JP2003069797A - Facsimile equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide facsimile equipment, with which a signal level to become the threshold of a received signal can be controlled so as not to be affected by an echo signal. SOLUTION: Reception of the echo signal to a CED transmitted by a MODEM 4 is confirmed before transmitting NSF, CSI and DIS. When reception of the echo signal is confirmed, in a bottom incoming level setting part 14, the signal level of the echo signal is measured and afterwards, a bottom incoming level higher than the measured signal level is set and applied to the MODEM 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile apparatus in which the modulation system of a received signal is switched.

[0002]

2. Description of the Related Art Conventionally, in facsimile machines,
When the image signal is not correctly received at the receiving side due to the influence of noise on the telephone line during communication, a request to retransmit the image signal is sent to the transmitting side, and the image signal that was not correctly received is retransmitted. , ECM function. When communication is being performed using this ECM function, FIG.
As described above, one frame of 256-byte image frame is transmitted up to 256 frames, and then the mode is switched to phase D, and PPS-EOP (Pertial Page Signal-End Of
Procedure) is transmitted from the sending facsimile machine.

The facsimile machine on the receiving side which receives the PPS-EOP recognizes that the transmission of the transmission signal of the last page has been completed. At this time, when there is a frame which is not correctly received due to noise being superimposed in the image signals of the maximum 256 frames transmitted, as shown in FIG. 3, the PPR for designating the frame which is not correctly received is used.
(Pertial Page Request) is sent to the sending facsimile machine.

The facsimile apparatus on the transmitting side which receives the PPR recognizes the frame which is not correctly received by the facsimile apparatus on the receiving side from the PPR, retransmits the image signal of the frame, and then transmits PPS-EOP. Upon receiving the image signal of the retransmitted frame, the facsimile apparatus on the reception side transmits PPR again if there is a frame that was not correctly received, and the above-described communication operation is repeated on the facsimile apparatuses on the reception side and the transmission side. Be done.

On the other hand, when the image signal is correctly received by the facsimile apparatus on the receiving side, the MCF indicating that the image signal is correctly received as shown in FIG.
(Message Confirmation) is sent. When the facsimile machine on the transmission side receives the MCF and recognizes that the image signal is correctly received, as shown in FIG.
A facsimile machine on the receiving side is notified that a CN (Disconnect) is transmitted to disconnect the line.

When facsimile communication is performed using the ECM function in this way, the image signal of the frame that was not correctly received is retransmitted until it is correctly received, so that the image is reliably sent to the receiving side facsimile device. A signal can be transmitted.

However, during the communication in the phases A and B for confirming the mutual communication connection before receiving the image signal as described above, and in the image signals in the phases C and D described above. When receiving, the line echo may receive the signal transmitted by the device itself together with the signal transmitted from the facsimile device as the communication partner. If the signal level of a signal received by such a line echo (hereinafter, referred to as “echo signal”) is high, the signal transmitted from the facsimile machine as a communication partner may not be normally received. In particular, the influence of this echo signal is greater when the image signal is received.

Further, as described above, even if both facsimile machines communicating with each other have the ECM function,
When receiving the image signal, if the signal level of the echo signal is high, an error occurs continuously, and the received signal in the modem provided in the facsimile machine on the receiving side diverges, and the image signal It may not be possible to continue reception. At this time, the facsimile machine on the receiving side cannot receive the PPS-EOP from the facsimile machine on the transmitting side, and as a result, the line may be disconnected while the communication is insufficient.

In view of such a problem, it is an object of the present invention to provide a facsimile apparatus capable of controlling a signal level which is a threshold value of a received signal so as not to be influenced by an echo signal.

[0009]

In order to achieve the above object, a facsimile machine according to claim 1 is a facsimile machine having a modem for transmitting and receiving a signal to and from another facsimile machine, and the transmission transmitted from the modem. When a signal is received as an echo signal by the modem by a line echo, after measuring the signal level of the echo signal, the lowest signal level that can be received by the modem is based on the measured signal level of the echo signal. Has a minimum incoming call level setting unit that sets the minimum incoming call level
It is characterized in that the modem receives only a signal having a signal level higher than the minimum incoming call level set by the minimum incoming call level setting unit.

In such a facsimile apparatus, as described in claim 2, in the minimum incoming call level setting section, the minimum incoming call level is set to a value higher than the measured signal level of the echo signal by a predetermined level. As a result, the influence of the echo signal on the signal received by the modem can be reduced.

Further, as described in claim 3, when the signal is continuously transmitted to another communication device, the lowest incoming call level setting unit is configured to detect the echo signal of the first signal transmitted previously. By setting the minimum incoming call level by measuring the signal level until the second signal transmitted next to the first signal is transmitted, the signal is transmitted from another communication device. Since only the echo signal can be measured when there is no signal, the signal level of the echo signal can be accurately measured.

The first signal for measuring the echo signal in this manner is CED as described in claim 4.
With this, it is possible to measure the signal level of the echo signal using an existing signal.

According to a fifth aspect of the present invention, in a facsimile machine having a modem for transmitting and receiving signals to and from another facsimile machine, the signal level of a test signal transmitted from the other facsimile machine is measured. After that, based on the measured signal level of the test signal, a minimum incoming call level setting unit for setting the minimum incoming call level which is the lowest signal level that can be received by the modem,
It is characterized in that the modem receives only a signal having a signal level higher than the minimum incoming call level set by the minimum incoming call level setting unit.

In such a facsimile apparatus, as described in claim 6, in the minimum incoming call level setting unit, the minimum incoming call level is set to be a value lower than the measured signal level of the test signal by a predetermined level. By doing so, the influence of the echo signal on the signal received by the modem can be reduced.

Further, as set forth in claim 7, the test signal is transmitted to the TCF before the image signal is transmitted.
Thus, the minimum incoming call level can be set using an existing signal.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the internal configuration of the facsimile apparatus of this embodiment.

The facsimile apparatus shown in FIG. 1 has a main control section 1 for controlling the entire apparatus, an encoding section 2 for encoding image data, a decoding section 3 for decoding a received signal, and a signal. NCU (Networ) that switches the connection between the modem 4 that performs modulation and demodulation and the telephone line between the facsimile and the telephone.
k Control Unit) 5, an image reading unit 6 configured by a photoelectric conversion element such as a CCD (Charge Coupled Device) sensor for reading the content of a transmission document, and image data obtained by the electric signal obtained by the image reading unit 6. An image processing unit 7 that performs image processing such as shading correction, binarization processing, or halftone processing; a recording processing unit 8 that performs image processing such as smoothing processing on the decoded image data; An output unit 9 that prints a received document on a recording paper according to the image data subjected to image processing by the processing unit 8 and discharges the printed recording paper, an operation unit 10 that gives an instruction for transmission / reception, and a destination telephone. A display unit 11 for displaying numbers and the like, a memory 12 for storing a telephone number of the other party, an image memory 13 for storing image data of a received document, And a minimum incoming level setting unit 14 for setting a threshold value of the signal level of the signal modem 4 receives on the basis of the echo signal received by the modem 4.

The facsimile apparatus having such a structure performs communication as shown in FIG. That is, when the operation unit 10 of the facsimile machine on the transmission side is operated to dial the destination telephone number, a calling operation is performed, and a CNG (Calling Tone) is used by the modem 4 and NCU
5 is transmitted. N of the facsimile machine on the receiving side
When CNG is received by CU5, it is recognized that facsimile communication is performed. Then, the facsimile machine on the receiving side sends CED (Called Tone) to the modem 4 and the NCU.
The data is transmitted to the facsimile machine on the transmission side through 5. still,
The CNG and CED identify the sender and the receiver as facsimile machines.

In this way, when the operation of phase A is performed and the communication connection is established between the sending side and the receiving side facsimile machines, the receiving side facsimile machine sends NSF.
(Non-Standard Facilities), CSI (Called Subscr
iber Identification), DIS (Digital Identificat)
ion Signal) is transmitted. At this time, NSF indicates the function of the facsimile device unique to the manufacturer, CSI indicates the telephone number of the receiving side, and DIS indicates the function of the G3 standard facsimile device. What is the function of the facsimile machine?
Indicates the type of modem, the width of the recording paper for documents to be sent and received, the communication speed, etc.

On the other hand, the facsimile machine on the transmission side sends NSS (Non-Standard Facilities Set-up) or TSI (Transmitting Subscriber Identificatio).
n) and DCS (Digital Command Signal) are transmitted. At this time, the transmission conditions of the manufacturer's own facsimile device in which NSS is set, TSI indicates the telephone number of the sender, and the transmission conditions of the G3 standard facsimile device in which DCS is set are shown. NSS and DCS are
It represents the transmission condition set according to the function of the receiving side recognized by the received NSF and DIS. Also, NSS, N
The SF is a signal that is recognized when the sending and receiving facsimile machines are manufactured by the same manufacturer.

Then, in order to test whether normal communication is possible, a TCF (Training
Check Field) is transmitted. When the receiving TCF receives this TCF, when no error is confirmed in the received TCF, a CFR (Confirmation to Receive) indicating that the transmitting operation is normally performed is sent to the transmitting facsimile. To send.

In this way, the communication operation of the phase B is performed, and after the transmission side facsimile apparatus is set to transmit under the transmission condition according to the function of the reception side facsimile apparatus, the communication is normally performed. Is confirmed,
Transition to Phase C. In this phase C, the image signal is transmitted from the transmitting side facsimile device to the receiving side facsimile device as a transmission signal.

In this way, when the signals are mutually exchanged in the phases A and B and the communication is established for transmitting and receiving the image signal, the minimum incoming call level setting unit is provided in order to prevent the reception of the echo signal which works as noise. At 14, the threshold of the signal level of the signal received by the modem 4 is set.
The threshold of the signal level of this received signal is
Called the "minimum incoming call level". The method of setting the minimum incoming call level will be described below. Further, it is assumed that the minimum incoming call level is set in advance.

<First Example of Setting Method of Minimum Incoming Level> As shown in FIG. 2, the facsimile apparatus on the receiving side receives the CNG from the facsimile apparatus on the transmitting side and transmits the CED. When this CED is transmitted, the facsimile machine on the receiving side waits for 75 ± 20 ms before NSF, CSI, D
Send IS. Therefore, the facsimile machine on the receiving side can confirm the reception of the echo signal by the CED after transmitting the CED and before transmitting the NSF, CSI, and DIS. In such a facsimile machine,
Dx is given in advance as the lowest incoming call level.

At this time, if the signal level of the echo signal by the CED is lower than the preset minimum incoming level Dx, the echo signal is not received by the modem 4. Therefore, the minimum incoming call level is not changed by the minimum incoming call level setting unit 14, and the minimum incoming call level remains Dx.

On the contrary, when the signal level of the echo signal by the CED is higher than the preset minimum incoming level Dx, the echo signal is received by the modem 4. Then, the lowest incoming level setting unit 14 measures the signal level D of the received echo signal. Further, the minimum incoming call level setting unit 14 sets the minimum incoming call level to a value D + Δd higher than the measured signal level of the echo signal by Δd. When the minimum incoming call level D + Δd thus set high is given to the modem 4, the modem 4
Only signals with a signal level higher than the newly set minimum incoming level are received.

That is, when the minimum incoming call level is preset to -43 dB, the signal level of the echo signal by the CED is higher than -43 dB, and the minimum incoming call level setting unit 14
In, it is assumed that the signal level of the echo signal by the CED received by the modem 4 is measured as -40 dB.
At this time, the minimum incoming call level setting unit 14 detects the minimum incoming call level from the signal level of -40 dB of the echo signal by 2
It is set to -38 dB, which is higher by dB. Therefore, thereafter, the modem 4 receives only the signal having the signal level higher than the minimum incoming call level -38 dB.

At this time, the minimum incoming call level is -4 in advance.
Since it is set to 3 dB, when the signal level of the echo signal by the CED is -47 dB, it is not received by the modem 4, and preset -43 dB is given to the modem 4 as the minimum incoming call level.

<Second example of setting method of lowest incoming call level>
Further, as shown in FIG. 2, before shifting to the phase C for receiving the image signal, a TCF for testing whether or not the transmitting facsimile machine can normally perform the transmitting operation is transmitted.
This TCF is a signal transmitted at the same transmission speed as the image signal transmitted after shifting to phase C. Therefore, the facsimile machine on the receiving side receives this TCF by the modem 4
By setting the signal level until you can receive enough with
Echo signals can be eliminated. In such a facsimile machine, Dx is set as the minimum incoming call level in advance.
Is given.

That is, when the receiving side facsimile apparatus receives the TCF by the modem 4, the lowest incoming level setting unit measures the signal level Da of the TCF. Then, the minimum incoming call level setting unit 14 compares the value Da-Δda lower than the measured signal level of the TCF by Δda with the preset minimum incoming call level Dx. Then, when Da-Δda becomes a level higher than Dx, D
Set a-Δda as the lowest incoming call level. When the minimum incoming call level Da-Δda set in this way is given to the modem 4, the modem 4 receives only a signal having a signal level higher than the set minimum incoming call level. Conversely, Da
When −Δda is lower than Dx, the minimum incoming call level setting unit 14 does not change the minimum incoming call level, and the minimum incoming call level remains Dx.

That is, when the minimum incoming call level is preset to -43 dB, the signal level of the TCF received by the modem 4 in the minimum incoming call level setting unit 14 is -35.
It shall be measured as dB. At this time, the lowest incoming call level setting unit 14 sets the signal level of the TCF to -2 dB from
Comparing -37 dB lower by dB with -43 dB,
Since it is higher than 43 dB, the minimum incoming call level is set to -37 dB. Therefore, thereafter, the modem 4 receives only a signal having a signal level higher than the minimum incoming call level -37 dB.

At this time, the minimum incoming call level is -4 in advance.
Since it is set to 3 dB, the signal level of TCF is-
When measured at 42 dB, the signal level of TCF is -42.
Comparing -44 dB, which is lower than dB by 2 dB, with -43 dB, it is lower than -43 dB, and preset -43 dB is given to the modem 4 as the lowest incoming level.

In this embodiment, the minimum incoming call level is automatically set based on the echo signal from the CED or the TCF. However, the operation unit 10 is provided with a key for setting the minimum incoming call level, and the facsimile is provided. When the receiving operation of the device cannot be performed accurately, the minimum incoming call level may be set by the user or service person. Also, echo signal by TC or TC
A signal other than F may be used to automatically set the minimum incoming call level by using the same setting method as in the first example or the second example of the setting method described above.

[0034]

According to the present invention, the minimum incoming call level setting unit measures the signal level of the echo signal or the test signal to set the minimum incoming call level. Therefore, the echo signal is received from the modem. It is possible to set the optimum minimum incoming call level to eliminate unnecessary noise such as. Therefore, it is possible to suppress divergence at the time of reception by the modem and improve the transmission quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing an internal configuration of a facsimile apparatus of the present invention.

FIG. 2 is a time chart showing the communication operation of the facsimile apparatus.

FIG. 3 is a time chart showing a communication operation of the facsimile device.

[Explanation of symbols]

1 Main control unit 2 Encoding section 3 Decoding section 4 modem 5 NCU 6 Image reading section 7 Image processing unit 8 Recording processor 9 Output section 10 Operation part 11 Display 12 memories 13 Image memory 14 Minimum incoming call level setting section

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiro Hashizume             1-22 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka Prefecture             Kyocera Mita Co., Ltd. (72) Inventor Katsuaki Yasui             1-22 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka Prefecture             Kyocera Mita Co., Ltd. (72) Inventor Hitoshi Asaka             1-22 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka Prefecture             Kyocera Mita Co., Ltd. F term (reference) 5C075 AA02 CD22 CD26 CE09

Claims (7)

[Claims] 1. A facsimile apparatus having a modem for transmitting and receiving a signal to and from another facsimile apparatus, wherein when a transmission signal transmitted from the modem is received as an echo signal by the modem by line echo,
After measuring the signal level of the echo signal, based on the measured signal level of the echo signal, a minimum incoming call level setting unit for setting a minimum incoming call level that is the lowest signal level that can be received by the modem, A facsimile apparatus, wherein the modem receives only a signal having a signal level higher than the minimum incoming call level set by the minimum incoming call level setting unit. 2. The facsimile apparatus according to claim 1, wherein the minimum incoming call level setting unit sets the minimum incoming call level to a value higher than the measured signal level of the echo signal by a predetermined level. . 3. When the signal is continuously transmitted to another communication device, the lowest incoming level setting unit sets the signal level of the echo signal of the first signal previously transmitted to the level next to the first signal. The facsimile apparatus according to claim 1 or 2, wherein the minimum incoming call level is set by measuring the second signal continuously transmitted to the second signal. 4. The facsimile apparatus according to claim 3, wherein the echo signal whose signal level is measured by the minimum incoming call level setting unit is a CED echo signal. 5. A facsimile machine having a modem for transmitting and receiving a signal to and from another facsimile machine, the signal level of the test signal measured after measuring the signal level of the test signal transmitted from the other facsimile machine. A minimum incoming call level setting unit that sets a minimum incoming call level, which is the lowest signal level that can be received by the modem, based on the level, wherein the modem sets the minimum incoming call level set by the minimum incoming call level setting unit. A facsimile machine, which receives only a signal of a higher signal level. 6. The facsimile machine according to claim 5, wherein the minimum incoming call level setting unit sets the minimum incoming call level to a value lower than the measured signal level of the test signal by a predetermined level. apparatus. 7. The facsimile apparatus according to claim 5, wherein the test signal is a TCF transmitted before an image signal is transmitted.