US2473202A - Telegraph system with code conversion and error detection - Google Patents

Telegraph system with code conversion and error detection Download PDF

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US2473202A
US2473202A US50311A US5031148A US2473202A US 2473202 A US2473202 A US 2473202A US 50311 A US50311 A US 50311A US 5031148 A US5031148 A US 5031148A US 2473202 A US2473202 A US 2473202A
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signals
relay
signal
code
unit
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Higgitt Harry Vernon
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Cable and Wireless Ltd
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Cable and Wireless Ltd
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M5/00—Conversion of the form of the representation of individual digits
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/47—Error detection, forward error correction or error protection, not provided for in groups H03M13/01 - H03M13/37
    • H03M13/51—Constant weight codes; n-out-of-m codes; Berger codes

Definitions

  • marking units andiour, spacing units are marking units andiour, spacing units.
  • This invention relates to telegraph apparatus for workingy with so-called ⁇ equal length* ⁇ codes, and' in'- particular; isf concerned with transnxittingk and" receiving apparatus fr'error-detecting or errorhindi'cating"equal" length codes.
  • o-iwhich the rst ve are the units of the corresponding signal in. the. primary standard vef unit code to Which three-.unitsare added in such a. way thateach signal. isconstituted by four from the general system for-theftwo signals which in thefive-unit code consist respectively of vemarking and five spacing units since it is not possible to arrive at a, four-marking four-spacing signal by the addition of'threeunits to either'of,
  • the present invention is concerned in particular with' telegraph apparatus for working withV error-Lv detecting co'des in which all 'tliefsignals consist of the same num-ber offmarki'ng and the same numy ber ofl spacing elements arranged"v in different; sequences; in one particular example of suchv codes; ⁇ each signal ⁇ consists' of three marking.V ele-1- mentsz' and fourfspacingelements 2g According to.
  • theinvention bothA codes em'- ployed--the non-error-detecting primary code: converted at the sending ⁇ end of a circuit into 4the;1 other codewhich isvan error-detecting code and is:- converted back at the receivingfendl of vthe cire cuit-employ signalsf, theI elements of whichitarel-l ⁇ divided into; two groups, of which*y one group'inil each: coole-is,Y inV general, the same in. marking and? spacing permutation for each signal while-the; other group in theerrori-detectinfg code is deter mined .by the. permutations of; both groups offthefr noneerror-detecting.code; appear'. later, in practice?.signalsrmayalso'vbe ein-fi ployed inn.which,.,in. changing from one code tol thefother, the elementsiof the -rst group haveltov bezconverted.'
  • theierror-detecting codes whichl arel employed intelegraph systems comprisingf apparatus according. to the presentinvention are: equal. length codes. consisting of signalsno'one:v of which, canbe converted into another, bythe., changeoi one or'r more unitsffromv marking. to spacing lorifice-versa.
  • the second group of each signal consists of two signal elements and there are four ways in which this group can be formed viz. MM, SM, MS and SS.
  • the second group is converted into four elements in accordance with the following scheme of conversion.
  • the first group in each signal contains two marking elements so that in the second group of the signals in the seven-unit code, only one marking element is required and to represent MM, SM, MS or SS of the second group of the five-unit signals, the first, second, third and fourth element respectively of the second group in the seven-unit code is made marking.
  • the rst group of each signal contains only one marking element so that in the second group of the signals in the seven-unit code, two marking elements are required and this second group is formed in a manner similar to that in the first series except that a second marking element is made to follow immediately after the marking element which has been provided in the conversion as described above for the rst series, for which purpose, the rst element is regarded as following immediately the last element.
  • the rst group is changed to MSS to form two of the signals and to SSM for the other two signals while the second group of the seven-unit signal is either MSMS or SMSM.
  • the four sevenunit signals are:
  • the primary code is a six-unit equal length code which is converted for transmission purposes into an eight-unit error detecting code, in which each signal consists of four marking elements and four spacing elements. Signals in this error-detecting code may be reconverted into the primary six-unit code at the receiver.
  • the following table shows how 64 different signals may be obtained in five series, the letter M in the signals representing a marking element and S a spacing element.
  • Table 2 Six-unit Primary Eight-unit error- Code detecting code Signals First Second First Second Group Group Group Group 1st series MMMS MM MMMS MSSS MMSM SM MMSM SMSS lVISMM MS MSMM SSMS i6 SMMM SS SMMM SSSNI 2nd series.
  • the signals in the two ⁇ codes are each divided into two groups and that in both codes, the rst group consists of four signal elements; the first three series of signals amounting to 56 signals in all.
  • the signal elements of the first group are the same in both codes as before.
  • the elements of the rst group in the primary code have to be changed in converting one code to the other, as will be explained later.
  • the second group of each signal in changing from the primary code to the errordetecting code is converted respee tively into the same four "elements as ln YTable 1 above.
  • the rst group in the 4th series there are no marking units in vthe primary code so that the rst group of lthe eight-unit code is made to contain two marking elements in each signal and the second group can then be the same as in Table 1.
  • there vare four marking units in the 5th series of signals, there vare four marking units .in the iirst group in the ,primary code which would only provide one signal in the eight-unit code, therefore the iirst group is changed in the eight-unit code as shown in Table 2 and the second group in that code is the same as in the 4th series.
  • Figure 2 is la diagram ofv connections for yreceivingsuch signals and for re-converting them into five-unit signals;
  • Figure 3 is a diagram of connections of a transmitting system for converting a six-unit primary code into'an eight-unit error-detecting code; and Figure ⁇ i isl a .diagram of connections of a receiving system suitable for converting signals in the eight-unit code back into the six-unit primary code.
  • the relays which are thus energised, are vlocked up through contact springs al eI and front contacts 5 thus connecting locking windings of the respective relaysl 'A E from vthe battery at l'6, through a brush 'B72 and continuous segment 1 to earth at 8, so that the relays in question are held locked until the end of transmission of a seven-unit signal.
  • the first three relays A, 1B and C deal with the three signal elements forming the firstgroup of a signal as shown in Table 1 above and each has seven contactsprings a'l a1., bI b1 and c'I.,. c1.
  • the relays M2 and M3 or the relays 'MI and M2 are energised and change the appropriate two mark- Ing elements to spacing elements as required for the rst group "in the seven-unit code ⁇ fory the fourth series of signals'as fsee'n in Table I.
  • This result is "clearly only obtained when Vthe first three'sg'nal elements :are 'marks in the five-unit primar-y code whereupon the relays A, B and C are energis'ed and which of the modifying relays MI, M2 and M3 are enetgised depends on the lstate of thefth pecker relay E.
  • the relays M2 and M3 are thus energised, breaking connection at AIl) and giving spaces for the rsecond and third signal elements on the segf ments S2 and S3.
  • the fifth signal element is a space, as can be seen from Table l, the first two elements of the seven-unit signal have to be spaces and vthen the vconnection from battery at Il goes through the back contact L3 oi the relay spring e3 and proceeds by the vcom d'ucto'r I4 to energise the modifying relays MII 'and M2 which break circuit at I0 and 4alter the rst and second sig-nal elements to spaces.
  • the relaysD, E control four supplementary r'elays F, G, H, K which, at their contact springs f3, g3, h3 and k3, connect battery at I5 respectively to the distributor segments S4, S5, S6 and S1.
  • the relays D and E are energised and the iirs't supplementary relay F is energised 'from battery at IS, relay spring e2, iront contact l1, relay spring d2, front contact I ⁇ 8 through the winding of relay F to earth at I9; thus relay F at its spring f3 connects bat tery to the distributor :segment S4, consequently the fourth element of the seven-unit signals is a mark as is required, as can be seen from the first 'signal in each of the series in Table 1.
  • the relay E is energised but the relay D is not energised so that the second supplementary relay (Er is now energised from battery at 16, springs e2, d2, back ycontact 20 and winding lof relay lG to earth at 2l, and now the fth element in the seven-unit vcode Vbecomes a mark.
  • the fourth element in the 'live-unit code is a mark but the lifth is a space, corresponding to the third srignalvin each series vin Table 1, Iit will be Aseen that the third supplementary relay His energised from battery at I6, spring e2, back contact 22, vspring d3, front contact 23 and winding of relay H to earth at v2li so 'that now, jas is required, the sixth element in the seven- 'unitsignal is a mark.
  • the fourth supplementary relay K is energised from battery at lt, spring e2, back contact 22, spring d3, back contact 25, winding of relay K to earth at 26 so 'that now 'the relay K at its spring 7c3 applies marking current to the seventh segment S1 Aso that vthe seventh signal element in the seven-unit code is now a mark.
  • This is arranged by connecting battery at 21 to the springs a3, b3 and c3 of the relays A, B and C and connecting the back contacts 28 of those springs respectively to the springs b2, c2 and a2 of the relays B, C and A next in order, for which purpose the relay A is treated as following the relay C and, further, by connecting the back contacts 29 of the springs a2, b2 and c2 together and to the springs fl, gl, hl and kl of the supplementary relays F, G, H and K by the conductor 30.
  • a third segment of the segments S4, S5, S6 and S1 receives a mark from battery in accordance with the third series of signals in Table l. This is eiected by connecting battery at 3l through relay spring a5 and back Contact 32, spring b5, its back contact 33, spring c5 and its back contact 34 which it will be seen, is connected by a conductor 35 to the springs f2, g2, h2, k2 of all the relays F, G, H, K.
  • the flrst group in the live-unit code is three marks which, as seen from Table 1, has to be converted to one mark followed by two spaces or two spaces followed by one mark, as determined by the fth signal element in the primary five-unit code; that is to say, if the fifth signal element is a mark and the relay E consequently energised, the rst group in the seven-unit code has to be MSS, while if the fifth signal element is a space, that group has to be SSM.
  • This conversion is effected oy energising the three modifying relays Ml, M2, MS' in the way described above as determined by the conditions of the relay E.
  • the first three relays A, B, C are arranged to connect battery at 36 through springs a4, b4 and c4 and their front contacts 31 in series to all the springs f2, g2, h2 and k2, with the result that the one of the relays F, G, H, or K which is energised, applies battery at 36 to the segment S4, S5, S6 or S1 which is two segments removed from that which receives a mark from the spring f3, g3, h3 or k3 on the relay which is energised.
  • relay F is energised, its spring f3 applies battery at l5 to the segment S4 but also through the circuit just described, battery' at 36 is con- 8 nected through the spring f2 and its front contact 38 to the conductor 39 and thence to segment S6 which is two segments removed from the segment S4. This is the necessary condition as can be seen from the second group in the seven-unit code in the fourth series as set out in Table 1.
  • the equipment for receiving the signals in the seven-unit error-detecting code and re-converting them into five-unit signals of the primary code is shown in Figure 2.
  • the seven-unit signals are received by the line relay LR whose spring Zr has marking and spacing contacts M, S, the former of which is connected to a brush Brl which sweeps over seven short segments RSl RSI, making contact in the middle of the respective periods of reception of the seven signal elements. Since each seven-unit signal contains three marks unless it has become mutilated, current i-s passed through the windings of three of seven receiving relays N, O, P, Q, R, S and T, each of which windings is connected to one of the segments RSI RST.
  • the three relays are energised in accordance with the particular signal being received by the line relay LR.
  • the brush Brl is driven in synchronism with the received signals by any of the usual means.
  • the relays N T which are thus energised, are locked up through contact springs nl tl, each of which is conected to battery and its front contact 4l) and a brush Br2 working over a long segment 4l in the circuits of the locking windings of the relays N T which are energised so that these three relays are held locked until the operation of re-transmitting the ve-unit signals formed in the receiver is completed, as will be described later.
  • the front contact 45 of the spring o2 and the back contact 46 of the spring o3 are both connected to the spring p3; while the back contact 4l of the spring o2 is connected to the spring p2 and the front contact 48 of the spring o3 is connected to the spring p4.
  • the rest ⁇ of the bank of contacts are connected forwards in a similar manner until at the end the spring t2 has its front contact 49 and the spring t3 has its back contact 50 both connected to the Winding of the test relay TR, the other end of which is earthed. If the circuit through the bank of contacts is traced it will be found that there is a connection to the winding of the relay TR only when precisely three of the relays N T are energised.
  • the rest relay TR When as a result, the rest relay TR is energised, its' spring trl ⁇ at its back contact 5I disconnects a connection 52 which leads to an error-indicator, while the spring trl at its contact 53 applies battery' to a number of relay springs and contacts which will be described' in detail later.
  • the battery connection to the spring t'rl passes from battery atv 54, through a brush Br3 and a segment 55, which only come into 'contact when the three of the relays N T in question have been locked.
  • test relay TR When the test relay TR is thus energised, it connects battery at 54 through the contact k53, inter alia to springs n4, o5, p5 respectively of the relays N, O and P, through a conductor 56.
  • the springs n4, o5, and p5 through their front contacts .57, when energised continue the connection from battery at 54 and through back contacts 58 and springs ma, mb, mc .of three modifying relays Ma, Mb, Mc and thence to the first three segments 59, 60 and 6l of the ve segments 59 G3; of the retransmitting distributor.
  • the second group of the signal in the seven-unit code is eitherl MSMS r SMSM, so that in the former event, the fourth and sixth relays Q and S are energised and in the latter event the relays R and T.
  • Certain springsof the relaysviz. Q6, q'l'; r6, r1; S5, s6 and t4, t are so interconnected that when. the.
  • second group lof a signal in the seven-unit code takes either of the above two forms and consequently the relays Q and S or R and T are energised, the three modifying relays Ma, Mbs, Mc are operated and Athen the test relay' TR., through f its spring trl and front contact l53 connects bat'- tery at 54 through the conductors 5.6 and. 64 to the front contacts 65 of all three. of the modifying relays Ma, Mb, Mc and also applies battery through the conductorlit ⁇ to the said bank. of springs and contacts of therelays Q T, in fact, at the back contact 61. of theL spring t4 and the front contact 68of the spring t5.
  • the test relay TR also 4applies battery to spring-s Q78, 18, s1, and t6 oi the relays. Q T.
  • springs q8, f8, sl, t@ and the springs q9, r9, S8 and t1 of the same four relays and their contacts are so interconnected that whether onlyl one of the receiving relays Q; T is operated, o r whether two of those relays which are adjacent are operated, or whether three of those re.- lays are operated, the result is that only one of four additional relays W, X, Y and Ziis ener;-
  • the' relay Q is regardedv as following the relay T.
  • the relayv W, X, Y or Z which is operated is that corresponding to the. rst vrelay of the operated sequence of the relays Q T when more than onevof the latterjare operated.
  • the above result can. be conrmed by checking the connections of ther springs 18,
  • relay Q only of the four in question 4is ener gised the coresponding additional relayI W- ,willbeenergised from conductor 56.- th-rough conductor 5.9, spring t6, its back contact 1.0, conductor 1l, spring Q9, its front contact: 12, ywinding of, relay W'tor earth.
  • the windings of the relays X, Yand Z have their circuits interrupted at the springs ,79, si), tl' respectively.
  • relay Z isenergised, which is that corresponding to the relay T which is the rst of the'operatedrelays T, Q and R in the sequence as explained above.
  • relay Z is ⁇ energised from the conductor 59, spring s1 and its ⁇ back contact 13, spring t1 and its front contact 14, through' the Winding of relay Z to earth; the circuitof relay W is interrupted at the spring t6, the circuit of relay X is interrupted at the spring q andthe circuit of the relay Y is, of course, interrupted at the spring S8 of the relay S which is not excited.
  • the relays W Z are operated to correspond to the second group of signal elements of the first' series in the seven-unit errord'etecting code.V
  • the test relay TR.' hasv connected battery through conductors 5.5' and 'l5 to the spring wl of the relay'W, and through conductors 56 and'G to the spring y of relayfY, while the springs and 2: of the relays X andl Z are connected* together; further the back contact 7T of the spring wl is connected to the back contact 18 of the spring e; the front contact 'I9 of' thespri'ngr wl and the front contact of the spring y are both directly connected to the fourth segment62 of the trans'- m'itting commutator; the spring w2 of the relay W isi connected to theback contact 8
  • the ve retransmitting segments 59 B3 may be used in conjunction with a preceding segment 90 and a following segment 9
  • battery is applied through the back contact 5I and conductor 52 to an error-indicator in any convenient manner to print an error-indicating signal on the printer normally operated by the signals from the retransmitting segments 59 63.
  • One way of doing this is to make the printer employed selective to the signal consisting of ve spaces which is not used in the standard five-unit code. Then the printer is arranged t print the error-indicating signal when this selection occurs.
  • the ve space signal is sent out by the brush Br4 because until the relay TR is energised, the battery at 54 is not connected to the relays. In such a case, the connection 52 and a separate error-indicating circuit is not required.
  • a Space signal can be retransmitted by providing a second spring tr2, shown in dotted lines, on the test relay TR, which spring has a back contact 92 connected by a conductor 92a to the third retransmitting segment 6 I.
  • the three signals cannot readily be sent under control of iive-unit perforated tape because only 32 different five unit signals are possible but these eXtra signals could be sent by providing switches for connecting the segments Si S1 in Figure l to alternative contact levers which may be controlled manually or otherwise according to requirements.
  • the above signal No. 33 or No. 34 may, for example, be used to give instructions to the sending operator of the return circuit, being sent once, twice or another number of times to convey different meanings such as stop, go ahead or repeat last message. The signal may cause a bell to ring.
  • the spring o4 of the relay O may connect the conductor 93 through a front contact M to a cut-off relay COR, the circuit being from battery at &3, brush BTB, segment 55, spring trl, contact 53, conductor 66 and through springs t4 or t5, S5 or s6,
  • the relay COR at its spring cOr2 and back contact 95 cuts off the tive-unit output from the brush Br4 to the line L and at its front contact 96, connects battery to line to give the stop signal.
  • the relay also at spring corl and front contact S1 connects battery to a bell 9S or other convenient indicator. By connecting battery at contact 96 to the line L, the stop signal is prolonged and continuous running of the printer avoided.
  • the relay CORl with a single spring which could cut oil the output from the brush Br4 to the line L and to connect that out put to a connection to the bell or other indicator.
  • a conductor 99 from the brush Br4 would be connected to the spring of the relay COR, the back Contact of the spring being connected to line L and its front contact to the bell or other indicator circuit.
  • each of these relays on being actuated closes the circuit of a locking winding battery at 6 through spring al ZI and its front contact 5 to a continuous segment 1 and through a brush BTZ to earth at 8.
  • the peckers pass through the perforations in the tape for a suitable period for example, that represented by X in Figure 3.
  • the point I 05 is connected by a conductor
  • the relay L has a spring Z3 with a back ⁇ contact I connected, directly to the transmitting segment S3 and al front contact I I2 connected directly to the transmitting segment S4'.
  • the iirst four units of a signal in the primary code are spaces so thaty the relays A, B, C and D are all degenergised. andy as already explained, under those conditions ⁇ there is a connection from battery at.
  • the relays A, B, C, D are all de energised so that none o f the springs a3, b4, c5 and d6 closes its contact.
  • the rst groupy always consists of four marking units which means that the four relays A, B, C, D are all energised with the vresult that battery at
  • the secondi group of units in the six-unit primary code is converted. into the second group intheeightfunit error-detectingv code in a manner similar to that described. with reference to Table 1' and Figure 1 for by comparison of Tables 1 andi 2 it will be seen that theconversion is preciselythe same in the'y tWocases.
  • the second mark unit to be addeds for'signal's in the second and third series, as compared with signals in theifirst series is introducedy through thepoint
  • the-four additional relays F, G, H and K are conn ected exactly as in Figure 1 so as to be controlled by the springs e2 and e3 of the relay E and by the spring Z2 oi the-relay L.
  • Thespring's fI, f2, andf 3 ofthe relay F, the springs gl, g2 and g3 of the relay G, the springs hI', h2 and h3- of the relay and the springs lcI, 1c2and k3 of the relay K are connected to one another exactlyas in Flgure 1 and4 to the distributor segments S5', S6, S1 and Sa. instead of segments S4, S5, S6 and S1, of course.
  • the point I I4 is connected to the springs fl, gl, hl and la! corresponding precisely to the similar connection in Figure 1.
  • the third mark unit ⁇ has to be added as seen from Table 2, by Way of the point IIIl ⁇ through another rectier Ri, tothe point I.I5.
  • a mark. corresponding tor thisy third4 mark is added in the same way for sig,- nals in the. fourth and fifth series but Without the second mark; itis added by Way of connections from points
  • FIG. 4 A suitable receiving system for the signals produced. as. ldescribed with reference to Figure 3 is illustrated in Figure ⁇ 4.
  • the eight-unit signals are received :by the line relay LR as in Figure 2 and, indeed,r the system is similar to that shown lin A Figure- 2 except that there is a certain; amount of simplification obtained ⁇ by the use of' rectifiers.
  • the spring Z1: of the line relay LR has a. iront marking contact M and aback spacing contact S, and, as in Figure 2, the marking contact M is connected to a brush BTI which sweeps over .eight short segmentsy SRI SRS, making .contact with them in the middle of the respective periods of reception of the eight signal elements.
  • each veight-unit. signal contains four marks unless itv has ,been mutilated, current is passed. through ⁇ the windings of four of eight receiving-l relays-N, lO, P, Q, R, S, T and U, the winding of each relay being. connected to one of the, segments RSI RSS and to earth.
  • the f our relays are yenergised by ,the line relay LR in accordance with ,the number of marks in the receivedA signals with which ⁇ the brush BTI is driven Ain syriclfnfonsrn by any of the usual means.
  • the four relays thus energised are locked Vup through AContact ⁇ springs nl ul ,ea-ch of which is connected' to ltigattery* and through its iront Contact 40' and' a brush Br2 which is'earthed andA werks over a long segment y4I so that the four relays which have :beenenergised are held locked until' the operation of rfa-transmitting the sixcriminels in the primary Code is 'completed- -When ⁇ there are thusl four marks in the re ceived eight-unit signal, neither more nor less, a circuit is completed through the test relay TR.
  • the winding of that relay is connected to battery at 62 by a bank of contacts controlled by springs 11,2; o2, o3; p2, p3, p4; q2, Q3, q, Q5; r2, rt, ril, rfi; s2, s3, sil, S5; 2,125, t4 and uit and a3.
  • This ⁇ bant: of springs is similar to that Dro-- vided in Figure 2 but is modified to suit the eightunit signals and, consequently, it is not necessary to describe these contacts in greater detail although it can be seen by tracing the circuits that battery is connected to the winding of relay TR only when exactly four yof the relays N U are energised.
  • test relay TR when the test relay TR is energis-ed in this way, its spring tr and its back contact 5i disconnect a connection 52 which leads to the circuit of an error-indicator. Connection is made to battery at 5d through brush BTS and a segment 55 but cont-act is only made when the four of the relays N U in question have been locked.
  • test relay TR When the test relay TR is thus energised, it connects battery at 54 through its front contact 53 by way of a conductor 51B inter alia to springs n, o5, p5 and q1. These s-prings, through their front contacts 5l, when energised continue the connection from battery to the first four segments Ii, Hl',
  • the conversion of the last four units of the eight-unit signal into the last two units of the six-unit signal in the primary code is effected in a manner similar to that described with reference to Figure 2 except that in the case of signals in the fourth and fifth series, marking is applied to the sixth retransmitting segment
  • the units in the rst group of the received eight-unit signals are repeated or passed on without change to the retransmitting segments H16,
  • the battery connection to the springs o5, p5 and q1 from the conductor 55 passes through the spring y and back contact
  • the relay Y is operated because, as can be seen from Table 2, in that series, the iirst unit of a signal in the eight-unit code is a space and therefore the spring 115 rests on its back contact
  • the rst unit of the received eight-unit signal is always a mark so that the relay N is energised and as the conductor 85 is connected to battery for al1 these signals for the reason mentioned above, the spring 115 at its front contact
  • the connection to battery at ccnductor is continued through the spring o4, its back contact
  • the signals 61 and 68 are sent by connecting battery at
  • a telegraph system arranged to transmit signals in an error-detecting code all the signals of which consist of the same number of marking and the same number of spacing units, comprising transmitting apparatus arranged to convert signals in a primary equal-length code into signals in said equal-length error-detecting code, said second-mentioned signals consisting of a greater number of units than the signals in said primary code, Said transmitting apparatus comprising means for passing forward and transmitting one group of units in each of at least the majority of the signals in said primary code, as a group of units in said error-detecting code which is the same in marking and spacing permutation as the group in said primary code and means for modifying a second group of units in each signal in said primary code and converting same into a group in said error-detecting code determined by the permutations of both groups of the respective signal in said primary code.
  • a telegraph system in which said modifying means convert a second group in each signal in said primary code containing only two units thus providing four permutations, into groups of units in said error-detecting code containing the necessary marking units to make up the predetermined number of marking units in each signal in said error-detecting code in consideration of the number of marking units in the first group of each signal in said error-detecting code.
  • a telegraph system in which said transmitting apparatus comprises means for -producing signals in said error-detecting code in a number of series, according to which said second groups of units in the signals contain a single marking unit in successive positions, contain a second marking unit in the position follow. ing the first marking unit and also contain a third marking unit in the position following the second marking unit respectively.
  • a telegraph system comprising relays controlled in accordance with the signal units in said primary code and a transmitting commutator connected to said relays so as to receive the first group of units of signals in said primary code unchanged at least for the majority of the signals.
  • a telegraph system comprising means for transmitting an additional series of signals in said primary code and means for converting the first group of each of said additional signals into a form depending upon Whether the last unit of each said signals in the primary code is a marking or a spacing unit and comprising modifying relays controlled by contacts of said relay which is controlled in accordance with the last unit of the signal in said primary code.
  • a telegraph system comprising transmitting apparatus arranged to convert a second group of signal units in said primary code each consisting of two units, into groups each consisting of four units in said errordetecting code, said two relays controlled in accordance with the units of the second groups of units in said primary code being arranged to control four additional relays connected to apply the second group of units in said error-detecting code to the segments of said transmitting commutator.
  • a telegraph system comprising receiving relays with means for applying the signal units in said error-detecting code to said receiving relays in succession, said relays having a bank of interconnected contacts, a testing relay so connected to said bank of contacts that when a received signal contains the predetermined number of marking units, no more and no less, said testing relay is energised through said bank of contacts and only when energised, allows the incoming signal to be set up by connecting battery to the appropriate relay contacts after said receiving relays have all been influenced by said incoming signal units.
  • a telgeraph system comprising receiving relays connected so as to be responsive to the respective units of the incoming signals in said error-detecting code, and a set of additional relays connected to set up the second group of signal units as reconverted into said primary code and also connected to said receiving relays corresponding to the signal units in the second group so as to be controlled thereby.

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  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Probability & Statistics with Applications (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Selective Calling Equipment (AREA)
US50311A 1947-09-22 1948-09-21 Telegraph system with code conversion and error detection Expired - Lifetime US2473202A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB25759/47A GB657751A (en) 1947-09-22 1947-09-22 Improvements relating to code telegraphy

Publications (1)

Publication Number Publication Date
US2473202A true US2473202A (en) 1949-06-14

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ID=10232838

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Application Number Title Priority Date Filing Date
US50311A Expired - Lifetime US2473202A (en) 1947-09-22 1948-09-21 Telegraph system with code conversion and error detection

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Country Link
US (1) US2473202A (xx)
FR (1) FR971845A (xx)
GB (1) GB657751A (xx)
NL (2) NL142399B (xx)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2622148A (en) * 1948-03-15 1952-12-16 Nederlanden Staat Error detector for telegraph printer codes
US2709199A (en) * 1948-03-15 1955-05-24 Nederlanden Staat Code signal converter
US2713084A (en) * 1953-04-17 1955-07-12 Collins Radio Co Odd mark detector

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE534009A (xx) * 1950-11-08

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2622148A (en) * 1948-03-15 1952-12-16 Nederlanden Staat Error detector for telegraph printer codes
US2709199A (en) * 1948-03-15 1955-05-24 Nederlanden Staat Code signal converter
US2713084A (en) * 1953-04-17 1955-07-12 Collins Radio Co Odd mark detector

Also Published As

Publication number Publication date
NL83199C (xx)
NL142399B (nl)
GB657751A (en) 1951-09-26
FR971845A (fr) 1951-01-22

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