JPS6113833A - Data transmitter in mca system - Google Patents

Abstract

PURPOSE:To transmit efficiently and surely a data by transmitting a check signal of transmission condition from the transmission side at transmission, checking the transmission condition and transmitting the data in the transmission speed suited to the said condition. CONSTITUTION:A forming circuit 11 forms a transmission condition check signal CHCK with a command of a control circuit 30 at the transmission side. The said signal is a digital signal including an error detection signal. The signal CHCK is formed into an MSK signal Sm via selector 13 and a modulation circuit 14 and then transmitted. The signal CHCK is extracted from the signal Sm at the reception side, a check circuit 46 checks the error rate and the result of check CKED is outputted. A transmission speed setting signal RATE is formed in response to the result CKED in the setting circuit 47 and the said signal corresponds the own reception system to the said speed. Further, the result CHED is formed into a CSK signal Sn by a modulation circuit 51 and then transmitted from an antenna 41. The signal Sn is extracted succeedingly at the transmission side, the result CKED is demodulated by a demodulation circuit 22 and a setting signal RATE in the transmission speed is formed by the setting circuit, and the modulation circuit 14 and a terminal equipment 12 are set to the said transmission speed by this signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a technique for efficiently and reliably transmitting digital data in an MCA system.

BACKGROUND TECHNOLOGY AND PROBLEMS In conventional consumer wireless communications, it was not allowed to transmit digital data from fax machines, personal computers, etc., but in the MCA system, it was not allowed to transmit digital data. It is being

However, in this MCA system, the call time for one call is limited to a maximum of 60 seconds (transmission will be forcibly stopped after 60 seconds), so when transmitting digital data, the call time is valid. It is necessary to use it for To achieve this, it is sufficient to transmit data at high speed, but in order to transmit data at high speed, transmission conditions such as S/N must be good.

Therefore, when transmission conditions are poor, it is necessary to improve the transmission conditions by increasing the transmission output or increasing the modulation degree.

However, in the MCA system, transmission power, modulation method, occupied bandwidth, etc. are specified, so it is not possible to improve transmission conditions using the methods described above. Errors may occur in the data obtained, or the conical rate may become large.

OBJECT OF THE INVENTION The present invention attempts to solve such problems.

Summary of the Invention Considering the actual transmission conditions, high-speed data transmission is possible when the distance between the transmitting side and the receiving side is short and there are no obstacles, that is, when the transmission conditions are good. It is. However, if the distance between the sender and the receiver is long and there are obstacles, in other words, if the transmission conditions are poor, high-speed data transmission is not practical due to frequent errors; however, low-speed data transmission This reduces errors and makes it practical.

Therefore, in this invention, when transmitting data,
First, a transmission condition check signal is sent from the sending side to the receiving side to check the transmission conditions between the sending side and the receiving side.
Next, the original data is transmitted at a transmission rate (baud rate) that meets the transmission conditions.

As with the embodiments, FIGS. 1 and 2 show an example of a signal system on the transmitting side and the receiving side.

In FIG. 1, (11) is a transmission condition check signal forming circuit, and (12) is a digital data signal d.
D is a terminal device such as a fax machine or a personal computer, (14) is an MSK modulation circuit (modulation circuit for a modem) that converts digital data into an MSK signal in the audio band, and (15) is a circuit from an FM modulation circuit to a high-frequency power amplifier. This is a transmitting circuit with

In addition, (21) is a receiving circuit that includes a west frequency tuning circuit to an FM demodulation circuit, (22) is an MSK9fi modulation circuit (modem demodulation circuit) that demodulates digital data from an MSK signal, and (23) is a digital data transmission circuit. The speed setting circuit (30) is a system control circuit.

Furthermore, in FIG. 2, (42) is a receiving circuit that includes a commercial wave tuning circuit to an FM demodulation circuit, and (43) is an MS
K demodulation circuit, (45) is a terminal device, (46) is an error check circuit that checks the error rate etc. from the transmitted check and check signals, and (47) is a data reception circuit corresponding to the error check result. This is a setting circuit that sets the speed. Also, (5I) is an MSK modulation circuit, and (52) is an FM
The transmission circuit includes everything from a modulation circuit to a high frequency power amplifier, and (6o) is a system control circuit.

Then, when an operation for making a call is performed, a communication channel is formed between the transmitting side and the receiving side by the system control circuits (30) and (60).

When this communication channel is formed, the data transmission rate is set using the protocol shown in FIG. 3, and the data is transmitted. That is, on the transmission side, a trigger signal is supplied from the control circuit (30) to the formation circuit (11) to form the transmission condition check signal CHCK. This signal CHCK is a digital signal with a predetermined bit pattern or a digital signal including an error detection signal such as BCH. Also, signal C
The transmission speed (bit rate) of H(: is the highest speed.

Then, this check signal CHCK is sent to the selector (13)
MSK signal S is supplied to the modulation circuit (14) through
m, and this signal Sn+ is supplied to the transmitting circuit (15) as an FM signal in the communication channel, and this signal Sn+ is
An M signal is transmitted from the antenna (16).

Then, on the receiving side, this FM signal is transmitted to the antenna (4
1), this is supplied to the receiving circuit (42) and the signal Sm is taken out, this signal 5L11 is supplied to the demodulation circuit (43) and the signal CHCK is taken out, and this signal CHCK is sent through the selector (44). The signal is supplied to a check circuit (46), where the error rate and the like are checked based on the signal CHCK, and the check result CKED is output. Then, this output CKED is supplied to the setting circuit (47) to form a signal RATE for setting the transmission rate corresponding to this check result CKED, and this signal RATE is received by the demodulation circuit (43) and the terminal device (45). These circuits (43) and devices (
45) is set to a reception speed (baud rate) corresponding to the check result CFIED.

Also, the check result CIIED is the modulation time ItpI (51
) is supplied to the MSK signal Sn, and this signal Sn is supplied to the transmitting circuit (52) to be converted into an FM signal and then transmitted through the antenna (41). Note that the transmission speed at this time is, for example, the lowest speed.

Furthermore, the check result CHE port is the control circuit (6
0) to inform that the transmission condition check has been completed, and as a result, the selector (44) is switched to the opposite state as shown in the figure by a control signal from the control circuit (60).

Next, on the transmitting side, the FM signal from the receiving side is received by the antenna (16), and this is sent to the receiving circuit (21).
This signal Sn is supplied to the demodulation circuit (22) to demodulate the check result CKED, and this signal GKHD is supplied to the setting circuit (23) to set the transmission rate setting signal RATE. This signal RATE is supplied to the modulation circuit (14) and the terminal device (12), and these are set to a transmission rate corresponding to the check result CKED.

It is also informed that the check result CKED from the demodulation circuit (22) has been supplied to the control circuit (30) and the transmission condition check result has been returned from the receiving side.
As a result, the selector (13) is switched to a state opposite to that shown in the figure by a control signal from the control circuit (30), and a sending permission signal is supplied from the control circuit (30) to the terminal device (12).

Therefore, from the terminal device (12), the check result CKED
Digital data DAT^ is output at a speed corresponding to . Then, this data DAT is supplied to the modulation circuit (14) through the selector (13) and made into an MSK output 5I11, and this signal 5I11 is further supplied to the transmission circuit (15) to be made into an FM signal and then sent to the antenna (16). Sent through.

Then, on the receiving side, a signal S is sent from the receiving circuit (42).
II+ is taken out, and this signal 5L11 is sent to the demodulation circuit (4
3), the data DAT^ is taken out, and this data is sent to the terminal device (through the selector (44)).
45).

Thus, according to the present invention, digital data is transmitted. In this case, in particular, according to the present invention, the check signal CHCK is transmitted to check the transmission conditions prior to transmitting the digital data DATA. Since the original digital data DATA is transmitted at the transmission speed (baud rate) according to this check result, the data DATA can be transmitted as fast as the transmission conditions allow, and therefore it can be efficiently transmitted to the data DAT. . Further, if the check results show that the transmission conditions are poor, the transmission speed is lowered and the data is transmitted, so that the data DATA can be reliably transmitted.

In addition, in the above description, depending on the modulation method of the signal 5I11, it is not necessary to supply the signal RATE to the circuits (14) and (43).

Effects of the Invention In the MCA system, digital data can be efficiently and reliably transmitted according to transmission conditions.

[Brief explanation of the drawing]

1 and 2 are system diagrams of an example of the present invention, and FIG. 3 is a diagram for explaining the same. (12), (45) are terminal devices, (15),
(52) is a transmitting circuit, (21) and (42) are receiving circuits, and (23). (47) is a setting circuit.

Claims (1)

[Claims] In an apparatus for transmitting digital data from a transmitting side to a receiving side using an MCA system, the transmitting side includes a check signal forming circuit for checking transmission conditions, and a modulating circuit that converts an input signal into an audio band modulated signal; A transmitting circuit that transmits the modulated signal through the communication channel of the MCA system, a receiving circuit that extracts the modulated signal transmitted from the receiving side through the communication channel of the MCA system, and a receiving circuit that extracts the modulated signal from the receiving circuit. and a setting circuit that sets the transmission rate of the transmitting terminal device, and the receiving side has a demodulating circuit that demodulates the signal of Another modulation circuit, a transmitting circuit, a receiving circuit, a demodulating circuit, a setting circuit for setting the transmission speed of the receiving terminal device, and a check for checking the transmission conditions between the transmitting side and the receiving side based on the check signal. When the communication channel is connected, the transmission side extracts the check signal from the formation circuit, supplies this check signal to the transmission circuit through the modulation circuit, and transmits it to the reception side. In the step, the check signal is extracted from the another demodulation circuit and supplied to the check circuit to check the transmission conditions, and the check result is supplied to the another transmission circuit through the another modulation circuit to check the transmission condition. At the same time, the check result is supplied to the another setting circuit to set the transmission speed of the receiving terminal device to a value corresponding to the check result, and on the transmitting side, the receiving circuit performs the above check. The result is taken out, and this check result is supplied to the setting circuit to set the transmission speed of the sending terminal device to a value corresponding to the checking result, and thereafter, digital data from the sending terminal device is transmitted according to the setting circuit. A data transmission device in an MCA system, which extracts and transmits data at a transmission speed of a value determined and supplies the data to the receiving terminal device.