1. * GB780001 (A)
Description: GB780001 (A) ? 1957-07-31
Improvements in code converting arrangements for telegraph systems
Description of GB780001 (A)
PATENT SPECIFICATION
780,001 Date of Application and filing Complete Specification: July 9,
1952.
-r [ K S A idNo. 17359/52.
Application made in Netherlands on July 12, 1951.
_____ (Patent of Addition to No. 680,798, dated June 24, 1948).
OkDOI Complete Specification Published: July 31, 1957.
Index at acceptance:-Class 40(3), H15X.
International Classification:-H041.
The inventor of this invention in Ithe sense of being the actual
deviser thereof within the meaning of Section 16 of the Patent Act,
1949, is ANTONIE SNIJDERS, a subject of the Queen of the Netherlands,
of 137 Driebergenstraat, The Hague, Holland.
COMPLETE SPECIFICATION
Improvements in Code Converting Arrangements for Telegraph Systems We,
STAATSBEDRIJF DER POSTERIJEN, TELEGRAFIE EN TELEFONIE, a Public
Department of the Netherlands, of Kortenaerkade 12, The Hague,
Holland, do hereby.declare the invention, for which we pray that a
patent may be granted to us, and the method by which it is to be
performed, to be particularly described in and by the following
statement: -
The invention relates to a code-converter for 'the conversion of
signals of a normal binary code (such as the five-unit code) into
signals of a so-called protected code (e.g., seven units
constant-ratio code) and vice versa. One of the purposes to which such
code conversion is applied is teleprinting over wireless connections.
A well-known protected code is the constant ratio code, the signals of
which have a predetermined number of mark and a predetermined number
of space units, the ratio of these mark and space-units being
constant.

2. The invention more particularly relates to a code-converter for the
conversion of input signals consisting of a predetermined plurality of
it units each represented by a mark or a space potential which are
applied in, this order to the first or second conductor or alternately
and to a succession of n pairs of input conductors dependent on
whether these units have mark or space polarity, into output signals
consisting of a predetermined plurality of s units, of which a
constant number of r units is of equal, either mark or space polarity,
and the remaining s-r units are respectively of space and mark
polarity.
The present applicants' United Kingdom Specification No. 680,798
describes a codeconverter conceived according to the mentioned
principles. This latter arrangement of code-converter, however,
comprises rectifiers and resistors, connected in such way, that five
different voltages may occur at any one central conductor.
[Price 3s. 6d.j This means that the mentioned rectifiers must be able
to withstand these five levels, when in blocking condition. This makes
the rectifiers more expensive than those for use in the arrangements
according to the present invention in which no more than two different
voltage levels occur, which may differ by as much as two successive
levels of the said five ones. Another deficiency of the described
circuit with respect to that according to the present invention is,
that according to the former arrangement the switching voltages
applied to the input side must be of a considerably greater amplitude
than the discriminating voltage values supplied at the output. The use
of switching units of uniform construction within the converter
circuit is made impossible by that circumstance.
On the contrary the converter circuits according to the present
invention offer the advantage, that such uniform switching units can
be provided at different stages of the circuit.
Circuits for switching purposes comprising rectifiers are known from
the Proceedings of the I.R.E 1949, page 139 (Brown and Rochester).
These circuits differ from those according to this invention as
neither central conductors are provided nor input- and' output
rectifiers which have their equal sides (either cathode- or anode
sides) connected at said central conductors. Therefore these circuits
cannot be used for the conversion of codes (in the way mentioned above
and vice Vellsa).
The invention will be described in details with reference to the
accompanying drawings from which:
Fig. 1A shows the wiring-diagram of the uniform switching unit, which
makes part of the converter circuit; Figs. la, b and c show the
exemplary circuit of a code converter for conversion of five-unit code
signals into seven-unit constantratio code signals and vce-versa;

3. Figs. 2a and b show a simplified circuit of a converter for conversion
of five-unit code signals into seven-unit code signals; Figs. 3a and b
show a simplified converter for conversion of seven-unit code signals
into five-unit code signals.
Fig. 1A shows an electronic switching circuit comprising two tubes Bla
and Bib (which constructively may be combined in one unit), of which
tube Bla is controlled via input 7, dependent on which one of the
tubes is conductive. The input 7 is connected to the control grid of
tube Bla via a resistor RiO, so that a grid current of limited value
is enabled to flow. The cathodes of the tubes are connected with the
negative terminal 11 of a voltage source V via a common cathode
resistor R15. The anode of tube Bla is connected to the positive
terminal2 of said voltage source V via anode resistor R1 parallel to
R2.
In the same way the anode of tube Bib is connected to said positive
terminal via paralleled anode resistors R4 and R5. The anode of tube
Bla is moreover connected to negative terminal (11) via a potential
divider R6. Rl.
In the same way the anode of tube Bib is connected via potential
divider R9, R19. The resistors R6 and R9 have the same resistive
values, just as R11 and R19, and said anode resistors have the same
value too. As a result equal jumps in potential (but of opposite
phase) occur responsive to any change in the conductive condition of
the tubes Bla and Bib, which potential levels are available, for
control of rectifier circuits, at terminals 9 and 4.
The anode of the first tube Bla is further connected at negative
battery (terminal 11) via a high-ohmic voltage divider RS, R16, of
which the resistors have the same ratio as those of the potential
divider R6, R11. The anodeofthesecondtube Blbis in a similar way
connected via a high-ohmic potential divider R7, R14. The high-ohmic
potential divider R8, R16 has a tapping point, which leads to the
control grid of tube Bib and via resistor R17 to the stabilizing
conductor (and -output) 6. The high-ohmic potential divider R7, R14
has its tapping point connected at terminal 5, the function of which
will be described hereinafter, and via resistor R13 to said
stabilizing conductor 6.
The potential dividers R6, Ri1 and R9, R19 are also connected -to said
stabilizing conductor 6 via resistors R12 and R18 respectively. The
circuit further comprises two neon tubes L1 and L2, which indicate the
conductive condition of the tubes Bla and Bib, which are connected
thereto with their anodes to said tubes Li and L2, which at the other
side are connected to positive battery (2) via a common high-ohmic
resistor R3.
It is supposed that tube BIa remains in conductive condition, so that

4. its control grid is positive with respect to its cathode; responsive
thereto output 4 supplies a potential that is positive with respect to
that occurring at output 9 as this latter output is connected to the
anode which gets current supplied via resistors R1 and R2. The
potential divider R8, R16 now keeps the control grid of the Bib
negative with respect to cathode, so that this tube is unable to
conduct until the condition of the other tube is changed. As resistors
R12 and R18 have equal resistive values the potential at point 6 will
have a mean value between the potential values which occur at
terminals 4 and 9.
The figures la, lb and lc together represent a code-converter circuit
for conversion of a five-unit binary code into a seven-unit code, the
signals in the latter code having a 3:4 ratio between the mark and
space units. The latter code may be replaced by any other seven-unit
constant-ratio code having at least 32 signals. The above mentioned
seven-unit code by way of example offers:
S, 7! 7c=7C,=- =35 3!.4! output signals, so that 35 -32 3 output
signals remain available for various purposes in the output code
employed.
The rectifiers 35 to 192 are divided into groups IP to V' and Il to V'
and are con- 9' nected to intermediate conductors 1 to 32 and also to
contacts I to V. The latter contacts are connected with the negative
battery 248 via resistors 225 to 234, whereas the contact tongues are
connected to earth potential at 1C point 249. In order to use all
possibilities of the exemplary seven-unit constant-ratio code,
including said three spare signals, extra signals can be converted
which are supplied at the input side by pressing the keys S1 to S3, in
iC a known way.
It has proved to be efficient to have the intermediate conductors I to
32 connected to resistors, which are supplied by a potential source,
the polarity of which depends upon 11 which sides of the rectifiers
are connected at the intermediate conductors. If the rectifiers have
their anode side connected at the intermediate conductor the potential
connected to the resistors must be positive; if the cathode ii side of
the rectifiers is connected, to the intermediate conductor, it must be
negative.
In the circuit shown these resistors are represented by 193 to 224,
which are connected to the earthed positive terminal of the battery 12
via the series connected keys S1 to S3. In Fig. lc. the intermediate
conductors 1 to 32 are in the arrangement according to the invention
connected to outgoing rectifiers, via which the control of the output
conductors 238 is 12 effected.
780,001 780,C The output signal can be scanned in time succession by
supplying to the control grid of tube 246, via the cyclically acting

5. contacts 239 to 245, the signalling potentials occurring at conductors
238, so that in the anode circuit of the tube 246 (which includes the
battery 247) current will flow, dependent upon whether positive
marking signalling potential occurs at any said output conductors 238.
o10 In the following table the conversion of signals according to the
exemplary circuit of figures la, lb and lc is illustrated:
TABLE 1
5-unit code 00000 XOOOO OXOOO XX00O OOXOO XOXOO OXXOO XXXOO OOOXO
XOOXO OXOXO XXOXO 00XXO XOXXO OXXXO XXXXO OOOOXXOOOX OXOOX
XXOOX
OOXOX XOXOX OXXOX XXXOX OOOXX XOOXX OXOXX XXOXX OOXXX XOXXX
OXXXX
XXXXX S1 S2 S3 7-unit code XOOXXXO XXXXOOO OXOOXXX XXOOXOX OOXOXXX
XOXOXOX OOOXXXX XOOXXOX OXXXXOO XOXOOXX OOXXOXX XOXXXOO OXOOXX
XXOXXOO
OXXOOXX XXXOXOO OXXXOXO XOOOXXX OOXXXOX XOXXOXO OXOXXOX
XXOXOXO
OXXOXOX XXXOOXO OXXXOOX XOXOXXO OOXXXXO XOXXOOX OXXXO0 XXOXOOX
OXXOXXO
XXXOOOX XOOXOXX XXOOOXX XXOOXXO The code conversion of the five-unit
code into the seven-unit code is established quite at will; that means
that any signal in the inputcode can be converted into any signal in
the output-code that can be predetermined at will.
If, however, one arranges the code-conversion in such a way, that
certain parts of the signals in the input- and output-code correspond
to each other (e.g. that the first and last unit of such groups are
equal in both codes) as is the case for most signals in Figs. 2a and
2b then 60 a considerable saving in rectifiers can be effected. An
arrangement according to this principle will be elucidated with
reference to Figures 2a and 2b, which show a converter for signals in
a five-unit into signals into a 65 seven-unit code.
The seven-unit code may be considered as a superposition of a two-unit
and a five-unit code, and therefore subdivided into, 22=4 groups of
signals which correspond with signals 70 in the five-unit code.
Because the seven-unit code signals have a ratio 3: 4 with respect to
marks and spaces said four groups of signals will not be fully
identical with the corresponding groups of signals in the five-unit
code. 75 As a result of ithe condition, that a sevenunit signal may
comprise no more than three "i+" units the two-unit code (making part
of this seven-unit code) shows three kinds of signals having two, one
and no '"+" symbols 80 respectively which kinds of signals express the
necessity that the complemental five-unit signals (making part too of
the seven-unit code) must comprise a number of one, two and three "+"
symbols respectively. In that way 85 the partial two-unit code

6. determines (the number of marks and spaces in the complementary
five-unitcode, and the number of signals which are present within each
group having an equal number of marks and spaces. 90 So, if one
considers that within each sevenunit code signal three "+" and four
"-" units are present, it is clear that the group of signals as
determined by the two-unit partial code signal " + +" comprises: 95
C(,-,)= 5 signals The group determined by the two-unit code signal "-
+" comprises:
5C,_2) = 10 signals The group determined by the two-unit code 100
signal " + -" comprises:
5C(-2),= 10 signals The group determined by the two-unit code signal
"- -" comprises:
5r_,) =- 10 signals In the five-unit output code, moreover, five
signals occur having each one " + " unit, ten signals comprising each
two "+" units, and ten signals having each three "+" units. Of the
remaining 7 signals in this latter code five 110 signal comprise four
"+" units, one signal comprises five " +" units and one signal
comprises no. "+" units at all.
Thus the way by which the two-unit code, making part of the seven-unit
code (to be 115 called "indicator code"), determines which group of
signals in the five-unit output code corresponds with the signals in
the seven-unit code from which said indicator-code is taken, is shown
in the following table:
TABLE 2
5-unit output code 2-unit indicator 7-unit input code code 5-unit
remaining code signals comprising:
1 "4-" unit 2 "-+" units 3 "±" units 4 -' units --"+ units 0 "+"
units} accessory signals, if any J It will be clear, that the
indicator signal "+ -" determines that more than the addition of two,
one, no " + " and/or "-" units occurs. In the original five-unit code
one finds at first the signals, comprising four " + " units and one
"-" unit. In order to satisfy the condition, that no more than three "
- " units may be present in the seven-unit code signal, of which one
must occur in the indicator signal, the remaining five-units must
comprise no more than two " + " units. For simplicity's sake it may be
mentioned, that the five-unit signal if considered cyclically, offers
two possibilities; one with "+ - + " and one with " + +", which
correspondIs with "- -" and - --" in the complementary part of the
signal respectively.
In order to simplify the identification the five signals in the
five-unit code signals having four " + " units (in which the one minus
unit occurs in a cyclical permutation) are considered identical with
the five signals in the seven-unit code in which the same combination
occurs. Of the five remaining signals in the seven-unit code using the

7. indicator combination " ±" two signals correspond to the remaining
signals "+ + + + + " and cc " of the five-unit code, whereas the three
remaining signals may be used as extra signals for service purposes.
This method of code conversion, however, is not restricted to the five
to seven conversion, but in general to a conversion of a r-unit
permutation code into a p-unit constant-ratio code, in which the
indicator determines a plurality of 2,-r) groups. If one defines the
ratio between "+" and "-" units so as to be n, to (p -n), than the
first group of signals characterized by the indicator having (p-r)
cc"+" units comprises a number of Cr 'n-p+r) signals. The second group
of signals, characterized by the indicator, having (p - r - 1) " - "
units and one " - " unit comprises a number of Cr (n-p+r+i> signals.
This latter plurality, however, occurs (p - r) times, because the "-"
unit may be cyclically changed within the signal. The number of
signals, existing in signals comprising:
+± 1 1" "unit -+ 2 "+" units _-- 3 "-+" units ± 2 "+" units groups,
characterized by indicators having (p-r-2) "+" units and two "-" units
(p-r)! amounts. Cr rn-p+r+2) (p-r-2)!2! The sum of all possible signal
combinations in such a code thus amounts to (p - r)! C p ' Cs
a--!+r+ThB (p-r-m)!.m! n!. (p-n)! m-0, 1, 2,....
in which m indicates the number of "-" units occurring in the
indicator signal, so that as a matter of fact m 4 p -r.
In practice, however, it will not always be necessary to use all the
indicator signals which are available, and therefore it will be most
economical to use indicator signals which need a smaller number of
rectifiers, as will be made clear hereinafter.
The code-converting circuit according to Figs. 2a and 2b will be
described in detail.
The units of the five-unit code are applied as either mark or space
potential, at the respective inputs (in the drawing at left) of the
five switching elements 1 to 5, which pass the (regenerated) switching
voltage at their right hand upper output terminal, whereas they pass
the inverted value of the applied switching voltage (also regenerated
as regards amplitude) at their left hand upper terminal. These
regenerating and voltage inverting elements are described in more
detail in the copending patent application 37888/56 (Serial No.
780.003) of the present applicants, which is divided from the present
specification. If a switching potential of negative polarity is
applied to the input of a switching element the upper righthand output
terminal of the same becomes negative too, whereas the upper lefthand
terminal supplies a potential of positive polarity. If, on the
contrary, a positive switching voltage is applied, the mentioned
output terminals will change polarity. The output potentials of the
said switching elements are applied to the group of conductors 10, of

8. which the 2nd, 4th to 10th inclusive 780,001 tor must be chosen for
the relevant five-unit signal. For one group of signals the conversion
is not performed in this way. For this group the indicator " + -" is
chosen. For the remainder the corresponding signals in the seven-unit
output code (as regards the relevant five-unit part) and the five-unit
input-code are identical as much as possible.
In case the signal to be converted by way of example is as follows:
"+;+ +.- -," the first, third, fifth, eighth and tenth conductors of
the input conductors supply a positive potential, whereas the second,
fourth, sixth, seventh and ninth conductor supply a negative
potential. The central conductors 11 to 30 are all connected to the
positive battery, so that they all should have positive battery
potential in case space potential should be thought applied at the
conductors 10 (the intermediate conductors 31 to 40 will be neglected
for the moment).
The signal C"+4 + - ±" (by way of example) effects that positive and
negative potentials occur at the various intermediate conductors, in
accordance with the following table:
are complementary to the 1st, 3rd to 9th inclusive.
The converted signals are supplied in principle by the group of
conductors 7, to which the switching elements I to VII are connected,
which form a buffer- and regenerating stage, in order not to influence
the circuit by any output circuit, which might vary in impedance.
The lower connections of the switching elements, as disclosed
hereinbefore represent the stabilizing conductors for obtaining a
fixed reference potential. These terminals are interconnected by being
grounded, as shown in the drawing. The way in which this is arranged
is described in more detail in the copending application No. 37887/56
(Serial No. 780,002) of the present applicants, which is divided from
the present specification.
The five-unit code that is to be converted, is divided into groups of
signals which determine a two-unit signal, to be called the "indicator
signal" as mentioned hereinbefore.
For this purpose each combination of five units representing a signal
must control an intermediate conductor in such a way that the latter
will be able to distinguish which indicaTABLE 3
POTENTIALS RESULTING FROM THE INPUT SIGNAL "q+±---" Intermediate
conductor Negative potential at the nth one of the conductors 10:
Positive potential at the nth one of the conductors 10:
4th, 6th 2nd, 6th 2nd, 4th 2nd, 4th, 6th, 7th 2nd, 4th, 6th, 9th 6th
4th 4th, 6th, 7th 4th, 6th, 9th 2nd 2nd, 6th, 7th 2nd, 6th, 9th 2nd,
4th, 7th 2nd, 4th, 9th 2nd, 4th, 6th, 7th, 9th 7th 9th 7th 9th 6th,
7th, 9th 4th, 7th, 9th 2nd, 7th, 9th 7th, 9th 2nd, 4th, 6th 1st, 8th,
10th 3rd, 8th, 10th 5th, 8th, 10th 10th 8th 1st, 3rd, 8th, 10th 1st,

9. 5th, 8th, 10th 1st, 10th 1st, 8th 3rd, 5th, 8th, 10th 3rd, 10th 3rd,
8th 5th, 10th 5th, 8th 1st 3rd 5th 1st, 3rd, 5th, 10th 1st, 3rd, 5th,
8th 1st, 3rd 1st, 5th 3rd, 5th 1st, 3rd, 5th 8th, 10th 11 12 13 14 16
17 18 19 21 22 23 24 26 27 28 29 31 32 33 34 36 780,001 As made clear
in table 3 the intermediate conductors 11 to 25 and 29 to 37 will be
kept negative, while intermediate conductors 26, 27 and 28 will be
kept positive, because the rectifiers associating with the considered
intermediate conductors are in conducting condition if negative
switching potentials are applied, whilst they are blocking for
positive potentials being applied. Now the third, fourth and fifth
conductor of group 7 will be positive without being influenced by the
intermediate conductors 31 to 36 as the controlling rectifiers block
any negative potential. The 1st, 2nd, 6th and 7th output conductor of
group 7 are kept negative. The switching elements I to VII are now
able to determine the sevenunit signal " - + + - -," which has - - as
an indicator signal.
For every signal to be converted a table may be constructed as table
3. It will appear then, that for five-unit code signals having one " +
" unit, one of the conductors 11 to 15 will be positive (so that the
indicator will be " + + ") and also one of the central conductors 26
to 30, in order to control the five-unit part of the output-signal.
For a signal having two " + " units, one of the intermediate
conductors 16 to 25 becomes positive and two of the central conductors
26 to 30. A signal having three "+" units has been described
hereinabove. The only kinds of signals yet to be described are those
having more than three " + " units and those, comprising no " + "
units at all.
It will be clear that, for the last-mentioned signals, the
intermediate conductors 11 to 25 are all kept negative, whilst the
intermediate conductors 26 to 30 would transmit the input signal to
the five-unit part of the seven-unit output-signal if no special means
were provided to prevent such. By way of example the working of the
circuit for the latter categories of signals will be described for the
signal "c+ + +I -." These latter categories have the indicator signal
+ -." The signal + + + - '," if applied, results in the intermediate
conductor 31 of group 31 to 37 becoming positive, so that the third
and sixth conductor of group 7 will be kept positive, thus controlling
the switching elements III and VI. The intermediate conductors 31 to
37 on the other hand have also a controlling action via the
intermediate conductor 8 with respect to switching element A. This
latter switching element in turn controls the intermediate conductors
26 to 30 and the first output-conductor of group 7. If all
intermediate conductors 31 to 37 are negative, intermediate conductor
8 will be kept negative too, so that the righthand upper output of

10. switching element A will also be kept negative; this latter negative
potential being prevented from reaching the first output conductor 7
as the relevant rectifier is blocking. Meanwhile the left hand upper
output terminal of switching element A will be kept positive. This
positive potential is unable to control intermediate conductors 26 to
30.
In case, however, one of the intermediate conductors 31 to 37 is kept
positive, the right 7 hand upper output of switching element A will
become positive too, and so will the first (left hand) conductor of
group 7. The left hand upper terminal of switching element A will
become negative then, so that inter- 7 mediate conductors 26 to 30 are
also kept negative. Thus the latter conductors are unable to control
the remaining conductors of group 7. The relevant one of the
intermediate conductors 31 to 37 now forms the corres- 8 ponding
five-unit part of the seven-unit output signal that is to be composed.
Again in the code-converting circuit of Figs. 2a and 2b, means are
provided to compose three remaining signals in the seven-unit 8 code.
Just as in the code-converter described hereinbefore the composition
of these signals may be effected by means of keys, whereby the
switching elements 1 to 5 have to be disabled meanwhile. 91 In the
circuit shown in the drawings another method has been followed, making
use of rectifiers and intermediate conductors. For transmittting one
of the three spare signals in this other method, an auxiliary code may
be 9' applied, taking two units, thus offering four signals. Three
signals directly correspond to the three spare signals respectively,
the fourth signal is used to indicate that the normal code conversion
is in operation. If one of the spare 10 signals is to be produced the
normal code conversion has to be prevented. For the auxiliary code two
auxiliary input conductors X and Y are provided, controlling two
switching elements. Generally the number of auxiliary 10 inputs
necessary could be supposed to be p, log p1 and a number of 2. -
conductors will log2 be necessary, in which p1 is a power of 2.
Then p must follow:
2 22 21 1oz2) < p < 2 11 In the exemplary circuit of Figs. 2a and 2h
the auxiliary signal "- -" means that the normal code conversion is
enabled. In this case the intermediate conductor 9 is kept negative
and the upper left- and righthand outputs of 11 switching element B
are unable to control the group of intermediate conductors 11 to 25
and the switching element A respectively. If one of the spare signals
has to be composed, however, one of the auxiliary signals " + -," 121
cc "- + " or + " has to be applied at X and Y. In this latter case
central conductor 9 is kept positive, thus keeping, via switching
element B, the central conductors 11 to 25 and 31 to 37 negative, that
is to say, disabled. 12i Moreover, via the righthand upper output of

11. switching element B, switching element A and 780,001 means of the
output rectifiers the corresponding output signal.
The number of rectifiers saved by using the circuit of figs. 2a and 2b
with respect to that 10 of figs. 1a, lb and lc amounts to:
left hand upper output of the latter the group of intermediate
conductors 26 to 30 are also disabled. The normal code-conversion is
thus disabled. For each of the spare signals indicated in Fig. 2b one
of the intermediate conductors 38 to 40 is enabled, which forms by x 5
= 50 for the group of signals having the indicator "- -" at the
seven-unit side x 1 = 5 for the group of signals having the indicator
" +'+ " at the seven-unit side x 2 = 20 for the group of signals
having the indicator "- + " at the seven-unit side x 1=10 for the
group of signals having the indicator .+ -" at the seven-unit side
Total= 85 rectifiers Furthermore for the group " + -" indicated
signals, 10 extra rectifiers are necessary for determining whether a
signal belonging to this group "(±" is applied, whereas 5 extra
rectifiers 'are needed for controlling central conductors 26 to 30,
and 1 extra rectifier is necessary for determining the indicator part
of the seven-unit signal.
Thus, a total of 85 - 16 = 69 rectifiers can be saved by using the
converter-circuit according to Figs. 2a and 2b. However, an extra
switching element A is necessary.
For controlling the circuit by auxiliary signals, so as to use the
three spare signals in the seven-unit code, requires a plurality of
extra rectifiers up to 8 rectifiers for the necessary extra
intermediate conductors, 22 rectifiers for disabling the remaining
intermediate conductors in case one of the three spare signals has to
be transmitted, a switching element B and one rectifier for
controlling switching element A in accordance with the operation
ofswitching element B. A considerably higher number of rectifiers can
yet be saved when converting a s-unit constant-ratio code into ar-unit
binary code, in case s>r. This will be elucidated for an exemplary
circuit, shown in Figs. 3a and 3b, suitable for conversion from
signals in a sevenunit constant-ratio code into signals in a fiveunit
binary code.
If the described principle should not be applied the number of
rectifiers, necessary for such conversion will amount to Then the
intermediate conductors 11 to 15 have to be disabled by being kept
negative.
Such disabling is not necessary, however, for the group of signals as
specified in table 4:
TABLE 4.
seven-unit code five indicator remaining units + - _+ _+ _ ± _ - + _ _
_-+ _._,+ five-unit code + +'+ + +'+I+ - + 75 j+,++ ++ + -'+ + +

12. -+.+1+ + + +t+ ++ As the five-unit code signals of the group of table
4 have two " + " units more (the last signal three + units more),
these signals can be converted by the addition of these "+" units,
using for this purpose central conductors 1 to 5, and one of the
intermediate conductors 16 to. 21.
The remaining signals, however, have to be converted whilst blocking
the central conductors 11 to 15. The result is, that 5CQ.3 + 5.2 2.4
+5.2 + 5 = 66 C.3 + 25-1.5 = 185, as appears from what is mentioned
hereinbefore.
In case the code is composed according to Figs. 3a and 3b it will not
be necessary to convert the indicator " + +," " - + " and - -,"
whereas the accessory signals can be converted directly via
intermediate conductors 1 to 5 in the corresponding five-unit code
signals. The group having the indicator 's;+ - " has to be selected
on'the contrary.
rectifiers appear to be necessary for the codeconversion, and one
extra switching element.
* Sitemap
* Accessibility
* Legal notice
* Terms of use
* Last updated: 08.04.2015
* Worldwide Database
* 5.8.23.4; 93p