JP3049839B2 - Facsimile machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile apparatus, and more particularly to a facsimile apparatus in which procedure control time is reduced.

[0002]

2. Description of the Related Art For example, when communication is performed between facsimile apparatuses adopting a standard called CCITT (International Telegraph and Telephone Consultative Committee) Group 3 (G3), as shown in FIG. In response to the call, the receiving station returns a CED signal indicating that the facsimile machine exists on the called side. Next, a continuous transmission frame composed of a preamble signal P for synchronizing, an NSF signal as a frame for exchanging communication connection parameters, and a DIS signal is transmitted from the receiving station to the transmitting station a plurality of times at fixed time intervals. Sent. Note that the NSF signal is a signal indicating a capability other than the standard function of the G3, and the DIS signal is a digital identification signal indicating that the device is a standard device. These signals are
CCITT Recommendation T. The data is continuously transmitted in frame units in a binary code command format known as 30.

When receiving data consisting of a plurality of frames transmitted continuously (hereinafter referred to as a continuous transmission frame), if data is received in the middle of the continuous transmission frame, correct data cannot be obtained. In such a case, the received data must be ignored.

Therefore, in the prior art, in order to shorten the time required for such procedure control, Japanese Patent Publication No. Sho 62-490 has been proposed.
As disclosed in Japanese Unexamined Patent Publication No. 3 (1993), when a carrier signal has already been detected at the start of frame reception, it is regarded that reception has started from the middle of the frame, the frame is ignored, and the carrier signal is cut off. Waiting to start frame reception.

However, in this method, when frame reception is started in the middle of the preamble signal P output at the beginning of the continuous transmission frame, although all the data that is originally required can be received substantially, However, this series of frames must be ignored, and a continuous transmission frame sent again must be waited. As a result, there is a problem that the procedure control time becomes longer.

In order to solve such a problem, Japanese Patent Application No. 2-150524 discloses that a continuous transmission frame is received even if a carrier signal has already been received. Is checked, when the NSF command is received, the NSF command is regarded as being normally received, and the NSF command is analyzed. When the expected binary code command is not received, the received frame is ignored. Thus, a method of receiving a new frame again has been proposed.

[0007]

The NSF signal is a signal for setting a non-standard function, and since most of the signals can be analyzed only between facsimile machines of the same manufacturer, only the standard function is provided. Inexpensive facsimile machines and facsimile machines for export often do not have the function of outputting NSF signals.

Therefore, in the above-mentioned prior art which analyzes the binary code command of the NSF signal and determines whether or not the frame is valid, as described above, the NSF
For a facsimile apparatus that does not output a signal, there is a problem that the effect cannot be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to quickly and reliably receive continuous transmission frames even in the case of transmission / reception with a facsimile apparatus having no function of outputting an NSF signal. To reduce the procedure control time.

[0010]

In order to achieve the above object, the present invention provides a carrier signal detecting means for detecting the presence or absence of a carrier signal, a frequency measuring means for measuring the frequency of a carrier signal, If the carrier signal is not detected, the frame associated with the subsequent carrier detection is determined to be a valid frame, and if the carrier signal has already been detected, the validity of the frame associated with the carrier detection is determined based on the frequency of the carrier signal. Effective frame determination means for determining the gender.

[0011]

In the above arrangement, even if the carrier signal has already been detected by the carrier signal detecting means and the frame reception is started halfway, the frequency of the carrier signal measured by the frequency measuring means is not changed. If the frequency is a predetermined frequency, for example, a frequency indicating that the signal is a CED signal, the subsequent NSF signal or DIS signal can be reliably received, so that the frame is determined as a valid frame.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an outline of the present invention will be described.

FIG. 2A is a timing chart of a continuous transmission frame output from a facsimile apparatus having a non-standard function, and FIG. 2B is a timing chart of a continuous transmission frame output from a facsimile apparatus having no non-standard function. 6 is a timing chart of a single transmission frame.

If the facsimile apparatus which has received the ringer signal from the transmitting station has a non-standard function, the facsimile apparatus has a CED signal, a preamble signal P, and an NS signal as shown in FIG.
The transmission sequence is continued if the NSS signal is output from the transmitting station, but the transmission sequence is continued if the NSS signal is output from the transmitting station. The preamble signal P, the NSF signal, and the DIS signal are repeatedly output.

On the other hand, if the facsimile machine on the receiving side does not have a non-standard function, as shown in FIG.
A single transmission frame signal composed of an ED signal, a preamble signal P, and a DIS signal is output. After that, if a DCS signal is output from the transmitting station, the transmission sequence is continued. After a second, the preamble signal P and the DIS signal are repeatedly output.

In such a configuration, if frame reception starts at time t1, complete reception of continuous transmission frames and single transmission frames becomes possible. On the other hand, if the frame reception is started at time t2, the carrier signal has already been detected. Therefore, in the first prior art disclosed in Japanese Patent Publication No. Sho 62-4903, both the continuous transmission frame and the single transmission frame are used. Although it is determined that the frame is invalid,
In a second prior art disclosed in US Pat.
By analyzing the signal, only the continuous transmission frame can be determined as a valid frame.

However, as shown in FIG. 1B, if the receiving station is a facsimile machine having no non-standard function, the NSF signal is not output. In spite of the fact that the frame is valid, the frame is determined to be an invalid frame.

[0018] CCITT Recommendation T. 30, for example, CE
It is defined that the D signal is a flat signal having a frequency of 2100 Hz. Therefore, the present invention focuses on this point, detects the presence or absence of a carrier signal and the frequency thereof, and if the carrier signal has already been detected, measures the frequency of the carrier signal and determines whether the measured value is 2100 Hz. For example, it is determined that the reception start timing is in the middle of the CED signal, and the frame is determined to be a valid frame.

FIG. 1 is a functional block diagram of the present invention.
FIG. 3 is a flowchart for explaining the operation of FIG.

In FIG. 1, a frame signal sent via a line 1 is supplied to a modem 11 via an NCU (network control unit) 10 and demodulated. On the other hand, the carrier detecting means 12 detects the presence or absence of a carrier signal, and outputs the detection result to the valid frame determining means 14 and the frequency measuring means 13. The frequency measuring means 13 includes the carrier detecting means 1
2, when the carrier signal is detected, the frequency of the carrier signal is measured, and the measurement result is used as an effective frame determination unit 1.
If the carrier signal is not detected by the carrier detection unit 12, the valid frame determination unit 14 that outputs the frame to the fourth unit 4 determines that a frame accompanying the subsequent carrier detection is a valid frame. If a carrier signal is detected, the validity of the frame accompanying the carrier detection is determined based on the frequency measurement result output from the frequency measurement unit 13.

When the valid frame determining unit 14 determines that the frame accompanying the carrier detection is a valid frame, the control unit 15 analyzes the contents thereof and executes a predetermined process to determine that the frame is an invalid frame. Is determined, a new frame is received again.

In such a configuration, when the transmission process is started, a ringer signal is output from the transmitting station to the receiving station in step S10, and the presence or absence of a carrier signal is determined by the carrier detecting means 12 in step S11. You. If a carrier signal is detected here, step S1
In 2, the frequency of the carrier signal is measured by the frequency measuring means 13 and the measurement result is used as the valid frame determining means 14
Is output to

In step S13, the valid frame determining means 14 determines whether or not the measured frequency is 2100 Hz indicating that the signal is a CED signal.
If the frequency is 2100 Hz, it is determined that the frame accompanying the carrier detection is an effective frame, and step S1
At 4, the frame is received.

On the other hand, if the measured frequency is not 2100 Hz, the frame associated with the carrier detection is determined to be an invalid frame, the received data is discarded, and the process is executed again to receive a new frame again. It returns to S11.

If it is determined in step S11 that a carrier signal has not been detected, it is determined that a frame accompanying subsequent carrier detection is a valid frame, and the process proceeds to step S14.

FIG. 5 is a diagram showing the configuration of an embodiment of the frequency measuring means 13. As shown in FIG.

In the figure, a received carrier signal is adjusted to a constant gain by a gain adjuster 13a and output to a square wave converter 13b. In the square wave converter 13b,
Converts the input signal into a square wave and converts it into a measurement clock counter 13c
Output to Also, from the measurement clock generator 13d,
The measurement clock serving as the reference clock is output to the measurement clock counting unit 13c. The measurement clock counting unit 13c counts the measurement clock using the carrier signal converted into a square wave as a gate signal, and counts the counting result as a frequency conversion unit 13e.
Output to The frequency converter 13e calculates the frequency of the carrier signal based on the frequency of the measurement clock and the count result.

According to this embodiment, the presence / absence of a carrier signal is detected, and if the carrier signal has already been received, whether or not the frame accompanying the carrier detection is an effective frame is determined based on the frequency. Thus, it is possible to receive a group of substantially effective frames without ignoring them, thereby shortening the communication time.

In the above-described embodiment, the case where each facsimile apparatus performing communication has only the G3 mode has been described as an example. However, the present invention is not limited to this. And the facsimile apparatus having the G3 mode.

That is, in the facsimile apparatus having the G2 / G3 mode, as shown in FIG.
After outputting the preamble signal P, (NSF signal) and DIS signal, an NSS signal or DCS
If no signal is detected, after 3 seconds a Gi signal for declaring communication in G2 mode, followed by a preamble signal P for declaring communication in G3 mode, and DIS
Output a signal.

[0031] CCITT Recommendation T. According to No. 30, since the Gi signal is defined as a flat signal having a frequency of 1650 Hz or 1850 Hz, even if frame reception is started in the middle of the Gi signal (time t3), the frequency measurement is performed. The frequency of the carrier signal measured by the means 13 is 1650 Hz or 1850 H
If it is determined that the frame is z, the transmission sequence can be continued in response to the subsequent DIS signal if the frame is determined to be a valid frame.

[0032]

As described above, according to the present invention, when frame reception is started during a period in which it is specified to output a signal of a predetermined frequency, such as a CED signal or a Gi signal, Regardless of whether the frame is a continuous transmission frame or a single transmission frame, the frame group can be received without ignoring it, so that the communication time can be reduced.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of the present invention.

FIG. 2 is a timing chart for explaining an outline of the present invention.

FIG. 3 is a flowchart for explaining the operation of FIG. 1;

FIG. 4 is a timing chart for explaining another embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an embodiment of a frequency measuring unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... NCU, 11 ... Modem, 12 ... Carrier detection means, 13 ... Frequency measurement means, 14 ... Effective frame determination means, 15 ... Control part

Claims (1)

(57) [Claims] Comprising a carrier signal detection means for detecting the presence or absence of 1. A carrier signal, and frequency measuring means for measuring the frequency of the carrier signal, and a valid frame determination means for determining the validity of the frame, said valid frame determination Means, at the start of frame reception , if the carrier signal is not detected by the carrier signal detection means, determines a frame accompanying the subsequent carrier detection as a valid frame, and that the carrier signal is detected at the start of frame reception Determining the validity of a frame accompanying the carrier detection based on the frequency of the carrier signal measured by the frequency measuring unit, and receiving a new frame again when the frame is determined to be invalid. Facsimile machine.