DE921947C - Modulator for AC telegraphy systems - Google Patents

Description

ISSUED JANUARY 7, 1955

L 1362p νΐΙΙα / Σία ¹

For a long time, the transmission relay in AC telegraphy devices has been replaced by the so-called telegraph modler, which has numerous important advantages over a relay. The main parts of the modler are non-linear resistors, the size of which is changed by the local circuit through the incoming direct current signals. These controllable resistors are interconnected to form a quadrupole, possibly with additional fixed resistors, in such a way that they are attenuated between one at the input. AC power source and a consumer connected on the output side. As an example, Fig. 1 shows such a Madler with a controllable series resistance R { and an oppositely controllable transverse resistance Rq in a greatly simplified representation. If the controlling voltage U _s or the controlling current 7 _{S changes} more or less abruptly between two specific values of opposite polarity, the quadrupole has only little damping, in the other case high damping. UT ₀ is the signal carrier source with the internal resistance R ₁ ', while R _{a represents} the consumer.

With regard to the telex dial-up traffic it must now be required that the modler depending on the telegraphic process has a certain attenuation when the control circuit is de-energized (quiescent attenuation). In the Arbeitsetrom process, the Quiescent damping must be large, but small in the quiescent current method. With the previously known modler types this was achieved by using non-linear switching elements for longitudinal and transverse branches very different resistance in the de-energized state or the same series and Transverse resistances were translated accordingly by transformers. The modler for work and Quiescent currents therefore have significant differences

on, which means that it is not possible to switch to the same modler without considerable additional effort and can thus be used for both processes.

S The present invention provides a modulator that all inexpensive. Properties of so far known types and, moreover, the transition with only minor switchings from working to closed-circuit operation and vice versa ίο permitted.

This is achieved by the damping at rest of the modulator by controlling the same or the same, non-linear resistors, preferably Rectifier, optionally adjustable to a high or low value.

The modulator according to the invention has the further essential compared to known circuits Advantage that its output with simple means for both switching states, so for idle state and during signaling, can be adapted to the consumer.

These and other features and advantages of the modulator according to the invention are now due to an exemplary embodiment and with reference to the drawing are explained in more detail.

In the already mentioned Fig. 1 as well as in the The following figures show modulators that contain two or more non-linear resistors. It is clear, however, that the invention applies equally to simple modulators with only one non-linear resistance in the longitudinal or cross-branch. The description is only therefore made exclusively on the basis of modulators with more than one non-linear resistance, because these can be used more universally. While

Fig. Ι represents the principle of a module already described according to the prior art, there Fig. 2 the principle,

3 shows an embodiment of the modulator according to the invention.

In FIG. 2 one can initially see the same elements UT ₀ , Ri and R _a as in FIG. 1. Here as there, the actual modulator, bordered by dash-dotted lines, is shown in a greatly simplified manner, since only the principle is to be explained with reference to this figure. R 1 and R _q are controllable resistors which, in contrast to R { and R / of FIG. _{1, are equivalent here.} They form the variable longitudinal or external resistance of the modulator and are controlled by. the voltage Ug controlled in the opposite sense, so that, for example, R _{ may assume its blocking resistance R ₈ and Rq its forward resistance R <i.

In order to achieve the desired high or low quiescent damping of the modulator, a suitably polarized bias voltage U _{x is} simply added to the controlling voltage U ₈ , which keeps the modulator in the switching state required for the relevant method if U _{5 fails.}

In addition to the fact that the requirement for switchability has been met, three further advantages are already apparent in this explanation of the principle. On the one hand, the two non-linear resistances can and must be exactly or approximately the same. So there is ¹ type restriction for the individual components.

On the other hand, they are biased by means of the bias voltage ± U _v so that the control voltage + U _s always finds a steeply falling or rising resistance characteristic of the controlled resistance in its effective direction and thus causes a considerable change in resistance. Is z. For example, if R _t is biased so that the working point is at the upper knee of the resistance voltage characteristic, then the situation at R ₁₁ is reversed at the same time, and its working point is at the lower knee. In both cases, ± U ₅ results in a shift along the steep branch of the characteristic. Bai Fig. Ι on the other hand, R { and R "'are both equally biased, namely to the potential o, so that the shift only z. B. at R {takes place in the direction of the steep branch of the characteristic curve, while at R ₁₁ ' it goes on in the flat part, so that only a relatively small change in resistance occurs.

Finally, the current consumed by the modler from the local circuit remains approximately the same for both switching states (+ and - Ü _s ) , so that there is no asymmetry in the local circuit load.

From Fig. 2 it can be seen that the modulator, seen from the generator, begins with the series resistance. The specification i?, · <S, R _a indicates that the modulator should have a high resistance compared to the internal resistance of the carrier source.

These circumstances make it possible, according to the further invention, in conjunction with the use of the resistor R ^, to dimension the modulator in such a way that there is an adaptation to the consumer R _a in all switching states. The most favorable tax effect is achieved when

is made. If one also chooses i? ^ Äii? _a , then one recognizes, since R _d ^ R _a = R _K -, the existence of the adaptation. If Ri = R ₈ and R _v = R _d , then the consumer sees the resistance

R _K + R _d is included

Conversely, if Ri = R _d and R _q = R ₈ , the consumer sees the resistance

R _K + R _d + Ri is there

_a R _a

Ri

However, since the size of R _a is generally fixed and only in the. In the rarest of cases suitable non-linear controls are available, the above adaptation conditions must be met, usually by means of transformers:

Fig. 3 shows as an example the complete circuit of a modulator according to the invention. The non-linear resistors are split and arranged in a bridge. The transformer Tr ₁ is used for

Adaptation of the generator resistance, Tr ₂ to adapt the consumer R _a .

The transformers also serve to decouple the modulator output and the carrier feed to the tax circle They are not particularly complicated Transformer required, and the carrier-side transformer can normally be used at the same time Output transformer of the generator.

The rectifier used normally ίο as nonlinear resistors require for their manufacturing tolerances, a linearisation, which is here achieved very simply in that the resistance R _K (Fig. 2) wholly or partly (divided up symmetrically) _q between R and Tr ₂ is placed I —Rr

of Fig. 3). This linearization works in the same way for R ₁ and R ₉ .

If the entire resistance R _{K from} FIG. 2 is not used for linearization, then one sets

ao expediently part of it as a resistor R _K " in series with the secondary winding of the transformer Tr _2. The use of the resistor R _K, which is already present for adjustment purposes, for linearization has the advantage that the quality

»5 of the modulator not through additional linearization resistors is reduced.

At the bottom; Part of FIG. 3 shows a possibility for introducing the bias voltage U _v . From the voltage source B , the positive or negative voltage is fed to the resistor R _{1 of} the local circuit, which is closed by the contact i of the pulse relay (not shown). The control voltage is tapped at R ₁ and fed to the modulator. The resistor R ₂ is used to produce a constant current. The circuit for producing the bias voltage U _v , which in the example is taken from the same voltage source as the control voltage, is closed by the contact ν . The current is passed through the series resistor R _v and the resistor R _s in series with R ₁ , at whose terminals the bias voltage U _v applied to the modulator is dropped.

The description was primarily based on an exemplary embodiment. It is clear that this is was only done for the sake of better comprehensibility and that there is no limitation of the essence therein of the invention can be seen.

Claims (10)

Patent claims: i. Modulator for alternating current telegraphy systems, characterized in that its Quiescent damping by controlling the same or the same non-linear resistances, preferably Rectifier, optionally to a high value for carrying out an operating current process or can be set to a low value for carrying out a closed-circuit current procedure is. 2. Modulator according to claim 1 with a plurality of non-linear resistors in bridge or Voltage divider circuit, characterized in that the non-linear. Resistances to each other are the same or approximately the same. 3. Modulator according to claim 1 and 2 with non-linear resistors in a voltage divider circuit, characterized in that the voltage divider with a controllable series resistance begins and parallel to the connection of the consumer a controllable. Cross resistance contains. 4. Modulator according to claim 1 to 3, characterized by dimensioning such that the consumer compared to the internal resistance the carrier wave has a high resistance. 5. modulator according to claim ^ characterized in that the consumer with a Resistance becomes effective which is approximately or exactly equal to the geometric mean The forward and reverse resistance of the controllable resistors is, and that this adaptation is through Transmitter takes place. 6. Modulator according to claim 1 to 5, characterized characterized in that the control of the damping at rest by supplying or changing a DC voltage takes place in the circle of its controllable resistors. 7. Modulator according to claim 6, characterized in that the DC voltage of the the same power source is taken as the actual control circuit (local circuit) feeds. 8. modulator according to claim 1 to 7, characterized characterized in that the output resistance of the modulator by a fixed, resistance is corrected in such a way that it is approximately or exactly for both switching states of the modulator is equal to the input resistance of the connected consumer. 9. Modulator according to claim 1 to 8 with linearization of the controllable resistors used rectifier, characterized in that for linearization in whole or in part the resistor used to correct the output resistance is used. 10. Modulator according to claim 9, characterized in that that the linearization for two or more of the controllable resistances by the same ohmic resistances he follows. 1 sheet of drawings 9577 12.54