JPS5832544B2 - Facsimile control signal transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a facsimile transmission system for transmitting a ternary image signal, and more particularly to a transmission system for control signals for controlling a receiving side.

In facsimile IJ transmission, one of the methods for sending image signals at high speed is a multi-value transmission method, and among them, a three-value transmission method is often used.

Figure 1 is a signal waveform diagram showing the principle of the three-value transmission system, where a is the original binary image signal, and b is the three-value image signal that is the original signal.
The value signal C is a waveform obtained by carrier suppression amplitude modulation with this ternary signal, and d is a waveform frequency modulated with the ternary signal.

The image signal is sent in a C or d signal format.

By the way, in facsimile transmission, in addition to image signals, various control signals are used to control the receiving side, such as synchronization signals, end signals indicating the end of image signals, signals for skipping all white lines, and fast forwarding. need to be sent.

Conventionally, as a transmission method for these control signals, a method has been considered in which, for example, a signal similar to a black signal of an image signal is periodically and repeatedly sent with a certain width, and this signal is used as a control signal.

However, in this method, in order to reliably distinguish it from the original image signal, the control signal is sent repeatedly many times, but at sufficient intervals (
For example, it needs to be sent once per line), and in any case, it takes a long time to transmit it, and it also takes time for the receiving side to make a determination.

This also leads to deterioration of transmission efficiency, resulting in the loss of the advantages of the multilevel transmission method.

The present invention has been made in view of these points, and an object of the present invention is to provide a facsimile control signal that can be transmitted in a short time and can be clearly distinguished from an image signal.

The present invention will be described in detail below with reference to the drawings.

As you can see from Figure 1, there are three states of the transmission signal using the ternary transmission method, for example, white feed (this means that when looking at the ternary signal as shown in Figure 1, the black signal is always 10" At the level,
The white signal level is sent by alternating between "-//1" level and tri" level, and conversely, the black signal level is sent by changing +//1", -, /1"K. If we consider the case of "transmission", the transition of the signal state is as shown in Fig. 2.

When FIG. 1C is made to correspond, the 0-phase carrier part is in the first state A, the π-phase carrier part is in the second state C, and the part without carrier is in the third state B1. Corresponds to B2.

Similarly, in Fig. 1 d, fl is A, f3 is C1, f2 is BI, B
Equivalent to 2.

In this way, in the ternary system, the signal states (level states in the ternary signal shown in Figure 1) are A, B (B1, B2).

There are three states (in the state transition diagram, there are 4 states), and the state transition is as follows: A-4-B→C→B→A→B→C.

, A and C cannot be transmitted due to band limitations.

On the other hand, state transitions such as A-'B→A→ and C-)B-+C can be transmitted, but are prohibited for transmitting image signals.

The present invention utilizes the fact that the state transition of A→B-→A or C-+B→C is prohibited for image signal transmission, and attempts to utilize this state transition for control signal transmission. It is something.

Incidentally, the transition from A→B−+A or C→B→C may also occur due to noise mixed in during transmission.

This situation is shown in the demodulated waveform (ternary signal) on the receiving side in FIG.

In other words, the noise N1 causes a state transition of A-+B-)A (level transition of +7.]''→7,0"→+//1"), and the noise N2 causes a state transition of C→B→C (-77.
1"→, Q //→-7,1" level transition) appears.

Such signal state transitions due to noise generally occur over a short period of time, and are not regular and do not occur continuously over a short period of time.

Therefore, to transmit the control signal, for example, one state transition of A→B→A (or C-+B→C) may be sent twice for a certain period of time as shown in FIG. 4a, or As in A-=B-”A-'B→A-'B→A (or C→
If the state transition between B→C→B→C→B−+C) and between A and B (between C and B) is sent multiple times, for example, about 3 to 4 times, it can be easily distinguished from noise. arrive.

Next, a specific example of an apparatus to which the present invention is applied will be explained.

FIG. 5 shows an example of the circuit configuration on the transmitting side based on the method of the present invention, and FIG. 6 is a waveform diagram of each part thereof.

a is a signal for switching the transmission error signal between 3-value and 2-value, and in the case of 3-value transmission, it is 7,1", and in the case of binary transmission, Q
// becomes.

b is a signal for switching the signal to be transmitted into a supplementary signal and a control signal, and all control signals are converted into two signals as shown in Fig. 4.
If it is sent in the form of a value signal, this signal may be the same as a as shown in FIG.

C is a binary human-powered image signal, and d is a human-powered control signal.

11 is an inverter, 12 and 13 are AND gates, 14
is a NOR gate, and an image signal C and a control signal d appear at the output e of the NOR gate 14 in a time-divided manner according to the signal 14.

However, the polarity is reversed.

15 is a flip-flop at J-, the state of the terminal at J,
That is, when the signal a is 771'', it is inverted at every falling point of the output e of the NOR gate 14 applied to the Cp terminal, and when it is 1., it is not inverted.

Therefore, its Q output becomes f.

16.17 is the Q and Q of flip-flop 15 to J-
For example, a portion of the output e of the NOR gate 14 that should be at the 771 // level and a portion of the output e of the NOR gate 14 are controlled by the outputs.
//1" This is an AND gate that separately takes out the part that should be at the level, and its outputs will be g and h, respectively.

Although the control signal component is included in the signal g here, it may also be included in the signal h depending on the state of the JK flip-flop.

These signals g and h are applied to an inverting input terminal and a non-inverting input terminal of operational amplifier 18, respectively.

As a result, the output i of the operational amplifier 18 has g of 71"
When h is 70"//1" level, g is Q/
When b is 71", the level is +u 1", and when g and h are both 7,0", the signal is /10", and this becomes the transmission signal.

In other words, the transmission signal alternately changes from 0 to 1 // level at both signals, but at the control signal it changes to 70 and -771 levels. I am traveling back and forth between the two.

This transmission signal is actually further guided to a modulator and transmitted in the form of an amplitude modulated wave (carrier the breath may also be used) or a frequency modulated wave.

Next, the receiving side will be explained.

FIG. 7 shows an example of the circuit configuration on the receiving side based on the method of the present invention (
(corresponding to FIG. 5), and FIG. 8 is a waveform diagram of each part thereof.

The received signal a demodulated into a ternary signal is sent to a level determination circuit 21
, 22.

The level determination circuit 21 has an input level of +tt 1 ”/
The level determination circuit 22 is configured to output an output when the human power level is less than -7,1''/2, and the output waveform is as follows. It becomes like c.

When these outputs are applied to the NOR gate 23, two binary signals and a control signal are obtained as shown in j, which is led to a recording section (not shown) as a recording signal.

22 and 25 are circuits that detect the falling points of the output byc of the level determination circuit 2L22, and the output waveform is dy
It becomes e.

26 is a set-reset flip-flop that is set at the falling edge of the output d of the falling point detection circuit 24 and reset at the falling edge of the output e of the falling point detection circuit 25, and its Q output is as shown in f. Become.

27 and 28 are AND gates whose inputs are the Q and q outputs of the flip-flops and the outputs 2 and 2 of the level determination circuits 21 and 22, and when the outputs of the AND gates 27 and 28 are added to the OR gate 29, Of the received signal a,
A signal having a pattern shown in g, which deviates from the rules for ternarizing image signals, is obtained.

30.degree. and 31 are the Q and Q outputs of the flip-flop 26 and the outputs of the level determination circuits 22 and 21, respectively.

When the outputs of the AND gates 30 and 310 are added to the NOR gate 32, a signal of the pattern shown in h, which conforms to the rules for ternarizing image signals, is obtained from the received signal a. can get.

33 is a control signal detection circuit which detects a control signal by examining the pattern of the output g of the OR gate 290 and determining whether or not this pattern is due to noise (for example, indicated by aKN in FIG. 8); The output of NOR gate 32 is used for reset.

For example, in this example, a counter is used as the control signal detection circuit 33, and is configured to output a detection output indicated by i when the number of pulses of the output g of the OR gate 29 is counted up to three.

As described above, this detection output may be used, for example, as a synchronization signal, or as an end signal, a skip fast-forward signal, or the like.

As explained above, in the present invention, the signal state of the image signal is
In the facsimile IJ transmission method in which the signal form is transmitted in a signal form that changes between the first and second states, the signal form to be transmitted is deviated from the rules for transmitting the image signal, that is, the first and second states. one state of the second state and the third state
It is configured such that it makes at least one round trip between the two states, and this round trip portion is transmitted as a control signal.

That is, according to the present invention, since the pattern itself of the control signal to be transmitted deviates from the rules for ternarization of image signals, it is possible to immediately distinguish it from the image signal.

For this reason, as in the conventional system, the control signal is sent more times than necessary in order to distinguish it from the image signal.1. It is not necessary to send the signal at long intervals, and the number of repetitions or the time required for one round trip of the signal state may be selected to the extent that it can be distinguished from noise.

Therefore, the transmission time of control signals can be shortened, contributing to improvement in transmission efficiency.

[Brief explanation of the drawing]

Figure 1 is a waveform diagram showing the principle of the three-value transmission method, and Figure 2 is a waveform diagram showing the principle of the three-level transmission method.
FIG. 3 is a waveform diagram when noise is mixed into the ternary signal; FIG. 4 is a waveform diagram showing an example of a control signal according to the method of the present invention; FIG. FIG. 5 is a diagram showing an example of the circuit configuration on the transmitting side based on the method of the present invention, FIG. 6 is a waveform diagram of each part of FIG. 5, and FIG. 7 is a diagram showing an example of the circuit configuration on the receiving side based on the method of the present invention. FIG. 8 is a waveform diagram of each part of FIG. 7. 11... Inverter, 12, 13, 16, 17
゜27.28,30,31...AND gate,
14゜23.32...NOR gate, 15.
...Flip-flop on J-, 18...
Amplifier, 21, 22...Level judgment circuit, 24
．． 25... Falling point detection circuit, 26...
・Set-reset flip-flop, 29...
...OR gate, 33...control signal detection circuit.

Claims (1)

[Claims] 1. In a facsimile transmission system in which an image signal is transmitted in a signal form in which the signal state alternately changes between the first and second states with a third state in between, the signal form to be transmitted is in the first and second states. A facsimile control signal transmission system characterized in that the facsimile control signal is transmitted at least once between one state and a third state, and the reciprocated portion is transmitted as a control signal.