent code signals may be useful, for example, in by detecting whether each data group in a data stream of some number of bytes less than 16 bytes (if the stream is 128 bits), e.g. Alternatively, this can be easily implemented by further detecting whether or not two consecutive 3-byte data include the above-mentioned selected independent code signal.

Further, by using about 3 bytes, a number smaller than this number of bytes can have another selected code, and it is also possible to detect a transmission error in one or more of these bytes. These and other embodiments of the invention include:
It will be clear to those skilled in the art. These embodiments and modifications that fall within the spirit and scope of the invention are included in the invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the communication network of a multiport modem used in the present invention, and FIG. 2 is a gui gamma gram showing a code signal that is sufficient to drop a DCDi signal to a remote modem. be. 10... Communication network, 12.14.16.
18... Data end not set (M (D ``rE), 20
+ 24-Multiport modulation/demodulation device, 22... Transmission IJ link, 26 Alarm 2B, 30.32... Data storage unit, 34.36/38.40. '42...Data. Patent Applicant: Lacal Data Communications,
1 Patent Attorney Aoyama Hougai representing Inkohoreitirado

Claims (1)

[Claims] (1) a multi-boat data receiving and transmitting device, each boat having a plurality of transmitting ports connected to a remote data receiving and transmitting device via a transmitting link and connected to each one of the plurality of first data terminals; communicating data from each one of the data terminals to each one of a plurality of second data terminals, each terminal connected to one of the plurality of transmitting ports of the remote data receiving and transmitting device; In a data transmission system that transmits and receives data on the basis of
means for maintaining a CD simulation, the means comprising a repeating stream of a plurality of binary digits '1' or 0', or repeating this stream, in the data assigned to and transmitted to each second data terminal; and a means for subsequently detecting the presence of a preselected code of multiple bits in the consecutive received data of a preselected number of bits. Multi-port data transmission system.