JP3337894B2 - Facsimile machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to signal transmission of a facsimile apparatus having 34 functions.

[0002]

2. Description of the Related Art In a conventional facsimile apparatus, a signal transmission level can insert a loss of 0 to 15 dB every 1 dB, and an average energy of 0 to 15 dB.
m had been sent. On the other hand, a fixed equalizer has been inserted for the purpose of correcting the amplitude characteristic of the subscriber line cable.

[0003] However, the conventional ITU-T Recommendation V.
21, V.I. 27ter, V.I. 29, V.I. In transmission up to 17, there was no particular problem because the difference between the average energy and the peak energy of signal transmission was small, and no signal suppression value and pre-emphasis were specified from the receiver.

[0004]

However, the ITU
-T Recommendation V. In 34, the receiver can specify the power suppression value and the pre-emphasis to be set to the transmitter, and supports up to a data rate of 33.6 kb / s. Is increased, and a problem is expected that the waveform is clamped at the entrance of the exchange and communication becomes impossible.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a facsimile apparatus capable of performing communication by appropriately controlling a transmission level based on a power suppression value from a receiver to a transmitter and pre-emphasis.

[0006]

Means for Solving the Problems The first invention of the present application is:
Setting means for setting the signal transmission level, setting means for setting the fixed equalizer, recognition means for recognizing the power suppression value notified from the receiver to the transmitter, and notification from the receiver to the transmitter A recognition unit for recognizing pre-emphasis, and based on the setting information of each of the setting units and the recognition information of each of the recognition units, the maximum amplitude value of the transmission signal approaches a predetermined value within a range not exceeding a predetermined value. By sending
Communication at the maximum transmission level within a range not clamped at the entrance of the exchange becomes possible, and transmission at a high speed such as 33.6 kb / s becomes possible.

According to a second aspect of the present invention, the facsimile apparatus further recognizes the frequency characteristic up to the terminal station, and transmits the signal with the maximum amplitude value approaching a predetermined value within a range where the maximum amplitude value does not exceed the predetermined value. In consideration of the frequency characteristics from the terminal to the terminal of the exchange, communication at the maximum transmission level within a range not clamped at the entrance of the exchange becomes possible, and 33.6 kb /
Transmission at a high speed such as s is possible.

In general, there is a loss from the facsimile apparatus to the terminal station of the exchange, and in a high frequency band, the signal is attenuated by the f1 ^{/ 2} characteristic. Becomes possible.

The third invention of the present application suppresses the voltage to a predetermined voltage or less by having a means for selecting which of the power suppression value and the pre-emphasis, which is notified from the receiver, to the transmitter. When this is not possible, it becomes possible to satisfy the specification from the receiver side, which is important for ensuring high-speed communication.

[0010]

FIG. 1 is a block diagram showing the configuration of a facsimile apparatus according to one embodiment of the present invention.

An NCU (network control unit) 2 connects to a terminal of the line in order to use the telephone network for data communication and the like.
It controls connection of the telephone exchange network, switches to a data communication path, and holds a loop. The NCU 2 connects the telephone line 2a to the telephone when the signal level (signal line 20a) from the control circuit 20 is "0", and connects the telephone line 2a when the signal level is "1".
Is connected to the facsimile machine side. In a normal state, the telephone line 2a is connected to the telephone 4 side.

The hybrid circuit 6 separates the transmission system signal and the reception system signal, sends the transmission signal from the fixed equalizer 25 to the telephone line 2a via the NCU 2, and transmits the signal from the other party via the NCU 2 And sends it to the modem 8 via the signal line 6a.

The modulator / demodulator 8 is based on ITU-T Recommendation V. 8,
V. 21, V.I. 27ter, V.I. 29, V.I. 17, V.I.
The modulation and demodulation are performed based on the signal line 34, and each transmission mode is designated by the signal line 20c. Modem 8
Inputs a signal output to the signal line 20b, outputs modulated data to the signal line 8a, inputs a received signal output to the signal line 6a, and outputs demodulated data to the signal line 8b.

The ANSam transmission circuit 10 is a circuit for transmitting an ANSam signal. When a signal of signal level "1" is output to the signal line 20d, the ANSam signal is output to the signal line 10a.
An NSam signal is transmitted, and no signal is output to the signal line 10a when the signal of the signal level "0" is output to the signal line 20d.

The addition circuit 12 receives the information on the signal line 8a and the information on the signal line 10a, and adds the result of the addition to the signal line 12a.
Output to

The pre-emphasis setting circuit 22 calculates f / s
(F is a frequency (Hz), s is a symbol rate) is a transmission spectrum specification corresponding to a normalized frequency defined by a ratio, in which a signal of the signal line 12a is input and a signal line 20f
2 and 3 according to the indexes 0 to 10 output to
, And outputs the corrected information to the signal line 22a.

FIGS. 2 and 3 show amplitude characteristics of indexes 0 to 5 output to the signal line 20f, and FIGS.
Represents amplitude characteristics of indexes 6 to 10 output to the signal line 20f.

The attenuation circuit 24 receives a signal on the signal line 22a and outputs a value (for example, 0 to 1) output on the signal line 20g.
Information attenuated by 0.5 dB up to 5 dB) is output to the signal line 24a.

The fixed equalizer 25 receives the signal on the signal line 24a and outputs the value on the signal line 20h (0 is not corrected, 1 is correction of the subscriber line cable 1.8km, 2 is the subscriber line). The information corrected based on the correction of the cable 3.6 km, the correction of the subscriber line cable 5.4 km for 3, and the correction of 7.6 km for 4 is output to the signal line 25a.

The reading circuit 14 reads an image of a document,
This read data is output to the signal line 14a. The recording circuit 16 sequentially records the information output to the signal line 20e line by line.

The memory circuit 18 is used to store raw information of read data or encoded information, and also stores received information or decoded information.

The amplitude characteristic judging circuit 26 receives, for example, a line probing signal at the return of the terminal station, judges the amplitude characteristic corresponding to the frequency of the subscriber line cable between the terminal station and the facsimile apparatus, and outputs the result as a signal. Output to line 26a.

The amplitude characteristic storage circuit 28 is a circuit for storing the amplitude characteristic corresponding to the frequency of the subscriber line cable between the terminal station and the facsimile machine via the signal line 28a.

The amplitude characteristic storage circuit 30 is a circuit that stores an amplitude characteristic with respect to frequency corresponding to each modulation method, baud rate, and bit rate via a signal line 30a.

When the setting circuit 32 performs transmission according to the pre-emphasis or power suppression value specified by the receiver, when the peak voltage value exceeds a predetermined voltage, which information specified by the receiver has priority. Is set. When pre-emphasis is selected, the signal line 3
A signal of signal level "0" is output to 2a, and a signal of signal level "1" is output to signal line 32a when the transmission level is selected.

The control circuit 20 controls the entire facsimile apparatus of the present embodiment. In the first embodiment, in particular, in the first embodiment, the set value of the signal transmission level, the set value of the fixed equalizer,
Based on the power suppression value notified from the receiver to the transmitter and the pre-emphasis information, the maximum amplitude value of the transmission signal is brought close to a predetermined value within a range not exceeding a predetermined value (for example, 2.2 V _PP ). The transmission is controlled.
In addition, in consideration of the pre-emphasis and the power suppression value notified from the receiver to the transmitter, when the maximum amplitude value of the transmission signal exceeds a predetermined value, control is performed based on the information of the circuit 32 to determine which one to place more weight on. Do.

FIGS. 6 to 8 are flowcharts showing the control flow of the control circuit 20 in the first embodiment of the present invention. In the first embodiment, the amplitude characteristic determination circuit 2
6. The amplitude characteristic storage circuit 28 is not used.

First, the operation starts in S40, and in S42, the amplitude characteristic corresponding to each modulation method, baud rate, and bit rate is stored in the amplitude characteristic storage circuit 30 via the signal line 30a.

In S44, a signal of signal level "0" is output to the signal line 20a to turn off the CML. In S46, a signal of signal level “0” is output to the signal line 20d,
The ANSam signal is not sent.

In step S48, a signal "1" is output to the signal line 20h, and the fixed equalizer 25 is set to the 1.8 km correction value of the subscriber line cable. In S50, a signal “0” is output to the signal line 20g, and the attenuation of the attenuation circuit 24 is set to 9 dB.

In S52, it is determined whether or not transmission has been selected. If so, the flow proceeds to S56, and if not, the flow proceeds to S54 to perform other processing.

In S56, a signal of signal level "1" is output to the signal line 20a to turn on the CML. In S58, ANSam reception, CM transmission, JM reception, CJ
V. 8 are executed, and in step S60, line probing is transmitted.

In S62, INFOh information is input,
The specified baud rate, pre-emphasis, and power suppression amount are stored. In S64, the information of the storage circuit 30 is input, and attention is paid to the transmission of the specified baud rate. Further, the maximum pre-emphasis and the maximum peak to peak on the time axis output to the signal line 2a from the specified amount of power suppression are performed.
Find the power of ak. At this time, the fixed equalizer 25 is 1.8
km and the attenuation circuit 24 has 9 dB of attenuation. Here, the modulator / demodulator 8 outputs a signal of 0 dBm.

In step S66, the maximum peak to pe
It is determined whether or not the voltage of a.k is 2.2 V or more.
If it is 2 V or more, the process proceeds to S68, and if it is less than 2.2V, the process proceeds to S74.

In step S68, the information of the signal line 32a is input, and it is determined whether the value of the pre-emphasis value specified by the receiver or the amount of power suppression is low, which is prioritized. If the small amount is selected, the process proceeds to S70, and when the power of the peak-to-peak on the time axis is output to the signal line 2a, the pre-emphasis amount is reduced so as to be 2.2 V or less, and the pre-emphasis is reduced. If the number is selected, the process proceeds to S72, where p on the time axis is selected.
When the voltage of “eak to peak” is output to the signal line 2a, the attenuation is increased so as to be 2.2 V or less.
Thereafter, the process proceeds to S80.

In step S74, the amount of attenuation is reduced until the maximum peak-to-peak voltage reaches 2.2 V when the voltage is output to the signal line 2a. And S76 represents transmission of long training. In S78, the designated bit rate is stored. Thereafter, the process proceeds to S86.

S80 represents transmission of long training, and S82 stores the designated bit rate. In S84, the amplitude characteristic information at the specified baud rate or less has been input from the circuit 30 and the maximum peak-to-peak voltage has been obtained. Here, the bit rate is actually determined. A peak-to-peak voltage is obtained in the same manner as in S64. Here, since the maximum peak-to-peak voltage is generally 2.2 V or less, the amount of pre-emphasis reduced based on the information of the setting circuit 32 and the increased attenuation amount are reduced to the maximum peak-to-peak voltage at the time of the signal line 2a. And return to 2.2V.

In S86, it is determined whether or not the maximum peak-to-peak voltage at the designated bit rate has reached 2.2 V at the time of the signal line 2a. If the voltage has not reached 2.2 V, the process proceeds to S88, and the process proceeds to S88. Maximum peak to
The amount of attenuation of the attenuation circuit 24 is reduced until the peak voltage becomes 2.2 V, and the process proceeds to S90. When the voltage is 2.2 V, the process proceeds to S90.

In S90, V.V. Then, the procedure and image transmission based on are performed, and the process proceeds to S44.

Next, in FIG. 8 procedures, V.I. 3
Four procedures and specific examples of image transmission will be described.

First, a signal (ANSam (signal obtained by modulating 2100 Hz at 15 Hz)) enabling full-duplex communication is transmitted from the called side. From the calling side, V. C by 8 modulation
An M signal is transmitted to notify a receiver of a transmission mode that can be transmitted at the time of image transmission. On the other hand, the called side, after receiving the CM signal,
The transmitter notifies the transmitter of a receivable transmission mode that can be received on the called side among the retransmission modes specified by the M signal. After receiving the JM signal, the calling side sends a CJ signal and notifies the receiver of the transmission mode.

After transmitting the CJ signal, the transmitter sends out a line probing signal (INFO _0c is output at the head) for checking the state of the telephone line 50 ms later, and the receiver responds to this signal. Signal (INFO at the head)
_0a is output) to notify the transmitter of the subsequent transmission level, amplitude level correction, and transmission baud rate.

The transmitter transmits a long training signal 50 ms after the transmission of the line proofing signal, and the receiver adjusts the equalizer of the modem by this signal.
Perform timing detection and the like.

The transmitter transmits a parameter exchange signal 50 ms after the transmission of the long training signal, and the receiver transmits a signal in response to this signal, and notifies the transmitter of subsequent link correction and bit rate. The receiver sends the CSI and DIS signals following the parameter exchange response signal, sends flags until the TSI and DCS signals are received, and sends the CFR signal after receiving the TSI and DCS signals. After receiving the CSI and DIS signals, the transmitter sends TSI and D
A CS signal is transmitted, and a flag is transmitted until a CFR signal is received.

After transmitting the flag signal, the transmitter transmits the image signal 50 ms after the transmission of the flag signal, transmits the PPS-MPS signal 50 ms after the completion of the transmission of the image signal, and transmits the flag until the MCF signal is received. After receiving the PPS-MPS signal, the receiver sends an MCF signal.

The transmitter transmits an image signal 50 ms after the flag signal is transmitted, transmits a PPS-EOP signal 50 ms after the completion of the image signal transmission, and transmits a flag until the MCF signal is received. After receiving the PPS-EOP signal, the receiver sends out the MCF signal.

Next, a second embodiment of the present invention will be described.

In the first embodiment, the maximum peak-to-peak in the output level of the facsimile apparatus is obtained.
The peak voltage did not exceed 2.2V. However, the frequency characteristic up to the terminal station is recognized, and the peak-to-peak value of the maximum amplitude value is set to a predetermined value (for example,
The voltage may be transmitted close to a predetermined value within a range not exceeding 2.2 V).

FIG. 10 is a flowchart showing a part of the control of the second embodiment which is different from that of the first embodiment.

In FIG. 10, S100 represents the above S54. Then, in S102, it is determined whether or not registration of the amplitude characteristic of the subscriber line cable is selected by an operation unit (not shown), and if it is selected, the process proceeds to S104, where the information of the signal line 26a is input, and the subscriber line cable is input. Is determined in the storage circuit 28 via the signal line 28a, and if not selected, the process proceeds to S106 (S44).

Then, S64, S70, S72, S
In each determination of 74, S84, and S88, the storage circuit 28
Is determined in consideration of the amplitude characteristic of the subscriber line cable stored in the terminal station, and further, in consideration of the maximum peak-to-peak voltage at the terminal station.

[0052]

As described above, according to the first aspect of the present invention, it is possible to transmit data at the maximum transmission level from the facsimile apparatus within a range that is not clamped at the entrance of the exchange. Transmission at a high speed such as s is possible.

Further, according to the second invention of the present application, taking into account the frequency characteristics from the facsimile apparatus to the terminal station of the exchange, the maximum transmission level from the facsimile apparatus within a range not clamped at the entrance of the exchange. And transmission at a high speed of 33.6 kb / s or the like becomes possible. In general, there is a loss from the facsimile machine to the terminal of the exchange, and the high frequencies are attenuated by f1 ^{/ 2} characteristics.
Transmission at a transmission level higher than that of the first invention described above, that is, communication at a high speed becomes possible.

Further, according to the third aspect of the present invention, when it is impossible to suppress the voltage to a predetermined voltage or less, the designation from the receiver which is more important for securing high-speed communication is satisfied. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the first embodiment of the present invention.

FIG. 3 is a flowchart showing the operation of the first embodiment.

FIG. 4 is a flowchart showing the operation of the first embodiment.

FIG. 5 is a flowchart showing the operation of the first embodiment.

FIG. 6 is a flowchart showing the operation of the first embodiment.

FIG. 7 is a flowchart showing the operation of the first embodiment.

FIG. 8 is a flowchart showing the operation of the first embodiment.

FIG. 8 procedures, V.I. FIG. 35 is an explanatory diagram showing a specific example of the image transmission in the 34th procedure.

FIG. 10 is a flowchart showing the operation of the second embodiment of the present invention.

[Explanation of symbols]

 2 ... NCU, 4 ... telephone, 6 ... hybrid circuit, 8 ... modulator / demodulator, 10 ... ANSam transmission circuit, 12 ... addition circuit, 14 ... read circuit, 16 ... recording circuit, 18 ... memory circuit, 20 ... control circuit, 22 ... pre-emphasis setting circuit, 24 ... attenuation circuit, 25 ... fixed equalizer, 26 ... amplitude characteristic determination circuit, 28, 30 ... storage circuit, 32 ... setting circuit.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/32-1/36 H04N 1/42-1/44

Claims (3)

(57) [Claims] 1. Setting means for setting a signal transmission level, setting means for setting a fixed equalizer, recognition means for recognizing a power suppression value notified from a receiver to a transmitter, and transmission from a receiver A recognition means for recognizing pre-emphasis to be notified to the device, based on the setting information of each of the setting means and the recognition information of each of the recognition means, within a range where the maximum amplitude value of the transmission signal does not exceed a predetermined value. A facsimile machine, wherein the facsimile machine sends the data close to a predetermined value. 2. The facsimile apparatus according to claim 1, further comprising recognizing the frequency characteristics up to the terminal station, and transmitting the terminal station with the maximum amplitude value approaching a predetermined value within a range not exceeding the predetermined value. . 3. The facsimile apparatus according to claim 1, further comprising means for selecting which of the power suppression value and pre-emphasis information notified from the receiver to the transmitter is prioritized.