DE1018904B - Method and circuit arrangement for measuring the reference distortion of telegraphic step sequences - Google Patents

Description

The invention relates to a method and a circuit arrangement for measuring the reference distortion ¹ of telegraphic step sequences.

There are procedures and circuit arrangements for measuring the distortion of the input signal in telegraphic characters known that work on a mechanical basis.

The devices used for this purpose are complex, fine-mechanical structures, the accuracy of which depends on the precise design of the cam disks used and the setting of the contact sets. As a result of mechanical wear and tear and soiling of these components, considerable measurement errors arise, as well as due to a slight puff of the friction coupling. In the developed due to the deficiencies mentioned devices on electrical or electronic basis usually ¹ the Strorrischritteinsätze be converted to the measured Tejegrafiezeichen in pulses. These pulses mark the instantaneous value of a breakover voltage that is generated in a generator that is started and braked by a start-stop generator.

The instantaneous values ^{1 of} this voltage are a measure of the reference distortion. A cathode ray tube serves as the inertia-free display element.

The disadvantage here is that a cathode ray tube is used to achieve a sufficiently high reading accuracy with a large screen diameter must be used, as one is written on the screen straight line corresponding to the diameter of the cathode ray tube is used as the time base.

It is known to circumvent these disadvantages by applying a spiral time base to the screen a cathode ray tube is written. The starting step of the telegraphic character triggers a sine wave generator from that over the duration of a telegraphic character with increasing or decreasing amplitude swings. This sine oscillation is converted into a sine and a cosine oscillation by means of a phase shifter disassembled and then used for horizontal and vertical deflection of the electron beam. An oscillation of the sine generator is equal to a current step duration. The momentary value the mutually phase-shifted voltages is a measure of the reference distortion and can e.g. B. can be made visible as a luminous point on the screen by means of point lightening.

The disadvantage is that the reading accuracy is based on the spiral paths moving to the center of the screen decreases, because the reference distortion is an angular measure with a value of 0%.

The invention is based on the object of making the reading accuracy essential for the reference distortion to increase.

Procedure and circuit arrangement

for measuring the reference distortion

of telegraphic steps

Applicant:

VEB Fernmeldewerk Arnstadt,
Arnstadt, Bierweg 6

Joachim Mehls, Berlin-Staaken, Fritz Kahl, Berlin,

and Jürgen Schönhoff, Ludwigsfelde,

have been named as inventors

It is assumed that an optimal reading accuracy can be achieved in particular with the aid of a circle as a time base. the Realization of this idea causes difficulties insofar as it is as a result of the mentioned Rising and falling of the corresponding amplitude of the sinusoidal oscillations does not succeed in the beginning the writing process of the circle time base with the beginning of the telegraphic character and the end of the writing process to make the circle time base coincide with any point of the telegraphic symbol.

This is where the invention comes in "by inducing a voltage surge in the resonant circuit of the SinusgeneiratOir is whose amplitude is dimensioned so that the sine wave generator with constant amplitude instantly and oscillates over the duration of the telegraphic sign. This oscillation is at the end of the telegraphic sign with simultaneous disconnection of the control voltage necessary for the circuit time base in this way damped that at a defined point in time of the oscillation, z. B. zero crossing, the voltage suspends. The required circular shape of the circular time base, which always remains unchanged, is given by a corresponding Selected negative feedback voltage obtained from the tube circuit of the sine wave generator is guaranteed.

The constant amplitude curve can be influenced, for example, by influencing the tube characteristic and the voltage surge induced in the resonant circuit as a result of a change in the direct current of the cathode achieve.

Figs. 1 to 3 treat as an embodiment a reference distortion meter with a corresponding one Circuit arrangement in which the method according to the invention is used.

7OD. 759/138

Claims (4)

With the invention it is achieved that the sine generator SG started by the first symbol step always oscillates with the same phase position and its amplitude remains constant from the first oscillation over the duration of a telegraph symbol. After a telegraphic character has elapsed, the sine wave generator is stopped with the aid of a start-stop generator St, and its oscillations are immediately suppressed. The individual processes are as follows: The start step arriving via the input circuit ES (cf. curve »in FIG. 1) triggers a start-stop generator 6 ″ G with curve form b and this triggers a sine wave generator with curve form c, which with oscillates at a frequency of 50 Hz. One oscillation corresponds to a distorted telegraphing step. After the five alpha time steps have elapsed, the sine generator is stopped during the time of the stop step of the telegraph signal, e.g. due to a short circuit in the oscillating circuit, and the same process is repeated through the next start step The generated sine oscillation c is, after amplification by means of a phase rotating element Ph, broken down in a known manner into a sine and a cosine voltage and used to generate the circle time base Katadenstrahles is then a measure of the ever temporary reference bias. The single ones. Step inserts can be converted into pulses and made visible as measuring marks as a result of brightness modulation or circular beam deflection. The circuit arrangement shown in Fig. 3 for performing the method according to the invention works in the following way: When a start step occurs, the input circuit ES (Fig. 2) consisting of the relay B, resistor Rl, capacitors C1 and C2 generates with the help of the relocated fr contact a: negative pulse that starts the start-stop generator St with the tube Rö 1. As a start-stop generator z. B. a monostable multivibrator. The .4 relay responds. The contacts el and α2, which are closed in the idle state of the circuit, open. Since the tubes Röl of the sinusoidal generator are operated without grid bias, the high cathode current flowing through the grid coil WI in the idle state is suddenly interrupted by means of contact σ-1. As a result of this change in current, a voltage is induced in the resonant circuit W1, C 3 according to the equation di U ~~ dt. At the same time, as a result of the opening of the contact al, the gate coil WI is released. Since the contact α2 has opened at the same time, the short circuit of the winding W3 provided for decoupling the control voltage is canceled. The sine generator begins to oscillate. The degree of feedback can be adjusted to an optimal value with the violin coupling resistor R2. With these. Measures are achieved that the oscillation of the sine generator always takes place in the zero crossing of the oscillations and with the same phase position. As a result of the side grille counter-coupling or the influencing of the characteristic curve, which can be achieved by means of the resistor R1, it is achieved that all vibrations have the same amplitudes. In contrast to sine generators operating according to other known methods, the sine generator described has a low harmonic content with a distortion factor of approximately 3%. This is essentially achieved by adjusting the feedback with the aid of the resistor R2, the optimum setting being characterized by a small feedback factor. Via the winding IV 3 and an amplifier with a tube 3, the sinusoidal voltage is applied to a phase shift element consisting of the resistor 4 and the capacitor C 4. The two voltages tapped at capacitor C 4, phase-shifted by 90 °, are fed to the cathode ray tube and generate the circular time base on the screen. The alphabet steps following the starting step are taken from the input circuit £ 5 * and, via the Wehnelt cylinder W, result in a brightness modulation of the cathode ray serving as a measuring mark. The start-stop generator St is dimensioned in such a way that it comes to rest after 130 ms. After this time, i.e. in the middle of the undistorted stop step, the contacts of the ^ relay are closed again. The contact short-circuits the coil W1 and the existing vibrations are dampened. The renewed oscillation is now prepared again by the occurrence of a high direct current in the grid coil WI. At the same time, the coil WZ is short-circuited by means of contact al, and the control voltage for the amplifier is thus switched off. Thus the beginning of the writing process of the circle time base coincides with the beginning of the telegraphic character and the end of the writing process of the circular time base with any point of the telegraphic drawing, in this case with the middle of the undistorted stop step. The method according to the invention is suitable for measuring telex characters with a one-and-a-half stop step. PATKNT CLAIMS: 1. Method for measuring the reference distortion of Tetlegran step sequences. characterized in that, using a sine tube generator (SG) generating a circular time base, a voltage surge is induced in its resonant circuit, its. The amplitude is dimensioned so that the sine wave generator oscillates instantly and with a constant amplitude for the duration of the telegraph symbol and this oscillation is dampened at the end of the telegraph symbol with simultaneous disconnection of the control voltage necessary for the circle time base in such a way that at a defined point in time the oscillation, z. B. zero crossing, the oscillation is interrupted, and that an appropriately selected counter-coupling voltage obtained from the tube circle ensures an unchanged circular shape of the time base. 2. The method according to claim 1, characterized in that that the voltage surge induced in the resonant circuit as a result of a change in the direct current of the cathode of the tube generator is obtained. 3. Departure according to claim 1, characterized in that that a constant amplitude curve over the duration of the part symbol consequently influencing the tube characteristics will. 4. Circuit arrangement for carrying out the method according to claims 1 to 3, characterized in that a relay (A) is provided in the circuit of a known start-stop Schailtong, the contacts (a1, a2) of which both the grid coil ( W2) of the sinus tube generator as well as that for the Decoupling of the expensive voltage of the circuit time base, short-circuit the intended winding (WZ). Considered publications:
German Patent Nos. 930 690, 854 225;
Telecommunications technology magazine, Heifto, 1953, p. 279 to 281; "Pocket book for telecommunications technology" by Goetsch, Volume 3, 11th edition, pp. 222 and 225. 1 sheet of drawings