JPS5849049B2 - Pulse sending circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse sending circuit that is used, for example, in a pulse repeater and is configured so that the pulse area (pulse amplitude x pulse width) of a unit pulse of an output pulse code string is constant. be.

In the conventional pulse sending circuit, as shown in FIG. 1, an input pulse from a pulse input terminal 11 is waveform-shaped by a pulse shaping circuit 12, and its output is amplified by a pulse amplifying circuit 13.
It is sent out from the pulse output terminal 14.

As described above, the conventional pulse sending circuit does not perform stabilization control on the waveform of the output pulse.

The first choice for pulse regeneration circuits that require high precision and highly stable transmission waveform characteristics, such as regeneration circuits for regenerative repeaters for PCM transmission.
When the pulse sending circuit shown in the figure is used, there is a drawback that variations in output pulse width and pulse amplitude occur, which deteriorates the operating characteristics of the next-stage repeater.

In order to solve these drawbacks, this invention detects fluctuations in the pulse area (pulse width x pulse amplitude) due to pulse width fluctuations and pulse amplitude fluctuations, and controls the pulse sending circuit to keep the area of the output pulse constant. do.

In order to detect variations in the pulse area, the average voltage and amplitude of the output pulse train are detected by an average value detection circuit and an amplitude detection circuit.

The detected average voltage variation amount and amplitude variation amount are detected by first and second variation detection circuits, respectively, and the amplitude and width of the output pulse are controlled according to the detected variation amount to output a pulse train. The average voltage is made to be a constant value.

Next, an embodiment of the pulse sending circuit according to the present invention will be described with reference to FIG. 2 and the following drawings.

A pulse is given to the pulse sending circuit 15 from the terminal 11,
The pulse sending circuit 15 sends out a pulse corresponding to the person's pulse to the output terminal 14.

The pulse sending circuit 15 is assumed to have at least one function such as pulse waveform shaping, pulse amplification, and pulse waveform conversion.

In this example, a pulse shaping circuit 12 and a pulse amplifying circuit 13
The pulse sending circuit 15 is configured.

Also, the average value of the input or output pulse train is constant, that is, the mark rate is constant, and for example, does it include DC? , whose average level is zero is used.

FIG. 2 shows a circuit component for controlling the pulse width, and a pulse width control circuit 16 is inserted between the pulse input terminal 11 and the pulse sending circuit 15.

In addition, the output pulse train of the output terminal 14 is transmitted to the average value detection circuit 11.
and the average voltage is detected.

The amount of variation in the detected average voltage is detected by the first variation detection circuit 18, and the pulse width control circuit 16 is controlled by the detected amount of variation.

Considering pulse width fluctuations and pulse amplitude fluctuations in terms of a binary pulse train, if "l 2+ , ft Q" occurs with equal probability, then if the pulse width expands from the solid line in Figure 3A to the dotted line, then The average value increases from ■ to ■h.

On the other hand, when the distance becomes narrower as shown by the one-dot chain line, the average value becomes as small as vl.

When the pulse amplitude increases from the solid line in Figure 3B to the dotted line, the average value increases from ■ to ■h, and vice versa.
When the value decreases as shown by the dotted chain line, the average value becomes small to ■l.

Therefore, if the pulse amplitude or pulse width of the output pulse train changes, in Fig. 2, the average value detection circuit 1T
The output pulse of changes.

The average value of the output pulse train detected by the average value detection circuit 17 is compared with a reference value initially set by the first fluctuation amount detection circuit 18, and the amount of fluctuation in the average value is detected.

The pulse width control circuit 16 changes the pulse width so as to reduce the amount of variation in the detected average value.

FIG. 4 shows a specific example of FIG. 2.

When the pulse shaping circuit 12 and the pulse control circuit 16 are used together, the emitters of the transistors 21 and 22 are connected to a common resistor 23 and grounded, an input pulse is given to the base of the transistor 21 from the terminal 11, and the emitters of the transistors 21 and 22 are connected to the common resistor 23 and grounded. The output of the first variation detection circuit 18 is supplied to the base of the circuit, and is configured as a differential switch circuit.

The collector output of the transistor 21 is supplied to the bases of transistors 24 and 25 constituting the differential amplifier circuit, and the collector of the transistor 24 is supplied to the output terminal 14.

The collector output of the transistor 25 is the average value detection circuit 11
is supplied to the base of transistor 26.

The collector of the transistor 26 is connected to the positive power supply terminal through a time constant circuit 21 consisting of a parallel circuit of a resistor and a capacitor, and the collector is connected to the first fluctuation amount detection circuit 18.
It is connected to an operational amplifier 29 through a resistor 28 within the circuit.

A set voltage is supplied to this operational amplifier 29 from a power supply 31 through a resistor.

The output of operational amplifier 29 is fed to the base of transistor 22, which acts as pulse control circuit 16.

For example, when the pulse width of the output pulse train of the output terminal 14 becomes dog, the average value of the pulse train supplied to the average value detection circuit 11 decreases, and this pulse train is averaged by the time constant circuit 27, which is the collector. Because it is connected to
The average voltage will rise above normal conditions.

This fluctuation is detected by the first fluctuation amount detection circuit 18, and the output voltage of the operational amplifier 29 decreases, and the pulse shaping circuit 1
The operating point of transistor 24 decreases, the width of the pulse obtained at the collector of transistor 21 increases, and this pulse
Since the polarity is reversed at , the pulse width of the pulse at the output terminal 14 becomes narrower, and the average value of the output pulse train decreases.

When the pulse width of the output pulse train becomes narrower than in the normal state, the pulse width of the output pulse increases in the opposite manner to that described above.

In this way, the width of the output pulse is held constant.

It is also possible to detect variations in pulse amplitude of the output pulse train using the circuit shown in FIG.

However, if the pulse is an RZ waveform, the pulse width can be controlled and held at a constant value against fluctuations in amplitude and width, but if the pulse is an NRZ waveform, the pulse width can be controlled only against fluctuations in width. is valid.

FIG. 5 shows how the pulse width of an NRZ pulse changes using an eye pattern, which is normally used as a means of observing a pulse train.The width changes shown by the broken line or the dashed line are detected and the operating point of the pulse shaping circuit 12 is changed. to control the waveform as shown in the solid line.

(2) FIG. 6 shows an example in which the pulse sending circuit 15 is provided with a function of converting a waveform, for example, converting an NRZ waveform into an RZ waveform.

In FIG. 6, the same reference numerals are given to the parts corresponding to those in FIG. 34.

The output voltage of the first variation detection circuit 18 is applied to the connection point between the AND circuit 33 and the capacitor 34 .

The inverted output and non-inverted output of the AND circuit 33 are connected to the transistors 24 . 25 bases each.

The pulse width of the pulse train of the output terminal 14 is the solid line 35 in Figure T.
When the points and lines 36 spread out, the average value detection circuit 1
The average value voltage detected at 1 becomes large as in the case of FIG. 4, and therefore the output voltage of the first variation detection circuit 18 decreases.

Therefore, for example, when the NRZ pulse at the input terminal 11 is indicated by the solid line 37 in FIG. The non-inverted output pulse width becomes narrower, and the pulse at the output terminal 14 returns to a solid line 35.

Pulse width fluctuations are thus automatically controlled.

The output of the second fluctuation amount detection circuit determines not the pulse width but
A circuit for controlling pulse amplitude will be explained.

For example, as shown in FIG. 8 with the same reference numerals attached to parts corresponding to those in FIG. 13, the amplitude of the output pulse is controlled.

FIG. 9 shows a specific example of a circuit for controlling pulse amplitude, with the same reference numerals attached to parts corresponding to those in FIG. 6.

This is an example in which the average value detection circuit 11 is used as the amplitude detection circuit.

The clock terminal 10 is directly connected to the AND circuit 33, and the emitter resistors of the transistors 24 and 25 are connected to the output side of the operational amplifier 29 through the diode 42 of the control circuit 41, without being directly grounded, and through the diode 43. Grounded.

Further, a time constant circuit 27 of the average value detection circuit 17 which operates as an amplitude detection circuit is provided on the emitter side of the transistor 26.

For example, when the pulse amplitude at the output terminal 14 becomes a dog, the average value of the pulses input to the average value detection circuit 11 decreases, and therefore the average voltage detected by the average value detection circuit 1T also decreases.

Therefore, the output voltage of the operational amplifier 29 increases, and the current flowing to the operational amplifier 29 through the transistor 24 and the diode 42 decreases, that is, the amplitude of the output pulse decreases.

In this way the average value of the output pulses is kept constant.

This invention makes it possible to control both pulse width and pulse amplitude, and basically has a configuration in which a pulse amplitude control means is added to the circuit shown in FIG.

An example thereof is shown in FIG. 10, in which parts corresponding to those in FIGS. 2 and 8 are given the same reference numerals.

In this case, the peak value detection circuit 44 is used as the amplitude detection circuit, and the amplitude of the pulse at the output terminal 14 is detected by the peak value detection circuit 44, and if the detected amplitude fluctuates from the set value, the second The pulse amplitude control circuit 41 is controlled by the detection output.

In this invention, since two feedback control circuits are configured for pulse width and pulse amplitude, the response time constants of these feedback control loops are made to differ from each other.

In this case, the time constant of the control loop for amplitude control is made smaller.

In other words, if the time constant of the control loop for the pulse width is made smaller, even if there is an amplitude fluctuation, the correction operation for the pulse width will be performed first, so the time constant for pulse amplitude control is made smaller.

According to the present invention, both the pulse width and the pulse amplitude can be controlled to constant values in this manner, and a pulse train with a constant pulse area can be stably obtained.

Although the above-mentioned specific embodiment has been shown only in the case where the present invention is applied to a binary code pulse sending circuit, circuits having the above-mentioned basic configuration can also be connected in parallel to a multi-value code pulse sending circuit of three or more values. A similar behavior can be obtained by

However, in the multilevel code pulse sending circuit, a waveform conversion circuit using a clipper circuit, a slicer circuit, a limiter circuit, etc. is required in order to separate the average value of each multilevel level in the average value detection circuit.

FIG. 11 shows an example of the basic configuration of a ternary code pulse sending circuit, and parts corresponding to those in FIG. 2 are denoted by the same reference numerals.

The output pulse from the output terminal 14 is separated into multiple levels by the waveform conversion circuit 46, and each level is sent to a separate average value detection circuit 1.
1.

As explained above, according to the present invention, a pulse train controlled so that the pulse area (pulse amplitude x pulse width) of a unit pulse is always constant can be obtained, so if it is used as a pulse sending circuit in code transmission, the pulse width It is possible to configure a highly accurate transmission system in which the received equalized waveform is less degraded by fluctuations and pulse amplitude fluctuations.

Although the pulse width control circuit 16 is provided integrally with the pulse shaping circuit 12 in FIG. 4, the output side of the average value detection circuit 17 may be directly connected to the pulse width or pulse amplitude control circuit 16 or 41 in some cases. The fluctuation amount detection circuit may be provided integrally with these control circuits.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the basic configuration of a conventional pulse sending circuit, Fig. 2 is a block diagram showing the constituent parts of a circuit that controls pulse width, which is the basis of this invention, and Fig. 3 shows pulse width fluctuation, pulse FIG. 4 is a schematic diagram showing the relationship between amplitude fluctuations and their average level; FIG. Fig. 6 is a connection diagram showing another example of the pulse width control circuit which is the basis of this invention, Fig. 7 is an explanatory diagram of its operation, and Fig. 8 shows the constituent parts of the pulse amplitude control circuit which is the basis of this invention. 9 is a connection diagram showing the specific embodiment of FIG. 8, FIG. 10 is a block diagram showing the configuration of an embodiment of the pulse sending circuit of the present invention, and FIG. 11 is a connection diagram showing the specific embodiment of the pulse sending circuit of the present invention. 1 is a block diagram showing an example of a basic configuration to which the present invention is applied. FIG. 10... Clock input terminal for shaping, 11...
...Pulse input terminal, 12...Pulse shaping circuit, 13...Pulse amplification circuit, 14...
・Pulse output terminal, 16... Pulse width control circuit, 17... Average value detection circuit, 18...
First variation detection circuit, 18'... Second variation detection circuit, 41... Pulse amplitude control circuit, 4
4...Peak value detection circuit.

Claims (1)

[Claims] 1. In a pulse sending circuit that is given a human pulse and outputs a pulse corresponding to the human pulse, there is an average value detection circuit that detects the average voltage of the output pulse train, and a second circuit that detects the output voltage fluctuation of the average value detection circuit. a first fluctuation amount detection circuit; and a pulse width control means for controlling the pulse width of the output pulse train so that the average voltage of the output pulse train approaches a predetermined value in accordance with the fluctuation amount detected by the first fluctuation amount detection circuit. and an amplitude detection circuit that detects the amplitude of the output pulse, a second fluctuation amount detection circuit that detects the output voltage fluctuation of this amplitude detection circuit, and an amplitude detection circuit that detects the output voltage fluctuation of the amplitude detection circuit, and and pulse amplitude control means for controlling the pulse amplitude of the output pulse train, wherein a time constant of the pulse width control means is set larger than a time constant of the pulse amplitude control means. Sending circuit.