JPS5875945A - Transmitter - Google Patents

Abstract

PURPOSE:To realize a sending-back test in online mode through a half-duplex communication transmitter which allows full-duplex communication, by forming a return path in response to a carrier detecting signal from a demodulating circuit and a signal which is not being transmitted from a transmitting circuit. CONSTITUTION:To transmit and receive a normal data signal between a master station 20 and a subordinate station on half-duplex communication basis, the switch 26 of the master station 20 is placed at the side of a transmitting circuit 24, and the switch of the subordinate station 21 is placed at the side of a transmitting circuit 35. For a sending-back test by the master station 20 a data signal from the transmitting circuit 24 of the master station 20 after its carrier signal is modulated by a modulating circuit 25 is inputted through a down transmission line 22 to the demodulating circuit 33 of the subordinate station and while its demodulated signal is outputted to a receiving circuit 34, a carrier detecting signal is inputted to an AND circuit 40; since no signal is being transmitted from the transmitting circuit 35, so the AND circuit 40 generates an output to change over the switch 37, and the output of the transmitting circuit 35 of the subordinate station is sent back from a modulating circuit 36 to make a comparison between the transmitted and received data through the comparing circuit 29 of the master station.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a transmission device that inspects transmission signals when online.

(2) Prior art In general, there are various communication methods for transmission systems that transmit the situation at a remote site to a control unit, and they can be broadly classified into the unidirectional optimization method, the half-21 tohaku method, and the all-21 tohaku method. There are three methods. Among these, the full-duplex communication method is often used in 1-1-1-1-time transmission systems, since the amount of information to be transmitted is large. This full-duplex communication system allows for simultaneous transmission and reception, so it has dedicated lines for both forward and reverse directions. Therefore, in conventional full-duplex communication systems, in fact, in devices that employ a communication method in which transmission and reception are time-dependent, the confirmation check of the transmission signal is performed on the other transmission. It was done using lines. In other words, a repeat test was conducted on the transmission equipment.

Hereinafter, a conventional transmission device employing this type of full-duplex communication system will be explained with reference to FIG. 1 is the master station, 2
is a slave station, and if the transmission line that transmits signals from master station 1 to slave station 2 is the lower transmission line, and the reverse transmission line is the lower transmission line, then the master station 1 and slave station 2 are Down transmission line 3 and soil! ll transmission line 4. Then, the station 1 modulates the carrier signal with the transmitting circuit 5 which outputs the data signal to be sent to the slave station 2, and the data signal h output from the transmitting circuit 5. Is it strange to output the modulated carrier signal to the transmission line 3? Equipped with a demodulation circuit 7 for demodulating the modulated carrier signal transmitted from the slave station 2 by the J7j circuit 6 and the local transmission line 4, and a reception circuit 8 for receiving the demodulated signal of the demodulation circuit 7, The output of the transmitting circuit 5 and the demodulating circuit 7
The configuration is such that the output is selected by a changeover switch 9 disposed on the input side of the modulation circuit 60.

On the other hand, slave station 2 ([1) also has the same configuration as the master station 1. In the figure, IQ is Xukun 1 circuit, 11
12 is a receiving circuit, 12 is a transmitting circuit, 13 is a modulation circuit, and 14 is a changeover switch.

When transmitting a signal from the master station l to the slave station 2 using the twelve lotus communication method in the device configured as described above, the changeover switch 9.14 is set to the transmission circuit l11i! i5 and 12 respectively. In this state, the data signal from the transmission circuit 5 is converted into a modulated carrier signal by the modulation circuit 6 and transmitted to the demodulation circuit 10 of the slave station 2 via the downlink transmission line 3f. The demodulation circuit 10 demodulates the signal into a data signal and inputs it to the reception circuit 11. Next, transmission from the slave station 2 to the master station 1 is carried out via the upstream transmission line 4, with the changeover switch 7.14 left as is, and the master station 1 and slave station 2 are in reverse positions. A transmission similar to that described above takes place.

Next, when conducting a return test of this transmission device, only the changeover switch 14 of the slave station 2 is switched from the output side of the transmitting circuit 12 to the output side of the "recovery" circuit 10. Then, when the transmission circuit 5 of the master station 1 outputs the υ data signal, the modulation circuit 6 → lower transmission line 3 → demodulation circuit 10 → changeover switch 1
The data signal outputted by the transmitting circuit 5 is received by the receiving circuit 9 of the master station 1 through a signal path of 4→modulation circuit 13→transmission line 4→demodulating circuit 8→receiving circuit 9.

(3) Problems with the Prior Art In the signal transmission device with the above configuration, it is difficult to manually operate the changeover switch 14 of the slave station 2 during a return test, or when a specific force is applied during a return test. A /f pilot signal 9 (for example, a tone signal when the transmission signal format is a frequency shift keying system) is sent, and the changeover switch 14 of the slave station 2 is switched by this signal. However, manual switching does not allow testing at all when the system is in regular operation, that is, at main line. One drawback is that the return test cannot be carried out during the local station period.In addition, in square systems that perform automatic switching, the output circuit that outputs a specific pilot signal and the receiver that receives that signal are important. There is a drawback in terms of simplification of the circuit configuration, such as the provision of a circuit.

(4) Purpose of the Invention The present invention provides a transmission device that can always perform signal transmission and return testing simultaneously without adding a specific pilot number when online. The invention relates to a transmission device that performs half-duplex communication capable of full-duplex optimization between a master station and a slave station, in which a carrier detection signal is output from a demodulation circuit, and a carrier detection signal is output from a transmission circuit to indicate whether or not transmission is in progress. The signal is taken out and the switch is changed according to the conditions of these two signals, and the data signal sent from the other station is sent back to the other station again. The above object is achieved by comparing data signals and performing a foldback test.

(6) Embodiment of the invention FIG. 2 shows an embodiment of the invention. 2o is a master station, 21 is a slave station), and both stations 20 and 21 are connected by a lower transmission line 22 and a lower transmission line 23.

The master station 20 is configured as follows.

24 is a transmitting circuit that outputs a data signal to be sent to the slave station 21 and a transmitting signal. Modulation circuit 2 that outputs
5 are connected via a changeover switch 26. Also 2
7 is a demodulation circuit for demodulating the modulated carrier signal transmitted from the slave station 21 through the upstream transmission line 23, and a receiving circuit 28 for receiving the demodulation circuit 270 is connected to this demodulation circuit 27. ing. Furthermore, this receiving circuit 28
A data comparison circuit 29 is connected between the transmitting circuit 24 and the transmitting circuit 24 to compare the transmitted data and received data of both. Further, the output side j of the demodulation circuit 27 or the output side of the transmission circuit 24 is selectively connected to the input side of the modulation circuit 25 by the changeover switch 26. Further, the demodulating circuit 27 and the transmitting circuit 24 output the carrier detection signal of the demodulation circuit 27 and the carrier detection signal line 30 which outputs the carrier detection signal of the transmitting circuit 27 and outputs a signal indicating the transmitting status of the transmitting circuit 24. signal line 3
1 are respectively provided, and the input terminals of an AND circuit 32 are connected to both lines 30' and 31, respectively.

Note that the input end on the transmitting signal line 3) side is an inverted end. The output of the AND circuit 32 causes the changeover switch 26 to perform a switching operation.

Next, the configuration of the slave station 21 is as follows. 33 is transmitted from the master station 20 by the lower transmission line 22.
c A demodulation circuit that demodulates the modulated carrier signal, and a receiving circuit 34 that receives the post-modulated signal of the demodulation circuit 33 is connected to this demodulation circuit 33 . Further, 35 is a transmitting circuit that outputs a data signal to be sent from the slave station 2 to the master station 2o, and this transmitting circuit 35 modulates a carrier signal with the data signal and outputs a modulated carrier signal to the upstream transmission line 23. A modulation circuit 36 is connected via a changeover switch 37.

Also, this changeover switch 37 allows the demodulation circuit 33 to
or the output side of the transmitting circuit 35 is selectively connected to the input 4JAll of the modulating circuit 36. Furthermore, the demodulation circuit 33 and the transmission circuit 3
5, the carrier detection signal line 38 which takes out the carrier detection signal of the old 01 path 33 and the signal indicating the fall i1 during transmission of the transmission circuit 35 are not taken out and the signal line 3 which is being transmitted is
9 is provided, and both lines 3B, , 99 have A
ND circuit circuit 4 people 0 Ru. Note that the input end of the transmitting signal line 390 is an inverted end. The changeover switch 37 performs a switching operation based on the output of the AND circuit 4o. Furthermore, a data comparison circuit 4 is connected between the receiving circuit 34 and the transmitting circuit 35 to compare the transmitted data and received data of both.

Next, to explain the operation of the device configured as above, first, when transmitting and receiving normal data signals between the master station 20 and the slave station 21 using the half-duplex communication method, Master station 2
The switching switch 26 of the slave station 2 is switched to the transmitting circuit 24 side, and the switching switch 37 of the slave station 2 is switched to the transmitting circuit 35 side, in the same manner as in the conventional device shown in FIG. Next, when performing a return test, a data signal is input from the transmitting circuit 24 of the master station 20 to the modulating circuit 25 via the changeover switch 26. This modulation circuit 25 modulates the data signal into a carrier signal for transmission, and this modulated carrier signal is transmitted to the slave station 21 via the lower transmission g122.
The signal is input to the demodulation circuit 33 of. The demodulation circuit 33 outputs the demodulated signal to the reception circuit 34 and at the same time outputs the carrier detection signal to the carrier detection signal line 38. This carrier detection signal is then input to the input terminal of the AND circuit 40 as an "H" level signal. On the other hand, since the transmission circuit 35 uses a half-duplex communication method, the slave station 21
is not in the transmitting state, so no transmitting signal is output. Therefore, since a signal of "L# level" is input to the inverting input terminal of the AND circuit 40, the direct input signal to the AND circuit 40 becomes "H" level. That is, based on this "H" level signal and the "H" level signal of the carrier detection signal, the AND10-circuit 40 outputs a "H" level signal. This °H″
The changeover switch 37 is switched to the transmission circuit 3 by the level output.
5 to the output side of the demodulation circuit 33. Then, the demodulated signal of the demodulation circuit 33 is inputted to the receiving circuit 34 and simultaneously inputted to the modulation circuit 36.

The modulation circuit 36 modulates the carrier signal with the modulation signal, and the modulated one carrier signal is input to the demodulation circuit 27 of the master station 20 via the upstream transmission line 23. This demodulated signal is demodulated by the demodulation 1 circuit 27, and the demodulated signal is input to the receiving circuit 28, and at the same time, the carrier detection signal is output to the carrier detection signal line 30. This carrier detection signal is then input to the input terminal of the AND circuit 32 as an "H" level signal. On the other hand, magnification circuit 2
4, the transmitting signal is sent to A via the transmitting signal line 31.
ND circuit circuit 3 = 0, and the interview input of AND circuit 32 becomes °L" level. In other words, this "L" level signal and the carrier detection signal's °H"H" level cause AND circuit 32 to
Outputs an L''' level signal.

In this "r7" level signal, the changeover switch 26
does not operate and remains in the same autumn state.

Further, the demodulated signal input to the receiving circuit 28 is compared with the transmitted data from the transmitting circuit 24 by the data comparing circuit 29 to check whether the returned data signals match. At this time, the transmission data outputted from the transmission circuit 24 to the data comparison circuit 29 has a delay time equal to the transmission time, taking into account the time required for transmission turnaround.

Furthermore, when performing a loopback test from the slave station 21 to the master station 20, the same operation as above is performed, only that the changeover switches 26 and 37 are in opposite positions, and the data comparison circuit 41 performs the data comparison. It is done by action.

As described above, in the above-mentioned embodiment, it is possible to conduct a return test not from the master station 20 but also from the slave station 21 if necessary. In addition, the data signal that is normally transmitted is in the form of a serial signal connected to the number of signal lines, and this data signal is converted into a parallel signal form in the receiving circuit and sent to the downstream electronic device (not shown in the figure). However, in the above embodiment, the data comparison circuit 29 can be used to check the returned data in serialized code form.

It should be noted that the present invention is not limited to the above embodiments, and can be implemented with various modifications without departing from the gist thereof.

(7) Effects of the Invention According to the present invention, in a transmission device that performs half-duplex communication in a full-duplex communication system, changes 1. Therefore, it is easy to perform foldback tests on digital circuits, demodulation circuits, and transmission lines without the need for special pilot signals for switching switches. Automatic switching of switches can be performed with Sensei. Furthermore, by enabling automatic switching, loopback tests can be performed online simultaneously with data transmission. That is, it is possible to provide a transmission device with a simple configuration that enables repeat testing regardless of whether it is online or offline.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional transmission device, and FIG. 2 is a block diagram of an embodiment of a transmission device according to the present invention. 20... Master station, 21... Slave station, 29.41... Data comparison circuit, 32.40... 1 manual inversion type AND circuit, 30, 38... Carrier detection signal line, 31
, 39·°° Transmitting signal line. Applicant's agent Patent attorney Takehiko Suzue 14-

Claims (1)

[Claims] In a half-duplex communication transmission device capable of full-duplex communication between a master station and a slave station, each of the master station and slave station demodulates a modulated carrier signal sent from the other station using a demodulation circuit. A first means for extracting a carrier detection signal and sending it to the carrier detection signal line; and a second means for extracting a signal being transmitted from a transmitting circuit that transmits data to a partner station and sending it to the transmitting signal line. and a changeover switch that performs a switching operation depending on whether the signals on the two lines are active or not, and selects either the output of the transmitting circuit or the output of the demodulating circuit as an input to the modulating circuit, and the transmitting data of the transmitting circuit. A transmission device comprising a data comparison circuit that compares data received by a reception circuit via the demodulation circuit, and constantly performs a call-back test between a master station and a slave station.