KR101040899B1 - Method of controlling zero crossing of data receiving apparatus - Google Patents

Abstract

The present invention relates to a zero crossing adjusting method of a data receiving apparatus. The zero crossing adjusting method of the data receiving apparatus according to the present invention includes receiving a symbol signal of Gaussian frequency shift modulated data, and storing the number of times zero crossing of the symbol signal occurs in each memory corresponding to the zero crossing counter. Detecting a zero crossing counter having the largest zero crossing cumulative value, adjusting a symbol signal coming after the detected zero crossing counter to zero crossing at a specific zero crossing counter, and if the zero crossing counter is adjusted, Initializing. According to the present invention, by adjusting the zero crossing counter in the preamble symbol stage of the Gaussian frequency shift modulated data, zero crossing may occur in the sample data having zero crossing counter in the header symbol stage. In addition, by adjusting the zero crossing counter at the header or payload symbol stage, the oversampling period is kept constant from time to time. Therefore, the center sample data is kept constant for each symbol so that the bit can be measured accurately.

Gaussian, Zero Crossing, Preamble, Header, Payload

Description

ZERO CROSSING OF DATA RECEIVING APPARATUS

The present invention relates to a method for adjusting zero crossing of a Gaussian frequency shift modulated symbol signal, and more particularly, to zero crossing of a data receiving apparatus capable of accurately measuring bits by constantly adjusting zero crossing of a received symbol signal. It is about a control method.

Technology for transmitting and receiving data divided into frames is widely used in the wired and wireless communication fields. In general, a data transmitting apparatus demodulates data and transmits the demodulated data to a data receiving apparatus. The data receiving apparatus modulates the demodulated data and outputs the demodulated data to the outside.

Gaussian Frequency Shift Keying ("GFSK") is one of the Frequency Shift Keying ("FSK") methods, which uses a Gaussian filter for binary 1 for positive deflection and binary 0 for negative deflection. Modulation method to convert. Gaussian frequency shift modulation is mainly used for Bluetooth wireless communication, and a data receiving device measures a bit by detecting a center sample (center part of a Gaussian distribution) of an oversampled signal. The data receiving apparatus measures a bit of the oversampled signal using a zero crossing algorithm.

1 shows zero crossings in a noise free channel. According to FIG. 1, it can be seen that in n times oversampling, the zero crossing counter remains constant at 0 even when a symbol signal is input. In other words, even if the zero crossing counter is constantly rotated from 0 to n-1, the zero crossing counter remains constant, so that the center sample of the symbol signal, that is, the portion where the signal is large, can be accurately detected and the bit can be measured.

However, noise may occur in a data transmission process due to a frequency offset, a white Gaussian noise, a multipath channel environment, and the like that occur in a wireless communication environment. 2 is a diagram illustrating zero crossing in a noisy channel. According to Fig. 2, in the noisy channel, the frequency offset causes the oversampling period to be inconsistent and the zero crossing counter is pushed or pulled. That is, it can be seen that in n times oversampling, the zero crossing counter is initially kept constant at 0 and then changed to 3 afterwards. Accordingly, since the bit is measured by accumulating data values of the peripheral part instead of the center part of the symbol, there is a problem in that the accurate bit measurement is not performed.

Accordingly, an object of the present invention is to provide a zero crossing adjusting method of a data receiving apparatus capable of adjusting zero crossing of a received symbol signal in Gaussian frequency shift communication.

According to an embodiment of the present invention, a zero crossing adjusting method of a data receiving apparatus includes: receiving a symbol signal of Gaussian frequency shift modulated data and zeroing the number of times zero crossing of the symbol signal occurs; Storing in each memory corresponding to a crossing counter, detecting a zero crossing counter with the largest zero crossing cumulative value, and adjusting a symbol signal following the detected zero crossing counter to zero crossing at a particular zero crossing counter And initializing the memory when the zero crossing counter is adjusted.

The Gaussian frequency shift modulated data is repeated with a value of 1 or 0, and may include a preamble, a header, and a payload composed of a plurality of sample data.

The Gaussian frequency shift modulated data may be oversampled, and the number of zero crossing counters may be equal to a multiple of the data oversampled.

In the detecting of the zero crossing counter having the largest zero crossing accumulation value, the zero crossing counter having the greatest zero crossing accumulation value when the last sample data included in the preamble symbol signal is input may be detected.

In the detecting of the zero crossing counter having the largest zero crossing accumulation value, the zero crossing counter in which the zero crossing accumulation value first reaches a reference value in the header or payload symbol signal may be detected.

The adjusting of the zero crossing at the specific zero crossing counter may include adjusting a zero crossing counter of sample data next to sample data having a zero crossing counter of 'k-2' when a 'k' zero crossing counter is detected. setting to 'n-1' and setting the zero crossing counter following the 'n-1' to the specific zero crossing counter.

A data receiving apparatus according to another embodiment of the present invention, a data receiving unit for receiving a symbol signal of the Gaussian frequency shift modulated data, a storage unit for storing the number of times zero crossing of the symbol signal occurs corresponding to the zero crossing counter, A control unit for detecting a zero crossing counter having the largest value of the zero crossing accumulation value, adjusting a symbol signal coming after the detected zero crossing counter to zero crossing at a specific zero crossing counter, and measuring a bit from the symbol signal Contains wealth.

The bit measuring unit may accumulate sample data values positioned in the center of the symbol signal to measure symbol data values.

As described above, according to the present invention, by adjusting the zero crossing counter in the preamble symbol stage of the Gaussian frequency shift modulated data, zero crossing may occur in the sample data having zero crossing counter in the header symbol stage. In addition, by adjusting the zero crossing counter at the header or payload symbol stage, the oversampling period is kept constant from time to time. Therefore, the center sample data is kept constant for each symbol so that the bit can be measured accurately.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

3 is a view showing a data receiving apparatus according to an embodiment of the present invention, Figure 4 is a view showing the structure of data transmitted and received according to an embodiment of the present invention.

According to FIG. 3, the data receiving apparatus 300 includes a data receiving unit 310, a control unit 320, a storage unit 330, and a bit measuring unit 340.

The data receiver 310 receives the decoded data from a data transmitter (not shown). The Gaussian frequency shift modulated data structure received by the data receiver 310 includes a preamble 410, a header 420, and a payload 430 as shown in FIG. 4. The preamble 410 and the header 420 are positioned before the payload 430 of a preset length. The data receiver 310 performs gain control, frequency synchronization, symbol synchronization, and the like during the reception of the preamble 410 in order to control the reception states of the header 420 and the payload 430 following the preamble 410.

The preamble 410 is located at the front of the received data and transmits data reception information to the data reception device 300. The header 420 includes bibliographic information such as the length of the payload 430, the data capacity, and the data generation time, and performs a function of synchronizing data. The payload 430 includes data information to be transmitted by the data transmission apparatus.

The control unit 320 detects a zero crossing counter having the largest zero crossing accumulated value at the symbol stage of the preamble 410 and the header 420 or the payload 430, respectively, and the symbol signal that comes after the detected zero crossing counter. Adjusts the zero crossing counter so that it becomes zero crossing at the zero crossing counter corresponding to '0'.

The storage unit 330 stores data received from the data transmission apparatus, generates a memory for each counter, and accumulates a counter when zero crossing. The bit measuring unit 340 may accumulate data values of central sample data that may represent data values of a symbol signal, and measure bits.

Hereinafter, a method of adjusting the zero crossing counter by the data receiving apparatus 300 at the preamble symbol stage will be described. 5 is a flowchart illustrating a method of adjusting a zero crossing counter in a preamble symbol stage according to an embodiment of the present invention.

First, the data receiving apparatus 300 receives data Gaussian frequency shift modulated (GFSK) from the data transmitting apparatus (S510). When Gaussian frequency shift modulation (GFSK) is performed, binary 1 is converted into positive deflection, and binary 0 is converted to negative deflection as shown in FIG. 6.

6 is an exemplary diagram illustrating a preamble symbol signal of Gaussian frequency shift modulated data.

According to FIG. 6, it is assumed that the symbol length of the preamble is m and the oversampling multiple (number) is n. Here, the symbol length m of the preamble is equal to the number n of symbols of the preamble, and the symbols of the preamble alternately have a positive value and a negative value. The symbols of the preamble alternately change between positive and negative values, with one sample containing n sample data. Therefore, when the symbol length of the preamble is m and the oversampling multiple is n, m preamble symbols include m * n sample data. Each sample data corresponds to n repeated zero crossing counters 0 to n-1, respectively, and the number of zero crossing counters 0 to n-1 is equal to the oversampling multiple n.

In FIG. 6, for convenience of explanation, an oversampling multiple n is assumed to be 8, and a symbol length m of the preamble is assumed to be 10. FIG. Therefore, according to FIG. 6, in principle, each preamble symbol includes eight sample data, and each sample data corresponds to a zero crossing counter (0, 1, 2, 3, 4, 5, 6, 7).

The data receiving apparatus 300 stores the number of zero crossings in the storage unit 330 each time zero crossing is performed for each zero crossing counter (S520). Here, the storage unit 330 includes a memory (register) corresponding to each zero crossing counter, and counts the number of zero crossings by increasing the accumulated value stored in the corresponding memory by one each time zero crossing is performed. do. In the case of FIG. 6, the storage unit 330 includes eight memories, and each memory corresponds to the zero crossing counters 0, 1, 2, 3, 4, 5, 6, and 7. Therefore, when the preamble symbol length is m, m zero crossings occur.

In operation S530, the data receiving apparatus 300 detects a memory having the largest zero-crossing accumulation value at the time when the last sample data included in the preamble is input. That is, when the symbol length of the preamble is m and the oversampling multiple is n, when the m * n-th sample data is input, the memory having the largest zero crossing accumulated value is detected among the n memories.

Next, the data receiving apparatus 300 adjusts a zero crossing counter value corresponding to the sample data so that zero crossing occurs when the zero crossing counter is '0' in a subsequent symbol signal (S540). That is, when it is determined that the zero crossing occurs most when the zero crossing counter is 'k', the data receiving device 300 zero-crosses the next sample data of the next sample data whose zero crossing counter is 'k-2'. Set the counter to 'n-1'.

For example, assume that zero crossings occur most when the zero crossing counter is '2' as shown in FIG. 6 (k = 2). Here, in the last symbol data of the preamble, the zero crossing counter of the sample data following the zero crossing counter corresponding to '0' (corresponding to k-2) becomes '7' (corresponding to n-1) instead of '1'. Adjust. Through this adjustment, '0' is set after the zero crossing counter '7', and zero crossing occurs in the sample data having the zero crossing counter '0'.

Accordingly, as shown in FIG. 6, the first zero crossing of the header stage occurs in sample data having a zero crossing counter of '0', thereby reducing data loss of the first symbol data input through the header stage. .

As such, after zero crossing is adjusted in sample data having a zero crossing counter value of '0', n memories (0, 1, 2, ..., n-1) corresponding to the zero crossing counter are initialized. (S550). That is, the number of zero crossing counters stored in the n memories is initialized to zero, so that a new counter is generated for the zero crossings that occur afterwards.

Hereinafter, a method of adjusting the zero crossing counter in the header or payload stage after the preamble will be described. 7 is a flowchart illustrating a method of adjusting a zero crossing counter in a header or payload stage according to an embodiment of the present invention.

The data receiving apparatus 300 receives data Gaussian frequency shift modulated (GFSK) from the data transmitting apparatus (S710).

8 is an exemplary diagram illustrating a header or payload symbol signal of Gaussian frequency shift modulated data. As in the case of the preamble stage, the symbol length of the header or payload is m, the oversampling multiple is n, and each symbol includes n sample data. Each sample data also corresponds to n repeated zero crossing counters 0 to n-1.

In operation S720, the data receiving apparatus 300 stores the number of times zero crossing is performed for each zero crossing counter in the storage unit 330.

In operation S730, the data receiving apparatus 300 compares the zero crossing accumulation value of the memory having the largest zero crossing accumulation value with the reference value. Here, the reference value can be adjusted by setting the register. In a noisy communication environment, it is necessary to adjust the zero crossings from time to time by setting the reference value to a small value. On the other hand, since false zero crossings can occur frequently due to noise, in this case, the error can be reduced by setting the reference value to a large value.

When the cumulative value of the specific memory reaches the reference value, the symbol signal subsequent to the preamble stage adjusts the zero crossing counter value corresponding to the sample data so that zero crossing occurs when the zero crossing counter is '0' (S740). .

As in the preamp stage, when the zero crossing counter value is 'k' and it is determined that the accumulated value of the zero crossing is the reference value, the zero crossing counter of the next sample data of the sample data whose zero crossing counter is 'k-2' is determined. Set to 'n-1'.

In FIG. 8, it is assumed that the reference value is 4, and it is assumed that when the zero crossing counter is '4', the zero crossing accumulation value is four (k = 4). Therefore, when the zero crossing accumulation value becomes 4, the reference value, the data receiving apparatus 300 decrements the zero crossing counter of the sample data that is next to the sample data having the zero crossing counter equal to '2' (corresponding to k-2). n-1 'is set.

Through this adjustment, zero crossing occurs when the zero crossing counter is '0', and the zero crossing counter is kept constant at '0' at the header or payload end.

After adjusting the zero crossing counter like the preamble stage, all n memories corresponding to the zero crossing counter are initialized (S650). Accordingly, a zero crossing counter is also performed on subsequent symbols, and when the cumulative value becomes a reference value, the zero crossing counter value corresponding to the sample data is adjusted so that zero crossing occurs when the zero crossing counter is '0'.

According to an exemplary embodiment of the present invention, since the zero crossing counter value of the center sample data, that is, the sample data having a large value of the signal, is determined at the header or payload stage, the symbol data value is precisely maintained. Can be measured. For example, in the case of an 8x oversampled header or payload, the sample data corresponding to 3 to 6 with a zero crossing counter may be set as central sample data that can represent symbol data values. Therefore, since the oversampling period is kept constant for each symbol, the bit value of each symbol can be accurately measured through the central sample data.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 shows zero crossings in a noise free channel.

2 is a diagram illustrating zero crossing in a noisy channel.

3 is a view showing a data receiving apparatus according to an embodiment of the present invention.

4 is a diagram showing the structure of data transmitted and received according to an embodiment of the present invention.

5 is a flowchart illustrating a method of adjusting a zero crossing counter in a preamble symbol stage according to an embodiment of the present invention.

6 is an exemplary diagram illustrating a preamble symbol signal of Gaussian frequency shift modulated data.

7 is a flowchart illustrating a method of adjusting a zero crossing counter in a header or payload stage according to an embodiment of the present invention.

8 is an exemplary diagram illustrating a header or payload symbol signal of Gaussian frequency shift modulated data.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

300: data receiving apparatus 310: data receiving unit

320: control unit 330: storage unit

340: bit measurement unit 410: preamble

420: header 430: payload

Claims (13)

Receiving a symbol signal of Gaussian frequency shift modulated data, Storing the number of times zero crossing of the symbol signal occurs in each memory corresponding to a zero crossing counter; Detecting a zero crossing counter with the largest zero crossing cumulative value; Adjusting a symbol signal coming after the detected zero crossing counter to zero crossing at a particular zero crossing counter, and And initializing the memory when the zero crossing counter is adjusted. The method of claim 1, The Gaussian frequency shift modulated data repeats a value of 1 or 0, and comprises a preamble, a header, and a payload of a plurality of sample data. The method of claim 2, The Gaussian frequency shift modulated data is oversampled, and the number of zero crossing counters is equal to a multiple of which the data is oversampled. The method of claim 3, The detecting of the zero crossing counter having the largest zero crossing accumulated value may include: And a zero crossing counter having the largest zero crossing accumulated value when the last sample data included in the preamble symbol signal is input. The method of claim 3, The detecting of the zero crossing counter having the largest zero crossing accumulated value may include: And a zero crossing counter in which the zero crossing accumulation value first reaches a reference value in the header or payload symbol signal. The method according to claim 4 or 5, Adjusting to zero crossing at the particular zero crossing counter, when the 'k' zero crossing counter is detected, setting the zero crossing counter of the next sample data of the sample data whose zero crossing counter is 'k-2' to 'n-1', and And setting a zero crossing counter following the 'n-1' as the specific zero crossing counter. A data receiver for receiving a symbol signal of a Gaussian frequency shift modulated data, A storage unit which stores the number of times zero crossing of the symbol signal occurs in each memory corresponding to a zero crossing counter; A controller for detecting a zero crossing counter having the largest zero crossing accumulation value and adjusting a symbol signal coming after the detected zero crossing counter to zero crossing at a specific zero crossing counter; and And a bit measuring unit measuring a bit from the symbol signal. The method of claim 7, wherein The Gaussian frequency shift modulated data is repeated with a value of 1 or 0, and comprises a preamble, a header, and a payload composed of a plurality of sample data. The method of claim 8, The Gaussian frequency shift modulated data is oversampled, and the number of zero crossing counters is equal to a multiple of the data oversampled. 10. The method of claim 9, The control unit, Detecting a zero crossing counter having the largest zero crossing accumulated value when the last sample data included in the preamble symbol signal is input; And a zero crossing counter in which the zero crossing accumulated value first reaches a reference value in the header or payload symbol signal. The method of claim 10, When the 'k'-th zero crossing counter is detected, the zero crossing counter of the sample data that comes next of the sample data whose zero crossing counter is' k-2' is set to 'n-1', and the 'n-1' Data receiving apparatus for setting a next zero crossing counter to the specific zero crossing counter. The method of claim 11, The bit measuring unit, And a sample data value accumulated in the center of the symbol signal to measure a symbol data value. The method of claim 12, The storage unit, And initialize the memory when the zero crossing counter is adjusted.

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