KR20000039664A - Frequency variable manchester coding system - Google Patents

Abstract

PURPOSE: A frequency variable manchester coding system is provided to vary a manchester code into RF signal and generate original data and data clock by decoding the varied manchester code. CONSTITUTION: A frequency variable manchester coding system comprises a manchester encoding unit and a manchester decoding unit. The manchester encoding unit comprises a first clock divider(200) dividing the frequency of system clock into 1/(2*n) a data generating system, and a manchester encoder(300) encoding the data generated from the generator to generate manchester codes coded to 2*n times frequency. The manchester decoding unit comprises a positive edge detector(500), a negative edge detector(600), a gate portion(700), an effective event detector(800), a data reproduction portion(750) and a decoding clock generator(800).

Description

Frequency Adjustable Manchester Coding System

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Manchester coding system, and more particularly, to generate a Manchester code having a frequency variable with a high frequency signal suitable for radio frequency communication using a magnetic field, and to restore the Manchester code having the frequency variable to original data. A variable frequency Manchester coding system.

In general, when receiving digital data, there is a problem that noise and jitter are introduced into the received data at the receiving end. In particular, when there is no clock, the start and end of the input data cannot be known, and the width of the bit cell is unknown. Cannot determine the order of input data. In addition, since the binarized data includes a DC component or a zero frequency signal according to a bit pattern that cannot be processed by most receivers, additional circuits are required to remove or accommodate such DC components.

In order to overcome the problems of asynchronous and DC levels of the clock generated when receiving the digital data described above, Manchester coding has been proposed to transcode and transmit the data to be transmitted, as illustrated in FIG. 1. Manchester coding converts data into Manchester code by XORing the data generated by the system 10 and the data clock CLK using a Manchester encoder 20 configured with an XOR (Exclusive-OR) gate at the transmitting side. .

On the other hand, Figure 2 is a detailed configuration of the Manchester decoder for receiving the Manchester code transmitted from the Manchester encoder side of Figure 1 to decode it to the original data, which Manchester decoder 3 August 1994 by the same applicant as the present invention Patent No. 21890 is disclosed in patent No. 149720, filed June 9, 1998. The prior art Manchester decoder shown in FIG. 2 is configured to detect an event of input Manchester code data, i.e., a rising edge and a falling edge, and to accept only valid events among the detected events. More specifically, the Manchester decoder of FIG. 2 includes a first detector 30 for detecting a rising edge event of Manchester code data according to a local clock, and a second detector 40 for detecting a falling edge event of Manchester code data according to a local clock. ), The gate unit 50 and the rising and falling edge detection unit 30 and 40 for selectively outputting the rising or falling event detection signal detected by the first and second detection units 30 and 40 according to the window signal. It is set according to the output of the window generator 60 and the gating unit 50 which receives the output and the selective event detection signal of the gating unit 50 to generate a window signal and provide it to the gating unit 300. And a data generator 60 that is reset to decode and output Manchester code data into original data.

The window generator 70 includes a counter for determining a valid event among rising and falling edge events detected by the first and second detection units 30 and 40. The counter in the window generating unit 70 starts counting and exists within a predetermined time when the valid event of either the rising edge or the falling edge is detected by the first detection unit 30 or the falling edge detection unit 40 from the Manchester code. The event to ignore is performed.

On the other hand, the data generation unit 60 configured as a latch generates a logic 1 as a decoded value by setting a latch when a falling edge occurs in the input Manchester code, and resets the latch to decode the logic 0 when a rising edge occurs. The restored data is generated and output in the manner of generating by value.

However, the conventional Manchester decoder illustrated in FIG. 2 is configured to supply a clock to the counter in the window signal generator 50 to perform a continuous count operation when the first rising or falling edge event occurs. Therefore, when the next new Manchester code is generated after a predetermined time has elapsed, the next Manchester code must be accepted and the decoding operation can be performed only after the latch in the window signal generator 50 is reset.

In addition, since the Manchester coding scheme of the above-described configuration essentially encodes the transmission data using a method of XORing the system clock to the data, the frequency of the encoded Manchester code is limited to the range of the frequency band of the system clock. Such low frequency signals can be used without any problem in wired communication systems. However, for example, when a low frequency signal is applied to a radio frequency communication system using a frequency band of about 120 KHz or more, data transmission efficiency is lowered. This is because the transmission of the high frequency signal in the wireless communication system is more advantageous than the transmission of the low frequency signal, and there is a problem that it is disadvantageous to apply the Manchester code limited to the low frequency generated according to the above-described prior art to the wireless communication system as it is.

Therefore, when the Manchester code coded using the above-described Manchester coding scheme is applied to short-range wireless communication using a relatively high frequency compared to wired communication, a low-frequency Manchester code limited to a range of frequency bands of a system clock is specified. It should be converted into high frequency signal by using.

Accordingly, an object of the present invention is to provide a Manchester encoding apparatus capable of varying a Manchester code into a high frequency signal, which is intended to solve the above-described problem.

It is another object of the present invention to provide a Manchester decoding apparatus capable of decoding original frequency coded Manchester codes to generate original data and data clocks.

Manchester coding system of the present invention for achieving the above object includes a Manchester encoding device and Manchester decoding device,

The Manchester encoding apparatus includes: first clock divider means for dividing a frequency of a system clock applied from the outside by 1 / (2 * n) times to generate a divided clock; A data generation system for generating data in accordance with the divided clock generated from said first clock division means; A Manchester encoder that encodes the data generated in the system using the system clock as an encoding clock to produce a Manchester code coded at a frequency of 2 * n times;

The Manchester decoding apparatus includes: a falling edge detector for detecting a falling edge event of the Manchester code and outputting a falling event detection signal; Gating means for selectively outputting the rising and falling edge event signals output from the rising and falling edge detectors according to valid event determination signals; A valid event detection unit operable in response to an event detection signal selectively output from the gating means to provide the gating means with the valid event determination signal for determining a valid event during the rising and falling events; A data reproducing unit which is set or reset according to an event detection signal selectively transmitted from the gating means and outputs data recovered from the Manchester code; And second clock dividing means for dividing the selective output of said gating means by 1 / (2 * n) times to produce a divided clock as a decoded clock.

1 is a schematic block diagram of a typical Manchester encoding device,

2 is a block diagram of a Manchester decoding apparatus of the prior art;

3 is a block diagram of a Manchester encoding apparatus for varying the frequency of transmission data according to the present invention;

4 is a detailed circuit diagram illustrating the clock divider shown in FIG. 3;

5 is a waveform diagram for comparing a Manchester code generated by the Manchester encoding apparatus of the prior art with the present invention;

6 is a block diagram of a Manchester decoding apparatus for decoding a frequency variable Manchester code according to the present invention;

FIG. 7 is a waveform diagram illustrating an operation of a valid event detection unit illustrated in FIG. 6;

8 is a waveform diagram generated in the frequency variable Manchester decoding apparatus of FIG.

9A and 9B are waveform diagrams for explaining header codes applied to Manchester codes generated by the frequency variable Manchester encoding apparatus of the present invention.

Explanation of symbols for main parts of the drawings

20, 200: Manchester encoder 300, 900: Clock divider

500: rising event detection unit 600: falling event detection unit

700: gating unit 750: data reproducing unit

800: valid event detection unit 810: gray code counter

820: Effective signal generator

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

3 is a block diagram of a Manchester encoding apparatus for varying frequencies configured according to the present invention, and includes a clock divider 200 and a Manchester encoder 300.

The clock divider 200 divides the system clock CLK and provides the divided clock to the system 100 as a data clock (see FIG. 5). The system 100 illustrated and described in the present invention is a system used for radio frequency communication using a frequency band of about 120 KHz or more, and transmits data to be transmitted to a receiver according to a clock divided by the clock divider 200. Create According to the present invention, the encoding clock has a higher frequency than the data clock divided in the clock divider 200, and this data clock can be usefully used to synchronize the clock rather than using a separate clock from the encoding clock. have.

Referring to FIG. 4, a detailed configuration of the clock divider 200 shown in FIG. 3 is shown. As shown in FIG. 4, the clock divider 200 has n, for example, two T-type flip-flops 210 and 220 connected in series. The serially connected T-type flip-flops 210 and 220 operate as 2 * n frequency divider circuits, reducing the frequency of the input system clock to 1 / (2 * n), i.e., 1/4 (Fig. 5). Output). Accordingly, the data generated in the system 100 generates data synchronized with a clock of a frequency reduced by 1 / (2 * n), that is, 1/4 times the system clock, and is provided to the Manchester encoder 300.

The Manchester encoder 300 composed of XOR gates uses a system clock (CLK) applied from the outside as an encoding clock (see FIG. 5) to encode data provided by the system 100 so that the frequency is encoded at 2 * n frequencies. Output Manchester code.

FIG. 5 is a waveform diagram illustrating a signal generated by the variable frequency Manchester encoder according to the present invention. The data clock output from the clock divider 200 is reduced to one quarter of the encoding clock and generated by the system 100. The data is XORed by the above-described data clock by the Manchester encoder 300 to be encoded and output as a clock having a frequency four times higher than the data clock.

In addition, as can be seen from the comparison between the variable frequency Manchester code generated by the present invention and the Manchester code generated in the prior art in FIG. 5, the Manchester code of the present invention has a higher frequency than the Manchester code of the prior art. Since it can be generated as a code having, it can be applied to wireless communication as it is without introducing a separate modulation equipment or process.

FIG. 6 shows a detailed block diagram of a frequency variable Manchester decoding apparatus for restoring original variable data to a frequency variable Manchester code transmitted by the frequency variable Manchester encoding apparatus shown in FIGS. 3 and 4.

The Manchester decoding apparatus of the present invention includes a rising edge detector 500, a falling edge detector 600, a gating unit 700, an effective event detector 800, a data reproducing unit 750, and a decoding clock generator 800. do.

The rising edge detector 500 includes a first D-type flip-flop 510 for latching rising edge variations of the Manchester code input according to a local clock, and an inverted output Q / of the first flip-flop 510. And a second D-type flip-flop 520 coupled to the AND gate 530 for ANDing the non-inverting output Q of the first and second flip-flops 510 and 520. On the other hand, the falling edge detection unit 600 is a first D-type flip-flop 610 for latching the falling edge transition of the Manchester code input in accordance with the local clock, and the inverted output of the first flip-flop 610 ( And a second D-type flip-flop 620 connected to Q /) and an AND gate 630 for ANDing the inverted outputs Q / of the first flip-flop 610 and the second flip-flop 620. do.

Typically, the Manchester decoder reads 0-to-1 data into 0 data when there is a 0-to-1 transition, and 1-to-0 data to 1, and the rising edge detector 500 itself. The 0-to-1 event of the Manchester code input according to the local clock generated by the rising edge is detected, and the falling edge detector 600 detects the 1-to-0 event of the Manchester code as the falling edge according to the local clock. do. The rising edge detection signal and the falling edge detection signal detected by the rising edge detector 500 and the falling edge detector 600 are provided to the gating unit 700.

The gating unit 700 logically multiplies the output from the rising edge detector 500 and the valid event determination signal from the valid event detector 800 to invert and output the output of the rising edge detector 500 to output the first NAND gate 710. ) And a second NAND gate 720 that inverts the output of the falling edge detector 600 by performing an AND operation on the output from the falling edge detector 600 and the valid event determination signal from the valid event detector 800. do. The gating unit 700 having the above-described configuration includes an event signal detected by each of the rising detector 500 and the falling edge detector 600 according to the valid event determination signal of the valid event detector 800 described below. 750). In more detail, the gating unit 700 inverts the rising and falling event detection signals provided to the first and second NAND gates 7109 and 720 only when the valid event determination signal is output from the valid event detecting unit 800. Transfer to regeneration unit 750. The event detection signal inverted by the gating unit 700 is generated by the data reproducing unit 750 as logic 0 in the case of the rising event and logic decoded data in the case of the falling event.

On the other hand, the rising or falling event detection signal passing through the gating unit 700 is provided to the valid event detection unit 800 via a two-input AND gate 760 that logically multiplies these signals.

The valid event detector 800 according to the present invention is a means for performing a function of determining a valid event among events detected from the Manchester code, and includes a counter 810 and a valid event signal generator 820. The counter 810 is implemented as a 3-bit gray code counter, and the valid signal generation unit 520 generates a valid event discriminating signal for adjusting a timing of discriminating valid events among events in the Manchester code. Consists of logic to perform.

The 3-bit gray code counter 810 is reset when a rising or falling event detection signal of the Manchester code is provided by the rising and falling edge detectors 500 and 600 through the gating unit 700, and starts counting operation. When the count output reaches 100 (= Q _C Q _B Q _A ), the state remains until a new event detection signal is provided. The operation of the counter 810 allows the effective signal generation timing to be adjusted to restore the original data even if a slight timing shift occurs in the input Manchester code. Table 1 below illustrates the output of the 3-bit gray code counter 810 and the output of the valid signal generated by the valid signal generator 820. The timing adjustment operation of the valid event detector 800 is illustrated in FIG. Reference is made in more detail as follows.

Q _C Q _B Q _A Effective signal 0 0 0 One 0 0 One 0 0 One One 0 0 One 0 0 One One 0 0 One One One 0 One 0 One One One 0 0 One

As shown in the timing diagram of FIG. 7, the 3-bit gray code counter 810 is reset to perform a count operation when the rising edge a of the Manchester code where some timing sheeting has occurred is detected by the rising edge detector 500. It starts. Thereafter, the 3-bit gray code counter 810 continues the count operation for the T period, and then maintains the state when the count output state reaches 100 (= Q _C Q _B Q _A ). Since the valid event determination signal output from the valid signal generator 820 through the line 850 during the T period is maintained at a low level (see Table 1), the output of the gating unit 700 is inhibited and the falling edge detector 600 is prevented. The falling event b of the Manchester code detected by is not recognized as a valid event. Thereafter, when a new event c occurring later than a predetermined timing is detected while the count state of the counter 820 is maintained at 100, the counter 810 in the valid event detecting unit 800 restarts the operation, thereby decoding the Manchester of the present invention. The device may continue decoding the Manchester code. Therefore, even if the falling edge b occurs two clock cycles after the predetermined timing, the Manchester decoding apparatus of the present invention can perform decoding correctly. That is, even if a slight time delay occurs in the Manchester code transmitted through the magnetic field in the short range wireless communication system, the original data can be restored. In this regard, the valid signal determination timing may be adjusted by modifying the valid signal generator 820 of FIG. 6.

Therefore, according to the present invention, when the last internal state of the 3-bit gray code counter 810 reaches 100, the counting stops and maintains the internal state 100 while no new event occurs in the Manchester code. Since the event is recognized as a valid event and the decoding is started, even if the Manchester code of a new frame is input after a certain time after the Manchester code of one frame is input, the original data can be decoded without any special manipulation to the Manchester decoder.

Meanwhile, when the inverted rising event detection signal is provided from the gating unit 700, the data reproducing unit 750 configured as a latch generates and outputs a logic 0 as decoded data, and the inverted falling event detection signal is provided. If it is set, it generates and outputs logical 1 as decoded data.

Since the decoding clock generator 900 has the same configuration as the clock divider 200 of the Manchester encoding apparatus illustrated in FIG. 4, a detailed circuit diagram thereof is omitted. The decoding clock generator 900 divides the output of the AND gate 760 at the same ratio as the clock divider 400 used when encoding the Manchester code, thereby providing a data clock having a frequency of 1 / (2 * n). Create

The operation of the Manchester decoder of the present invention having the above-described configuration will be described in detail as follows with reference to the timing diagram of FIG.

In the initial state, the D-flip flops 510, 520; 610, 620 in the first and second detectors 500 and 600, the data reproducing unit 750, and the counter 810 in the effective event detector 800 are 100. (= Q _C Q _B Q _A ) State is maintained. At this time, the state of the valid event determination signal, which is the output of the valid event generator 820 on the line 850, is a high level state as illustrated in Table 1, and the respective NAND gates 710 and 720 of the gating unit 700 are provided. It is set to the state which passes the event detection signal input to.

Now, when the Manchester code illustrated in the fourth row of FIG. 8 is input, a falling event is detected by the falling edge detector 600, and a falling event detection signal is output through the line 650, and the rising edge detector 500 is output. As a result of the rising event, a rising event detection signal is output through the line 550. The rising and falling event detection signals detected by the rising and falling detection units 500 and 600 are provided to one inputs of the NAND gates 710 and 720 of the gating unit 700, respectively. At this time, since the high level valid signal, which is the output of the valid event detector 800, is applied to the type forces of the NAND gates 710 and 720 of the gating unit 700, the falling edge detector 600 detects the first. The falling event detection signal is applied to the set terminal of the data reproducing unit 750 as a signal state inverted via the corresponding NAND gate 720.

Meanwhile, the falling event detection signal inverted via the NAND gate 720 is provided to the reset terminal RESET of the counter 810 through the AND gate 760. Accordingly, the counter 810 starts a count operation, and according to the count output Q _C Q _B Q _A of the counter 810, the valid signal generation unit 820 determines the valid event in a state as illustrated in Table 1. The signal is provided to the NAND gates 710 and 720 of the gating unit 700 through the line 850. At this time, since the event detected while the valid event determination signal is generated at the low level (that is, the rising edge 560 of FIG. 8) is ignored, the rising event detection signal on the line 550 is NAND of the gating unit 700. While not passing through the gate 710, the falling event detection signal on the line 650 may be inverted through the NAND gate 720 and then provided to the latch 750 of the data reproducing unit.

Thereafter, when the 3-bit gray code counter 810 reaches the count state 100 illustrated in Table 1, the state is maintained until a new event (for example, the falling edge 660 of FIG. 8) occurs. .

Accordingly, the data reproducing unit 750 generates and outputs logic 1 as decoded data until a new event 660 is generated according to the inverted falling event detection signal as illustrated in the last row of FIG. 8. Thereafter, the latch 750 of the data reproducing unit generates and outputs logic 0 as decoded data when the inverted falling event detection signal is provided, and generates logic 1 as decoded data when the inverted falling event detection signal is provided. Output

The operation of the Manchester decoder of the present invention as described above is repeatedly performed, thereby decoding the frequency variable Manchester code illustrated in FIG. 8 into raw data.

Meanwhile, the decoding clock generator 900 generates a decoding clock 34 to store the output decoded data 33 in a digital system of the next stage.

Referring back to FIG. 3, the system 100 used in the Manchester encoding apparatus according to the present invention inserts a header code into the data generated as described above, and provides the header code to the Manchester encoder. Data used for synchronization in the Manchester decoding apparatus, which will be described in detail with reference to FIG.

As described above, the Manchester decoding device detects an event present in the Manchester code transmitted through the wireless communication channel from the Manchester encoding device and decodes the Manchester code into original data. When one event is detected, the counter 810 ignores an event existing within a predetermined period of time, and thus, may be erroneously decoded into a next code due to an incorrectly detected event. In other words, if a Manchester decoding device initially detects a bad event, it can continue to decode it as bad data.

To illustrate this situation, it is assumed, for example, that a logic value currently stored by the rising and falling event detectors 500 and 600 of the Manchester decoding apparatus illustrated in FIG. 6 is 0, and as illustrated in FIG. 9A. Likewise, it is assumed that a Manchester code having an original data of ... 111 is provided as an input of the Manchester decoding device.

In this case, when the Manchester decoding device starts decoding at the starting point a, the Manchester decoding device decodes data 1 by detecting a falling edge event. The rising edge event occurring next is ignored, and the falling edge event occurring at the next timing is recognized and the original data 1111 can be decoded normally. However, if the decoding starts from the starting point b, the Manchester decoding device decodes the data 0 by first detecting the first rising edge event, ignoring the next falling edge event, and recognizing the next rising edge as an event. The original data 1111 cannot be decoded normally but is decoded as 0. In order to solve this problem, the header code is first transmitted to the Manchester decoding apparatus before transmitting the Manchester code data. According to the present invention, the header code inserted into the data generated from the system 100 is set to 101.

How header code 101 set by the present invention affects event detection will be described with reference to FIG. 9B.

In FIG. 9B, it is assumed that raw data starts with ..00, and is encoded by the Manchester encoder 200 by adding a header code 101 at the beginning of this raw data. If the Manchester decoding device starts decoding from the starting point a, the Manchester decoding device detects the first rising edge event and decodes 10100. However, if the decoding starts from the starting point b, the Manchester decoding device recognizes the falling edge event and thus decodes 10100. In this case, the first bit 0 of the 101 transmitted as the header code is not recognized and the header is recognized as 10. However, 0, which is the original data transmitted next, can be decoded normally. In other words, when 101 is encoded as data as a header code and transmitted, the Manchester decoding device can normally decode the original data.

Therefore, the Manchester encoding apparatus according to the present invention can be applied to a wireless communication system without converting the Manchester code by converting the frequency of the Manchester code to a higher frequency without employing a specific modulation means. In addition, the Manchester decoding apparatus according to the present invention can accurately decode the Manchester code of every frame inputted with time delay in a wireless communication system using a magnetic field by delaying until the Manchester code of the next frame is input using a gray code counter. It is possible to recover the decoding clock suitable for use in a wireless communication system with the restoration of the original data from the received frequency variable Manchester code.

Claims (9)

A Manchester encoding apparatus for generating a Manchester code by encoding transmission data generated from a system to be transmitted through a wireless communication channel, Clock dividing means for dividing a frequency of a system clock applied from the outside by 1 / (2 * n) times to generate a divided clock; A Manchester encoder for encoding said transmission data using said system clock as an encoding clock to produce a frequency variable Manchester code having a 2 * n clock frequency; And said system generates said transmission data in accordance with a clock divided by said clock division means, wherein said transmission data includes a header code for synchronizing with a receiving side. The method of claim 1, wherein the clock divider means: A variable frequency Manchester encoding device comprising n T-type flip-flops connected in series. A Manchester decoding device for decoding a frequency-varying Manchester code having a 2 * n clock frequency transmitted through a wireless communication channel, A rising edge detector for detecting a rising edge event of the Manchester code and outputting a rising event detection signal; A falling edge detector for detecting a falling edge event of the Manchester code and outputting a falling event detection signal; Gating means for selectively outputting the rising and falling edge event signals output from the rising and falling edge detectors according to valid event determination signals; A valid event detection unit operable in response to an event detection signal selectively output from the gating means to provide the gating means with the valid event determination signal for determining a valid event during the rising and falling events; And a data reproducing unit which is set or reset according to an event detection signal selectively transmitted from the gating means, and outputs data recovered from the Manchester code. The apparatus of claim 3, wherein the valid event detector comprises: The count operation is reset until the preset count state is reached by resetting by the event detection signal output from the gating unit, and until a new event is provided from the gating unit when the preset count state is reached. Counter means for maintaining a state; And a valid signal generator for supplying the valid event discrimination signal to the gating unit to adjust the discrimination timing of the valid event according to the count state output from the counter means. 5. The apparatus of claim 4, wherein the counter means is a gray code counter and the preset count state is a last count value of the gray code counter. The method of claim 3, wherein the rising edge detection unit: A first flip-flop operating according to a local clock to latch a rising transition state of the Manchester code; A second flip flop connected to an inverted output of the first flip flop; And a logical multiplication means for generating a rise event detection signal that detects the rising variation of the Manchester code by ANDing each of the non-inverted outputs of the first and second flip-flops, The falling edge detection unit: A first flip-flop operating according to a local clock to latch a falling transition state of the Manchester code; A second flip flop connected to an inverted output of the first flip flop; And logical AND means for generating a falling event detection signal for detecting a falling variation of the Manchester code by ANDing each of the inverted outputs of the first and second flip-flops. The method of claim 3, wherein the gating portion: First logical multiplication means for performing an AND operation on the output from the rising edge detector and the valid event determination signal from the valid event detector to invert and output the output of the rising edge detector; And second logical multiplication means for performing an AND operation on the output from the falling edge detector and the valid event determination signal from the valid event detector to invert and output the output of the falling edge detector. 4. The apparatus of claim 3, wherein the data reproducing section comprises: A latch that generates and outputs logical 0 as data to be reset and decoded by the output of the first AND function, and generates and outputs a logical 1 as the decoded data that is set by the output of the second AND product; The variable frequency Manchester decoding device characterized in that it comprises. 4. The apparatus of claim 3, wherein the Manchester decoding apparatus further comprises clock divider means for dividing the selective output of the gating means by 1 / (2 * n) times to generate a divided clock as a decoded clock. Variable Manchester decoding device.