JP3967098B2 - Facsimile device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a facsimile apparatus in which a modulation method of a received signal is switched.
[0002]
[Prior art]
Conventionally, in a facsimile machine, when an image signal was not correctly received on the receiving side due to the influence of noise or the like on the telephone line during communication, a retransmission request for the image signal was made to the transmitting side and was not received correctly An ECM function is provided to retransmit the image signal. When communication is performed using this ECM function, as shown in FIG. 3, a maximum of 256 image frames of 256 frames are transmitted, and then the mode is switched to phase D, and PPS-EOP (Pertial Page Signal -End Of Procedure) is sent from the sending facsimile machine.
[0003]
The receiving facsimile machine that has received the PPS-EOP recognizes that the transmission of the transmission signal of the last page has been completed. At this time, if there is a frame that is not correctly received due to noise superimposed in the transmitted image signal of a maximum of 256 frames, a PPR for designating a frame that is not correctly received as shown in FIG. (Pertial Page Request) is transmitted to the facsimile machine on the transmission side.
[0004]
The transmitting facsimile apparatus that has received the PPR recognizes a frame that is not correctly received by the receiving facsimile apparatus from the PPR, retransmits the image signal of the frame, and then transmits the PPS-EOP. When the receiving facsimile apparatus receives the image signal of the retransmitted frame, if there is a frame that is not correctly received, the PPR is transmitted again, and the above-described communication operation is repeated in the receiving and transmitting facsimile apparatuses. It is.
[0005]
On the other hand, when the image signal is correctly received in the receiving facsimile apparatus, an MCF (Message Confirmation) indicating that the image signal has been correctly received is transmitted as shown in FIG. Then, when the transmission side facsimile apparatus receives the MCF and recognizes that the image signal has been correctly received, a DCN (Disconnect) is transmitted to disconnect the line as shown in FIG. Inform the device.
[0006]
Thus, when facsimile communication is performed using the ECM function, the image signal of the frame that has not been correctly received is retransmitted until it is correctly received, so the image signal is reliably transmitted to the receiving facsimile machine. can do.
[Problems to be solved by the invention]
However, at the time of communication in the phases A and B for confirming the mutual communication connection before receiving the image signal as described above, or at the time of receiving the image signal in the above phases C and D, by line echo, The signal transmitted by the device itself may be received together with the signal transmitted from the facsimile machine as the communication partner. If the signal level of a signal received by such line echo (hereinafter referred to as “echo signal”) is high, a signal transmitted from a facsimile machine as a communication partner may not be received normally. In particular, the effect of this echo signal is greater when receiving an image signal.
[0007]
As described above, even if both communicating facsimile machines have the ECM function, if the signal level of the echo signal is high when the image signal is received, an error occurs continuously. The received signal from the modem provided in the facsimile machine on the receiving side may diverge, and the image signal cannot be normally received continuously. At this time, PPS-EOP cannot be received from the transmission-side facsimile apparatus by the reception-side facsimile apparatus, and as a result, the line may be disconnected with insufficient communication.
[0008]
In view of such a problem, an object of the present invention is to provide a facsimile apparatus capable of controlling a signal level serving as a threshold of a received signal so as not to be affected by an echo signal.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a facsimile apparatus according to the present invention, in a facsimile apparatus having a modem that transmits and receives signals to and from other facsimile apparatuses, transmits a transmission signal transmitted from the modem as an echo signal by the modem by line echo. When received, after measuring the signal level of the echo signal, the measured signal level of the echo signal is compared with the lowest incoming signal level that is the lowest signal level that can be received by the modem, when the signal level of the echo signal is higher than the lowest incoming level has a minimum incoming level setting unit for setting change signal level based on the signal level of the echo signal as the lowest incoming level, the modem, outermost low incoming Receive only signals with a signal level higher than the minimum incoming level set in the level setting section. And features.
[0010]
Further, when such a facsimile apparatus continuously transmits signals to other communication apparatuses, the minimum incoming signal level setting unit sets the signal level of the echo signal of the first signal transmitted previously to the first signal level. The minimum incoming level is set by measuring until the second signal transmitted continuously after one signal is transmitted.
[0011]
In such a facsimile apparatus, the echo signal whose signal level is measured by the minimum incoming signal level setting unit is an echo signal by CED.
In the facsimile apparatus of the present invention, in the facsimile apparatus having a modem for transmitting / receiving signals to / from another facsimile apparatus, the signal level of the test signal transmitted from the other facsimile apparatus is measured, and then the measured test is performed. A signal level that is lower than the signal level of the test signal by a predetermined level and a minimum incoming level that is the lowest signal level that can be received by the modem, and the predetermined level is lower than the signal level of the test signal A minimum incoming level setting unit for setting and changing the signal level lower than the signal level of the test signal by the predetermined level as the lowest incoming level when the signal level is lower than the lowest incoming level; Receive only signals having a signal level higher than the minimum incoming level set by the minimum incoming level setting unit. And it features.
[0015]
In addition, by setting the test signal to TCF transmitted before the image signal is transmitted, the minimum incoming signal level can be set using an existing signal.
[0016]
DETAILED DESCRIPTION OF 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.
[0017]
The facsimile apparatus in FIG. 1 performs a main control unit 1 that controls the entire apparatus, an encoding unit 2 that encodes image data, a decoding unit 3 that decodes a received signal, and modulation / demodulation of a signal. A photoelectric conversion element such as an NCU (Network Control Unit) 5 for switching the connection between the modem 4 and a telephone line between a facsimile and a telephone, and a CCD (Charge Coupled Device) sensor for reading the contents of a transmission document An image reading unit 6 comprising: an image processing unit 7 for performing image processing such as shading correction, binarization processing or halftone processing on image data based on electrical signals obtained by the image reading unit 6, and decoding A recording processing unit 8 that performs image processing such as smoothing processing on the converted image data, and printing of a received document on recording paper according to the image data image-processed by the recording processing unit 8 An output unit 9 for discharging the printed recording paper, an operation unit 10 for instructing transmission / reception, a display unit 11 for displaying a destination telephone number, a destination telephone number, and the like are stored. And a memory 12 for storing image data of a received document, and a minimum incoming signal for setting a threshold of a signal level of a signal received by the modem 4 based on an echo signal received by the modem 4 And a level setting unit 14.
[0018]
The facsimile apparatus having such a configuration performs communication as shown in FIG. That is, when the operation unit 10 of the transmission side facsimile apparatus is operated and the other party's telephone number is dialed, a calling operation is performed and the CNG (Calling Tone) is connected to the modem 4 and the other party in order to read the other party. Sent through NCU5. When CNG is received by the NCU 5 of the receiving facsimile machine, it is recognized that facsimile communication is performed. Then, the facsimile machine on the receiving side transmits CED (Called Tone) through the modem 4 and the NCU 5 to the facsimile machine on the transmitting side. Note that CNG and CED identify that the transmitting side and the receiving side are facsimile machines.
[0019]
When the operation of phase A is performed in this way and communication connection is established between the transmission side and the reception side facsimile apparatus, the reception side facsimile apparatus receives NSF (Non-Standard Facilities), CSI (Called). Subscriber Identification) and DIS (Digital Identification Signal) are transmitted. At this time, NSF indicates a manufacturer's original facsimile device function, CSI indicates a receiving telephone number, and DIS indicates a G3 standard facsimile device function. The function of the facsimile apparatus represents the type of modem, the recording paper width of a document to be transmitted / received, the communication speed, and the like.
[0020]
In response to this, a non-standard facilities set-up (NSS) or a transmitting subscriber identification (TSI) and a digital command signal (DCS) are transmitted from the facsimile machine on the transmission side. At this time, the transmission condition of the manufacturer's original facsimile apparatus in which NSS is set, the telephone number of the transmission side in TSI, and the transmission condition of the G3 standard facsimile apparatus in which DCS is set are shown. NSS and DCS represent transmission conditions set according to the function on the receiving side recognized by the received NSF and DIS. NSS and NSF are signals recognized when the transmission / reception facsimile apparatuses are of the same manufacturer.
[0021]
Then, a TCF (Training Check Field) is transmitted from the transmitting facsimile machine in order to test whether communication can be performed normally. When the receiving side facsimile apparatus receiving this TCF does not confirm an error in the received TCF, a CFR (Confirmation to Receive) indicating that the transmission operation has been normally performed is sent to the transmitting side facsimile apparatus. To send.
[0022]
In this way, after the communication operation of phase B is performed and the transmission side facsimile apparatus is set to transmit under the transmission condition according to the function of the reception side facsimile apparatus, communication may be normally performed. If confirmed, the process proceeds to phase C. In this phase C, the image signal is transmitted as a transmission signal from the transmission side facsimile apparatus to the reception side facsimile apparatus.
[0023]
Thus, in order to prevent reception of an echo signal that acts as noise when establishing communication in order to exchange signals in phases A and B and perform transmission and reception of image signals, The threshold of the signal level of the signal received by the modem 4 is set. The signal level threshold of the received signal is hereinafter referred to as “minimum incoming call level”. A method for setting the minimum incoming call level will be described below. In addition, it is assumed that the minimum incoming call level is set in advance.
[0024]
<First example of setting method of minimum incoming call level>
As shown in FIG. 2, the receiving facsimile apparatus receives the CNG from the transmitting facsimile apparatus and transmits the CED. When this CED is transmitted, the receiving facsimile apparatus transmits NSF, CSI, and DIS after 75 ± 20 ms has elapsed. Therefore, the facsimile machine on the receiving side can confirm reception of the echo signal by CED after transmitting CED and before transmitting NSF, CSI, and DIS. In such a facsimile machine, Dx is given in advance as a minimum incoming call level.
[0025]
At this time, if the signal level of the echo signal by CED is lower than the preset minimum incoming level Dx, the modem 4 does not receive the echo signal. Therefore, the minimum incoming call level is not changed by the lowest incoming call level setting unit 14, and the minimum incoming call level remains Dx.
[0026]
Conversely, when the signal level of the echo signal by CED is higher than the preset minimum incoming level Dx, the modem 4 receives the echo signal. Then, the lowest incoming level setting unit 14 measures the signal level D of the received echo signal. Further, the lowest incoming level setting unit 14 sets the lowest incoming level to a value D + Δd higher by Δd than the measured signal level of the echo signal. When the minimum incoming level D + Δd set in this way is given to the modem 4, the modem 4 receives only a signal having a signal level higher than the newly set minimum incoming level.
[0027]
That is, when the minimum incoming level is set to -43 dB in advance, the signal level of the echo signal by CED is higher than -43 dB, and the signal level of the echo signal by CED received by the modem 4 in the minimum incoming level setting unit 14 Is measured as -40 dB. At this time, the minimum incoming signal level setting unit 14 sets the minimum incoming signal level to -38 dB which is higher by 2 dB than the signal level of the measured echo signal --40 dB. Therefore, thereafter, the modem 4 receives only a signal having a signal level higher than the lowest incoming level −38 dB.
[0028]
At this time, since the minimum incoming level is set to -43 dB in advance, when the signal level of the echo signal by CED is -47 dB, it is not received by the modem 4 and is set to -43 dB in advance. Is given to the modem 4 as the minimum incoming call level.
[0029]
<Second example of setting method of minimum incoming call level>
Further, as shown in FIG. 2, before the transition to the phase C in which the image signal is received, a TCF for testing whether or not the transmission side facsimile apparatus can normally perform the transmission operation is transmitted. This TCF is a signal transmitted at the same transmission speed as the image signal transmitted after the transition to the phase C. Therefore, the echo signal can be eliminated by setting the TCF to a signal level at which the modem 4 can sufficiently receive the TCF. In such a facsimile machine, Dx is given in advance as a minimum incoming call level.
[0030]
That is, when the facsimile machine on the receiving side receives the TCF by the modem 4, the signal level Da of the TCF is measured at the minimum incoming level setting unit. Then, the lowest incoming level setting unit 14 compares the value Da−Δda lower than the measured TCF signal level by Δda with a preset lowest incoming level Dx. When Da-Δda is higher than Dx, Da-Δda is set as the lowest incoming level. When the minimum incoming 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 level. On the contrary, when Da-Δda is lower than Dx, the lowest incoming level is not changed by the lowest incoming level setting unit 14, and the lowest incoming level remains Dx.
[0031]
That is, it is assumed that when the minimum incoming level is preset to -43 dB, the minimum incoming level setting unit 14 measures the signal level of the TCF received by the modem 4 as -35 dB. At this time, the lowest incoming signal level setting unit 14 sets the lowest incoming signal level to -37 dB because -37 dB, which is 2 dB lower than the TCF signal level -35 dB, is higher than -43 dB when compared with -43 dB. Therefore, thereafter, the modem 4 receives only a signal having a signal level higher than the lowest incoming level −37 dB.
[0032]
At this time, since the minimum incoming signal level is set to -43 dB in advance, when the TCF signal level is measured to be -42 dB, comparing -44 dB with -43 dB, which is 2 dB lower than the TCF signal level -42 dB. Since it is lower than -43 dB, a preset -43 dB is given to the modem 4 as the lowest incoming call level.
[0033]
In the present embodiment, the minimum incoming call level is automatically set based on the echo signal by the CED or the TCF. However, a key for setting the minimum incoming call level is provided on the operation unit 10 to receive the facsimile apparatus. When the operation cannot be performed accurately, the minimum incoming call level may be set by the user or the service person. In addition, by using an echo signal by CED or a signal other than TCF, it is possible to automatically set the minimum incoming call level by using the same setting method as the first example or the second example of the above setting method. I do not care.
[0034]
【The invention's effect】
According to the present invention, since the minimum incoming signal level is set by the lowest incoming signal level setting unit measuring the signal level of the echo signal or test signal, an echo signal or the like is unnecessary from the signal received by the modem. An optimal minimum incoming level can be set to eliminate noise. Therefore, it is possible to suppress the divergence at the time of modem reception and to improve the transmission quality.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an internal configuration of a facsimile apparatus according to the present invention.
FIG. 2 is a time chart showing a communication operation of the facsimile apparatus.
FIG. 3 is a time chart showing a communication operation of the facsimile apparatus.
[Explanation of symbols]
1 Main Control Unit 2 Encoding Unit 3 Decoding Unit 4 Modem 5 NCU
6 Image reading unit 7 Image processing unit 8 Recording processing unit 9 Output unit 10 Operation unit 11 Display unit 12 Memory 13 Image memory 14 Minimum incoming level setting unit

Claims (5)

In a facsimile machine having a modem that transmits and receives signals to and from other facsimile machines,
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, the modem set to the measured signal level of the echo signal The lowest incoming signal level, which is the lowest signal level that can be received, is compared. When the signal level of the echo signal is higher than the lowest incoming signal level, a signal level that is higher than the signal level of the echo signal by a predetermined level is set to the lowest incoming signal level. It has a minimum incoming level setting part that changes the setting as a level,
The 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.   When continuously transmitting a signal to another communication device, the minimum incoming signal level setting unit continuously transmits the signal level of the echo signal of the first signal transmitted first after the first signal. 2. The facsimile apparatus according to claim 1, wherein a minimum incoming call level is set by measuring before transmitting the second signal. 3. The facsimile apparatus according to claim 1, wherein the echo signal whose signal level is measured by the minimum incoming signal level setting unit is an echo signal by CED . In a facsimile machine having a modem that transmits and receives signals to and from other facsimile machines,
After measuring the signal level of the test signal transmitted from the other facsimile apparatus, the lowest signal level that can be received by the modem that is set to a signal level lower by a predetermined level than the measured signal level of the test signal. When the signal level that is lower than the signal level of the test signal is lower than the signal level of the test signal, the signal level is lower than the signal level of the test signal. A minimum incoming signal level setting unit that changes the setting of a signal level that is lower by the minimum incoming signal level;
The 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. 5. The facsimile apparatus according to claim 4 , wherein the test signal is a TCF transmitted before an image signal is transmitted.

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