DE1238367B - Method and device for the electrical transmission of information represented by the magnitude of a direct current with a certain polarity - Google Patents

Description

GERMAN #IW PATENT OFFICE

EXTENSION PAPER G08d

German class: 74 b -8/05

Number: 1 238 367

File number: C 37200 IX d / 74 b

1238 367 Filing date: October 15, 1965

Opened on: April 6, 1967

The invention relates to a method for the electrical transmission of information represented by the magnitude of a direct current of a certain polarity by means of a transmitter and a receiver, both of which are related to an identical sequence of n periodic reference signals supplied by the same network, the positions of which are fixed within the reference period , the transmitted signal being obtained from successive comparisons between the direct current representing the information to be transmitted and a sum of calibrated direct currents, as well as a device for carrying out this method.

There are devices known, the numerically or digitally present information in binary coded Form transmitted, the coding being carried out in such a way that one proportional to the information Voltage is compared with several calibrated voltages and depends on the result of this comparison a device permitting the transmission of a digit is actuated. This device will thereby from a flip-flop, a device working with phase shift, a storage flip-flop arrangement or an arrangement with coupled switching gates.

The main disadvantage of these known devices is that they are used to synchronize the processes Pulse generators or timers are required on the sending and receiving side, which increases the complexity of the arrangements further increase and also the susceptibility of the transmission device to faults enlarge.

It is also known a device in which the coding of the signal to be transmitted by successive This signal is attenuated. The decoding is done by successive Attenuation of a calibrated reference signal achieved.

This also requires a device which transforms the signal to be transmitted in the course of the reference period Complicated circuitry equipment, both in terms of cost and Adversely affect operational safety.

Furthermore, a transmission method is known in which the analog signal to be coded in a plurality different frequencies is converted. A synchronization of the sending side and the receiving side of the device used is achieved in that a motor is used in the decoding device which is fed from the electrical power supply network.

In addition to the complexity of the required due to the use of different frequencies Circuit arrangement is a disadvantage in particular method and device for electrical Transmission of a polarity represented by the magnitude of a direct current information

Applicant:

Charbonnages de France, Paris Representative:

Dr. W. Müller-Bore, Dipl.-Ing. H. GraIfs and Dipl.-Phys. Dr. rer. nat. G. Manitz, Patent Attorneys, Munich 22, Robert-Koch-Str. 1

Claimed priority:

France of October 16, 1964 (991781) - -

to state that in the known method there is no clear assignment between a reference period and the synchronization signals is given, since the reference period is different from the mains period can.

Furthermore, a device is known in which a determined by the size of a direct current Information represented in polarity is transmitted electrically by means of a transmitter and a receiver, whereby both the transmitter and the receiver are based on an equal sequence of periodic reference signals are related.

Since this known device requires a translation compression device, is also in this Case of a very complicated structure not to be avoided.

Finally, there is also a device for converting one of the signals to be transmitted derived analog current is known in a binary code in which successive comparisons calibrated between the direct current representing the information to be transmitted and a sum Direct currents are made.

With this device too, special pulse generators or timers are required for synchronization. and in addition, the coded signals obtained must be transformed in special devices, so that they can be transmitted.

The aim of the invention is to provide a method for electrical transmission through size

709 548/227

of a direct current of a certain polarity, which works according to a principle that is as simple as possible and largely free of errors in the decoding of the transmitted information and allows the construction of a transmission device which, in particular, using the devices described in the German Auslegeschrifts 1230 691 and 1230 692 to a possible simple, inexpensive and, above all, reliable arrangement leads.

This is achieved according to the invention in that on the transmission side

each of the (n — Y) first periodic reference signals can be used to switch a comparison element through which a calibrated direct current flows when switched on,

the sum of the calibrated direct currents for the purpose of coding with one of the

20th

current carrying information is compared,

depending on the direction of the differential current from the measurement current resulting from the comparison and the sum of the calibrated direct currents, on the one hand, the brief emission of a high-frequency oscillation can be triggered or not and, on the other hand, the switching of the comparison element that was last switched on at the moment of the comparison is maintained or not,

by means of the last periodic reference signal, all comparison elements held in the switched state are in the non-switched state are reset, where

^&

the information through the short-term emitted during a period of the reference signals of the network High-frequency vibrations represented in a manner known per se as a binary expression is,

and that on the receiving side

In the same way as the flow of calibrated direct currents on the transmitting side can be brought about by opening at least one of (n-Y) gates which can be actuated when a brief high-frequency oscillation and the associated one of the («-1) first periodic reference signals occur at the same time,

the gates during the period which corresponds at least to the period of the reference signals, are closed or open and can be kept open

the value representing the information is taken as the sum of the calibrated direct currents which is determined by the open gate or gates.

According to a preferred embodiment, the method is designed so that the values of the Calibrated direct currents that can be triggered on the receiving side are proportional to the values of the calibrated direct currents that flow through the corresponding switched-on comparison elements on the sending side. Next is provided that the AC power supply network, which supplies the periodic reference signals, a Is three-phase network.

The number of periodic reference signals is six. The procedure here is that the five

first reference signals on the transmitting side each control the switching of a comparison element, while the sixth reference signal the unlocking of all locked toggled comparison elements in the course the period of the reference time controls.

Finally, the method according to the invention can expediently be designed so that the Control of the gates on the receiving side with respect to the assigned reference signals on the receiving side takes place with a delay in opening and with an advance in closing.

The invention also relates to a device for carrying out the method according to the invention. The device according to the invention is characterized in that the comparison elements on the transmitting and receiving sides are calibrated resistors whose values increase in the order of switching according to a geometric law with the ratio 2 and which are connected in parallel between two points of constant potential .

According to an expedient embodiment, the device according to the invention is developed in such a way that that the switching of each comparison element on the transmission side via the connection emitter-collector a switching transistor takes place, which is conductive by the assigned reference signal applied to its base is made.

It can further be provided that the current resulting from the comparison between the information representing direct current and the sum of the switched comparison elements flowing through calibrated direct currents results, when showing a certain direction, the conduction of a switch in brings about the output circuit of an oscillator switched transistor, the oscillator continuously supplies a fixed high frequency.

According to a further embodiment, the device according to the invention is developed in such a way that that the blocking of a comparison element on the sending side by one with the base of the corresponding Switching transistor connected resistance-capacitance arrangement is ensured, which differs from the the comparison resulting current is fed if it has a certain sense of direction.

In a further embodiment it is provided that the unlocking of the switched locked Comparison elements by discharging the corresponding capacitors via the emitter-collector connection of a transistor which is rendered conductive by the sixth reference signal applied to its base will.

Appropriately, the device according to the invention can be designed so that the lock a gate on the receiving side is realized by means of a resistor-capacitance arrangement, whose time constant is slightly larger than the reference time period.

Finally, an embodiment of the invention provides that the reference signals on the transmission and Receiving side of a polyphase transformer with coupled multiple secondary windings and Supplied with a polarized connection between the secondary windings and the neutral conductor will.

The invention is described for example with reference to the drawing; in this shows

F i g. 1 shows a principle diagram to illustrate the method according to the invention and

F i g. 2 and 3 exemplary embodiments of a coding or decoding arrangement according to the invention.

It should be noted that for the sake of simplicity in the following only those for understanding the invention necessary elements are described.

In the principle scheme of FIG. 1 are the coding arrangement I and the decoding arrangement II shown separated by a dash-dotted line.

Each of the arrangements I and II is connected on the one hand to the three-phase network R of the general energy supply of a company and on the other hand to a two-wire telephone network Tph .

In the following description, "six-fold linkage transmission circuit" CEH and "six-fold linkage receiver circuit" CRH designate the circuit arrangements described in German laid-open documents 1230 691 and 1230 692, which are used in the method and device according to the invention. In the same way, that electronic circuit is referred to as the evaluation circuit, which allows the transmission of a number in the form of a high-frequency pulse. In general, the transmission arrangement ensuring the analog-numeric coding comprises the following elements:

A six- link transmission circuit CEH, which is connected to the three-phase network R via a three / six-phase transformer Tr ₁ . This circuit delivers six synchronization pulses of the same duration, which are evenly phase-shifted by ~

are. The repetition period of a pulse is the same as that of the network R. The total of the six pulses forms the evaluation cycle.

An arrangement of six COM ₁ switches, each of which is controlled by one of the six pulses supplied by CEH.

An evaluation block ΒΡΕ, which is composed of five calibrated resistors, which are switched one after the other by the first five switches and whose values each increase in the sequence of switching according to a geometric series with a ratio of 2. When switched, every resistor has a calibrated direct current Ipi flowing through it.

An analog block Ba, which is arranged in front of the evaluation block and supplies a measuring direct current I _m , the value of which is proportional to the information measure Inf to be transmitted.

An AE amplifier for the branched-off Stroni

Ia - ^ IPi - Im,
which comes into action when

Im > ^ IPi ■

A transmitter EHF which is activated by the control current Ia and which supplies a fixed "high frequency" F to the network Tph.

A timer which allows the resistors to be kept switched so that

Im> ^ IPi ■

A zero resetting device R ₀ , which is controlled by the sixth pulse supplied by CEH and ensures that the five resistors forming the evaluation block are switched off from the circuit before the end of the evaluation cycle.

And finally, a power supply A ₁ , which supplies energy for the transmission arrangement I.

The receiving arrangement II is composed of the following elements:

A sixfold linkage - receiver circuit CRH, which according to the German Auslegeschrift 1230 692 twelve synchronization pulses of the same

Duration supplies that are evenly out of phase

are. It is connected to the three-phase network R via a three- phase transformer Tr _2. The repetition period of a pulse is equal to that of the network R.

A filter / tuned to the "high frequency" passing through Tph .

A rectifier amplifier AR that is in front of / arranged.

An arrangement of five changeover switches COM ₂ , which are each controlled by the simultaneous action of one of the first five pulse pairs supplied by CRH and the rectified signal supplied by AR.

An evaluation block BPR, which has five calibrated resistors, the values of which increase in the sequence of the switchings according to a geometric series with a ratio of 2 and are each switched by one of the five aforementioned switches and, when they are switched, by a calibrated direct current I'pi are flowed through, the value of which is proportional to that of the current that flows through the resistance of the simultaneously switched block BPE.

A time switching device which allows the one or more switched in the course of the evaluation cycle Resistors switched to during a period of time at least equal to that of the evaluation cycle keep.

An integration device G which forms the sum Γ ρ of the currents Ip / which flow through the evaluation block BPR.

And finally, a power supply A ₂ , which supplies energy for the receiving arrangement.

From the method described in the two German interpretative publications mentioned above, it follows that, if all switching conditions are met, the "th resistance of the evaluation block BPE and the equivalent" th resistance of the evaluation block BPR are switched over simultaneously and cyclically, the period of the simultaneous switchovers is equal to the period of the network R. The synchronization is thus brought about by the network R itself.

The operation of the in F i g. 1 illustrated system can be better understood if the F i g. 2 and FIG. 3 is referred to, each showing an embodiment of the numeric-analog coding apparatus or represent the analog-numerical decoding device, which the transmission of the Information measure in the form of a train of pulses with a fixed frequency according to the natural binary code allowed five moments.

In Fig. 2 the three / six-phase transformer Tr _{1 is} shown, which is connected to the network R and at points I to VI six evenly around

- supplies phase-shifted voltages.

The DC supply voltage for the entire arrangement is generated by means of diodes up to d ₆

is regulated to a constant potential by means of Zener diodes Z ₁ and Z ₂ with a common point P.

The sixfold linkage transmission circuit CEH is composed of six diodes d { to d ₆ , each in series with the collector-emitter circuits of the transistors T ₁ ', T _i ', T ₃ ', T _i ', T _b ', T _{n are} switched.

It follows that each transistor is only made conductive during one sixth of the evaluation cycle. Thus, when it is conductive, a synchronization pulse with a duration of ¹ I ₃₀₀ seconds (in the case of a 50 Hz network) is picked up.

The five first pulses thus obtained are used to effect the coding of the information which e.g. B. in the form of a DC voltage U _m , which is applied to the input of the analog block formed by the Darlington pair T ₁ - T _2.

For this purpose, the device comprises five evaluation paths of identical structure, of which the first described below is structured as follows:

In series with the connection emitter-collector of T ₁ is the evaluation control circuit, which comprises the resistor R ₁ , the connection base-emitter of the transistor T ₁ " and the neutral conductor N of Tr _1.

Parallel to the control circuit is the timing circuit, which connects the emitter-collector of the transistor Ti ₁ , the diode D ₁ ', the arrangement R ₁ " to C ₁ ", the time constant of which is slightly greater than the duration of the evaluation cycle, and the neutral conductor N. covered by Tr ₁ .

The evaluation circle drawn in thick lines comprises in series the evaluation resistor R ₁ ', the connection emitter-collector of the switching transistor T ₁ ", the base of which is connected to the arrangement R ₁ " to C _i " , and the neutral conductor N of Tr ₁ .

The five evaluation resistors R ₁ to R ₅ ' have a common point M, which forms part of the output circuit of the analog block T ₁ and T _i . This point M is on the other hand connected to the base of the transistor T ₃ , which forms the first element of the amplifier with the transistors T ₃ , T ₁ , T _b . The output circuit of this amplifier is connected on the one hand to the point P and on the other hand to the base of the transistor Ti ₁ via a diode J ₁ ″, which is switched on in the direct sense.

Finally, the point common to Ti ₁ and D _{1 is} connected via r _x to the base of the transistor T ₆ , which is normally blocked and, when it conducts, ensures that the "high frequency" F continuously supplied by the transmitter EHF is transmitted.

Because of the presence of a directly switched on diode d between points Af and N , point M has a constant potential and the current Ipu which flows in a switched evaluation resistor is calibrated, its value being a function of the size of the resistance.

The following table summarizes the respective values of the resistances and the calibrated values flowing through them Currents together, where the current flowing through the resistor with the greatest value is assumed to be 1 is.

resistance R% - 2 Ri Ä _S '= AR ₁ ' R / - 8 Ri R ⁱ '= - UR ₁ ' current Ip ₁ = 16 / IPs = = Ai Ip _l = 2i I Ph = i

It can now be seen that the arrangement delivers a current with an accuracy of approximately 3% can code whose value is less than or equal to 31 ζ.

The following explains the coding mechanism, starting from the beginning of the evaluation cycle is assumed.

The switching transistors T ₁ " to T _s ", the transistors Ti ₁ to Ti ₅ , the transistors T ₃ , T _i , T ₅ , T _e , T ₁ and T _s are in the blocked state, as are the transistors T ₁ to T ₅ '.

The capacitances C ₁ " to C ₅ " are discharged.

The first synchronization pulse appearing at the collector of T ₁ is transmitted via R ₁ to the base of T ₁ ″ , which makes it conductive for the entire duration of this pulse, i.e. for V300 seconds.

The evaluation circuit is closed and Ip ₁ = 16 / flows through the resistance R _1. Three streams can now get to point M :

1. the current I _m supplied by the analog block ;

2. the calibrated current Ip ₁ = 16 /;

3. a branched stream Ia ,.

Applying Kirchhoff's law to point M one obtains:

I _m + Ia - 16 / = 0, i.e. Ia = 16i-I _m .

Three cases are now possible:
a) I _m = 16 /

The branched off current is then zero, and in particular the transistors T ₃ , T _i , T _s , Ti ₁ and T ₆ remain in the blocked state. No frequency pulse is emitted by the EHF , which corresponds to the number O.

b) J ^r _w <16 1, i.e. I _d > O

The current Ia supplied by the power supply flows through the diode d, which increases the blocking of T ₃ .

T ₆ remains in the blocked state and no pulse is sent out by the EHF.

c) I _m > 16i, ie I _d < O

55 The branched off StromZ _t J flows through the base-emitter connection of T ₃ and is amplified.

The emitter-base circuit of Ti ₁ is then closed via d { and the emitter-collector connection of T ₅ . TT ₁ is thus made conductive. A part of the current h, which flows through the connection emitter-collector of TY ₁ , is transmitted via r ₁ to the base of T ₆ , which is opened and causes the emission of a frequency pulse by EHF. A digit is transmitted through the network Tph.

At the same time, the other part of I _e ensures that the capacitance C _{1 is} charged via the diode D ₁ .

After the first synchronization pulse has disappeared, the transistor Ti ₁ returns to the blocked state; however, the following also applies:

Λ. In the above cases a) and b), the transistor T ₁ ″ returns to the blocked state, the currents Ip ₁ and Ia disappear, and the transistors T ₃ , T _i , T ₀ and T ₆ return to the blocked state;

2. In case c) above, the capacitance C ₁ discharges " via R ₁ " in series with the base-emitter connection of T ₁ ", which remains conductive for at least the duration of the evaluation cycle.

The resistor R ₁ remains switched on and the current Ip ₁ remains for the duration of the evaluation cycle.

When the second pulse appears at the collector of T ₂ ' , the resistor R ₂ ' is activated due to the same processes as described above and the current Ip ₂ = 8 i flows through it.

There are two possibilities:

d) R ₁ is no longer connected [previous cases a) and b)] = I _{m is} compared with the current Ip ₂ = 8 i;

e) R ₁ remains connected [previous case c)] = I _{m is} compared with the current

Ip = Ip ₁ + Ip ₂

24 z

etc.

In summary, one compares the measuring current I _m with the sum of the currents I pt which flow through the switched-on evaluation resistors at every instant.

if

applies, no frequency pulse is transmitted by the transmitter EHF , which corresponds to the number 0. if

I _m >

X IPi

a frequency pulse is sent out, which corresponds to the number 1.

The following table summarizes the numerical analog coding of an assumed current Im equal to, for example, 29.5 / *

Valuation
path ι pi Ic - Int Ip Digit 1 16 z 16 z 29.5-16 = 13.5 e.g. 1 2 8th/ 24z 29.5-24 = 5.5z 1 3 4z 28 1 29.5-28 = 1.5z 1 4th 2 1 30 z 29.5-30 = -0.5 1 0 5 i 29 z 29.5-29 = + 0.5z 1

The binary number corresponding to I _m - 29.5 i is transmitted in the form of the binary expression 11101. It should be noted that the smaller cycle of this printout has a shorter duration than the evaluation cycle. The sixth synchronization pulse supplied by T ₁ causes the opening of the transistor T _s , the emitter-collector circuit of which closes the discharge circuit of the capacitances C ₁ " to C ₅ " _{via the respective diodes D 1} "to D ₅ ".

In this way and before the end of the evaluation cycle, the transistors T ₁ ″ to T ₅ ″ are returned to the blocked state, as are the transistors Γ ₃ , T _i , T ₅ , T _e , Ti ₁ to Ti ₅ . The transmission arrangement is ready for a second evaluation cycle. It should be noted that the diodes (I ₁ to d _s ", D ₁ to D ₅ and D ₁ to D ₅ " ensure the decoupling between the evaluation paths.

The analog block is thus biased by means of the voltage divider bridge r _s - r _{8 in} order to compensate for the voltage drops in the Darlington pair T ₁ - T ₂ when U _m = 0.

The information encoded in the manner described and transmitted through the telephone network is received by the one shown in Fig. 3 receiving arrangement and decoded which provides therefrom by means of a measuring device G a proportional value.

The receiving arrangement comprises in particular the following elements:
An amplifier AR which is connected to the network Tph and behind which a filter / tuned to the frequency of the train of pulses is switched on.
The received wave is _{two- way rectified by the diodes D 1} and D 2, the direct voltage thus formed being applied to the control electrode of a thyristor Th , the anode-cathode connection of which forms part of the control circuit of the evaluation paths.

The control circuit operates a six-link receiving circuit which is constructed as follows is:

A three-twelve-phase transformer Jr ₂ is connected to the network R and supplies at the points I.

up to XII twelve regularly out of phase

Tensions. The neutral conductor JV is connected to the anode of Th .
Twelve transistors are also provided, the emitters of which are each connected to points I to XII via a diode d ₁ to d ₁₂ , the diodes being switched on in a direct sense.

A star with six equivalent arms connects the collectors of the even-numbered transistors to the cathode of Th, each arm including a resistor R ₁ to R ₆ and a diode d { to d ₆ ' , the diodes being switched on in a direct sense .
Six switching transistors T ₁ ' to T _e ' are also provided, the emitter-base connections of which are each connected to the terminals of one of the resistors R ₁ to R ₆ via a directly switched on diode ^ ₁ "to d ₆ " .
The evaluation group shown in strong lines includes according to the drawing:

A regulated voltage supply A ₂ , a measuring device G of the milliammeter type, which is connected on the one hand to one of the terminals of the regulated voltage supply and on the other hand to an arrangement having five equivalent branches connected in parallel. These branches each include a calibrated evaluation resistor R ₁ to R ₅ ' and the connection between emitter and collector

709 548/227

Switching transistor T ₁ " to T ₅ ", which are normally in the blocked state. The second common point of these five branches is connected to the second terminal of the regulated voltage supply.

The evaluation resistors have values that increase in the order in which they are switched on according to a geometric series with the ratio 2, and are each traversed by a current I'pt which is proportional to the current Ipi , which is the simultaneously connected evaluation resistor in the evaluation block BPE in the previously described transmission arrangement flows through.

The transistors T ₁ " to T ₅ " are each controlled by the collector current of the corresponding switching transistor T ₁ to T ₅ , via an arrangement R ₁ ", C ₁ " to R ₅ ", C ₅ " whose time constant is slightly greater than is the evaluation cycle.

The operation of this decoding arrangement is as follows:

The transistors T ₁ to T ₁₂ are consecutively conductive for a period equal to one twelfth of the evaluation cycle, that is to say for a 50 Hz network Veoo seconds. Consequently, the transistors of the even order T ₂ , T _i , T _e , T _s , T _{10 have} successive conduction times equal to one twelfth of the evaluation cycle, separated by safety times equal to one twelfth of the evaluation cycle.

The first five of these transistors T ₂ , T _i , T ₉ , T _s , T ₁₀ are used to decode the "expression" carried by Tph and containing five digits.

At the beginning of the evaluation cycle, all transistors are in the blocked state and the thyristor Th is in the blocked state.

If T ₂ is in the conductive state, two cases are possible:

a) The number 0 is sent out simultaneously by EHF. No frequency is received by AR and Th , like the other transistors, remains in the blocked state;

b) the number 1 is broadcast at the same time by EHF . The received frequency is amplified by AR , rectified by D ₁ and D ₂ , and the DC voltage thus generated causes Th to open.

The control circuit of the evaluation paths , which contains in series N-Th _{-Ci 1} R ₁ -T ₂ -Ci ₂ - winding Tr ₂ -N , is closed.

The voltage developed at the terminals of simultaneously causes the conduction of T ₁ and the charge of C ₁ ″ .

The transistor T ₁ " is made conductive, and an evaluation current Tp ₁ flows in the circuit + A ₂ -GT ₁ " -A ₂ .

When T _{2 is} no longer conductive, the anode-cathode connection is no longer fed by Th , and the thyristor blocks just like T ₁ '.

The capacitor C ₁ ″ discharges through the base-emitter connection of T ₁ ″ and ensures the conduction of T ₁ ″ for a period of time which is greater than that of the evaluation cycle.

The measuring instrument G experiences a deflection proportional to Γ P ₁ .

The transistor T _i becomes conductive by Veoo seconds later, and a return to the above cases a) and b) has taken place.

At the end of the evaluation cycle, the meter is off the stream

Γ ρ = X Vp _i

flowed through, which flows in the resistors switched in the course of the evaluation cycle, d. H.

Γ ρ = kl ρ = KU _m .

It can therefore be seen that G carries out a continuous measurement of the information measure in such a way that it can change slowly without noticeable influence on the measured value, provided that the change has a frequency which is very much smaller than that of the evaluation cycle.

It should be noted that the corresponding evaluation resistors are only switched on simultaneously during Veoo seconds, while the evaluation resistor of the numerical-analogous coding device is switched on for V300 seconds. In this way any overlap in the following ways is avoided.

The arrangements according to the invention are statically very robust and of great reliability.

They do not require a synchronization device (clock), which is difficult to realize and require for each transmitting or receiving arrangement a minimum of only one connection to the three-phase AC power supply network.

The arrangements according to the invention are well suited for the transmission of information that in the form of a slowly changing polarized current, with the analog block on an amplifier can be reduced or even omitted.

The arrangements contain only a few calibrated elements, which increases their reliability.

Furthermore, the arrangements according to the invention allow simple alarm control in special cases with multiple levels.

If you look at the following table:

Level of information Ip Binary expression 1 31 / 11 111 V ₂ 16 / 10,000 V * 8th/ 01000 V ₈ 4 / 00100 Vie 2 / 00 010

one finds that level ¹ I ₂ corresponds to the appearance of the number 1 at the beginning of the expression, level ¹ I ₁ corresponds to the appearance of the number 1 in the second position of the binary expression, and so on.

It is therefore sufficient to provide an alarm controlled by the current I'pi (or by the corresponding number) in order to know that the level "16 /" or "V ₂ information" has been reached or exceeded. This can be particularly easy z. B. done by connecting a signal lamp to the terminals of R ₁ or R _1.

It should be noted that the first five synchronization pulses are used alone to to ensure the coding and decoding of the information, while the sixth can serve to to transmit further information of the type YES - NO with the same device.

Claims (11)

The invention is not limited to the illustrated embodiment. It would be possible to take advantage of the six synchronization pulses by dividing the information into six levels and by ensuring that it is reset to zero by means other than transistor Ts. Patent claims: 1. A method for the electrical transmission of information represented by the magnitude of a direct current of a certain polarity by means of a transmitter and a receiver, both of which are related to an identical sequence of n periodic reference signals supplied by the same network, the positions of which are fixed within the reference period, with the transmitted signal is obtained from successive comparisons between the direct current representing the information to be transmitted and a sum of calibrated direct currents, characterized in that on the transmitting side each of the (n - 1) first periodic reference signals can be used to switch a comparison element (Ri ') through which a calibrated direct current (Ipi) flows when switched on, the sum (Ip) of the calibrated direct currents is compared with a current (I _m ) corresponding to the information to be transmitted for the purpose of coding, Depending on the direction of the differential current (U) from the measurement current (I _m ) and the sum of the calibrated direct currents (Ip) resulting from the comparison, on the one hand the brief emission of a high-frequency oscillation can be triggered or not and, on the other hand, the switchover of the last switched on at the moment of the comparison Predicate (Ri ') is maintained or not, by means of the last periodic reference signal, all comparison elements (Ri ') held in the switched state are reset to the non-switched state, with the information given by the short-term in the course of a period of the reference signals of the network emitted high-frequency vibrations is represented in a manner known per se as a binary expression, and that on the receiving side in the same way as on the transmitting side, the flow of calibrated direct currents (Ipi) can be brought about by opening at least one of (n - 1) gates (Th, T ₂ , T _i , ... T ₁₂ ) which, when receiving a short-term high-frequency oscillation and the associated one of the (n - 1) first periodic reference signals can be actuated, the gates during the period which corresponds at least to the period of the reference signals, are closed or open and can be kept open the value representing the information is taken as the sum of the calibrated direct currents (Ip ') determined by the opened gate or gates. 2. The method according to claim 1, characterized in that the values of the calibrated direct currents (Ipi) which can be triggered on the receiving side are proportional to the values of the calibrated direct currents (Ipi) which flow through the corresponding switched-on comparison elements (Ri ') on the transmitting side. 3. The method according to claim 1 or 2, characterized in that the AC power supply network delivering the periodic reference signals is a three-phase network (R) . 4. The method according to one or more of the preceding claims, characterized in, that six periodic reference signals are provided. 5. The method according to claim 4, characterized in that the five first reference signals on the transmission side each control the switching of a comparison element (Ri ') , while the sixth reference signal controls the unblocking of all switched comparison elements blocked in the course of the period of the reference time. 6. The method according to one or more of the preceding claims, characterized in that the control of the gates (Th, T ₂ , T _i , T ₁₂ ) on the receiving side with respect to the associated reference signals on the receiving side with a delay in opening and with a There is an advance in closing. 7. The device for performing the method according to one or more of the preceding claims, characterized in that the comparison elements on the transmitting and receiving sides are calibrated resistors (Ri ') , the values of which are in the order of switching according to a geometric law with the Ratio 2 increase and which are connected in parallel between two points (P, M, -A ₂ , + A ₂ ) of constant potential. 8. Apparatus according to claim 7, characterized in that the switching of each comparison element (Ri ') takes place on the transmission side via the emitter-collector connection of a switching transistor (77 ") which is made conductive by the associated reference signal applied to its base. 9. Device according to one of claims 7 and 8, characterized in that the current resulting from the comparison between the direct current representing the information (I _m ) and the sum of the switched comparison elements (Ri ') flowing through calibrated direct currents (Ιρϊ) results, when exhibiting a certain direction brings about the conduction of a transistor (T _e ) connected as a switch in the output circuit of an oscillator (EHF) , the oscillator continuously supplying a fixed high frequency. 10. The device according to one or more of claims 7 to 9, characterized in that the locking of a comparison element (Ri ') on the sending side by a "connected resistor-capacitor arrangement (Ri with the base of the corresponding switching transistor (Ti)," Ci ") is guaranteed, which is fed by the current resulting from the comparison if it has a certain sense of direction. 11. The device according to one or more of claims 7 to 10, characterized in that