JPH01291556A - Data transmission equipment - Google Patents

Abstract

PURPOSE:To prevent step out between transmission and reception by sending a synchronizing signal from a data converter to a radio equipment for a longer term as the level of the present reception electric field obtained from the radio equipment is lower, and prohibiting the delivery of data from a data terminal equipment to the data converter. CONSTITUTION:The data converter 2 always or periodically receives the information of the present reception electric field RSSi from the radio equipment 3. And a control part 5 turns ON a press signal PTT for the radio equipment 3 as usual when receiving a transmission request RS from the data terminal equipment 1, and also, decides the level of the present reception electric field RSSi, and generates the synchronizing signal SS for a time longer as the level of the reception electric field RSSi goes lower, and sends it out via the radio equipment 3. While the synchronizing signal SS is generated, the data converter 2 supplies a transmission prohibiting signal CS to the data terminal equipment 1, and controls the data converter 2 so as not to send out the data SD of the equipment 2.

Description

[Detailed Description of the Invention] [Summary] Regarding a data transmission device that converts data from a data terminal device using a data conversion device and transmits the converted data using an MCA wireless device, the purpose of this is to prevent synchronization between transmission and reception. The conversion device includes a received electric field level detection unit that detects the level of the received electric field from the MCA wireless device, and when receiving a transmission request from the data terminal device, transmits a synchronization signal to the MCA wireless device for a longer period as the received electric field is lower. and a control section that sends a data transmission prohibition signal to the data terminal device during the period.

[Industrial application field]

The present invention relates to a data transmitting device, and more particularly to a data transmitting device that converts data from a data terminal device using a data converting device and transmits the converted data using an MCA wireless device.

MCA (Multi-channel access) such as MCA radio used for business using a dedicated line, low power radio, etc.
In this type of data transmitting device, it is essential to synchronize transmission and reception, and for this reason, a bit synchronization signal, a frame synchronization signal, etc. are required.

[Conventional technology]

Figure 4 shows the MCA using bit/frame synchronization signals.
A typical block diagram of a data wireless communication system based on the above-described method is shown, in which a data transmitting device on the base station side and a data transmitting device on the mobile station side are connected by a wireless control station 10. The data transmission device in the base station or mobile station includes a data terminal equipment (DTE) 1, a data conversion device 2 as an interface device that performs data rate conversion, etc., and an MC.
A wireless device 3. The data terminal device l on the base station side is, for example, a host computer.

The operation of the data transmitting device of the base station or mobile station in such a communication system will be explained with reference to FIG.

Normally, when making a call, the data terminal device 1 sends a data (telegram) sending request R out of the signal line of the V24-100 interface.
Turn on 3. The data conversion device 2 that received this turns on the press PTT to start up the transmitter (not shown) of the wireless device 3 and sends out a synchronization signal SS (bit synchronization signal BS + frame synchronization signal FS), and then Send data. In the wireless device 3, this synchronization signal SS
and the subsequent data.

[Problem to be solved by the invention]

In such a conventional data transmitting device, data is transmitted if there is a request for data transmission even when the device is in motion, so data loss frequently occurs due to fading or the like.

In this case, the data itself is usually subjected to error correction processing to provide protection against burst errors, random errors, etc., but the bit/frame synchronization signal is not processed.

Therefore, since the period of the bit/frame synchronization signal SS generated by the data conversion device 2 shown in FIG. 5 is always constant, if these bit/frame synchronization signals are lost, the receiving side There was a problem that synchronization could not be achieved and data could not be received.

Therefore, an object of the present invention is to prevent synchronization between transmission and reception in a data transmission device that converts data from a data terminal device using a data conversion device and transmits the converted data using an MCA wireless device.

[Means to solve the problem]

FIG. 1 is a diagram conceptually showing a data transmitting device of the present invention, which has been made to achieve the above object.
A received electric field level detection unit 4 that detects the level of 5I and a data terminal device! When receiving a transmission request RS from 1, the lower the received electric field RSS i, the longer the synchronization signal SS is sent to the MCA radio device 3, and the data SD transmission prohibition signal is sent to the data terminal device 1 during the period. and a control unit 5 that sends C3.

(Function) In the data transmitting device shown in FIG. 1, the data converting device 2 constantly or periodically detects the
Information on the current received electric field RSS j is received from. Then, as shown in the time chart of FIG. 2, when the control unit 5 receives the transmission request R3 from the data terminal device 1, it turns on the press signal PTT to the wireless device 3 as usual, and also outputs the current received electric field R3S l. The synchronization signal SS is generated for a longer time as the level of the received electric field R3Si becomes lower, and is sent out via the wireless device 3. While this synchronization signal SS is being generated, the data conversion device 2 gives a transmission prohibition signal C3 to the data terminal device 1, and controls the data conversion device 2 not to send the data (telegram) SD.

As a result, this data transmitting device lengthens the transmission period of the synchronization signal SS when the received electric field is low due to fading or the like, so that synchronization can be reliably performed on the receiving side.

(Example) Hereinafter, an example of the data transmitting device according to the present invention will be described.

FIG. 3 shows an embodiment of the data conversion device 2 used in the data transmission device of the present invention conceptually shown in FIG. An A/Di converter 11 that constantly or periodically receives the received electric field R3Si from 3 and converts it into a digital signal, and a level converter that divides this digital signal into multi-stage electric field information at fixed time intervals in synchronization with a clock. It is composed of a container 12.

Further, the control unit 5 stores the average value and fluctuation width of the electric field level from the multi-stage electric field information output from the level converter 12, and generates a timer setting value that becomes longer as the electric field level becomes lower from this information. arithmetic circuit 13 and transmission request 1? from data terminal device 1? A timer 14 generates a transmission prohibition signal C3 as a timer signal determined by the timer setting value from the arithmetic circuit 13 by inputting S, and transmits a transmission signal TXD (synchronization signal/transmission data) to the wireless device in response to the transmission request R3. 3, a press generator 16 that generates a press signal to the wireless device 3 in response to the transmission request R3, and a receiver 17 that receives data (telegram)'SD from the data terminal device l; An error correction circuit 18 that corrects errors in this data and sends it to the transmitter 15, a receiver 19 that receives data from the wireless device 3, and a data terminal bag W, l that sends this received data through the error correction circuit 18.
It consists of a transmitter 20 that sends data to Also, transmitter 1
5 is composed of a synchronization signal (bit synchronization signal BS in this case) generator 21, a data transmitter 22, and an OR gate 23.

Next, the operation of the embodiment shown in FIG. 3 will be explained with reference to the time chart shown in FIG.

In the data conversion device 2, the received electric field R35I is constantly or periodically inputted from the wireless device 3 to the A/D converter 11 of the received electric field detector 4, and the received electric field is converted into the received electric field by the electric field level calculation circuit 13 via the level converter 12. A corresponding timer setting value is given to the timer circuit 14.

Here, when a transmission request RS is issued from the data terminal device t, in response to this, the press signal PTT is first turned on from the press generator 16 to start up the wireless device 3, and at the same time, the synchronization signal generator of the transmitter 15 is activated. 21 supplies the bit synchronization signal SS to the radio device 3 via the OR gate 23 as a transmission signal TXD. At this time, the transmission request RS is also given to the timer circuit 14, so in response, the timer circuit 14 sends a transmission prohibition signal C3 to the data terminal device 1.

As a result, the data terminal device 1 cannot send data (telegram) SD for a period T shown in FIG.

Then, when the period T has elapsed, the transmission prohibition signal C8 becomes “H”.
” level, the data terminal bag R1 starts transmitting data SD.

This transmission data SD is sent to the receiver 17 and the error correction circuit 18.
The data is sent to the data transmitter 22 via the . Then, the data transmitter 22 gives a stop control signal to the synchronization signal generator 21 to stop the generation of the bit synchronization signal BS, and also sends the transmission data SD to the radio device 3 from the OR gate 23 as the transmission signal TXD.

In this case, in FIG. 2, a bit synchronization signal generator is used as the synchronization signal generator 21, so the frame synchronization signal FS is generated by the data transmitter 22 after the bit synchronization signal BS is completed. The bit synchronization signal B is sent by the synchronization signal generator 21, which is attached before the SD.
It is also possible to generate not only the frame synchronization signal FS but also the frame synchronization signal FS.

〔Effect of the invention〕

As described above, according to the data transmitting device of the present invention, the lower the current received electric field level obtained from the wireless device, the longer the synchronization signal is sent from the data converter to the wireless device, and the data converter transmits the synchronization signal from the data terminal device to the wireless device. Since the configuration is configured to prohibit the sending of data to the device, the period of the synchronization signal can be made variable depending on the quality of the wireless line.

Therefore, when the line quality is poor, the synchronization signal can be lengthened to prevent synchronization loss, and when the line quality is good, the synchronization signal can be shortened, which has the effect of shortening the data transmission time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the principle configuration of a data transmitting device according to the present invention, FIG. 2 is an operation time chart of the data transmitting device according to the present invention, and FIG. 3 is an implementation of the data transmitting device according to the present invention. FIG. 4 is a block diagram showing an example. FIG. 4 is an overall configuration diagram of a data communication system using a data transmitting device. FIG. 5 is an operation time chart of a conventional data transmitting device. In FIG. 1, 1... data terminal device, 2... data conversion device, 3... wireless device, 4... received electric field detection section, 5... control section. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] Data from a data terminal device (1) is converted into a data conversion device (
2), the data conversion device (2) detects the level of the received electric field (RSSi) from the MCA wireless device (3). A detection unit (4), when receiving a transmission request (RS) from the data terminal device (1), sends a synchronization signal (SS) to the MCA wireless device (3) for a longer period as the received electric field (RSSi) is lower. At the same time, data (SD) is sent to the data terminal device (1) during the period.
) a control unit (5) that sends a transmission prohibition signal (CS).