JPH11186949A - Tifu system and aircraft satellite communication system using the tifu system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a terminal interface function unit(TIFU) that prevents the malfunctions of plural terminals from being switched into a different communication mode during communication and that conducts accurate communications and to provide the aircraft satellite communication system using the TIFU. SOLUTION: TIFUs 151, 153 are installed respectively to a ground station 15 and an aircraft station 17 that make communications via a satellite 16. The TIFU 151 (173) is provided with an identification means 151b (173b) that identifies a facsimile signal or a voice signal, by discriminating whether or not each amplitude of the facsimile signal and the voice signal for each frequency band of a prescribed level at the frequency band of the received signal including at least the facsimile signal and the voice signal. The TIFUs are also provided with a communication mode conversion means 151a (173a) that converts the communication mode of its own equipment so as to apply signal processing to only the identified signal component, based on the identification result by the identification means 151b (173b).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TIFU apparatus for performing voice / facsimile / data communication between a ground station connected to a general public network via a satellite line and an aircraft station installed on an aircraft. And an improvement of an aeronautical satellite communication system using the TIFU device.

[0002]

2. Description of the Related Art Generally, a ground station GES (Ground Earth Station) connected to a public network via a satellite line and an aircraft station AES (Aircraft Earth Statio) installed on an aircraft.
An aeronautical satellite communication system for performing voice / facsimile (hereinafter, referred to as FAX) / data communication with n) is configured, for example, as shown in FIG.

That is, various terminals such as a telephone 11, a facsimile machine 12, and a personal computer 13 are connected to a ground station 15 via a network 14 such as an external communication network.
Then, signals generated from various terminals are input to the TIFU device 151 in the ground station 15. The TIFU unit 151 includes a voice / fax / data communication unit 151a.

[0004] An output signal from the TIFU unit 151 is modulated by a satellite modem 152, emitted as a radio wave via an antenna 153, and received by the antenna 171 of the aircraft station 17 via the satellite 16. The signal received by the antenna 171 is demodulated by the satellite modem 172,
It is supplied to the U device 173. Also, the TIFU device 173
As in the case of the TIFU device 151, voice / fax /
A data communication unit 173a is provided, and is connected to various terminals such as a telephone 18, a FAX 19, and a personal computer 20 on an aircraft.

[0005] The output signal of the TIFU unit 173 is
8, a facsimile 19, a personal computer 20, and other various terminals. For this reason, telephone 11, fax 12
Also, various terminals such as the personal computer 13 can communicate with various terminals such as the telephone 18, the FAX 19, and the personal computer 20 on the aircraft.

In the aeronautical satellite communication system described above, all signals corresponding to various terminals are handled transparently during voice communication or FAX / data communication. HDLC (High Leve) with 30 protocols
l Data Link Control) signal is not confirmed, and the distinction between voice communication and FAX communication is made by judging the V.21ch2 preamble signal of FAX. Therefore, T
If a spectrum component close to the facsimile V.21ch2 preamble signal is present during voice communication by the IFU device, it is erroneously converted to the facsimile communication mode, and voice communication cannot be performed during that time. Further, there is a problem that a preamble sound of V.21ch2 of FAX is mixed for several seconds during voice communication.

[0007]

As described above, in the conventional TIFU apparatus, the distinction between voice communication and fax communication is made by F.
Since the determination is made based on the determination of the AX V.21ch2 preamble signal, if a spectrum component close to the FAX V.21ch2 preamble signal is present during voice communication, there is a problem that the FAX communication mode is erroneously converted. ing.

An object of the present invention is to provide a TIFU device capable of preventing a malfunction of switching to a different communication mode during communication with a plurality of types of terminals and performing accurate communication, and an aeronautical satellite communication system using this device. It is in.

[0009]

Means for Solving the Problems TIFU according to the present invention
The device is a device installed in a communication station that performs communication via a satellite, and in a frequency band of a signal including at least a facsimile signal and a voice signal that are input, an amplitude level of a frequency band of each signal is a predetermined level. By determining whether or not this is the case, an identification unit for identifying the facsimile signal and the audio signal, and a communication mode of the own apparatus so as to perform signal processing of only the identified signal component based on the identification result by the identification unit. And a communication mode conversion means for converting

According to this configuration, in the frequency band of the input signal, it is determined whether or not the amplitude level of the frequency band of the signal corresponding to each of a plurality of types of terminals is equal to or higher than a predetermined level, so that the input signal is A determination is made as to whether the signal is a facsimile signal or a voice signal, and based on the result of the determination, the communication mode of the own device is converted to a communication mode in which signal processing is performed only for the signal components for which the determination has been made.

As a result, when a facsimile signal having a frequency close to the voice signal is input to the various terminals, for example, during communication of the voice signal, the terminal switches to a different communication mode by determining its amplitude level. Malfunction can be prevented, and accurate communication can be performed.

Further, the TIFU device according to the present invention is mounted on a ground station connected to a communication line and an aircraft station connected to a communication line installed on an aircraft, respectively. Are connected to each other by a wireless channel via a satellite, and are used for an aeronautical satellite communication system for communicating with each other.

The TIFU unit identifies signal components by comparing amplitude levels in respective frequency bands with at least an input signal including a facsimile signal and a voice signal generated from one communication line, and identifies the signal component. After the communication mode of the own device is converted based on the identification result, the identified signal is transmitted from the ground station to the aircraft station or from the aircraft station to the ground station and provided to the other communication line.

According to this configuration, for example, when a facsimile signal having a frequency close to the voice signal is input between the aircraft station and the ground station during communication of the voice signal to various terminals, for example, By judging the amplitude level, a malfunction such as switching to a different communication mode can be prevented, and accurate communication can be performed.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of an aeronautical satellite communication system using a TIFU device according to the present invention.

In FIG. 1, the same parts as those of FIG. The difference from FIG. 4 is that the TIFU device 151 of the ground station 15 has a voice / fax identification unit 151b.
And the TIFU unit 173 of the aircraft station 17
This is a point that a facsimile identification unit 173b is provided. That is, the voice / fax identification means 151b discriminates a voice signal and a facsimile (hereinafter, referred to as a facsimile) for an input signal, and at least in a frequency band of the facsimile signal and the voice signal for facsimile. The facsimile signal and the voice signal are identified by determining whether the amplitude level of the specified frequency band is equal to or higher than a predetermined level.

The identified signal is supplied to a voice / fax / data communication unit 151a. The voice / fax / data communication unit 151a is a voice / fax identification unit 151.
The communication mode is converted so that signal processing of only the identified signal component is performed based on the identification result by b. When the identified signal is a voice signal, the voice / fax / data communication unit 151a forms a fixed-length frame after converting the digital signal into, for example, 9.6 kbps digital data by a voice codec. After converting to digital data of, for example, 9.6 kbps at maximum depending on the transmission speed, error correction is added to form a fixed-length frame, and thereafter,
The satellite 16 is transmitted from the antenna 153 via the satellite modem 152 to the satellite 16.
Send to

At the aircraft station 17, the signal received via the satellite 16 is received by the antenna 171, converted to digital data of, for example, 9.6 Kbps via the satellite modem 172, and supplied to the TIFU 173. The TIFU device 173 detects any one of voice / fax / data from the received signal, and thereafter transmits it to the corresponding telephone 18, fax 19 and various terminals of the personal computer 20.

FIG. 2 shows the spectrum characteristics in the frequency band of the audio signal and the FAX signal identified by the audio / FAX identification means 151b. In FIG. 2, the horizontal axis represents frequency, and the vertical axis represents amplitude level.

That is, the voice / fax identification means 151b
Calculates the amplitude level of the V.21ch2 signal band (BF) of the facsimile and the amplitude level of the other audio bands (BL, BH). FIG. 2 (a) shows the state during voice communication or facsimile.
FIG. 2B shows a state in which there is noise during communication.
The state at the time of AX communication is shown.

Here, the voice / fax identification means 151b
Operates as shown in the flowchart of FIG. First, it is determined whether or not the amplitude level of the FAX signal is equal to or higher than a predetermined level α (step S11). If the amplitude level is not equal to or higher than α (NO), it is determined that the input signal is a voice signal (step S12). If the amplitude level of the FAX signal is equal to or greater than α (YES), the difference between the average amplitude level and the average amplitude level obtained by normalizing the audio band (BL, BH) by frequency is determined (step S13). In some cases (YE
In S), it is determined that the input signal is a facsimile signal (step S14). If the value is not equal to or more than the predetermined value (NO),
The process proceeds to step S12, where it is determined that the input signal is an audio signal.

Further, the voice / fax identification means 151b
As a second detection process, it is determined whether or not the V.21ch2 signal of the FAX identified by the amplitude level comparison process in the frequency band of the input signal is demodulated to detect the preamble signal “7E”. If "7E" is detected here, this information is sent to the voice / fax / data communication means 151a. At this point, the voice / fax / data communication means 151
a is shifted to the FAX mode.

Therefore, according to the above embodiment, for example, the voice / fax identification means 151b of the ground station 15 sets the frequency band of the signal corresponding to the telephone 11, the facsimile 12 and the personal computer 13 in the frequency band of the input signal. The signal component is determined by determining whether or not the amplitude level is equal to or higher than a predetermined level (α). Based on the determination result, the communication mode of the own device is determined by the voice / fax communication unit 151a. The communication mode is converted to a communication mode in which signal processing is performed only on the signal components. Thereafter, the identified signal is transmitted to the aircraft station 17 via the satellite 16 and given to the terminal corresponding to one of the telephone 18, the FAX 19 and the personal computer 20 by the TIFU unit 173.

Therefore, for example, during communication of an audio signal to various terminals, an FA having a frequency close to the audio signal is used.
By determining the amplitude level when the X signal is input, it is possible to prevent a malfunction such as switching to a different communication mode and perform accurate communication. Further, a case where signals corresponding to various terminals are transmitted from the aircraft station 17 to the ground station 15 can be similarly implemented.

Further, the voice / FAX discriminating means 151b detects whether the preamble signal of the FAX signal is included in the determined signal component after the process of determining the amplitude level of the frequency band, so that more is obtained. Accurate communication can be performed. The process of detecting the preamble signal of the FAX signal may be performed simultaneously with the process of determining the amplitude level of the frequency band.

It should be noted that the present invention is not necessarily limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0027]

As described in detail above, according to the present invention,
TIF that can prevent incorrect operation of switching to a different communication mode during communication with multiple types of terminals and perform accurate communication
A U-device can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an aeronautical satellite communication system using a TIFU device according to the present invention.

FIG. 2 is a spectrum characteristic diagram in a frequency band of the voice signal and the FAX signal identified by the voice / FAX identification unit of the embodiment.

FIG. 3 is an exemplary flowchart for explaining the processing operation of the voice / fax identification means according to the embodiment;

FIG. 4 is a block diagram showing a conventional aeronautical satellite communication system.

[Explanation of symbols]

 11, 18: Telephone, 12, 19: FAX, 13, 20: Personal computer, 14: Network, 15: Ground station, 17: Aircraft station 151, 173: TIFU device, 151a, 173a: Voice / FAX / data communication means 151b, 173b voice / fax identification means, 152, 172 satellite modem, 153, 171 antenna, 16 satellite.

Claims (6)

[Claims] 1. An apparatus installed in a communication station that performs communication via a satellite, wherein an amplitude level of a frequency band of each signal is at least in a frequency band of a signal including at least a facsimile signal and a voice signal. Determining whether or not the signal level is equal to or higher than a predetermined level; identifying means for identifying the facsimile signal and the audio signal; and automatically performing signal processing of only the identified signal component based on an identification result by the identifying means. And a communication mode conversion means for converting a communication mode of the device.
nit) equipment. 2. The method according to claim 1, wherein the identifying unit is configured to output the facsimile signal when the amplitude level of the frequency band specified for the facsimile is equal to or higher than a predetermined level and the difference between the amplitude levels of the other frequency bands is equal to or higher than a predetermined value. 2. The TIF according to claim 1, further comprising means for determining that
U device. A ground station connected to a communication line; and an aircraft station connected to a communication line installed on the aircraft,
An aeronautical satellite communication system in which the aircraft station and the ground station are connected by a wireless channel via a satellite and the TIFU device according to claim 1 is mounted on the aircraft station and the ground station. At least a facsimile signal generated from one communication line, an input signal including a voice signal is compared with an amplitude level in each frequency band to identify a signal component. An aeronautical satellite communication system characterized by transmitting an identified signal from the ground station to the aircraft station or from the aircraft station to the ground station after converting the communication mode and providing the signal to the other communication line. 4. An apparatus installed in a communication station that performs communication via a satellite, wherein an amplitude level of a frequency band of each signal is at least in a frequency band of a signal including at least a facsimile signal and a voice signal. First identification means for identifying the facsimile signal and the audio signal by determining whether or not the level is equal to or higher than a predetermined level; and whether or not the identification result of the first identification means includes a preamble signal of the facsimile signal. The second to detect
And communication mode conversion means for converting the communication mode of the own device based on the result of identification by the second identification means so as to perform signal processing of only the identified signal component. A TIFU device characterized by the above-mentioned. 5. The method according to claim 1, wherein the first discriminating means is arranged so that the amplitude level of the frequency band specified for the facsimile is equal to or higher than a predetermined level, and the difference between the amplitude levels of the other frequency bands is equal to or higher than a predetermined value. The communication mode conversion means converts the own apparatus to a facsimile communication mode when a preamble signal of the facsimile signal is detected by the second identification means. 5. The TIF according to claim 4, further comprising means.
U device. 6. A ground station connected to a communication line, and an aircraft station connected to a communication line installed on an aircraft,
An aeronautical satellite communication system in which the aircraft station and the ground station are connected by a wireless channel via a satellite and the TIFU device according to claim 4 is mounted on the aircraft station and the ground station. Comparing at least a facsimile signal generated from one communication line, an input signal including a voice signal, with an amplitude level in each frequency band, and detecting whether or not a preamble signal of the facsimile signal is included. By identifying the signal components and converting the communication mode of the own device based on the identification result,
An aeronautical satellite communication system wherein the identified signal is transmitted from the ground station to the aircraft station or from the aircraft station to the ground station and provided to the other communication line.