JPS5822896B2 - Sign determination method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a modulator/demodulator (MO) for data transmission.
This relates to the sign determination method of DEM), especially when determining the determination plane by comparing x and y coordinate values using ROM.
The present invention relates to a system in which the absolute values of the X and y coordinate values are first compared using a ROM, and then the sign is determined by considering the sign and the negative, and the final sign is determined.

When transmitting data using a telephone line, MODEM
is used.

There are many types of MODEMs depending on the number of bits that can be transmitted per second, but a 9600 bits/second model is being researched to increase the number of bits that can be transmitted.

The International Telegraph and Telephone Consultative Committee (CCITT) has recommended that the quadrature amplitude modulation method be adopted for the above-mentioned 9600 bits/second MODEM.

This converts the information to be transmitted into one piece of information every 4 bits, and then demodulates the information into 4-bit information again on the receiving side.Therefore, the actual modulation process is performed at 2400 Hz.

This information is configured to be identified by amplitude and phase.

This point will be explained in more detail based on FIG.

Now, when we set the coordinates of the X and y axes on the plane, we set the scales to the proportions of 1, 2, 3, and 4.5 for the X and y axes, respectively, and set the 3 points on the Let the point of A, 5 be A'.

It is assumed that A represents 4-bit information "0000" and A' represents [1000].

Also, x, y are 1, 1. The point of is B, the point of 3,3 is B',
3. -3 point is D, B is "0001", B' is "
1001'' and D represents ``1111''.

In this way, 16 points or signal points of 4-bit information from 1-0000J to [1111J are determined at the positions shown in FIG. 1.

Each signal point is transmitted as a quadrature amplitude modulated wave modulated such that its amplitude is the distance from the origin of the coordinates, and its phase angle is the angle between the line connecting that point and the origin and the y-axis.

Here, the orthogonal amplitude modulated wave is a combination of amplitude modulation and phase modulation.

For example, when actually transmitting the information "00001001", this is divided into 4-bit information "0000" and "1001".

Since 1'-0000J is converted as point A,
M as an analog wave modulated with an amplitude of 3 and a phase of 0 degrees.
Since it is transmitted from the ODEM and "1001" is converted as point B', it is transmitted as an analog wave with an amplitude of 3JΣ and a phase modulated at 45 degrees.

Then, in the receiving MODEM, these are demodulated as l''-0O00J and [1001j, respectively, and these are concatenated to receive transmission data "00001001".

However, even if the signal sent from the transmitting side is a distortion-free signal, by the time it is actually transmitted through the transmission line and received, noise is mixed in due to the influence of various types, for example, Even if information C is transmitted, when it is received, it will not be focused on point C, but will be blurred over a considerable range, as shown by the dotted line C'.

Therefore, even if such a blank signal is received, it is necessary to determine the sign that it is point C.

For this purpose, conventionally, as shown in FIG. 2, the plane is divided into 16 areas each having one signal point, such as point A
An address comparison table is created in a storage device such as a ROM so that when a received signal is present in the area AO where the point A exists, this is determined to be the point A.

That is, the value of X exists in the range of X1 to X2, and the value of y is +
A comparison table of areas for each point is prepared so that all received signals in the range from y1 to -y1 are regarded as point A.

In order to divide the above 16 regions, the y-axis is divided into 16 regions from +2 to -2, and the y-axis is also divided into 16 regions from +2 to -2.
Since the coordinates are determined by dividing the area up to 16, the comparison table stored in the ROM requires 4 bits for the y-axis, and uses 4 bits for the y-axis as well as address bits. A total of 8 bits are used.

On the other hand, there is phase sickness in the signal transmission line, which causes a phenomenon in which the signal point oscillates in the phase angle direction around the origin.

For example, at point C shown in FIG. 2, there is a phenomenon of vibration in the direction of the arrow around point C.

However, in the case of point C, if the phase moves by ±16.9 degrees, it will exceed that area and invade other determination planes.

Moreover, in the determination areas as shown in FIG. 2, all of the determination areas do not intrude into other determination areas at ±16.9 degrees, and are extremely non-uniform.

For this purpose, for example, in order to improve the non-uniformity of the determination area at point C, if the area is expanded and shifted by one scale on the y-axis and the y-axis,
This time, a disadvantage arises in that the determination area for adjacent points E and F becomes too narrow.

To improve this, it is possible to determine the decision plane by dividing the region from +2 to -2 on the y-axis and y-axis into 32 equal parts, but in this method] This requires 4 times the capacity of the ROM.

Therefore, the present invention enables a code determination method to improve such problems without increasing the capacity of the ROM. A signal point is provided on a plane, and the plane is divided into a plurality of areas, so that one signal point exists in each area, and when received information is in a certain area, the received information is transmitted within that area. In the code determination method for determining that the information is information of a signal point existing in the received information, an absolute value converting circuit that converts the X coordinate value and the X coordinate value into absolute values, excluding the code bit in the received information, and the absolute value converting circuit an X-coordinate value converted into an absolute value and a storage device that is indexed by the X-coordinate value; and a code that determines in which of the regions the received information is located based on the index information output by the storage device and the code bit. and a determination circuit, and the code determination circuit performs bit inversion processing on the inputted index information according to the logic condition of the code bit, and outputs the final received output.

Next, one embodiment of the present invention will be described based on FIGS. 3, 4, and 5.

FIG. 3 is a code determination pattern used in the present invention, and FIG. 4A is a circuit configuration diagram of an embodiment of the present invention.
The same figure is an explanatory drawing, and FIG. 5 is a flow chart explaining the present invention in detail.

In the figure, 1 is an address register for the X coordinate, 2 is an address register for the X coordinate, 3 and 4 are absolute value conversion circuits, and 5
is a ROM, 6 is a sign determination circuit, 7 is an address register for the X coordinate, 8 is an address register for the X coordinate, and 9 is a ROM.

In the present invention, as shown in FIG. 3, the plane is divided into 32 areas from +2 to -2 on both the y-axis and the y-axis.

For this purpose, 5 bits are used each for the address for the X coordinate and the address for the X coordinate.

This means that the address of the conventional sign determination pattern shown in Figure 2 uses 1 extra bit compared to the address that uses 4 bits on both the y-axis and y-axis, and the coordinates can be subdivided by that amount. It shows.

As a result, the information area where each signal point exists can be determined as shown in FIG.

According to the information area shown in FIG. 3, for example, in the information area where point C exists, a phase variation of ±24.3 degrees is allowed, and the phase variation in the case of FIG. 2 is ±1.
This is a significant improvement compared to the case where the temperature was 6.9 degrees.

Of course, in Figure 3, phase fluctuations up to +30 degrees are allowed in the information area where point F exists, and the ratio of phase fluctuations with respect to the information area where point C exists is considerably larger than in the case of Figure 2. They are close to each other, and it can be seen that they are equalized from this perspective as well.

However, in the present invention, when determining in which area the received information is located, five bits are used each as the y-axis and y-axis address bits.

However, as shown in FIG. 4A, the X coordinate information and the X coordinate information of the received information are stored in the X coordinate address register 1 and the X coordinate address register 2, respectively, and then the absolute value conversion circuit 3 and 4 are converted into absolute values.

This absolute value conversion circuit outputs 4 for both the X coordinate and the X coordinate, with one bit of the sign indicating positive or negative omitted.
This is output as bit address information, and this is R,0M.
The position on the first quadrant is determined by comparing with the comparison table of 4-bit information stored in 5.

Then, on the first quadrant, "0001" and "0000".

``1000j, ``1001j, ``0O1
The first quadrant determination bit is determined to be in one of the areas 0j and "1010", and as a result, the first quadrant determination bit in which one of the six types of binary data is selected is sent to the sign determination circuit 6.

The sign determination circuit 6 determines whether the X-coordinate address and the X-coordinate address of the received information are positive or negative, respectively.
Information is transmitted from code bits 1' and 2' of the address register 1 for the X coordinate and the address register 2 for the X coordinate.

The first quadrant determination bit sent from the ROM 5 is controlled as follows based on this positive or negative value.

That is, as shown in FIG. 5, the first quadrant determination bit is
When Qt Q2 Qa Q4J, (1) First, Q4
It is determined whether or not is "0", and if it is not "0", it is determined whether the y-axis address is + or -.

Then, if -, Q2 is inverted, that is, if Q2 is "0", it is inverted to rlJ, and if it is "1", it is inverted to "0", and then only either the X coordinate address or the X coordinate address is -. Determine whether it exists or not.

If only one of the above addresses is negative, Q3 is further inverted, and the output thus obtained is the final received output.

(2) If the above Q4 is “0”, then Q3 is “0”
Determine whether or not.

If Q3 is "0", it is determined whether the X-coordinate address is -, and if it is a square, 0.2 is inverted and used as the final received output.

(3) If Q3 is not "0", it is determined whether the X coordinate address is -, and if it is negative, Q2 is inverted and used as the final received output.

The above explanation will be explained using an example.

Now suppose that ``0100J'' is sent.

At this time, on the receiving side, "0000" is output from the ROM 5, and the X coordinate address is -.

According to the flow chart of FIG. 5, it is first determined whether Q4 is "0" or not.

Since Q4=0, it is next determined whether or not Q3 is 10, which is also YES.

Then, it is determined whether the X coordinate address is - or not,
Since this is also YES, Q2 is inverted, and the resulting "0100" is determined as a determination bit in the sign determination circuit 6, and this determination bit is output as received data.

Also, if "1101" is sent, the receiving side's ROM
5 outputs "1001", and the fact that both the X coordinate address and the X coordinate address are - is transmitted to the sign determination circuit 6.

Therefore, first, Q4=1 and the X coordinate address is negative] Q3 is inverted at □, but since both the X coordinate address and the X coordinate address are negative, other bits are not inverted.

Therefore, the sign determination circuit 6 determines "1101" as the determination bit, and this determination bit is output as received data.

In the present invention, the absolute value of both the X-coordinate address and the X-coordinate address is set to 4 bits, and then compared with the comparison table stored in the ROM 5.

Therefore, the comparison table stored in the ROM 5 only needs to be for the first quadrant of 4 bits each, and only the comparison table for % of the total area needs to be prepared, so the capacity of the ROM 5 can be small.

By the way, as shown in Figure 4, when the received 5 bits of the X coordinate address and 5 bits of the This requires a ROM with a capacity four times that of the present invention.

As explained above, according to the present invention, it is possible to equalize each information area against blurring, and it is also possible to compare the absolute value of the address when determining a signal point. There is almost no need to increase the capacity of the ROM.

Although the above explanation has been made for the example of the signal point arrangement as shown in FIG. 1 for a 9600 bit/sec MODEM, the present invention is of course not limited to this.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of signal points, FIG. 2 is a conventional sign determination pattern, FIG. 3 is a sign determination pattern according to the present invention, and FIG.
Figure A is a circuit configuration diagram of an embodiment of the present invention, and Figure A is an explanatory drawing.
FIG. 5 is a flow chart illustrating the invention in detail. In the figure, 1 is an address register for the X coordinate, 2 is an address register for the X coordinate, 3 and 4 are absolute value conversion circuits, and 5
is 1' (0M16 is a sign determination circuit, 7 is an address register for the X coordinate, 8 is an address register for the X coordinate,
9 each indicates a ROM.

Claims (1)

[Claims] 1 A plurality of signal points representing certain information according to coordinate positions are provided on a plane, and the plane is divided into a plurality of areas, so that one signal point exists in each area, and the received information is In a code determination method that determines that received information is information of a signal point existing in a certain area when the received information is in that area, the X coordinate value and the an absolute value converting circuit for converting to an absolute value; an X coordinate value converted into an absolute value by the absolute value converting circuit; and a storage device indexed by the X coordinate value; and a sign determination circuit that determines in which of the regions the information is located, and the sign determination circuit performs bit inversion processing on the inputted index information according to the logic condition of the sign bit to obtain a final received output. A sign determination method characterized by: