JPS5830782B2 - Pulse Densou Houshiki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse transmission method, and more specifically, to a pulse signal processing method on the receiving side in a repeater, receiver, etc. when a signal is converted into a binary pulse and transmitted. .

Conventionally, when communicating through a transmission path with large nonlinearity such as optical communication, a binary pulse train that is less affected by this nonlinearity is often used.

If the receiver does not pass the DC component of the signal in such a transmission path, or if it is undesirable to pass the DC component and low frequency component due to unstable operation at low frequencies, it is necessary to shield this. In this case, the usual method is to place certain constraints on the binary pulse train to prevent components near DC from occurring in the transmitted pulse train, thereby preventing deterioration in signal quality.

In this case, the required bandwidth for pulse transmission increases due to the above constraints.

This increase in bandwidth will not be much of a problem in broadband transmission lines such as optical fibers, but in the future when fiber loss becomes extremely small and transmission distances can be extremely large, or extremely high-speed transmission will be possible. In such cases, the attenuation up to high frequencies will be greater than that for low frequencies, and this will need to be equalized by a repeater or receiver, and the amplification degree at high frequencies will increase, so the increase in the band will cause noise. This results in a significant increase in the signal-to-noise ratio, which poses a serious problem.

The purpose of the present invention is to realize a binary pulse transmission processing method that suppresses components near DC without increasing noise.

That is, to realize a pulse transmission processing method that transmits a constrained binary pulse that suppresses components near DC, reduces the high frequency component that increases in that case, and eliminates the need for amplification of the high frequency component by equal volume etc. With the goal.

In order to achieve the above object, in the present invention, a code whose polarity is reversed at the edge or center of a time slot is used on the transmitting side, and this is used on the receiving side to delay the received pulse train by 100 time slots. Create a sum with things and perform signal processing using kneading.

That is, as shown in Fig. 1, in the original signal a, the code 1 is transmitted with its polarity inverted alternately, the 0 is transmitted with its polarity inverted at the center of the time slot, and the polarity of the 0 is reversed with the adjacent pulse at the end of the time slot. If the received waveform is summed with waveform C delayed by 7 time slots on the receiving side, it will correspond to 1 as shown in the same figure. A waveform in which the polarity of the pulses alternately reverses is obtained.

This is a so-called AMI (bipolar) code, and the spectrum of the transmitted waveform has a pulse repetition closed wave number f as shown in Fig. 2a.

However, in this waveform d, f
.

(Strictly speaking, the bandwidth can be expanded infinitely, but 1. All information is f.

It is below. ) Therefore, compared to processing the waveform shown in Figure 1 as is, the band is higher, the influence of high-frequency noise is smaller, and the signal-to-noise ratio is significantly improved (equalization with a large gain at high frequencies). ) will be improved.

As shown in FIG. 3, this transmits a waveform whose polarity is inverted to 10- at the center of the time slot corresponding to code 1, and which is inverted to -+ in response to code 0. The same applies to the case where a received waveform (also designated as b) and a waveform C delayed by 100 time slots are summed to obtain a type of AMI waveform as shown in d of the figure.

The present invention will be explained in detail below using examples.

Since the apparatus for producing waveform S from waveform a in FIG. 1 or 3 is well known, the explanation thereof will be omitted, and the apparatus for producing waveform d from waveform C will be explained here.

In principle, this can be done by adding the waveform applied to the input terminal 1 and the output 3 obtained by adding the delay line 2 of 7 time slots to the adder 4 as shown in FIG. can get.

More specifically, as shown in FIG. 5, the received signal applied to the input terminal 1 (corresponding to the waveform in FIG. 3) is a waveform 3 applied to the delay line 2 using the transistor 6 as a buffer,
They are added in adder 4 by summing resistors 7 and 8.

Note that in this adder, resistor 9 provides negative feedback to transistor 0, and plays the role of making the input impedance to the transistor extremely low.

Although an example using a delay line has been shown above, it will be shown next that the receiving section of the present invention can be constructed without using a delay line.

In other words, the transfer characteristic of the configuration shown in FIG. 4 is as shown in FIG.
o or higher) characteristics are not required.

Therefore, the transfer function shown in FIG. 6a can be approximately expressed as a cascade of transfer characteristics as shown in FIG. 6C and b.

An embodiment of the p-wave amplification section of the repeater (or receiver) in this case is shown in FIG.

That is, the received signal applied to the input terminal 11 (corresponding to the waveforms in FIGS. 1 and 3) passes through the amplifier 12, and is synthesized by the solid line in FIG. The anti-resonant circuit 1 passes through the filter 13 (dotted line in Figure 6).
4 (which realizes the pole in FIG. 6 d), and the waveform d in FIG. 1 or 3 is obtained at the output terminal 15 as its output.

It goes without saying that the filters 13 and 14 can be combined into one in some cases.

As explained above, according to the present invention, a pulse train encoded to suppress binary DC components is transmitted through a transmission path that attenuates high frequencies, and the receiving side performs equalization to reduce high frequencies. Because of the amplification of the parts, it is possible to provide a pulse transmission system that is less susceptible to the effects of high-frequency noise, and its contribution is extremely significant in realizing high-quality pulse transmission.

[Brief explanation of drawings]

1 and 3 are time charts explaining the present invention in detail, FIG. 2 is a frequency spectrum diagram explaining the present invention in detail, and FIGS. 4, 5, and 7 are examples of the present invention. , FIG. 6 is an explanatory diagram illustrating the principle of the embodiment of FIG. 7. 1.11...Input terminal, 2...Delay line, 3...Delay line output signal, 4...Adder, 5, 15...・・・Output terminal, 6, 10...
...Transistor, 1,8...Additional resistor,
9...Negative feedback resistor, 12...Amplifier, 13.14...Suppressor.

Claims (1)

[Claims] 1. Transmit a binary pulse train whose polarity is reversed at the edge or center of each time slot,
A pulse transmission method characterized in that a received pulse train and a time slot delayed version of the received pulse train are added to form a ternary bipolar code on the receiving side, and then signal processing is performed.