US2709199A - Code signal converter - Google Patents

Description

May 24, 1955 H. c. A. VAN DUUREN CODE SIGNAL ONVERTER Filed Apil 18, 1953.

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United States Patent Cona SIGNAL CONVERTER Hendrik Cornelis Anthony Van Duuren, Wassenaar, Netherlands, assigner to Staatsbedrijf der Posterijen, Telegraiie en Telefonie, The Hague, Netherlands Application April 18, 1951, Serial No. 221,612 Claims priority, application Great Britain March 15, 1948 14 Claims. (Cl. 178-2) The present invention relates to apparatus for converting signals of a code having a given number of units into signals of a code employing a different number olf units, as for example, for converting signals from a ve to an eight unit code. The invention is particularly directed to a signal conversion system which is operative with a monitor unit disclosed in my copending application which was tiled March l5, 1949, and which issued as U. S. Patent 2,622,148 on December 16, 1952.

The use in the telegraphy field of codes in which each ot' the signals comprise a predetermined total number of marking and spacing elements in a coded arrangement has become somewhat conventional in the telegraphy field. One of the more commonly accepted codes is the so-called tive unit Baudet code, in which each signal consists of tive elements arranged in a predetermined assigned code combination, see tor example British Patent Letter 5l9,633 which issued April 2, 1940.

in the transmission of these ve element signals over wireless systems, however, the possibility of element transposition is extremely great, and it has accordingly become conventional practice to build up the ve element signal into signals comprising seven or eight elements. One well known method, for example, consists of building each `tive unit signal up to comprise a total of seven elements in such a manner that all combinations comprise three marking units and four spacing units. Such manner of code conversion, of course, requires equipment which is somewhat complicated in nature, and in which a certain amount of undesirable delay time in conversion is experienced.

There is a definite need in the tield for a simpliiied signalling converter in which conversion of signals in a first code to signals in a second code may be conveniently, accurately and quickly accomplished. Serious problems have long prevented the previous provision of such desirable type signalling equipment heretofore, one of these being the inability` to provide a suitable converter system in which monitoring ot' the reconverted signal may be accomplished in an equally reliable and rapid manner. That is, even though a signal is built up to a seven or eight element code, atmospheric and power line disturbances may still cause message mutilation and it has more or less become mandatory in the field to provide equipment for monitoring the signals as received to check for possible distortion. Therefore, any new signal conversion system developed must be equallyv successful with regard to monitoring provisions.

One. type of monitoring arrangement used in systems in which the signals are converted from a live element signal into a seven element signal is predicated upon the use of a code in which each of the seven element signals will comprise the same number of marking' elements (three) and the same number of spacing elements (four). Monitoring devices disposed at the receiving end of the system are operative to scan each incoming signal to determine the existence of this given ratio of marking rater-ated and signalling elements and to register a warning whenever the given ratio ot' elements is not present.

In using this particular 3-4 code in the interests of monitoring, the large number or signals used in telegraphy transmission required that the vlive unit signals be completely re-arranged in their transposition into the seven unit signal; that is, the signal in the seven unit code does not bear any resemblence to the signals as they appear in the live unit code. it is obvious that in making such complete transition of signals in converting from one code to the other, the code converting equipment and monitoring equipment are both somewhat complicated in structure and in operation, and additionally the chance of error in the process of conversion is more eminent.

It is the object of this invention, therefore, to provide a more simple, accurate and reliable type telegraphy system in which conversion of signals of one code to signals of another is accomplished by retaining the basic elements of the rst code in their given order in the signal as completed in the second code, and in which the added portion or" the signal is indicative of the number of mark elements in the signal as it appeared before conversion from the first code to the second code.

The apparatus of the present invention accomplishes a more simplilied form of code converter and greatly expedites and facilitates both the conversion and monitoring eliected in the telegraphy system. in operation, in converting a ve element signal into an eight element signal, for example, the equipment effects the addition ot three predetermined elements which are grouped in a predetermined manner to represent and indicate the number of mark elements that were contained in the original live unit signal. Such signal, in addition to being readily and simply formed, is especially suited to monitoring purposes in that the basic and supplemental portions of the signal may be applied to the given bridge arrangement for comparison purposes; that is, to determine it the number of mark elements in the basic signal portion is the same as the number oi marks indicated by the supplemental portion of the signal, a fault finding relay in the galvanometer branch ot the bridge arrangement may be used to indicate an imbalance whenever a discrepancy is detected. Such arrangement is shown in detail in the aioredescribed copending application.

Referring to Figure 2, in. the left hand column there shown is a tabulated arrangement of the signals in a conventional tive unit code and the right hand column illustrates the eight unit code which results when three elements are added in such manner that the supplemental three elements are characteristic of the number of marking elements in the original tive unit signal. The added elements have eight possible variations. That is, XOO, OXO, OOX, XXO, OXX, OOO and XXX, wherein X signifies a mark and O signifies a space, and in which basic arrangement, the marks in the live unit signal may be from 0 to 5 inclusive. The apparatus and its operation will become further apparent with reference to the following description and drawings in which:

Figure l is a schematic illustration of a circuit arrangement l`or converting a live element code into an eight element code in the aforedescribed manner; and

Figure 2 is tabulation of the conventional tive element Baudot code and the eight element code provided by the converter unit of Figure l responsive to receipt of the signals in the tive unit Baudot code.

In more particular, with reference to Figure 1 the code converter arrangement there shown comprises a vertical bank of iivel movable contacts designated 1 to 5, inclusive, which are adapted to be operated into engagement with one of two associated stationary contacts by a perforated tape in its movement therepast.

The conventional five unit Baudet code used in the telegraphy system is imprinted on the tape member whenever a signal is to be transmitted, the marking ele-V ments being represented by perforation in the tape and the space elements being represented by a solid tape portion. Thus, as the tape moves past a series of movable contacts, those contacts of l to 5 which engage tape perforations will lie against the upper contacts which carry negative battery, and those contacts of 1 to 5 which engage the tape solid portion will be against the lower contacts which are connected to ground. Contacts 1 to 5, inclusive, have further connection to a series of outgoing code conductors I to V, inclusive, whereby voltage values indicative of marking or spacing elements as they appear at the contacts l to 5, are also impressed on the conductors I to V. A second series of outgoing conductors VI to VIII, inclusive, connected to the outgoing side of the converter are arranged to carry the added three elements as provided by the converter equipment.

The supplemental portion of the signal is generated by three code-converting polarized relays A, B and C, inclusive, which are connected to the outgoing code conductors il to 5, inclusive, by associated conductor groups 12, llt and I respectively. Each conductor group 10, 11 and l2 comprises iive conductors, each conductor being connected via a resistance member between an associated one of the conductors I to V and the upper terminal of an associated one of the polarized relays A, B and C. All of these group resistances are of an equal given predetermined value.

The lower terminal of each of the polarized relays A, B and C is connected over an associated resistance a', b and c' to associated resistance networks which are in turn connected to a source or" energizing potential. The resistance network for relay A, for example, comprises a network of two resistances connected between 120 volts to ground, having a junction point for connection with the resistance a' and relay A which is normally at a value of approximately -60 volts, as shown in Figure l.

The resistance network of relay B comprises two resistances connected between a source of -120 volt potential and ground having a junction point for connection with resistance b' and relay B which is normally at approximately -90 volts. The resistance network for relay C comprises a series of four resistances, which are connected between *120 volts and ground, having a junction point for connection with resistance c' which is normally at approximately 30 volts as shown in the drawing.

Contacts a, b and c of the relays A, B and C are adapted to be connected alternatively to 120 volt potential source or ground. As shown in Figure l, the relays are inoperative and the contacts are in a rest position so as to connect 120 volt potential to the outgoing conductors VI, VII and VIII. The contacts are operative, in accordance with the operation of their associated relays, to supplement the basic tive element signal, which is applied to conductors I to V, inclusive, with three additional elements, on conductors VI to VIII. Such supplement is based on, and indicative of, the number of marking elements included in the basic tive unit signal as will hereinafter appear.

Two pairs of resistance elements I3 and 14 are connected between the upper terminal of relay A and conductors VII and VIII respectively, whereby relay A of the polarized relays is controlled in its operation both by the position of the contacts b, c and the position of contacts 1 to 5 inclusive.

Rectier units, such as I and l5, are connected across each of the relays A, B and C, their lower terminals being connected to potential sources of suicient value to render the rectiier operative slightly after operation of their associated relays whereby a nearly constant voltage drop over the polarized relays results for all possible combinations of marking and spacing elements in the basic signal. In this manner the relay windings are protected against current overload.

In operation, the code converter unit is arranged to respond to receipt of a ve element signal in the conventional Baudet code to supplement such signal with three additional elements, the nature of these additional elements being determined by the number of marking elements which are included in the incoming basic tive element signal. Specifically, relays A, B and C are operative to supplement the incoming signals in the following manner.

Number of marking Position of Contact of Relay elements in received signal A B l C up X mark..- up X mark. .-l up X mark. down O space. up X marin... up X mark. up X mark. up X mark down O space. down O space. up X mark down O space.

up X markm. down O spacedown O space.

down O space. down O spacedown O space.

Thus, with reference to Figure 2, it will be noted that 3 letter A in the Baudet code comprises, XXOOO, or two marks and three spaces. The apparatus of Figure l is therefore operative responsive to receipt of this basic signal to supplement the signal with the elements XXO to effect the representative signal XXOOOXXO. See Figure 2 and the chart above.

In considering operation of the apparatus to provide these supplemental signals, it will be rst assumed that a signal having 5 spacing elements is received. The contacts 1 to 5 will therefore remain in their illustrated positions and ground is connected to the upper terminals of each of the relays A, B and C over groups 10, 1I and 12. The lower terminal of relay C is negatively biased with respect to ground by the associated resistance network at its lower terminal and relay C is therefore inoperative at this time. Likewise relay B, which is connected over its associated resistance b to a point which is at approximately volts, is likewise inoperative responsive to connection of ground over the resistance group 11 to its upper terminal.

With relays B and C in the restored condition, the

r upper terminal of relay A is connected to a source of volt potential over contacts b and c and resistance groups 13 and 14. The resistance group I2, however, is connected over contacts 1 and 5 to a source of ground. Thus of the equal value resistances which are connected to the upper terminal of A, four extend to a source of -120 volt battery and the other iive extend to ground. Accordingly, the value of voltage appearing at the upper terminal of relay A will be positive with respect to the value of potential at the lower terminal of relay A which is connected over resistance a to a source of potential in the order of *60 volts, and relay A will not operate at this time.

Accordingly, -120 volt battery is connected by contacts a, b and c to conductors Vl, VII and VIII and the signal which appears on the output side of the converter over conductors 1 to 3, inclusive, will comprise a basic signal of OOOOO plus the supplemental signal of XXX. See Figure 2. l

Assuming now the receipt of a ve letter signal in which one mark appears, such as for example, the letter E which contains the letter XOOOO one of the tape contacts will be moved to its upper position, and the contacts 2 to 5, inclusive, will remain in the lower position. The voltage drop across each resistance of the group conductors 10, l1 and 12 may be assumed to be somewhere in the vicinity of negative 24 volts, and since four resistances of each group 10, 11 `and 12 are now connected to ground by contacts 2 to 5 and one resistance is connected to -120 volt source by contact I, the voltage at the upper terminal of relays C and B is still positive with respect to aromas the negative bias imposed over resistances b' and c 'at the lower terminals thereof and the relays therefore remain inoperative at this tine-e.

In that relays B and C are inoperative, the four resistances in the groups 13 and 14 are connected to 120 volt battery over contacts b and c. However, since the resistance of group 12, which is connected to conductor 1, is connected to -120 volt source by the tape contact 1, the voltage at the upper terminal A becomes more negative by an amount which is sufficient to bias the upper terminal of relay A negative relative to the biasing voltage which appears at the lower terminal of relay A. Relay A responsively operates to move its associated contacts a to its lower position and to apply ground to conductor VI. The outgoing signal is accordingly XOOOO OXX, the supplemental portion indicating that the basic portion should have one marking element therein.

it is apparent from the foregoing description that with the receipt of a iive element signal having two marking elements the voltage impressed upon the upper terminals of relay B and C by the resistance of groups 11 and 12, which are connected to the source of negative potential will be such as to bias the upper terminal of relays B and C by voltages of an equal value which is sui'licient to render the upper terminal of relay C negative with respect to its lower terminal and which is insuiiicient to render the upper terminal of relay B negative with respect to its lower terminal. Relay C operates and relay B does not operate with the occurrence of such condition.

Since relay C at its contacts c effects connection of group resistance 14 to ground as well as three of the resistances of group 12 are connected to ground by the tape contacts, and only the group resistances 13 are connected to k120 volt potential, the voltage appearing at the upper' terminal of relay A is therefore positive with respect to the lower terminal, and relay A will not operate. Signal XXO appears on conductors Vi to Vlll as a result.

Similarly, as a signal having three marks is received, the voltage at the upper terminals of relay C will be negative with respect to its lower terminals and at relay B the upper terminal will still be positive with respect to its lower terminal. Relay C, at its contacts c, connects group resistances 14 to ground and relay B at its contacts b connects group resistances 13 to 120 volt battery. With three marking elements, three resistances of the group 12 are connected to n-l20 volt battery and the voltage at the upper terminal of relay A is negative with respect to its lower terminal and relay A will therefore be rendered operative. The supplemental signal (OXO) is therefore Vl to VIII.

With the receipt of a signal having four marks, relays B and C operate as heretofore described and at their contacts b and c connect both resistance groups 13 and 14 to ground. inasmuch as only four of the resistances of group 12 are now connected to *120 volt battery, the voltage at the upper terminal of relay A is positive with respect to the lower terminal and relay A will not operate. The signal on conductors Vl to VIII is accordingly XOO.

Finally, with receipt of a signal having tive marking elements, relays B and C are operated and resistance groups 13 and i4 are connected to ground. However, since the ive resistances of group 12 are now connected to -120 volt battery, the operating voltage of the upper terminal of relay A is negative with respect to the lower terminal and relay A will operate. The signal on conductors VI to VIII is now OOO.

The rectifier members, such as 15 and 16, are operative to limit the current through the relay windingin a well known manner. For example, the lower terminal of rectifier 15 associated with relay C is connected to a potential source of approximately -48 volts and is operative as the voltage at the upper terminal apimpressed on conductors proaches or exceeds -4-8 volts. The lower terminal of rectifier 16 is connected to a -24 volt potential source in a manner whereby with increased negative voltage at the upper terminal of the relay, the ow of current thereto will be blocked by the rectifier.

The other protective rectifiers are arranged in similar manner, the connected potential sources being of values which are proportional to the operating limits of the associated relays.

The disclosed code converter, in addition to being extremely simple in construction and having a minimum of operating elements, is further desirable by reason of its ready use with monitoring arrangements. That is, inasmuch as the supplemental portion of the signal is based on the number of marking elements in the basic five units of the signal, a correctly coded signal must have the same basic relation upon completion. Accordingly, a circuit arrangement which is adapted to compare the actual basic portion of the completed signal with the indications encoded in the supplemental portion of the signal, will provide a positive and reliable monitoring arrangement such arrangement is illustrated and more fully described in the copending application heretofore mentioned.

While I have illustrated and described what I regard to be the preferred embodiment of my invention, nevertireless it will be understood that itis merely exemplary and that numerous modifications and rearrangements may be made therein without departing from the essence of the invention.

i claim:

l. In a signal converter for converting signals from a rst code to a second code for transmission purposes, the combination of a plurality of incoming signal conductors over which basic signals of said iirst code comprising elements of one class and elements of another class are received, and a plurality of code converting relays for converting said signals ot said first code to said second code operated responsive to receipt of each oi said basic signals or'. said first code to supplement the unaltered basic signal with a predetermined number or additional elements less in number than the elements in the basic signal, said elements for each signal being of an arrangement to indicate the total number of elements of said one class contained in said basic signal as received.

Z. in a signal converter of the class described, the combination of live sets of tape transmitter contacts and tive incoming conductors which extend through said converter and over which said contacts are operative to transmit marking and spacing elements in given five element code arrangements, a plurality of code converting relays which are connected to said conductors and operated to supplement each of the rive unit signals with three additional elements which are indicative of the total number of marking elements contained in said basic tive unit signal as received by the code converting relays, and means on the output side of said converter over which the basic unaltered signal and said supplemental signal are transmitted as a single converted signal of eight elements.

3. in a signal converter as claimed in claim 2 in which the marking and spacing elementes are represented respectively by the presence and absence of potential on said said conductors and which includes means for biasing said code relays to operate only with application of a predetermined individual value ot' potential thereto by said signal carrying conductors, the predetermined biasing values for each relay being different, whereby signals having a different number of marks eiiect operation of a different combination of relays.

4. In a signal converter as set forth in claim 3 in which one of said relays is controlled in its operation by the value of potential applied thereto by said signal carrying conductors and a further potential as applied to said output means by the others of said relays.

5. In a signal converter, of the class described, the combination of a plurality of tape transmitter contacts and associated incoming conductors over which basic signals are received as marking and spacing elements in code arrangements of a given number, said contacts effecting transmission of a marking element with connection of a given negative battery potential to its associated conductor and transmission of a spacing element with connection of ground to its associated conductor, a code converting unit connected to said incoming conductors for supplementing said incoming basic signal with a predetermined number of additional elements, the nature of said added elements being determined by, and indicative of, the number of marking elements which are present in said basic signal; said code converting unit comprising a given number of relays, each of which has one side connected to a source of potential of a predetermined value, each of said relay energizing potentials being different from each other, a plurality of groups of equal value resistance members, each one of said resistance groups being arranged to connect the other side of an associated one of said relays to said incoming conductors, whereby a diterent predetermined value of potential is applied over said resistance groups to said other relay sides with each change in the number of marking and spacing elements in the incoming signals, said relays being operative whenever said potential applied at said other side is more negative in value than its biasing potential at said one side, whereby with said diierent biasing values of said relays, a diierent combie nation of said relays operates for incoming signals having a different number of mark' and space elements; means for extending said basic signal through said converter unaltered, and signalling means controlled by each of said relays in their operation to supplement said basic signal with a given number of elements which are indicative of the number of marking elements in said basic signal portion.

6. In an arrangement as claimed in claim 5, in which each relay is assigned to provide a predetermined element in the sequence of each supplemental signal portion, and in which said signalling means comprise contacts individual to each of said relays which are controlled with operation of its associated relay to provide a spacing element and with restoration of its associated relay to provide a marking element.

7. In a signal converter of the class described, the combination of a plurality of tape transmitter contacts and associated incoming conductors over which basic signals are received as marking and spacing elements in code arrangements of a given number, said contacts efiecting transmission of a marking element with connection of a given negative battery potential to its associated conductor and transmission of a spacing element with connection of ground to its associated conductor, a code converting unit connected to said incoming conductors for supplementing said incoming basic signal with a predetermined number of additional elements, the nature of said added elements being determined by, and indicative of, the number of marking elements which are present in said basic signal; said code converting unit comprising a given number of relays, each of which has one side connected to a source of potential of a dilerent predetermined value, the value for each of said relays being diterent; a plurality of groups of equal value resistance members, each one of said resistance groups being arranged to connect the other side of -an associated one of said relays to said incoming conductors, said relays being operative whenever said potential applied to said other side over said resistanees is more negative in value than its biasing potential at said one side; a further set of resistance groups connected to `said other side of one of said relays, and signalling means controlled by each of said relays to supplement said basic signal with a given number of elements which are indicative of the number ot"marking elements in tit) said basic signal portion, said further resistance groups being controlled in their connection of said one relay to said alternate sides of said energizing source in accordance with the positions of said signalling means of the other of said relays, whereby the nature of the incoming signal and the position of said other relays determines the position of the signalling means of said one relay.

8. In a signal converter as set forth in claim 7, in which said signalling means comprise contacts for alternatively connecting negative potential or ground to associated outgoing conductors, said relays being operative in their normal rest position to control said contacts to connect negative potential to said outgoing conductors and being effective in their operated condition to control said contacts to connect ground to said outgoing conductors.

9. In a signal converter of the class described, the combination of tive incoming conductors over which basic five element signals are received as marking and spacing elements in code arrangements of a given number, said marking elements being represented by appearance of a given value of negative battery potential thereon and said spacing elements being indicated by ground, a code converting unit connected to said conductors for supplementing said basic tive element signal with three additional elements, the nature of said added three elements being determined by, and indicative of, the number of marking elements which are present in said basic five element signal; said code converting unit comprising three polarized relays, each of which has one side connected to a source of potential of predetermined value, the value of each of said relays being different, a plurality of groups of equal value resistance members, each one of said resistance groups comprising five resistor members each of which connects the other side of the associated one of said relays to said ve incoming conductors, whereby a predetermined value of potential is applied over said resistor members to said other relay sides which is determined by the number of marking and spacing elements in the incoming signal; said relays being operative whenever said potential applied at said other side is more negative in value than its biasing potential at said one side, whereby with said different biasing values for said relays, a different combination of relays operate for each of the incoming signals having a different number of mark and space elements; and signalling means controlled by each of said relays in their operation to supplement said basic ve element signal at the converter output side with three additional elements which are indicative of the number of marking elements in said basic signal portion.

l0. In a signal converter as set forth in claim 9 which includes a further resistance group for varying the valued potential connected to said other side of one of said relays, said further resistance group being controlled in its connection by the operated condition of the signalling means associated with the other two of said relays.

ll, in a telegraph system of the class described, the combination of a predetermined number of incoming conductors over which basic signals are transmitted as marking and spacing elements in groups of a predetermined number, a code converter unit comprising a plu rality of code converting relays which are connected to each of said conductors and which are operative with transmission of a basic signal thereover, to supplement said basic signal with a predetermined number of additional elements, the nature of which is determined by the number ot marking elements in said basic signal, said conductors being arranged to extend the basic signal through said code converter in an unaltered condition,

a series of additional conductors connected to the out" put side of said converter in parallel relation with saidv first channels which extend therethrough, said supplemental signal being transmitted over said additional channels so as to be indicative of the number or" marking arcanes signals on said lirst channels, and to effect, with said basic signal, a complete signal of the desired increased number of elements, whereby with signal generation the number of marking elements in the basic signal portion of the completed signal may be compared with the number of marking elements indicated as present therein by the supplemental portion of the completed signal to determine the accuracy of the signal as effected by the converter unit.

12. 1n a signal converter for converting signals from a first code to a second code for transmission purposes, the combination of a plurality of incoming signal conductors over which basic signals of said first code comprising elements of one class and elements of another class are received, and a plurality of code converting relays for converting said signals of said first code to said second code operated responsive to receipt of each of said basic signals to supplement the unaltered basic signal with a given number of additional elements, said elements for each signal being of a predetermined number and arrangement to indicate the total number of ele ments of said one class contained in said basic signal as received, relay control means for biasing each of said relays to operate at a predetermined value of potential. the value for each relay being diiferent, and integrating means for supplying a relay operating potential to said relays as each signal is received which is of a value determined by the number of marking elements in the basic signal as received, and signal output means controlled by same relays for providing a supplemental signal portion which is representative of the number of relays operated responsive to the relay operating potential supplied by said integrating means.

13. In a signal converter for converting signals from a rst code to a second code for transmission purposes,

the combination of a plurality of incoming signal conductors over which basic signals of said rst code comprising elements of one class and elements of another class are received, and a plurality of code converting relays for converting said signals of said rst code to said second code operated responsive to receipt of each of said basic signals of said first code to supplement the unaltered basic signal with a predetermined number ot additional elements, the nature of the supplement being determined entirely by the total number of elements of said one class contained in said basic signal as received and being representative of such number.

14. ln a signal converter for converting signals from a ve element code to an eight element code for transmission purposes, the combination of a plurality of incoming signal conductors over which the ve basic sigbals of said iirst code comprising elements of one class and elements of another class are received, and a plurality of code converting relays for converting said 'tive signals of said rst code to said second code operated responsive to receipt of each of said ve code basic signals to supplement the unaltered basic signal with three elements of a nature which is determined by the total number of elements of said one class in said basic signal.

References Cited in the file of this patent UNITED STATES PATENTS 2,459,904 Watson Jan. 25, 1949 2,473,202 Higgitt June 14, 1949 2,512,038 Potts June 20, 1950 2,520,142 Herbst Aug. 29, 1950 2,552,629 Hamming et al May 14, 1951 2,575,268 Griffith Nov. 13, 1951 2,596,199 Bennett May 13, 1952

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