KR20000026398A - Direct detection circuit of sine/cosine value about phase error angle of qam demodulator and method thereof - Google Patents

Abstract

PURPOSE: A direct detection circuit of sine/cosine value about a phase error angle of QAM demodulator directly calculates a sine/cosine value of a phase error angle from a baseline coordinates of the receiving signal and symbols. CONSTITUTION: A QAM demodulator calculates a power by using coordinate data of a receiving data, stores a proportion data of mapping the receiving data as a baseline having a predetermined power level, and reads a proportion data by using a calculated power as access value. The QAM demodulator stores the coordinate data of anticipation receiving symbols having the same power mapped as the baseline, and reads the coordinate data by using the output power value as access address. The coordinate data of the receiving data is multiplied by a proportion data read from the proportion value storage part, the QAM demodulator performs a mapping by using a baseline. Then, the QAM demodulator calculates a sine/cosine value(215,216) about a phase difference of the read coordinate data corresponding to the mapping coordinates. The QAM demodulator compares the calculated sine/cosine value with another sine/cosine value(215,216) calculated by the phase error of the received data, and determines a sine/cosine value(215,216) being identical with the calculated sine/cosine value.

Description

Direct extraction circuit of sine / cosine value for phase error angle of RAM demodulator and its method

The present invention relates to a phase error tracking circuit and a method for synchronizing carriers in a QAM demodulator, and more particularly, to a circuit and a method for directly extracting a sine / cosine value for a phase error angle of a QAM demodulator.

In today's society, called the information society, high-speed digital modems are needed to deliver interactive multimedia services that can provide users with the information they want at the time they want it. As a demodulation device for transmitting to a terminal, a QAM method capable of high-speed data transmission is expected to be used.

Meanwhile, in order to provide a multimedia service through a QAM scheme, a transmitting side sends a baseband signal to a carrier, and a receiving side needs to remove the carrier once to restore the baseband. In particular, in the QAM demodulator, it is necessary to track and recover phase errors generated during transmission.

1 is a diagram illustrating an embodiment to which a phase recovery method of a conventional QAM demodulator is applied. A power calculator 103 for receiving data I and Q coordinates 101 and 102 of the constellations of the symbols received by the QAM demodulator and outputting power values of the received symbols; A symbol predictor 104 for outputting information on I coordinates and Q in constellations for symbols that may have the same level of power, and arctan (tan ^-1) to obtain a phase angle of a received signal. (θ) A phase determination unit 116 of a received signal having a ROM function and a phase difference calculator for outputting difference values of phase angles between the symbols predicted by the symbol predictor 104 and the received symbols; And a phase error angle by comparing the data on the phase differences currently applied from the phase difference calculator 109 and stored in the memory unit with the data on the phase differences applied immediately before and stored in the memory unit. Phase error angle determination unit 114 and the determined phase error angle (θ) Phase error angle (θ) It consists of a storage unit 115 for outputting a sine / cosine value for.

However, the phase recovery circuit used in the conventional QAM demodulator cannot obtain the exact phase error angle in tracking the phase error generated during transmission.

In digital communication systems, the larger the bit width of the sampled data, the more accurate data can be obtained, but in general, the speed of ROM decreases significantly as the bus width of the address increases. . In other words, the address of the ROM is determined according to the bit width of the received signal. In general, as the bit width of the received signal increases, the access speed of the ROM decreases, which causes a large degradation in the overall speed performance of the circuit. There was a problem. Also, the phase error angle is arctan (tan ^-1 (θ) Is obtained by using and compared with the phase angles of the predicted symbols. (θ) Extracting the sine / cosine values for again using ROM is absurd in converting from coordinate to angle and from angle to coordinate.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to obtain the power value for the exact reception symbol from the I, Q coordinates of the constellation diagram for the reception symbol in the QAM demodulator The present invention provides a circuit and a method for directly extracting a sine / cosine value for a phase error angle from coordinates of a currently received symbol and an expected symbol by predicting symbols that may have a level.

1 is a phase error angle in carrier synchronization of a conventional QAM demodulator. (θ) Block diagram showing an embodiment in which a circuit is applied to extract a sine / cosine value for

2 is a phase error angle in carrier synchronization of a QAM demodulator according to the present invention. (θ) Block diagram showing an embodiment in which a method of extracting a sine / cosine value of is applied

3 is a diagram illustrating that a received signal and an expected symbol are mapped to a baseline according to the present invention.

4 is a phase error angle of the QAM demodulator according to the present invention. (θ) Drawing showing an example of obtaining the sine / cosine value of

Explanation of symbols on the main parts of the drawings

101, 201: Received signal I 102, 202: Received signal Q

103: power calculation unit 104: symbol prediction unit

105-108: Information about I and Q coordinates in constellations

109: phase difference calculation unit

110 to 113: difference values of the phase angle 114: phase error angle determining unit

115: storage unit 118: cosine of phase error angles

119: sine of phase error angles 203: power calculation signal portion

204: expected symbol mapping coordinate storage unit

205 to 208: I coordinate and Q coordinate 209: Phase difference calculation unit

210 to 213: cos and sin values of phase error angles

214: phase error angle determiner 215: cos value of the phase error angle

216: sin value of phase error angle

217: I coordinate value of the received signal after mapping to the baseline

218: Q coordinate value of the received signal after mapping to the baseline

219: proportional value storage unit 220: reception data mapping unit

In order to achieve the above object, the direct extraction method of the sine / cosine of the phase error angle of the QAM demodulator of the present invention,

A first process of calculating power using coordinate data on constellations of the received data;

A second process of storing a proportional value for mapping the received data to a baseline having a predetermined power level and reading the proportional value using the power calculated in the first process as an access address;

A third step of storing coordinate data on constellations of expected reception symbols having the same power mapped to the baseline and reading the coordinate data by using the power value output in the first step as an access address;

A fourth process of multiplying the coordinate data on the constellation of the received data by the proportional value read from the proportional value storage unit and mapping the coordinate data to a baseline;

A fifth step of calculating a sine / cosine value for the phase difference of the coordinate data read out from the third step with respect to the coordinate mapped by the fourth step;

And a sixth process of determining the corresponding sine / cosine values by comparing the sine / cosine values calculated in the fifth process with the sine / cosine values calculated by the phase error of the full-time received data. .

In order to achieve the above object, the direct extraction circuit of the sine / cosine value for the phase error angle of the QAM demodulator of the present invention,

A received data power calculator for calculating power by using coordinate data on the constellation of the received data;

A proportional value storing unit storing a proportional value for mapping the received data to a baseline having a predetermined power level, and reading the proportional value by using the power calculated from the power calculating unit as an access address;

Stores coordinate data on constellations of predicted received symbols having the same power mapped to the baseline, and stores predicted symbol mapping coordinates to read the coordinate data using the power value output from the received data power calculator as an access address. Wealth,

A reception data mapping unit for multiplying the coordinate data on the constellation of the received data by a proportional value read from the proportional value storage unit and mapping the coordinate data to a baseline;

A phase difference calculator for calculating a sine / cosine value of a phase difference between coordinate data read from the predicted symbol mapping coordinate storage unit for the coordinates mapped by the received data mapping unit;

The phase error determining unit may be configured to compare the sine / cosine values calculated by the phase difference calculator with the sine / cosine value calculated by the phase error of the received data in full time to determine a matched sine / cosine value.

Here, the proportional value storage unit and the expected symbol mapping coordinate storage unit are each configured as a ROM, and the prediction symbol mapping coordinate storage unit preferably stores mapping coordinates for four expected symbols in a word of one memory. .

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a phase error angle tracking circuit to which the phase error angle tracking circuit of the QAM demodulator according to the present invention is applied.

Referring to the drawings, the phase error angle tracking circuit of the present invention to which the phase error angle tracking circuit of the QAM demodulator is applied receives and receives data (201, 202) of I coordinate and Q coordinate of the constellation for the received symbol, respectively. A power calculator 203 for outputting a power value of one symbol, and a proportional value for mapping the received data to a baseline having a predetermined power level, and storing the power calculated from the power calculator 203 as an access address. A coordinate value storage unit 219 for reading the proportional value, and coordinate data on constellations of expected reception symbols having the same power mapped to a baseline, and outputting from the received data power calculator 203. Read from the predicted symbol mapping coordinate storage unit 204 for reading the coordinate data by using the power value as an access address, and the coordinate data and the proportional value storage unit 219 on the constellation of the received data. A phase difference between the coordinates data read from the received data mapping unit 220 and a predicted symbol mapping coordinate storage unit 204 with respect to the coordinates mapped by the received data mapping unit 220 by multiplying the multiplied proportional values and mapping them to the baseline. A phase difference calculator 209 for calculating a sine / cosine value with respect to the sine / cosine values calculated by the phase difference calculator 209 and a sine / cosine value calculated by a phase error of the received data for the entire time. Phase error angle determination unit 214 for determining the corresponding sine / cosine values 215 and 216 by comparing the corresponding sine / cosine values 215 and 216 with the sine / cosine values calculated by the phase error of the full-time received data. The operation is as follows.

3 is a diagram illustrating mapping of a received symbol to a baseline. The received symbol 303 is multiplied by a proportional value to be mapped to a baseline output from the proportional value storage unit 219 having the power value calculated by the power calculator 203 as an address, and mapped to a baseline. It is represented by the symbol 311 mapped to a line. In addition, when the power calculation unit 203 receives data on the I and Q coordinates of the constellation for the received symbol, calculates and outputs a power value of the received symbol, the expected symbol mapping coordinate storage unit 204 is Mapped from the memory that maps the information on I and Q coordinates in the constellations for the symbols 304 to 306 that can have the same level of power as the address of the received symbol. Coordinates 308 to 310 are output.

The phase difference calculator 209 obtains and outputs a sine / cosine value for the difference value of the phase angle from the coordinates of the symbols predicted by the predicted symbol mapping coordinate storage unit 204 and the respective coordinates of the currently received symbol. The formula is as shown in Equation 1. This phase error angle is that the received signal 405 of FIG. 4 is the I and Q coordinates mapped to the baseline of the currently received signal, and one of the predicted symbols 405 is for one of the received signals. Up to four symbols can be predicted, and one of these signals is mapped to a baseline. The phase difference between the two signals can be obtained by Equation 1. Unlike the conventional method from the equation, the sine / cosine value for the phase error angle can be directly obtained from the baseline mapping coordinates of the received signal and symbols.

The phase error determiner 214 compares the sine / cosine values of the phase differences of the currently received symbols stored in the memory with the sine / cosine values of the symbols received at the previous symbol rate, and receives the current values. It is determined by the sine / cosine value of the phase error angle included in the symbol.

As described above, according to the direct extraction circuit and the method of the sine / cosine value for the phase error angle of the QAM demodulator according to the present invention, the sine / cosine value for the phase error angle is the baseline mapping coordinates of the received signal and symbols There is a very good effect of calculating the sine / cosine value of the phase error angle directly.

In addition, preferred embodiments of the present invention are disclosed for the purpose of illustration, those skilled in the art will be able to various modifications, changes, additions, etc. within the spirit and scope of the present invention, these modifications and changes should be seen as belonging to the following claims. something to do.

Claims (5)

In the phase error tracking method of the QAM demodulator, A first process of calculating power using coordinate data on constellations of the received data; A second process of storing a proportional value for mapping the received data to a baseline having a predetermined power level and reading the proportional value using the power calculated in the first process as an access address; A third step of storing coordinate data on constellations of expected reception symbols having the same power mapped to the baseline and reading the coordinate data by using the power value output in the first step as an access address; A fourth process of multiplying the coordinate data on the constellation of the received data by the proportional value read from the proportional value storage unit and mapping the coordinate data to a baseline; A fifth step of calculating a sine / cosine value for the phase difference of the coordinate data read out from the third step with respect to the coordinate mapped by the fourth step; And a sixth process of determining the corresponding sine / cosine values by comparing the sine / cosine values calculated in the fifth process with the sine / cosine values calculated by the phase error of the full-time received data. Direct extraction of sine / cosine values for phase error angle of QAM demodulator. In the phase error tracking circuit of the QAM demodulator, A received data power calculator for calculating power by using coordinate data on the constellation of the received data; A proportional value storing unit storing a proportional value for mapping the received data to a baseline having a predetermined power level, and reading the proportional value by using the power calculated from the power calculating unit as an access address; Stores coordinate data on constellations of predicted received symbols having the same power mapped to the baseline, and stores predicted symbol mapping coordinates to read the coordinate data using the power value output from the received data power calculator as an access address. Wealth, A reception data mapping unit for multiplying the coordinate data on the constellation of the received data by a proportional value read from the proportional value storage unit and mapping the coordinate data to a baseline; A phase difference calculator for calculating a sine / cosine value of a phase difference between coordinate data read from the predicted symbol mapping coordinate storage unit for the coordinates mapped by the received data mapping unit; QAM demodulator comprising a phase error determiner for determining the sine / cosine value calculated by the phase difference calculation unit and the sine / cosine value matched by the phase error of the received data over time Direct extraction circuit of sine / cosine values for phase error angle The method of claim 2, The proportional value storage unit is composed of a ROM, and a direct extraction circuit of a sine / cosine value for a phase error angle of the QAM demodulator. The method of claim 2, The expected symbol mapping coordinate storage unit ROM (ROM) characterized in that the direct extraction circuit of the sine / cosine value for the phase error angle of the QAM demodulator. The method of claim 2, And a sine / cosine value for a phase error angle of the QAM demodulator, wherein the coordinates of four expected symbols are stored in a word of one memory of the expected symbol mapping coordinate storage unit.