KR900008272Y1 - The coding and decoding circuitry of ppm data - Google Patents

Abstract

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Description

PPM Data Coding and Decoding Circuit

1 is a PPM data coding circuit diagram.

2 is a waveform diagram of each part of FIG.

3 is a decoding circuit diagram of PPM data.

4 is an angular waveform diagram of FIG.

5 is a data waveform diagram at the time of error occurrence in the means.

* Explanation of symbols for main parts of the drawings

10: oscillator 20-40, 130-140: flip-flop

50-60, 150 Exclusive Noah Gate 70: Endgate

110: clock regeneration circuit 120: ideal phase

The present invention relates to an apparatus for transmitting digital data, and more particularly, to a circuit capable of coding and transmitting PPM data and receiving and decoding coded PPM data. ; PPM data (Pulse Position Modulation Data) generates a short pulse indicating the position of the side because the information is not in the pulse itself but at the time position of the pulse side.

In the conventional data coding and decoding circuit, when data is consecutively held in a "high" or "low" signal, it is necessary to add data for synchronization separately in order to extract a clock. It was difficult to do it, it was influenced by jitter, and the transmission and reception data and the delay time were long, such as 5 clock delay in the HDB-3 system based on the system clock. There was a problem that the circuit became complicated due to a large number of parts.

Accordingly, an object of the present invention is to provide a PPM data coding circuit that can be coded in different specific forms with PPM data in a "high" state or a "low" state.

Another object of the present invention is to provide a PPM data decoding circuit capable of receiving coded PPM data and decoding the original PPM data accurately.

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

1 is a PPM data coding circuit diagram, comprising: an oscillator 10 and flip-flops 20-30, first means for generating a first division signal for dividing an oscillation pulse and a second division signal for four division; A second means for performing a gate relay for matching by outputting data by using the flop 40 as a clock for the first divided signal of the first means, and the first by means of the exclusive noar gate 50; A third means for logically combining the second divided signal of the means and the data of the second means to determine the coding position according to the state of the data (“high”, “low”), and to the exclusive no-gate 60. A fourth means for compensating timing by gate-delaying the first divided signal, and the output of the third means and the fourth means by the logical AND of the output, and the coding state of the coded PPM data ("1000") and the "low" state according to the data state. Causes coding PPM ("10") Fig. 2 is an operation waveform diagram of each part of Fig. 1, and Fig. 3 is a decoding circuit for coded PPM data, which is composed of a clock reproducing signal 110 and an ideal phaser 120 and clocked from coding data. First means for reproducing and shifting by 90 °, second means for outputting coded PPM data as an output of the first means by flip-flop 130, and first means for flip-flop 140; The third means for dividing the playback clock of the second means, and the exclusive means for decoding the original PPM data by logical combination of the data of the second means and the playback clock of the third means by the exclusive Noah gate 150 4 is an operation waveform diagram of each part of FIG. 3, and FIG. 5 is a view showing a predetermined form according to "high" and "low" of PPM data. 0010) (me) like "ha Regardless of the " state 1000 ", a pulse exists and indicates an error state when the pulse is lost as shown in (c).

Based on the above-described configuration, the present invention will be described in detail with reference to the first, second, third, fourth, and fifth degrees.

First, a coding method of PPM data will be described.

In order to determine the transmission speed and the system clock by the same waveform as the 2a diagram output from the oscillator 10, the output of the oscillator 10 of the flip-flop 20 is input to the clock stage and its inverted output Q is inputted to the data. In response to the terminal D, the output of the oscillator 10, such as the 2a diagram, is divided into two, and a signal having a duty ratio of 50% is output as shown in the 2b diagram.

The flip-flop 30 divides the output of the flip-flop 20 again and outputs the same signal as the second c degree having a duty of 50%. The flip-flop 30 divides the output of the oscillator 10 of the flip-flop 30 into four.

When the output of the flip-flop 20 is applied to the clock terminal of the flip-flop 30 as a system clock, the PPM data outputs the flip-flop 40 as shown in the second diagram.

Here, the output of the flip-flop 40, such as the 2d diagram of the exclusive Noah gate 50, and the output of the flip-flop 30, which is divided into four, the output of the oscillator 10, such as the 2c diagram, are input. When the data is in "high" state, the half-cycle is "high" for the corresponding data bit time, the second half of the cycle is "low", and the data is in the "low" state. "Low" and the second half of the cycle is "high".

The exclusive Noah gate 60 inputs the output of the flip-flop 10, such as 2b, which divides the output of the power supply VCC and the oscillator 10 into two, and outputs the same signal as the 2f. This is for delaying a predetermined time to match the timing with the sieve noah gate 50. In other words, the flip-flop 40 and the exclusive noble gate 60 are gate delay elements for adjusting timing, which makes the PPM data pulse position constant by data and the pulse width fixed.

In FIG. 2, the solid line portion indicates that the PPM data is "low" and the dotted line portion indicates that the input PPM data is "high", and the AND gate 70 for inputting the output of the exclusive Noah gate 60 as shown in FIG. ) Multiplies these two signals and outputs the same PPM data as the second g degree.

The control signal CTL applied to the clear terminal of the flip-flop 20-30 is used to determine an initial operating condition at the start of data transmission.

In the above-described process, the coding data has a specific form according to the state of the PPM data. The "high" state date and time of the PPM data is shown in the first half of the data as indicated by the dotted line as shown in FIG. "The date and time appear in the latter part of the data like a solid line (" 10 "). Such PPM data coding waveforms always have a constant pulse width and appear pulses regardless of whether the data is" high "or" low ". According to the "high" or "low" state, the position is fixed to one of the two data cycles, so the clock extraction is easy and the system down and the line monitoring on the opposite side can be easily executed.

Second, the process of decoding the coded PPM data will be described.

The clock reproducing circuit 110 for inputting the coded PPM data as shown in FIG. 4A can easily extract the coded PPM data as shown in FIG. 4B since the coded PPM data is necessarily present at a position according to the "high" or "low" state during the corresponding data period. The fourth clock is applied to the clock stage of the flip-flops 130 and 140 by delaying the pulse by applying a regeneration clock such as the 4b diagram to the phase shifter 120 and shifting by 90 ° as shown in the 4c diagram.

At this time, the flip-flop 130 samples the PPM data coded as the 4a diagram with the delay clock as the 4c diagram and outputs the 4d diagram as the 4d diagram, and the flip-flop 140 divides the applied delay clock by 50% of the duty ratio by 2 minutes. 4e Print with tile.

The exclusive no-gate 150, which inputs the PPM data of the flip-flop 130 and the reproduction clock divided by the flip-flop 140, calculates the two signals and decodes the original data as shown in the 4f diagram.

As described above, the coded PPM data must have a pulse during the period regardless of whether the data is in the "high" state or the "low" state. In the case of the decoded signal form, as shown in (c) of FIG. 5B, the half position of the front end is "low" and the rear half is "high" during the corresponding data bit time.

As described above, according to the "high" or "low" state of PPM data coding, a certain pulse may be generated at a predetermined position for the corresponding data bit time, thereby facilitating clock extraction when receiving and decoding coding data. Because the coded data has pulses regardless of the state of the data, it is easy to detect data errors such as pulse loss, and is less affected by jitter in clock extraction and has a shorter transmission delay time (data bit 1/8) Real-time control can be implemented, and the clock phase fluctuation does not occur due to noise, and it has the advantage of high reliability and compact and lightweight system.

Claims (1)

In the PPM data coding and decoding circuit, a first division signal for generating a second division signal for generating a first division signal for dividing an oscillation pulse into a system clock and generating a second division signal for setting a period of coding data is first generated. Means for outputting PPM data by the first divided signal and compensating for timing with the second divided signal, and the second divided signal of the first means and PPM data of the second means. Third means for calculating the position of the coding data according to the "high" or "low" state of the PPM data, and timing the system clock of the first means according to the coding data positioning of the third means. The fourth means, and the fifth means for generating the coding data by logically multiplying the outputs of the third means and the fourth means, and the reproduction clock is extracted from the coding data of the fifth means by 90 ° or more. A sixth means, a seventh means for outputting coding data by the clock of the sixth means, an eighth means for dividing the reproduction clock of the sixth stage into two, and an output of the seventh and eighth means. And a ninth means for decoding the quintessential coded data into the original PPM data by means of exclusive novulation.